Replace CLI I/O argument duplication with common facilities

- Replace `sq_cli::types::IoArgs` with the more granular
  `sq_cli::types::FileOrStdin`, `sq_cli::types::FileOrCertStore` and
  `sq_cli::types::FileOrStdout`.
- Replace all generic `input` (describing single files) and `output`
  arguments with the respective new facilities to share code and not
  repeat ourselves.
- Replace the `open_or_stdin()` function with `FileOrStdin::open()`.
- Replace the `create_or_stdout()` function with the private
  `FileOrStdout::create()`, so that it can not be called directly.
- Replace the `emit_unstable_cli_warning()`
  and `create_or_stdout_unsafe()` functions with
  `FileOrStdout::create_unsafe()`.
- Replace the `create_or_stdout_safe()` function with
  `FileOrStdout::create_safe()`.
- Replace the `create_or_stdout_pgp()` function with
  `FileOrStdout::create_pgp_safe()`.
- Remove the field `unstable_cli_warning_emitted` from `Config`, as
  it is replaced by the static `UNSTABLE_CLI_WARNING`, which allows for
  tracking whether a warning has been emitted across several instances
  of `FileOrStdout`.

Cargo.toml

@@ -38,7 +38,7 @@ sequoia-net = { version = "0.27", default-features = false }
 anyhow = "1.0.18"
 chrono = "0.4.10"
 # For an MSRV of 1.63: 4.0.32.
-clap = { version = "4", features = ["derive", "env", "wrap_help"] }
+clap = { version = "4", features = ["derive", "env", "string", "wrap_help"] }
 itertools = "0.10"
 once_cell = "1.17"
 sequoia-cert-store = "0.3"
@@ -53,8 +53,9 @@ terminal_size = "0.2.6"
 
 [build-dependencies]
 anyhow = "1.0.18"
+buffered-reader = { version = "1.0.0", default-features = false, features = ["compression-deflate"] }
 # For an MSRV of 1.63: 4.0.32
-clap = { version = "4", features = ["derive", "env", "wrap_help"] }
+clap = { version = "4", features = ["derive", "env", "string", "wrap_help"] }
 # For an MSRV of 1.63: 4.0.7.
 clap_complete = "4"
 # For an MSRV of 1.63: 0.2.6
@@ -64,6 +65,7 @@ sequoia-openpgp = { version = "1.13", default-features = false }
 sequoia-net = { version = "0.27", default-features = false }
 subplot-build = { version = "0.7.0", optional = true }
 cfg-if = "1"
+terminal_size = "0.2.6"
 
 [dev-dependencies]
 subplotlib = "0.7.0"

src/commands/autocrypt.rs

@@ -10,7 +10,6 @@ use sequoia_autocrypt as autocrypt;
 
 use crate::{
     Config,
-    open_or_stdin,
     sq_cli,
 };
 
@@ -19,9 +18,9 @@ pub fn dispatch(config: Config, c: &sq_cli::autocrypt::Command) -> Result<()> {
 
     match &c.subcommand {
         Decode(command) => {
-            let input = open_or_stdin(command.io.input.as_deref())?;
+            let input = command.input.open()?;
-            let mut output = config.create_or_stdout_pgp(
+            let mut output = command.output.create_pgp_safe(
-                command.io.output.as_deref(),
+                config.force,
                 command.binary,
                 armor::Kind::PublicKey,
             )?;
@@ -34,9 +33,8 @@ pub fn dispatch(config: Config, c: &sq_cli::autocrypt::Command) -> Result<()> {
             output.finalize()?;
         }
         EncodeSender(command) => {
-            let input = open_or_stdin(command.io.input.as_deref())?;
+            let input = command.input.open()?;
-            let mut output =
+            let mut output = command.output.create_safe(config.force)?;
-                config.create_or_stdout_safe(command.io.output.as_deref())?;
             let cert = Cert::from_reader(input)?;
             let addr = command.address.clone()
                 .or_else(|| {

src/commands/certify.rs

@@ -150,8 +150,8 @@ pub fn certify(config: Config, c: certify::Command)
 
 
     // And export it.
-    let mut message = config.create_or_stdout_pgp(
+    let mut message = c.output.create_pgp_safe(
-        c.output.as_deref(),
+        config.force,
         c.binary,
         sequoia_openpgp::armor::Kind::PublicKey,
     )?;

src/commands/export.rs

@@ -13,6 +13,7 @@ use sequoia_cert_store as cert_store;
 use cert_store::Store;
 use cert_store::store::UserIDQueryParams;
 
+use crate::sq_cli::types::FileOrStdout;
 use crate::{
     Config,
     print_error_chain,
@@ -76,8 +77,12 @@ pub fn dispatch(config: Config, cmd: export::Command) -> Result<()> {
         return Err(anyhow::anyhow!("Invalid arguments."));
     }
 
-    let mut sink = config.create_or_stdout_pgp(
+    let output = FileOrStdout::default();
-        None, cmd.binary, armor::Kind::PublicKey)?;
+    let mut sink = output.create_pgp_safe(
+        config.force,
+        cmd.binary,
+        armor::Kind::PublicKey,
+    )?;
 
     let mut exported_something = false;
 

src/commands/import.rs

@@ -12,10 +12,8 @@ use sequoia_cert_store as cert_store;
 use cert_store::LazyCert;
 use cert_store::StoreUpdate;
 
-use crate::{
+use crate::sq_cli::types::FileOrStdin;
-    Config,
+use crate::Config;
-    open_or_stdin,
-};
 
 use crate::sq_cli::import;
 
@@ -32,8 +30,7 @@ pub fn dispatch<'store>(mut config: Config<'store>, cmd: import::Command)
 
     let inner = || -> Result<()> {
         for input in inputs.into_iter() {
-            let input = open_or_stdin(
+            let input = FileOrStdin::from(input).open()?;
-                if input == PathBuf::from("-") { None } else { Some(&input) })?;
             let raw_certs = RawCertParser::from_reader(input)?;
 
             let cert_store = config.cert_store_mut_or_else()?;

src/commands/inspect.rs

@@ -25,26 +25,23 @@ use crate::SECONDS_IN_YEAR;
 use crate::SECONDS_IN_DAY;
 
 use crate::sq_cli::inspect;
+use crate::sq_cli::types::FileOrStdout;
 
-pub fn inspect(mut config: Config, c: inspect::Command)
+pub fn inspect(config: Config, c: inspect::Command)
     -> Result<()>
 {
     // sq inspect does not have --output, but commands::inspect does.
     // Work around this mismatch by always creating a stdout output.
-    let output = &mut config.create_or_stdout_unsafe(None)?;
+    let output_type = FileOrStdout::default();
+    let output = &mut output_type.create_unsafe(config.force)?;
 
     let policy = &config.policy;
     let time = Some(config.time);
 
     let print_certifications = c.certifications;
 
-    let input = c.input.as_deref();
+    let input = c.input;
-    let input_name = if let Some(input) = c.input.as_ref() {
+    write!(output, "{}: ", input)?;
-        format!("{}", input.display())
-    } else {
-        "-".to_string()
-    };
-    write!(output, "{}: ", input_name)?;
 
     let mut type_called = false;  // Did we print the type yet?
     let mut encrypted = false;    // Is it an encrypted message?
@@ -56,16 +53,16 @@ pub fn inspect(mut config: Config, c: inspect::Command)
 
     let mut bytes: Vec<u8> = Vec::new();
     let mut ppr = if c.cert.is_empty() {
-        if let Some(input) = input {
+        if let Some(path) = input.inner() {
-            if ! input.exists() &&
+            if ! path.exists() &&
-                format!("{}", input.display()).parse::<KeyHandle>().is_ok() {
+                format!("{}", input).parse::<KeyHandle>().is_ok() {
                 eprintln!("The file {} does not exist, \
                            did you mean \"sq inspect --cert {}\"?",
-                          input.display(), input.display());
+                          input, input);
             }
         }
 
-        openpgp::parse::PacketParser::from_reader(crate::open_or_stdin(input)?)?
+        openpgp::parse::PacketParser::from_reader(input.open()?)?
     } else {
         let cert_store = config.cert_store_or_else()?;
         for cert in c.cert.into_iter() {
@@ -174,7 +171,7 @@ pub fn inspect(mut config: Config, c: inspect::Command)
             writeln!(output, "  Cert: {}", is_cert.unwrap_err())?;
             writeln!(output, "  Keyring: {}", is_keyring.unwrap_err())?;
             writeln!(output)?;
-            writeln!(output, "Hint: Try 'sq packet dump {}'", input_name)?;
+            writeln!(output, "Hint: Try 'sq packet dump {}'", input)?;
         }
     } else {
         unreachable!()

src/commands/key/adopt.rs

@@ -20,12 +20,11 @@ use openpgp::Result;
 use sequoia_openpgp as openpgp;
 
 use crate::decrypt_key;
-use crate::open_or_stdin;
 use crate::sq_cli;
 use crate::Config;
 
 pub fn adopt(config: Config, command: sq_cli::key::AdoptCommand) -> Result<()> {
-    let input = open_or_stdin(command.certificate.as_deref())?;
+    let input = command.certificate.open()?;
     let cert = Cert::from_reader(input)?;
     let mut wanted: Vec<(
         KeyHandle,
@@ -209,7 +208,7 @@ pub fn adopt(config: Config, command: sq_cli::key::AdoptCommand) -> Result<()> {
 
     let cert = cert.clone().insert_packets(packets.clone())?;
 
-    let mut sink = config.create_or_stdout_safe(command.output.as_deref())?;
+    let mut sink = command.output.create_safe(config.force)?;
     if command.binary {
         cert.as_tsk().serialize(&mut sink)?;
     } else {

src/commands/key/attest_certifications.rs

@@ -5,7 +5,6 @@ use openpgp::serialize::Serialize;
 use sequoia_openpgp as openpgp;
 
 use crate::decrypt_key;
-use crate::open_or_stdin;
 use crate::sq_cli;
 use crate::Config;
 
@@ -16,7 +15,7 @@ pub fn attest_certifications(
     // Attest to all certifications?
     let all = !command.none; // All is the default.
 
