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rust: Create generic ref_from_raw_ptr function

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I need to do some hunting for a "ffi helper" crate.  I kind of
understand why these things aren't in the std library.

Anyways this is easy for now, prep for adding more types.

Closes: #1641
Approved by: jlebon
This commit is contained in:
Colin Walters 2018-10-26 10:02:21 -04:00 committed by Atomic Bot
parent 92d207de5d
commit 202192d61e
2 changed files with 15 additions and 14 deletions
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8
rust/src/ffiutil.rs
View File

@ -55,6 +55,14 @@ pub fn dir_from_dfd(fd: libc::c_int) -> io::Result<openat::Dir> {
Ok(r)
}
/// Assert that a raw pointer is not `NULL`, and cast it to a Rust reference
/// with the static lifetime - it has to be static as we can't tell Rust about
/// our lifetimes from the C side.
pub fn ref_from_raw_ptr<T>(p: *mut T) -> &'static mut T {
assert!(!p.is_null());
unsafe { &mut *p }
}
// Functions to map Rust's Error into the "GError convention":
// https://developer.gnome.org/glib/stable/glib-Error-Reporting.html
// Use e.g. int_glib_error() to map to a plain "int" C return.

21
rust/src/lib.rs
View File

@ -45,13 +45,6 @@ mod journal;
use journal::*;
mod utils;
// It's not really &'static of course...but we can't
// tell Rust about our lifetimes from the C side.
fn tf_from_raw(tf: *mut Treefile) -> &'static mut Treefile {
assert!(!tf.is_null());
unsafe { &mut *tf }
}
// Some of our file descriptors may be read multiple times.
// We try to consistently seek to the start to make that
// convenient from the C side. Note that this function
@ -88,12 +81,12 @@ pub extern "C" fn ror_treefile_new(
#[no_mangle]
pub extern "C" fn ror_treefile_get_dfd(tf: *mut Treefile) -> libc::c_int {
tf_from_raw(tf).primary_dfd.as_raw_fd()
ref_from_raw_ptr(tf).primary_dfd.as_raw_fd()
}
#[no_mangle]
pub extern "C" fn ror_treefile_get_postprocess_script_fd(tf: *mut Treefile) -> libc::c_int {
tf_from_raw(tf)
ref_from_raw_ptr(tf)
.externals
.postprocess_script
.as_mut()
@ -105,7 +98,7 @@ pub extern "C" fn ror_treefile_get_add_file_fd(
tf: *mut Treefile,
filename: *const libc::c_char,
) -> libc::c_int {
let tf = tf_from_raw(tf);
let tf = ref_from_raw_ptr(tf);
let filename = OsStr::from_bytes(bytes_from_nonnull(filename));
let filename = filename.to_string_lossy().into_owned();
raw_seeked_fd(tf.externals.add_files.get_mut(&filename).expect("add-file"))
@ -113,7 +106,7 @@ pub extern "C" fn ror_treefile_get_add_file_fd(
#[no_mangle]
pub extern "C" fn ror_treefile_get_passwd_fd(tf: *mut Treefile) -> libc::c_int {
tf_from_raw(tf)
ref_from_raw_ptr(tf)
.externals
.passwd
.as_mut()
@ -122,7 +115,7 @@ pub extern "C" fn ror_treefile_get_passwd_fd(tf: *mut Treefile) -> libc::c_int {
#[no_mangle]
pub extern "C" fn ror_treefile_get_group_fd(tf: *mut Treefile) -> libc::c_int {
tf_from_raw(tf)
ref_from_raw_ptr(tf)
.externals
.group
.as_mut()
@ -131,12 +124,12 @@ pub extern "C" fn ror_treefile_get_group_fd(tf: *mut Treefile) -> libc::c_int {
#[no_mangle]
pub extern "C" fn ror_treefile_get_json_string(tf: *mut Treefile) -> *const libc::c_char {
tf_from_raw(tf).serialized.as_ptr()
ref_from_raw_ptr(tf).serialized.as_ptr()
}
#[no_mangle]
pub extern "C" fn ror_treefile_get_rojig_spec_path(tf: *mut Treefile) -> *const libc::c_char {
let tf = tf_from_raw(tf);
let tf = ref_from_raw_ptr(tf);
if let &Some(ref rojig) = &tf.rojig_spec {
rojig.as_ptr()
} else {