-    let input = open_or_stdin(command.key.as_deref())?;
+    let input = command.key.open()?;
     let key = Cert::from_reader(input)?;
 
     // Get a signer.
@@ -63,7 +62,7 @@ pub fn attest_certifications(
     // Finally, add the new signatures.
     let key = key.insert_packets(attestation_signatures)?;
 
-    let mut sink = config.create_or_stdout_safe(command.output.as_deref())?;
+    let mut sink = command.output.create_safe(config.force)?;
     if command.binary {
         key.as_tsk().serialize(&mut sink)?;
     } else {

src/commands/key/extract_cert.rs

@@ -4,7 +4,6 @@ use openpgp::Cert;
 use openpgp::Result;
 use sequoia_openpgp as openpgp;
 
-use crate::open_or_stdin;
 use crate::sq_cli;
 use crate::Config;
 
@@ -12,9 +11,8 @@ pub fn extract_cert(
     config: Config,
     command: sq_cli::key::ExtractCertCommand,
 ) -> Result<()> {
-    let input = open_or_stdin(command.io.input.as_deref())?;
+    let input = command.input.open()?;
-    let mut output =
+    let mut output = command.output.create_safe(config.force)?;
-        config.create_or_stdout_safe(command.io.output.as_deref())?;
 
     let cert = Cert::from_reader(input)?;
     if command.binary {

src/commands/key/generate.rs

@@ -14,6 +14,7 @@ use sequoia_openpgp as openpgp;
 
 use crate::sq_cli;
 use crate::Config;
+use crate::sq_cli::types::FileOrStdout;
 
 pub fn generate(
     config: Config,
@@ -123,7 +124,7 @@ pub fn generate(
     let (cert, rev) = builder.generate()?;
 
     // Export
-    if let Some(key_path) = command.export.as_ref() {
+    if let Some(key_path) = command.export {
         if &format!("{}", key_path.display()) == "-"
             && command.rev_cert.is_none()
         {
@@ -132,10 +133,12 @@ pub fn generate(
             ))
         }
 
+        let key_path = FileOrStdout::from(key_path);
+
         let rev_path = if command.rev_cert.is_some() {
-            command.rev_cert
+            FileOrStdout::new(command.rev_cert)
         } else {
-            Some(PathBuf::from(format!("{}.rev", key_path.display())))
+            FileOrStdout::from(PathBuf::from(format!("{}.rev", key_path)))
         };
 
         let headers = cert.armor_headers();
@@ -147,7 +150,7 @@ pub fn generate(
                 .map(|value| ("Comment", value.as_str()))
                 .collect();
 
-            let w = config.create_or_stdout_safe(Some(key_path))?;
+            let w = key_path.create_safe(config.force)?;
             let mut w = Writer::with_headers(w, Kind::SecretKey, headers)?;
             cert.as_tsk().serialize(&mut w)?;
             w.finalize()?;
@@ -161,7 +164,7 @@ pub fn generate(
                 .collect();
             headers.insert(0, ("Comment", "Revocation certificate for"));
 
-            let w = config.create_or_stdout_safe(rev_path.as_deref())?;
+            let w = rev_path.create_safe(config.force)?;
             let mut w = Writer::with_headers(w, Kind::Signature, headers)?;
             Packet::Signature(rev).serialize(&mut w)?;
             w.finalize()?;

src/commands/key/password.rs

@@ -8,7 +8,6 @@ use openpgp::Result;
 use sequoia_openpgp as openpgp;
 
 use crate::decrypt_key;
-use crate::open_or_stdin;
 use crate::sq_cli;
 use crate::Config;
 
@@ -16,7 +15,7 @@ pub fn password(
     config: Config,
     command: sq_cli::key::PasswordCommand,
 ) -> Result<()> {
-    let input = open_or_stdin(command.io.input.as_deref())?;
+    let input = command.input.open()?;
     let key = Cert::from_reader(input)?;
 
     if !key.is_tsk() {
@@ -82,8 +81,7 @@ pub fn password(
         key = key.insert_packets(encrypted)?;
     }
 
-    let mut output =
+    let mut output = command.output.create_safe(config.force)?;
-        config.create_or_stdout_safe(command.io.output.as_deref())?;
     if command.binary {
         key.as_tsk().serialize(&mut output)?;
     } else {

src/commands/key/subkey.rs

@@ -9,7 +9,6 @@ use openpgp::Cert;
 use openpgp::Result;
 use sequoia_openpgp as openpgp;
 
-use crate::open_or_stdin;
 use crate::sq_cli::key::EncryptPurpose;
 use crate::sq_cli::key::SubkeyCommand;
 use crate::sq_cli::key::SubkeyAddCommand;
@@ -32,7 +31,7 @@ fn subkey_add(
     config: Config,
     command: SubkeyAddCommand,
 ) -> Result<()> {
-    let input = open_or_stdin(command.io.input.as_deref())?;
+    let input = command.input.open()?;
     let cert = Cert::from_reader(input)?;
     let valid_cert = cert.with_policy(&config.policy, config.time)?;
 
@@ -59,8 +58,7 @@ fn subkey_add(
         .set_key_validity_period(validity)?
         .attach_cert()?;
 
-    let mut sink =
+    let mut sink = command.output.create_safe(config.force)?;
-        config.create_or_stdout_safe(command.io.output.as_deref())?;
     if command.binary {
         new_cert.as_tsk().serialize(&mut sink)?;
     } else {

src/commands/key/userid.rs

@@ -19,7 +19,6 @@ use openpgp::Result;
 use sequoia_openpgp as openpgp;
 
 use crate::commands::get_primary_keys;
-use crate::open_or_stdin;
 use crate::sq_cli;
 use crate::Config;
 
@@ -39,7 +38,7 @@ fn userid_add(
     config: Config,
     command: sq_cli::key::UseridAddCommand,
 ) -> Result<()> {
-    let input = open_or_stdin(command.io.input.as_deref())?;
+    let input = command.input.open()?;
     let key = Cert::from_reader(input)?;
 
     // Fail if any of the User IDs to add already exist in the ValidCert
@@ -183,8 +182,7 @@ fn userid_add(
     // Merge additional User IDs into key
     let cert = key.insert_packets(add)?;
 
-    let mut sink =
+    let mut sink = command.output.create_safe(config.force)?;
-        config.create_or_stdout_safe(command.io.output.as_deref())?;
     if command.binary {
         cert.as_tsk().serialize(&mut sink)?;
     } else {
@@ -197,7 +195,7 @@ fn userid_strip(
     config: Config,
     command: sq_cli::key::UseridStripCommand,
 ) -> Result<()> {
-    let input = open_or_stdin(command.io.input.as_deref())?;
+    let input = command.input.open()?;
     let key = Cert::from_reader(input)?;
 
     let orig_cert_valid = key.with_policy(&config.policy, None).is_ok();
@@ -238,8 +236,7 @@ signatures on other User IDs to make the key valid again.",
         }
     }
 
-    let mut sink =
+    let mut sink = command.output.create_safe(config.force)?;
-        config.create_or_stdout_safe(command.io.output.as_deref())?;
     if command.binary {
         cert.as_tsk().serialize(&mut sink)?;
     } else {

src/commands/keyring.rs

@@ -30,7 +30,6 @@ use openpgp::{
 use crate::{
     Config,
     Model,
-    open_or_stdin,
     output::KeyringListItem,
 };
 
@@ -138,10 +137,11 @@ pub fn dispatch(config: Config, c: keyring::Command) -> Result<()> {
             // better to use Kind::SecretKey here.  However, this
             // requires buffering all certs, which has its own
             // problems.
-            let mut output =
+            let mut output = command.output.create_pgp_safe(
-                config.create_or_stdout_pgp(command.output.as_deref(),
+                config.force,
                 command.binary,
-                                            armor::Kind::PublicKey)?;
+                armor::Kind::PublicKey,
+            )?;
             filter(&command.input, &mut output, filter_fn, to_certificate)?;
             output.finalize()
         },
@@ -151,35 +151,38 @@ pub fn dispatch(config: Config, c: keyring::Command) -> Result<()> {
             // better to use Kind::SecretKey here.  However, this
             // requires buffering all certs, which has its own
             // problems.
-            let mut output =
+            let mut output = c.output.create_pgp_safe(
-                config.create_or_stdout_pgp(c.output.as_deref(),
+                config.force,
                 c.binary,
-                                            armor::Kind::PublicKey)?;
+                armor::Kind::PublicKey,
+            )?;
             filter(&c.input, &mut output, Some, false)?;
             output.finalize()
         },
         Merge(c) => {
-            let mut output =
+            let mut output = c.output.create_pgp_safe(
-                config.create_or_stdout_pgp(c.output.as_deref(),
+                config.force,
                 c.binary,
-                                            armor::Kind::PublicKey)?;
+                armor::Kind::PublicKey,
+            )?;
             merge(&c.input, &mut output)?;
             output.finalize()
         },
         List(c) => {
-            let mut input = open_or_stdin(c.input.as_deref())?;
+            let mut input = c.input.open()?;
             list(config, &mut input, c.all_userids)
         },
         Split(c) => {
-            let mut input = open_or_stdin(c.input.as_deref())?;
+            let mut input = c.input.open()?;
             let prefix =
             // The prefix is either specified explicitly...
                 c.prefix.unwrap_or(
                     // ... or we derive it from the input file...
-                    c.input.and_then(|i| {
+                    c.input.and_then(|x| {
-                        let p = PathBuf::from(i);
                         // (but only use the filename)
-                        p.file_name().map(|f| String::from(f.to_string_lossy()))
+                        x.file_name().map(|f|
+                            String::from(f.to_string_lossy())
+                        )
                     })
                     // ... or we use a generic prefix...
                         .unwrap_or_else(|| String::from("output"))

src/commands/mod.rs

@@ -4,7 +4,6 @@ use std::cmp::Ordering;
 use std::collections::{HashMap, HashSet};
 use std::fs::File;
 use std::io::{self, Write};
-use std::path::Path;
 use std::time::SystemTime;
 
 use sequoia_net::pks;
@@ -39,6 +38,7 @@ use cert_store::Store;
 
 use sequoia_wot::store::Store as _;
 
+use crate::sq_cli::types::FileOrStdout;
 use crate::{
     Config,
 };
@@ -946,25 +946,20 @@ pub fn join(config: Config, c: packet::JoinCommand) -> Result<()> {
     let kind = c.kind.into();
     let output = c.output;
     let mut sink = if c.binary {
-            // TODO: Does this mean kind is silently ignored if binary is given?
         // No need for any auto-detection.
-            Some(config.create_or_stdout_pgp(output.as_deref(),
+        Some(output.create_pgp_safe(config.force, true, armor::Kind::File)?)
-                                             true, // Binary.
-                                             armor::Kind::File)?)
     } else if let Some(kind) = kind {
-            Some(config.create_or_stdout_pgp(output.as_deref(),
+        Some(output.create_pgp_safe(config.force, false, kind)?)
-                                             false, // Armored.
-                                             kind)?)
     } else {
         None // Defer.
     };
 
     /// Writes a bit-accurate copy of all top-level packets in PPR to
     /// OUTPUT.
-    fn copy(config: &Config,
+    fn copy<'a, 'b>(config: &Config,
             mut ppr: PacketParserResult,
-            output: Option<&Path>,
+            output: &'a FileOrStdout,
-            sink: &mut Option<Message>)
+            sink: &'b mut Option<Message<'a>>)
             -> Result<()> {
         while let PacketParserResult::Some(pp) = ppr {
             if sink.is_none() {
@@ -978,9 +973,9 @@ pub fn join(config: Config, c: packet::JoinCommand) -> Result<()> {
                     _ => armor::Kind::File,
                 };
 
-                *sink = Some(config.create_or_stdout_pgp(output,
+                *sink = Some(
-                                                         false, // Armored.
+                    output.create_pgp_safe(config.force, false, kind)?
-                                                         kind)?);
+                );
             }
 
             // We (ab)use the mapping feature to create byte-accurate
@@ -1000,13 +995,13 @@ pub fn join(config: Config, c: packet::JoinCommand) -> Result<()> {
             let ppr =
                 openpgp::parse::PacketParserBuilder::from_file(name)?
                 .map(true).build()?;
-            copy(&config, ppr, output.as_deref(), &mut sink)?;
+            copy(&config, ppr, &output, &mut sink)?;
         }
     } else {
         let ppr =
             openpgp::parse::PacketParserBuilder::from_reader(io::stdin())?
             .map(true).build()?;
-        copy(&config, ppr, output.as_deref(), &mut sink)?;
+        copy(&config, ppr, &output, &mut sink)?;
     }
 
     sink.unwrap().finalize()?;

src/commands/net.rs

@@ -42,13 +42,13 @@ use crate::{
     },
     Config,
     Model,
-    open_or_stdin,
     serialize_keyring,
     output::WkdUrlVariant,
     print_error_chain,
 };
 
 use crate::sq_cli;
+use crate::sq_cli::types::FileOrStdout;
 
 const NP: NullPolicy = NullPolicy::new();
 
@@ -409,9 +409,9 @@ pub fn dispatch_keyserver(mut config: Config, c: sq_cli::keyserver::Command)
                 let cert = rt.block_on(ks.get(handle))
                     .context("Failed to retrieve cert")?;
 
-                if let Some(output) = c.output {
+                if c.output.path().is_some() {
-                    let mut output =
+                    let mut output = FileOrStdout::from(c.output)
-                        config.create_or_stdout_safe(Some(&output))?;
+                        .create_safe(config.force)?;
                     if !c.binary {
                         cert.armored().serialize(&mut output)
                     } else {
@@ -432,9 +432,9 @@ pub fn dispatch_keyserver(mut config: Config, c: sq_cli::keyserver::Command)
                 let certs = rt.block_on(ks.search(addr))
                     .context("Failed to retrieve certs")?;
 
-                if let Some(output) = c.output {
+                if c.output.path().is_some() {
-                    let mut output =
+                    let mut output = FileOrStdout::from(c.output)
-                        config.create_or_stdout_safe(Some(&output))?;
+                        .create_safe(config.force)?;
                     serialize_keyring(&mut output, &certs, c.binary)?;
                 } else {
                     let certs = if let Some((ca_filename, ca_userid)) = ca() {
@@ -454,7 +454,7 @@ pub fn dispatch_keyserver(mut config: Config, c: sq_cli::keyserver::Command)
             }
         },
         Send(c) => {
-            let mut input = open_or_stdin(c.input.as_deref())?;
+            let mut input = c.input.open()?;
             let cert = Cert::from_reader(&mut input).
                 context("Malformed key")?;
 
@@ -514,9 +514,9 @@ pub fn dispatch_wkd(mut config: Config, c: sq_cli::wkd::Command) -> Result<()> {
             // ```
             // But to keep the parallelism with `store export` and `keyserver get`,
             // The output is armored if not `--binary` option is given.
-            if let Some(output) = c.output {
+            if c.output.path().is_some() {
-                let mut output =
+                let mut output = FileOrStdout::from(c.output)
-                    config.create_or_stdout_safe(Some(&output))?;
+                    .create_safe(config.force)?;
                 serialize_keyring(&mut output, &certs, c.binary)?;
             } else {
                 let certs = certify_downloads(
@@ -528,7 +528,7 @@ pub fn dispatch_wkd(mut config: Config, c: sq_cli::wkd::Command) -> Result<()> {
         Generate(c) => {
             let domain = c.domain;
             let skip = c.skip;
-            let f = open_or_stdin(c.input.as_deref())?;
+            let f = c.input.open()?;
             let base_path = c.base_directory;
             let variant = if c.direct_method {
                 wkd::Variant::Direct
@@ -587,9 +587,9 @@ pub fn dispatch_dane(mut config: Config, c: sq_cli::dane::Command) -> Result<()>
             // Because it might be created a WkdServer struct, not
             // doing it for now.
             let certs = rt.block_on(dane::get(&email_address))?;
-            if let Some(output) = c.output {
+            if c.output.path().is_some() {
-                let mut output =
+                let mut output = FileOrStdout::from(c.output)
-                    config.create_or_stdout_safe(Some(&output))?;
+                    .create_safe(config.force)?;
                 serialize_keyring(&mut output, &certs, c.binary)?;
             } else {
                 let certs = certify_downloads(

src/commands/revoke.rs

@@ -15,11 +15,12 @@ use openpgp::Result;
 use openpgp::serialize::Serialize;
 use openpgp::types::KeyFlags;
 use openpgp::types::ReasonForRevocation;
+use crate::sq_cli::types::FileOrStdin;
+use crate::sq_cli::types::FileOrStdout;
 use crate::{
     commands::cert_stub,
     Config,
     load_certs,
-    open_or_stdin,
     parse_notations,
 };
 
@@ -147,7 +148,7 @@ pub fn revoke_userid(config: Config, c: revoke::UseridCommand) -> Result<()> {
 
 /// Parse the cert from input and ensure it is only one cert.
 fn read_cert(input: Option<&Path>) -> Result<Cert> {
-    let input = open_or_stdin(input)?;
+    let input = FileOrStdin::from(input).open()?;
 
     let cert = CertParser::from_reader(input)?.collect::<Vec<_>>();
     let cert = match cert.len() {
@@ -182,7 +183,8 @@ fn revoke(config: Config,
           notations: &[(bool, NotationData)])
     -> Result<()>
 {
-    let mut output = config.create_or_stdout_safe(None)?;
+    let output_type = FileOrStdout::default();
+    let mut output = output_type.create_safe(config.force)?;
 
     let (secret, mut signer) = if let Some(secret) = secret.as_ref() {
         if let Ok(keys) = super::get_certification_keys(

src/commands/sign.rs

@@ -1,7 +1,6 @@
 use anyhow::Context as _;
 use std::fs;
 use std::io;
-use std::path::Path;
 use std::path::PathBuf;
 use std::time::SystemTime;
 use tempfile::NamedTempFile;
@@ -20,6 +19,7 @@ use openpgp::serialize::stream::{
     Message, Armorer, Signer, LiteralWriter,
 };
 use openpgp::types::SignatureType;
+use crate::sq_cli::types::FileOrStdout;
 use crate::{
     Config,
 };
@@ -28,7 +28,7 @@ pub struct SignOpts<'a, 'certdb> {
     pub config: Config<'certdb>,
     pub private_key_store: Option<&'a str>,
     pub input: &'a mut (dyn io::Read + Sync + Send),
-    pub output_path: Option<&'a Path>,
+    pub output_path: &'a FileOrStdout,
     pub secrets: Vec<openpgp::Cert>,
     pub detached: bool,
     pub binary: bool,
@@ -61,11 +61,12 @@ fn sign_data(opts: SignOpts) -> Result<()> {
         notations, ..} = opts;
     let (mut output, prepend_sigs, tmp_path):
     (Box<dyn io::Write + Sync + Send>, Vec<Signature>, Option<PathBuf>) =
-        if detached && append && output_path.is_some() {
+        if detached && append && output_path.path().is_some() {
+            let output_path = output_path.path().unwrap();
             // First, read the existing signatures.
             let mut sigs = Vec::new();
             let mut ppr =
-                openpgp::parse::PacketParser::from_file(output_path.unwrap())?;
+                openpgp::parse::PacketParser::from_file(output_path)?;
 
             while let PacketParserResult::Some(pp) = ppr {
                 let (packet, ppr_tmp) = pp.recurse()?;
@@ -84,12 +85,12 @@ fn sign_data(opts: SignOpts) -> Result<()> {
             // successful with adding our signature(s), we rename the
             // file replacing the old one.
             let tmp_file = NamedTempFile::new_in(
-                PathBuf::from(output_path.unwrap()).parent()
+                PathBuf::from(output_path).parent()
                     .unwrap_or(&PathBuf::from(".")))?;
             let tmp_path = tmp_file.path().into();
             (Box::new(tmp_file), sigs, Some(tmp_path))
         } else {
-            (config.create_or_stdout_safe(output_path)?, Vec::new(), None)
+            (output_path.create_safe(config.force)?, Vec::new(), None)
         };
 
     let mut keypairs = super::get_signing_keys(
@@ -159,17 +160,20 @@ fn sign_data(opts: SignOpts) -> Result<()> {
 
     if let Some(path) = tmp_path {
         // Atomically replace the old file.
-        fs::rename(path,
+        fs::rename(
-                   output_path.expect("must be Some if tmp_path is Some"))?;
+            path,
+            output_path.path().expect("must be Some if tmp_path is Some"),
+        )?;
     }
     Ok(())
 }
 
 fn sign_message(opts: SignOpts) -> Result<()> {
-    let mut output =
+    let mut output = opts.output_path.create_pgp_safe(
-        opts.config.create_or_stdout_pgp(opts.output_path,
+        opts.config.force,
         opts.binary,
-                                    armor::Kind::Message)?;
+        armor::Kind::Message,
+    )?;
     sign_message_(opts, &mut output)?;
     output.finalize()?;
     Ok(())

src/sq.rs

@@ -7,10 +7,10 @@
 #![doc = include_str!(concat!(env!("OUT_DIR"), "/sq-usage.md"))]
 
 use anyhow::Context as _;
+use sq_cli::types::FileOrStdin;
 
 use std::borrow::Borrow;
 use std::borrow::Cow;
-use std::fs::OpenOptions;
 use std::io;
 use std::io::Write;
 use std::path::{Path, PathBuf};
@@ -21,7 +21,7 @@ use once_cell::unsync::OnceCell;
 
 use terminal_size::terminal_size;
 
-use buffered_reader::{BufferedReader, Dup, File, Generic, Limitor};
+use buffered_reader::{BufferedReader, Dup, File, Limitor};
 use sequoia_openpgp as openpgp;
 
 use openpgp::{
@@ -36,7 +36,7 @@ use openpgp::packet::prelude::*;
 use openpgp::parse::{Parse, PacketParser, PacketParserResult};
 use openpgp::packet::signature::subpacket::NotationData;
 use openpgp::packet::signature::subpacket::NotationDataFlags;
-use openpgp::serialize::{Serialize, stream::{Message, Armorer}};
+use openpgp::serialize::Serialize;
 use openpgp::cert::prelude::*;
 use openpgp::policy::StandardPolicy as P;
 use openpgp::serialize::SerializeInto;
@@ -70,17 +70,6 @@ mod commands;
 pub mod output;
 pub use output::{wkd::WkdUrlVariant, Model, OutputFormat, OutputVersion};
 
-
-fn open_or_stdin(f: Option<&Path>)
-                 -> Result<Box<dyn BufferedReader<()>>> {
-    match f {
-        Some(f) => Ok(Box::new(
-            File::open(f)
-                .with_context(|| format!("Failed to open {}", f.display()))?)),
-        None => Ok(Box::new(Generic::new(io::stdin(), None))),
-    }
-}
-
 /// Loads one TSK from every given file.
 fn load_keys<'a, I>(files: I) -> openpgp::Result<Vec<Cert>>
     where I: Iterator<Item=&'a Path>
@@ -250,37 +239,12 @@ fn help_warning(arg: &str) {
     }
 }
 
-/// Prints a warning if sq is run in a non-interactive setting without
-/// a terminal.
-///
-/// Detecting non-interactive use is done using a heuristic.
-fn emit_unstable_cli_warning() {
-    if terminal_size().is_some() {
-        // stdout is connected to a terminal, assume interactive use.
-        return;
-    }
-
-    // For bash shells, we can use a very simple heuristic.  We simply
-    // look at whether the COLUMNS variable is defined in our
-    // environment.
-    if std::env::var_os("COLUMNS").is_some() {
-        // Heuristic detected interactive use.
-        return;
-    }
-
-    eprintln!("\nWARNING: sq does not have a stable CLI interface.  \
-               Use with caution in scripts.\n");
-}
-
 pub struct Config<'a> {
     force: bool,
     output_format: OutputFormat,
     output_version: Option<OutputVersion>,
     policy: P<'a>,
     time: SystemTime,
-    /// Have we emitted the warning yet?
-    unstable_cli_warning_emitted: bool,
-
     // --no-cert-store
     no_rw_cert_store: bool,
     cert_store_path: Option<PathBuf>,
@@ -297,73 +261,6 @@ pub struct Config<'a> {
 }
 
 impl<'store> Config<'store> {
-    /// Opens the file (or stdout) for writing data that is safe for
-    /// non-interactive use.
-    ///
-    /// This is suitable for any kind of OpenPGP data, or decrypted or
-    /// authenticated payloads.
-    fn create_or_stdout_safe(&self, f: Option<&Path>)
-                             -> Result<Box<dyn io::Write + Sync + Send>> {
-        Config::create_or_stdout(f, self.force)
-    }
-
-    /// Opens the file (or stdout) for writing data that is NOT safe
-    /// for non-interactive use.
-    ///
-    /// If our heuristic detects non-interactive use, we will emit a
-    /// warning.
-    fn create_or_stdout_unsafe(&mut self, f: Option<&Path>)
-                               -> Result<Box<dyn io::Write + Sync + Send>> {
-        if ! self.unstable_cli_warning_emitted {
-            emit_unstable_cli_warning();
-            self.unstable_cli_warning_emitted = true;
-        }
-        Config::create_or_stdout(f, self.force)
-    }
-
-    /// Opens the file (or stdout) for writing data that is safe for
-    /// non-interactive use because it is an OpenPGP data stream.
-    fn create_or_stdout_pgp<'a>(&self, f: Option<&Path>,
-                                binary: bool, kind: armor::Kind)
-                                -> Result<Message<'a>> {
-        let sink = self.create_or_stdout_safe(f)?;
-        let mut message = Message::new(sink);
-        if ! binary {
-            message = Armorer::new(message).kind(kind).build()?;
-        }
-        Ok(message)
-    }
-
-    /// Helper function, do not use directly. Instead, use create_or_stdout_safe
-    /// or create_or_stdout_unsafe.
-    fn create_or_stdout(
-        f: Option<&Path>,
-        force: bool,
-    ) -> Result<Box<dyn io::Write + Sync + Send>> {
-        match f {
-            None => Ok(Box::new(io::stdout())),
-            Some(p) if p == Path::new("-") => Ok(Box::new(io::stdout())),
-            Some(f) => {
-                if !f.exists() || force {
-                    Ok(Box::new(
-                        OpenOptions::new()
-                            .write(true)
-                            .truncate(true)
-                            .create(true)
-                            .open(f)
-                            .context("Failed to create output file")?,
-                    ))
-                } else {
-                    Err(anyhow::anyhow!(format!(
-                        "File {:?} exists, use \"sq --force ...\" to \
-                                overwrite",
-                        f.display()
-                    )))
-                }
-            }
-        }
-    }
-
     /// Returns the cert store's base directory, if it is enabled.
     fn cert_store_base(&self) -> Option<PathBuf> {
         if self.no_rw_cert_store {
@@ -1118,13 +1015,12 @@ fn main() -> Result<()> {
         None
     };
 
-    let mut config = Config {
+    let config = Config {
         force,
         output_format,
         output_version,
         policy: policy.clone(),
         time,
-        unstable_cli_warning_emitted: false,
         no_rw_cert_store: c.no_cert_store,
         cert_store_path: c.cert_store.clone(),
         pep_cert_store_path: c.pep_cert_store.clone(),
@@ -1147,9 +1043,8 @@ fn main() -> Result<()> {
 
         SqSubcommands::Decrypt(command) => {
 
-            let mut input = open_or_stdin(command.io.input.as_deref())?;
+            let mut input = command.input.open()?;
-            let mut output =
+            let mut output = command.output.create_safe(config.force)?;
-                config.create_or_stdout_safe(command.io.output.as_deref())?;
 
             let certs = load_certs(
                 command.sender_cert_file.iter().map(|s| s.as_ref()),
@@ -1197,10 +1092,10 @@ fn main() -> Result<()> {
             recipients.extend(
                 config.lookup_by_userid(&command.recipients_userid, false)
                     .context("--recipient-userid")?);
-            let mut input = open_or_stdin(command.io.input.as_deref())?;
+            let mut input = command.input.open()?;
 
-            let output = config.create_or_stdout_pgp(
+            let output = command.output.create_pgp_safe(
-                command.io.output.as_deref(),
+                config.force,
                 command.binary,
                 armor::Kind::Message,
             )?;
@@ -1224,8 +1119,8 @@ fn main() -> Result<()> {
             })?;
         },
         SqSubcommands::Sign(command) => {
-            let mut input = open_or_stdin(command.io.input.as_deref())?;
+            let mut input = command.input.open()?;
-            let output = command.io.output.as_deref();
+            let output = &command.output;
             let detached = command.detached;
             let binary = command.binary;
             let append = command.append;
@@ -1238,12 +1133,16 @@ fn main() -> Result<()> {
             let notations = parse_notations(command.notation)?;
 
             if let Some(merge) = command.merge {
-                let output = config.create_or_stdout_pgp(output, binary,
+                let output = output.create_pgp_safe(
-                                                         armor::Kind::Message)?;
+                    config.force,
-                let mut input2 = open_or_stdin(Some(&merge))?;
+                    binary,
+                    armor::Kind::Message,
+                )?;
+                let data: FileOrStdin = merge.into();
+                let mut input2 = data.open()?;
                 commands::merge_signatures(&mut input, &mut input2, output)?;
             } else if command.clearsign {
-                let output = config.create_or_stdout_safe(output)?;
+                let output = output.create_safe(config.force)?;
                 commands::sign::clearsign(config, private_key_store, input, output, secrets,
                                           time, &notations)?;
             } else {
@@ -1263,10 +1162,8 @@ fn main() -> Result<()> {
             }
         },
         SqSubcommands::Verify(command) => {
-            // TODO: Fix interface of open_or_stdin, create_or_stdout_safe, etc.
+            let mut input = command.input.open()?;
-            let mut input = open_or_stdin(command.io.input.as_deref())?;
+            let mut output = command.output.create_safe(config.force)?;
-            let mut output =
-                config.create_or_stdout_safe(command.io.output.as_deref())?;
             let mut detached = if let Some(f) = command.detached {
                 Some(File::open(f)?)
             } else {
@@ -1289,7 +1186,7 @@ fn main() -> Result<()> {
 
         // TODO: Extract body to commands/armor.rs
         SqSubcommands::Armor(command) => {
-            let input = open_or_stdin(command.io.input.as_deref())?;
+            let input = command.input.open()?;
             let mut want_kind: Option<armor::Kind> = command.kind.into();
 
             // Peek at the data.  If it looks like it is armored
@@ -1308,8 +1205,7 @@ fn main() -> Result<()> {
                 && (want_kind.is_none() || want_kind == have_kind)
             {
                 // It is already armored and has the correct kind.
-                let mut output =
+                let mut output = command.output.create_safe(c.force)?;
-                    config.create_or_stdout_safe(command.io.output.as_deref())?;
                 io::copy(&mut input, &mut output)?;
                 return Ok(());
             }
@@ -1324,8 +1220,7 @@ fn main() -> Result<()> {
             let want_kind = want_kind.expect("given or detected");
 
             let mut output =
-                config.create_or_stdout_pgp(command.io.output.as_deref(),
+                command.output.create_pgp_safe(config.force, false, want_kind)?;
-                                            false, want_kind)?;
 
             if already_armored {
                 // Dearmor and copy to change the type.
@@ -1339,9 +1234,8 @@ fn main() -> Result<()> {
             output.finalize()?;
         },
         SqSubcommands::Dearmor(command) => {
-            let mut input = open_or_stdin(command.io.input.as_deref())?;
+            let mut input = command.input.open()?;
-            let mut output =
+            let mut output = command.output.create_safe(config.force)?;
-                config.create_or_stdout_safe(command.io.output.as_deref())?;
             let mut filter = armor::Reader::from_reader(&mut input, None);
             io::copy(&mut filter, &mut output)?;
         },
@@ -1367,10 +1261,9 @@ fn main() -> Result<()> {
 
         SqSubcommands::Packet(command) => match command.subcommand {
             packet::Subcommands::Dump(command) => {
-                let mut input = open_or_stdin(command.io.input.as_deref())?;
+                let mut input = command.input.open()?;
-                let mut output = config.create_or_stdout_unsafe(
+                let output_type = command.output;
-                    command.io.output.as_deref(),
+                let mut output = output_type.create_unsafe(config.force)?;
-                )?;
 
                 let session_key = command.session_key;
                 let width = if let Some((width, _)) = terminal_size() {
@@ -1384,9 +1277,9 @@ fn main() -> Result<()> {
             },
 
             packet::Subcommands::Decrypt(command) => {
-                let mut input = open_or_stdin(command.io.input.as_deref())?;
+                let mut input = command.input.open()?;
-                let mut output = config.create_or_stdout_pgp(
+                let mut output = command.output.create_pgp_safe(
-                    command.io.output.as_deref(),
+                    config.force,
                     command.binary,
                     armor::Kind::Message,
                 )?;
@@ -1404,15 +1297,16 @@ fn main() -> Result<()> {
             },
 
             packet::Subcommands::Split(command) => {
-                let mut input = open_or_stdin(command.input.as_deref())?;
+                let mut input = command.input.open()?;
                 let prefix =
                 // The prefix is either specified explicitly...
                     command.prefix.unwrap_or(
                         // ... or we derive it from the input file...
-                        command.input.and_then(|i| {
+                        command.input.and_then(|x| {
-                            let p = PathBuf::from(i);
                             // (but only use the filename)
-                            p.file_name().map(|f| String::from(f.to_string_lossy()))
+                            x.file_name().map(|f|
+                                String::from(f.to_string_lossy())
+                            )
                         })
                         // ... or we use a generic prefix...
                             .unwrap_or_else(|| String::from("output"))

src/sq_cli/armor.rs

@@ -1,6 +1,9 @@
 use clap::Parser;
 
-use crate::sq_cli::types::{ArmorKind, IoArgs};
+use super::types::ArmorKind;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 // TODO?: Option<_> conflicts with default value
 // TODO: use indoc to transparently (de-)indent static strings
@@ -29,8 +32,20 @@ $ sq armor binary-message.pgp
 "
     )]
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         long = "label",
         value_name = "LABEL",

src/sq_cli/autocrypt.rs

@@ -1,6 +1,8 @@
 use clap::{ValueEnum, Args, Parser, Subcommand};
 
-use crate::sq_cli::types::IoArgs;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -47,8 +49,20 @@ $ sq autocrypt decode autocrypt.eml
 "
 )]
 pub struct DecodeCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(short = 'B', long, help = "Emits binary data")]
     pub binary: bool,
 }
@@ -81,8 +95,20 @@ $ sq autocrypt encode-sender --prefer-encrypt mutual juliet.pgp
 "
 )]
 pub struct EncodeSenderCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     // TODO the help message looks like "primary userid" might be the default
     // email. clarify
     #[clap(

src/sq_cli/certify.rs

@@ -5,7 +5,9 @@ use clap::Parser;
 use crate::sq_cli::THIRD_PARTY_CERTIFICATION_VALIDITY_DURATION;
 use crate::sq_cli::THIRD_PARTY_CERTIFICATION_VALIDITY_IN_YEARS;
 
+use super::types::ClapData;
 use super::types::Expiry;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -49,12 +51,13 @@ $ sq certify --time 20130721 neal.pgp ada.pgp Ada
 )]
 pub struct Command {
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,

src/sq_cli/dane.rs

@@ -1,9 +1,10 @@
-use std::path::PathBuf;
-
 use clap::{Args, Parser, Subcommand};
 
 use crate::sq_cli::types::NetworkPolicy;
 
+use super::types::ClapData;
+use super::types::FileOrCertStore;
+
 #[derive(Parser, Debug)]
 #[clap(
     name = "dane",
@@ -63,10 +64,11 @@ pub struct GetCommand {
     )]
     pub binary: bool,
     #[clap(
-        short,
+        default_value_t = FileOrCertStore::default(),
+        help = FileOrCertStore::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE instead of importing into the certificate store"
+        value_name = FileOrCertStore::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrCertStore,
 }

src/sq_cli/dearmor.rs

@@ -1,6 +1,8 @@
 use clap::Parser;
 
-use crate::sq_cli::types::IoArgs;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -28,6 +30,18 @@ $ sq dearmor ascii-message.pgp
 ",
     )]
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
 }

src/sq_cli/decrypt.rs

@@ -2,7 +2,10 @@ use std::path::PathBuf;
 
 use clap::Parser;
 
-use crate::sq_cli::types::{IoArgs, SessionKey};
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
+use super::types::SessionKey;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -44,8 +47,20 @@ $ sq decrypt ciphertext.pgp
 )]
 // TODO use usize
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         short = 'n',
         long = "signatures",

src/sq_cli/encrypt.rs

@@ -6,7 +6,9 @@ use clap::{ValueEnum, Parser};
 use sequoia_openpgp as openpgp;
 use openpgp::KeyHandle;
 
-use crate::sq_cli::types::IoArgs;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -39,8 +41,20 @@ $ sq encrypt --symmetric message.txt
 ",
 )]
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,

src/sq_cli/inspect.rs

@@ -1,10 +1,11 @@
-use std::path::PathBuf;
-
 use clap::Parser;
 
 use sequoia_openpgp as openpgp;
 use openpgp::KeyHandle;
 
+use super::types::ClapData;
+use super::types::FileOrStdin;
+
 #[derive(Parser, Debug)]
 #[clap(
     name = "inspect",
@@ -42,10 +43,11 @@ $ sq inspect --time 20130721 cert.pgp
 )]
 pub struct Command {
     #[clap(
-        value_name = "FILE",
+        default_value_t = FileOrStdin::default(),
-        help = "Reads from FILE or stdin if omitted",
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
     )]
-    pub input: Option<PathBuf>,
+    pub input: FileOrStdin,
     #[clap(
         long = "cert",
         value_name = "FINGERPRINT|KEYID",

src/sq_cli/key.rs

@@ -4,7 +4,9 @@ use clap::{ValueEnum, ArgGroup, Args, Parser, Subcommand};
 
 use sequoia_openpgp::cert::CipherSuite as SqCipherSuite;
 
-use crate::sq_cli::types::IoArgs;
+use crate::sq_cli::types::ClapData;
+use crate::sq_cli::types::FileOrStdin;
+use crate::sq_cli::types::FileOrStdout;
 use crate::sq_cli::types::Expiry;
 use crate::sq_cli::types::Time;
 use crate::sq_cli::KEY_VALIDITY_DURATION;
@@ -249,8 +251,20 @@ $ sq key password --clear < juliet.encrypted_key.pgp > juliet.decrypted_key.pgp
 ",
 )]
 pub struct PasswordCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         long = "clear",
         help = "Emit a key with unencrypted secrets",
@@ -286,8 +300,20 @@ $ sq key extract-cert --output juliet.cert.pgp juliet.key.pgp
 ",
 )]
 pub struct ExtractCertCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,
@@ -344,8 +370,20 @@ $ sq key userid add --userid \"Juliet\" --creation-time 20210628 \\
 ",
 )]
 pub struct UseridAddCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         value_name = "USERID",
         short,
@@ -406,8 +444,20 @@ $ sq key userid strip --userid \"<juliet@example.org>\" \\
 ",
 )]
 pub struct UseridStripCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         value_name = "USERID",
         short,
@@ -469,17 +519,19 @@ pub struct AdoptCommand {
     )]
     pub allow_broken_crypto: bool,
     #[clap(
+        default_value_t = FileOrStdin::default(),
         value_name = "TARGET-KEY",
-        help = "Adds keys to TARGET-KEY",
+        help = "Adds keys to TARGET-KEY or reads keys from stdin if omitted",
     )]
-    pub certificate: Option<PathBuf>,
+    pub certificate: FileOrStdin,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,
@@ -529,17 +581,19 @@ pub struct AttestCertificationsCommand {
     )]
     pub all: bool,
     #[clap(
+        default_value_t = FileOrStdin::default(),
         value_name = "KEY",
-        help = "Changes attestations on KEY",
+        help = "Changes attestations on KEY or reads from stdin if omitted",
     )]
-    pub key: Option<PathBuf>,
+    pub key: FileOrStdin,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,
@@ -618,8 +672,20 @@ $ sq key subkey add --output alice-new.key.pgp --can-sign --cipher-suite rsa3k -
 #[clap(group(ArgGroup::new("sign-group").args(&["can_sign", "can_encrypt"])))]
 #[clap(group(ArgGroup::new("required-group").args(&["can_authenticate", "can_sign", "can_encrypt"]).required(true)))]
 pub struct SubkeyAddCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         long = "private-key-store",
         value_name = "KEY_STORE",

src/sq_cli/keyring.rs

@@ -2,6 +2,10 @@ use std::path::PathBuf;
 
 use clap::{Args, Parser, Subcommand};
 
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
+
 #[derive(Parser, Debug)]
 #[clap(
     name = "keyring",
@@ -79,12 +83,13 @@ pub struct FilterCommand {
     #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
     pub input: Vec<PathBuf>,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         long = "userid",
         value_name = "USERID",
@@ -174,15 +179,16 @@ $ sq keyring join juliet.pgp romeo.pgp alice.pgp
 ",
 )]
 pub struct JoinCommand {
-    #[clap(value_name = "FILE", help = "Sets the input files to use")]
+    #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
     pub input: Vec<PathBuf>,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Sets the output file to use"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long = "binary",
@@ -210,18 +216,16 @@ $ sq keyring merge certs.pgp romeo-updates.pgp
 ",
 )]
 pub struct MergeCommand {
-    #[clap(
+    #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
-        value_name = "FILE",
-        help = "Reads from FILE",
-    )]
     pub input: Vec<PathBuf>,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long = "binary",
@@ -251,10 +255,11 @@ $ sq keyring filter --domain example.org certs.pgp | sq keyring list
 )]
 pub struct ListCommand {
     #[clap(
-        value_name = "FILE",
+        default_value_t = FileOrStdin::default(),
-        help = "Reads from FILE or stdin if omitted",
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
     )]
-    pub input: Option<PathBuf>,
+    pub input: FileOrStdin,
     #[clap(
         long = "all-userids",
         help = "Lists all user ids",
@@ -288,10 +293,11 @@ $ sq keyring merge certs.pgp | sq keyring split
 )]
 pub struct SplitCommand {
     #[clap(
-        value_name = "FILE",
+        default_value_t = FileOrStdin::default(),
-        help = "Reads from FILE or stdin if omitted",
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
     )]
-    pub input: Option<PathBuf>,
+    pub input: FileOrStdin,
     #[clap(
         short = 'p',
         long = "prefix",

src/sq_cli/keyserver.rs

@@ -1,9 +1,11 @@
-use std::path::PathBuf;
-
 use clap::{Args, Parser, Subcommand};
 
 use crate::sq_cli::types::NetworkPolicy;
 
+use super::types::ClapData;
+use super::types::FileOrCertStore;
+use super::types::FileOrStdin;
+
 #[derive(Parser, Debug)]
 #[clap(
     name = "keyserver",
@@ -62,12 +64,13 @@ the usual way.
 )]
 pub struct GetCommand {
     #[clap(
-        short,
+        default_value_t = FileOrCertStore::default(),
+        help = FileOrCertStore::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE instead of importing into the certificate store"
+        value_name = FileOrCertStore::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrCertStore,
     #[clap(
         short = 'B',
         long,
@@ -88,6 +91,10 @@ pub struct GetCommand {
     about = "Sends a key",
 )]
 pub struct SendCommand {
-    #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
+    #[clap(
-    pub input: Option<PathBuf>,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
 }

src/sq_cli/packet.rs

@@ -2,7 +2,11 @@ use std::path::PathBuf;
 
 use clap::{Args, Parser, Subcommand};
 
-use crate::sq_cli::types::{ArmorKind, IoArgs, SessionKey};
+use super::types::ArmorKind;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
+use super::types::SessionKey;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -64,8 +68,20 @@ $ sq packet dump --session-key AAAABBBBCCCC... ciphertext.pgp
 ",
 )]
 pub struct DumpCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         long = "session-key",
         value_name = "SESSION-KEY",
@@ -102,8 +118,20 @@ $ sq packet decrypt --recipient-file juliet.pgp ciphertext.pgp
 ",
 )]
 pub struct DecryptCommand {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         short = 'B',
         long,
@@ -154,8 +182,12 @@ $ sq packet split juliet.pgp
 ",
 )]
 pub struct SplitCommand {
-    #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
+    #[clap(
-    pub input: Option<PathBuf>,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
     #[clap(
         short = 'p',
         long = "prefix",
@@ -191,12 +223,13 @@ pub struct JoinCommand {
     #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
     pub input: Vec<PathBuf>,
     #[clap(
-        short,
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE or stdout if omitted"
+        value_name = FileOrStdout::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrStdout,
     #[clap(
         long = "label",
         value_name = "LABEL",

src/sq_cli/sign.rs

@@ -2,7 +2,9 @@ use std::path::PathBuf;
 
 use clap::Parser;
 
-use crate::sq_cli::types::IoArgs;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -36,8 +38,20 @@ $ sq sign --time 20020304 --detached --signer-file juliet.pgp message.txt
 ",
     )]
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     // TODO: Why capital B?
     #[clap(
         short = 'B',

src/sq_cli/types.rs

@@ -1,7 +1,14 @@
 use std::fmt::Display;
 use std::fmt::Formatter;
+use std::fs::OpenOptions;
+use std::io::Write;
+use std::io::stdin;
+use std::io::stdout;
+use std::path::Path;
 use std::path::PathBuf;
 use std::str::FromStr;
+use std::sync::atomic::AtomicBool;
+use std::sync::atomic::Ordering;
 use std::time::Duration;
 use std::time::SystemTime;
 
@@ -9,28 +16,413 @@ use anyhow::anyhow;
 use anyhow::Context;
 use anyhow::Result;
 
+use buffered_reader::BufferedReader;
+use buffered_reader::File;
+use buffered_reader::Generic;
 use chrono::{offset::Utc, DateTime};
 /// Common types for arguments of sq.
-use clap::{ValueEnum, Args};
+use clap::ValueEnum;
 
+use openpgp::armor;
 use openpgp::fmt::hex;
+use openpgp::serialize::stream::Armorer;
+use openpgp::serialize::stream::Message;
 use openpgp::types::SymmetricAlgorithm;
 use sequoia_openpgp as openpgp;
+use terminal_size::terminal_size;
 
 use crate::sq_cli::SECONDS_IN_DAY;
 use crate::sq_cli::SECONDS_IN_YEAR;
 
-#[derive(Debug, Args)]
+/// A type wrapping an AtomicBool to guard emitting a CLI warning only once
-pub struct IoArgs {
+struct CliWarningOnce(AtomicBool);
-    #[clap(value_name = "FILE", help = "Reads from FILE or stdin if omitted")]
+/// A static `CliWarningOnce` indicating whether a warning about the unstable
-    pub input: Option<PathBuf>,
+/// CLI has been emitted already
-    #[clap(
+static UNSTABLE_CLI_WARNING: CliWarningOnce =
-        short,
+    CliWarningOnce(AtomicBool::new(false));
-        long,
+
-        value_name = "FILE",
+impl CliWarningOnce {
-        help = "Writes to FILE or stdout if omitted"
+    /// Emit a warning message only once
-    )]
+    pub fn warn(&self) {
-    pub output: Option<PathBuf>,
+        if !self.0.swap(true, Ordering::Relaxed) {
+            // stdout is connected to a terminal, assume interactive use.
+            if terminal_size().is_none()
+                // For bash shells, we can use a very simple heuristic.
+                // We simply look at whether the COLUMNS variable is defined in
+                // our environment.
+                && std::env::var_os("COLUMNS").is_none() {
+                eprintln!(
+                    "\nWARNING: sq does not have a stable CLI interface. \
+                    Use with caution in scripts.\n"
+                );
+            }
+        }
+    }
+}
+
+/// A trait to provide const &str for clap annotations for custom structs
+pub trait ClapData {
+    /// The clap value name
+    const VALUE_NAME: &'static str;
+    /// The clap help text
+    const HELP: &'static str;
+}
+
+/// A type wrapping an optional PathBuf to use as stdin or file input
+///
+/// When creating `FileOrStdin` from `&str`, providing a `"-"` is interpreted
+/// as `None`, i.e. read from stdin. Providing other strings is interpreted as
+/// `Some(PathBuf)`, i.e. read from file.
+/// Use this if a CLI should allow input from a file and if unset from stdin.
+///
+/// ## Examples
+/// ```
+/// use clap::Args;
+///
+/// #[derive(Debug, Args)]
+/// #[clap(name = "example", about = "an example")]
+/// pub struct Example {
+///     #[clap(
+///         default_value_t = FileOrStdin::default(),
+///         help = FileOrStdin::HELP,
+///         value_name = FileOrStdin::VALUE_NAME,
+///     )]
+///     pub input: FileOrStdin,
+/// }
+/// ```
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct FileOrStdin(Option<PathBuf>);
+
+impl ClapData for FileOrStdin {
+    const VALUE_NAME: &'static str = "FILE";
+    const HELP: &'static str = "Reads from FILE or stdin if omitted";
+}
+
+impl FileOrStdin {
+    pub fn new(path: Option<PathBuf>) -> Self {
+        FileOrStdin(path)
+    }
+
+    /// Return a reference to the inner type
+    pub fn inner(&self) -> Option<&PathBuf> {
+        self.0.as_ref()
+    }
+
+    /// Returns `None` if `self.0` is `None`, otherwise calls f with the wrapped
+    /// value and returns the result
+    pub fn and_then<U, F>(self, f: F) -> Option<U>
+    where
+        F: FnOnce(PathBuf) -> Option<U>,
+    {
+        self.0.and_then(|x| f(x))
+    }
+
+    /// Get a boxed BufferedReader for the FileOrStdin
+    ///
+    /// Opens a file if there is Some(PathBuf), else opens stdin.
+    pub fn open(&self) -> Result<Box<dyn BufferedReader<()>>> {
+        if let Some(path) = self.inner() {
+            Ok(Box::new(
+                File::open(path)
+                .with_context(|| format!("Failed to open {}", self))?))
+        } else {
+            Ok(Box::new(Generic::new(stdin(), None)))
+        }
+    }
+}
+
+impl Default for FileOrStdin {
+    fn default() -> Self {
+        FileOrStdin(None)
+    }
+}
+
+impl From<PathBuf> for FileOrStdin {
+    fn from(value: PathBuf) -> Self {
+        if value == PathBuf::from("-") {
+            FileOrStdin::default()
+        } else {
+            FileOrStdin::new(Some(value))
+        }
+    }
+}
+
+impl From<Option<PathBuf>> for FileOrStdin {
+    fn from(value: Option<PathBuf>) -> Self {
+        if let Some(path) = value {
+            FileOrStdin::from(path)
+        } else {
+            FileOrStdin::default()
+        }
+    }
+}
+
+impl From<&Path> for FileOrStdin {
+    fn from(value: &Path) -> Self {
+        if Path::new("-") == value {
+            FileOrStdin::default()
+        } else {
+            FileOrStdin::from(value.to_owned())
+        }
+    }
+}
+
+impl From<Option<&Path>> for FileOrStdin {
+    fn from(value: Option<&Path>) -> Self {
+        if let Some(path) = value {
+            FileOrStdin::from(path)
+        } else {
+            FileOrStdin::default()
+        }
+    }
+}
+
+impl FromStr for FileOrStdin {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        if "-" == s {
+            Ok(FileOrStdin(None))
+        } else {
+            Ok(FileOrStdin(Some(PathBuf::from(s))))
+        }
+    }
+}
+
+impl Display for FileOrStdin {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        match &self.0 {
+            None => write!(f, "-"),
+            Some(path) => write!(f, "{}", path.display()),
+        }
+    }
+}
+
+/// A type wrapping an optional PathBuf to use as stdout or file output
+///
+/// Use this if a CLI should allow output to a file and if unset output to
+/// a cert store.
+///
+/// ## Examples
+/// ```
+/// use clap::Args;
+///
+/// #[derive(Debug, Args)]
+/// #[clap(name = "example", about = "an example")]
+/// pub struct Example {
+///     #[clap(
+///         help = FileOrCertStore::HELP,
+///         long,
+///         short,
+///         value_name = FileOrCertStore::VALUE_NAME,
+///     )]
+///     pub output: Option<FileOrCertStore>,
+/// }
+/// ```
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct FileOrCertStore(Option<PathBuf>);
+
+impl ClapData for FileOrCertStore {
+    const VALUE_NAME: &'static str = "FILE";
+    const HELP: &'static str
+        = "Writes to FILE instead of importing into the certificate store";
+}
+
+impl FileOrCertStore {
+    /// Consume self and return the inner PathBuf
+    pub fn into_inner(self) -> Option<PathBuf> {
+        self.0
+    }
+
+    /// Return a reference to the inner type
+    pub fn path(&self) -> Option<&PathBuf> {
+        self.0.as_ref()
+    }
+}
+
+impl Default for FileOrCertStore {
+    fn default() -> Self {
+        FileOrCertStore(None)
+    }
+}
+
+impl FromStr for FileOrCertStore {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        Ok(FileOrCertStore(Some(PathBuf::from(s))))
+    }
+}
+
+impl Display for FileOrCertStore {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        match &self.0 {
+            Some(path) => write!(f, "{}", path.display()),
+            None => write!(f, "-"),
+        }
+    }
+}
+
+/// A type wrapping an optional PathBuf to use as stdout or file output
+///
+/// When creating `FileOrStdout` from `&str`, providing a `"-"` is interpreted
+/// as `None`, i.e. output to stdout. Providing other strings is interpreted as
+/// `Some(PathBuf)`, i.e. output to file.
+/// Use this if a CLI should allow output to a file and if unset output to
+/// stdout.
+///
+/// ## Examples
+/// ```
+/// use clap::Args;
+///
+/// #[derive(Debug, Args)]
+/// #[clap(name = "example", about = "an example")]
+/// pub struct Example {
+///     #[clap(
+///         default_value_t = FileOrStdout::default(),
+///         help = FileOrStdout::HELP,
+///         long,
+///         short,
+///         value_name = FileOrStdout::VALUE_NAME,
+///     )]
+///     pub output: FileOrStdout,
+/// }
+/// ```
+#[derive(Clone, Debug, Eq, PartialEq)]
+pub struct FileOrStdout(Option<PathBuf>);
+
+impl ClapData for FileOrStdout {
+    const VALUE_NAME: &'static str = "FILE";
+    const HELP: &'static str = "Writes to FILE or stdout if omitted";
+}
+
+impl FileOrStdout {
+    pub fn new(path: Option<PathBuf>) -> Self {
+        FileOrStdout(path)
+    }
+
+    /// Return a reference to the optional PathBuf
+    pub fn path(&self) -> Option<&PathBuf> {
+        self.0.as_ref()
+    }
+
+    /// Opens the file (or stdout) for writing data that is safe for
+    /// non-interactive use.
+    ///
+    /// This is suitable for any kind of OpenPGP data, decrypted or
+    /// authenticated payloads.
+    pub fn create_safe(
+        &self,
+        force: bool,
+    ) -> Result<Box<dyn Write + Sync + Send>> {
+        self.create(force)
+    }
+
+    /// Opens the file (or stdout) for writing data that is NOT safe
+    /// for non-interactive use.
+    ///
+    /// If our heuristic detects non-interactive use, we will emit a
+    /// warning once.
+    pub fn create_unsafe(
+        &self,
+        force: bool,
+    ) -> Result<Box<dyn Write + Sync + Send>> {
+        UNSTABLE_CLI_WARNING.warn();
+        self.create(force)
+    }
+
+    /// Opens the file (or stdout) for writing data that is safe for
+    /// non-interactive use because it is an OpenPGP data stream.
+    pub fn create_pgp_safe(
+        &self,
+        force: bool,
+        binary: bool,
+        kind: armor::Kind,
+    ) -> Result<Message> {
+        let sink = self.create_safe(force)?;
+        let mut message = Message::new(sink);
+        if ! binary {
+            message = Armorer::new(message).kind(kind).build()?;
+        }
+        Ok(message)
+    }
+
+    /// Helper function, do not use directly. Instead, use create_or_stdout_safe
+    /// or create_or_stdout_unsafe.
+    fn create(&self, force: bool) -> Result<Box<dyn Write + Sync + Send>> {
+        if let Some(path) = self.path() {
+            if !path.exists() || force {
+                Ok(Box::new(
+                    OpenOptions::new()
+                        .write(true)
+                        .truncate(true)
+                        .create(true)
+                        .open(path)
+                        .context("Failed to create output file")?,
+                ))
+            } else {
+                Err(anyhow::anyhow!(format!(
+                    "File {:?} exists, use \"sq --force ...\" to overwrite",
+                    self,
+                )))
+            }
+        } else {
+            Ok(Box::new(stdout()))
+        }
+    }
+}
+
+impl Default for FileOrStdout {
+    fn default() -> Self {
+        FileOrStdout(None)
+    }
+}
+
+impl From<FileOrCertStore> for FileOrStdout {
+    fn from(value: FileOrCertStore) -> Self {
+        FileOrStdout::new(value.into_inner())
+    }
+}
+
+impl From<PathBuf> for FileOrStdout {
+    fn from(value: PathBuf) -> Self {
+        if value == PathBuf::from("-") {
+            FileOrStdout::default()
+        } else {
+            FileOrStdout::new(Some(value))
+        }
+    }
+}
+
+impl From<Option<PathBuf>> for FileOrStdout {
+    fn from(value: Option<PathBuf>) -> Self {
+        if let Some(path) = value {
+            FileOrStdout::from(path)
+        } else {
+            FileOrStdout::default()
+        }
+    }
+}
+
+impl FromStr for FileOrStdout {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        if "-" == s {
+            Ok(FileOrStdout::default())
+        } else {
+            Ok(FileOrStdout(Some(PathBuf::from(s))))
+        }
+    }
+}
+
+impl Display for FileOrStdout {
+    fn fmt(&self, f: &mut Formatter) -> std::fmt::Result {
+        match &self.0 {
+            Some(path) => write!(f, "{}", path.display()),
+            None => write!(f, "-"),
+        }
+    }
 }
 
 #[derive(ValueEnum, Debug, Clone)]

src/sq_cli/verify.rs

@@ -5,7 +5,9 @@ use clap::Parser;
 use sequoia_openpgp as openpgp;
 use openpgp::KeyHandle;
 
-use crate::sq_cli::types::IoArgs;
+use super::types::ClapData;
+use super::types::FileOrStdin;
+use super::types::FileOrStdout;
 
 #[derive(Parser, Debug)]
 #[clap(
@@ -59,8 +61,20 @@ $ sq verify --time 20130721 msg.pgp
 ",
     )]
 pub struct Command {
-    #[clap(flatten)]
+    #[clap(
-    pub io: IoArgs,
+        default_value_t = FileOrStdin::default(),
+        help = FileOrStdin::HELP,
+        value_name = FileOrStdin::VALUE_NAME,
+    )]
+    pub input: FileOrStdin,
+    #[clap(
+        default_value_t = FileOrStdout::default(),
+        help = FileOrStdout::HELP,
+        long,
+        short,
+        value_name = FileOrStdout::VALUE_NAME,
+    )]
+    pub output: FileOrStdout,
     #[clap(
         long = "detached",
         value_name = "SIG",

src/sq_cli/wkd.rs

@@ -1,9 +1,11 @@
-use std::path::PathBuf;
-
 use clap::{Args, Parser, Subcommand};
 
 use crate::sq_cli::types::NetworkPolicy;
 
+use super::types::ClapData;
+use super::types::FileOrCertStore;
+use super::types::FileOrStdin;
+
 #[derive(Parser, Debug)]
 #[clap(
     name = "wkd",
@@ -89,12 +91,13 @@ pub struct GetCommand {
     )]
     pub binary: bool,
     #[clap(
-        short,
+        default_value_t = FileOrCertStore::default(),
+        help = FileOrCertStore::HELP,
         long,
-        value_name = "FILE",
+        short,
-        help = "Writes to FILE instead of importing into the certificate store"
+        value_name = FileOrCertStore::VALUE_NAME,
     )]
-    pub output: Option<PathBuf>,
+    pub output: FileOrCertStore,
 }
 
 #[derive(Debug, Args)]
@@ -138,10 +141,11 @@ pub struct GenerateCommand {
     )]
     pub domain: String,
     #[clap(
+        default_value_t = FileOrStdin::default(),
         value_name = "CERT-RING",
-        help = "Adds certificates from CERT-RING to the WKD",
+        help = "Adds certificates from CERT-RING (or stdin if omitted) to the WKD",
     )]
-    pub input: Option<PathBuf>,
+    pub input: FileOrStdin,
     #[clap(
         short = 'd',
         long = "direct-method",