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Merge pull request #18124 from ryncsn/initrd

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initrd: add an env variable to accept non-ramfs rootfs
This commit is contained in:
Lennart Poettering 2021-01-15 09:58:17 +01:00 committed by GitHub
commit f1c86dd9ab
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2 changed files with 46 additions and 13 deletions
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10
docs/ENVIRONMENT.md
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@ -52,9 +52,13 @@ All tools:
* `$SYSTEMD_EFI_OPTIONS` — if set, used instead of the string in the
SystemdOptions EFI variable. Analogous to `$SYSTEMD_PROC_CMDLINE`.
* `$SYSTEMD_IN_INITRD` — takes a boolean. If set, overrides initrd detection.
This is useful for debugging and testing initrd-only programs in the main
system.
* `$SYSTEMD_IN_INITRD=[auto|lenient|0|1]` — if set, specifies initrd detection
method. Defaults to `auto`. Behavior is defined as follows:
`auto`: Checks if `/etc/initrd-release` exists, and a temporary fs is mounted
on `/`. If both conditions meet, then it's in initrd.
`lenient`: Similiar to `auto`, but the rootfs check is skipped.
`0|1`: Simply overrides initrd detection. This is useful for debugging and
testing initrd-only programs in the main system.
* `$SYSTEMD_BUS_TIMEOUT=SECS` — specifies the maximum time to wait for method call
completion. If no time unit is specified, assumes seconds. The usual other units

49
src/basic/util.c
View File

@ -52,13 +52,14 @@ int prot_from_flags(int flags) {
}
bool in_initrd(void) {
struct statfs s;
int r;
const char *e;
bool lenient = false;
if (saved_in_initrd >= 0)
return saved_in_initrd;
/* We make two checks here:
/* We have two checks here:
*
* 1. the flag file /etc/initrd-release must exist
* 2. the root file system must be a memory file system
@ -66,18 +67,46 @@ bool in_initrd(void) {
* The second check is extra paranoia, since misdetecting an
* initrd can have bad consequences due the initrd
* emptying when transititioning to the main systemd.
*
* If env var $SYSTEMD_IN_INITRD is not set or set to "auto",
* both checks are used. If it's set to "lenient", only check
* 1 is used. If set to a booleen value, then the boolean
* value is returned.
*/
r = getenv_bool_secure("SYSTEMD_IN_INITRD");
if (r < 0 && r != -ENXIO)
log_debug_errno(r, "Failed to parse $SYSTEMD_IN_INITRD, ignoring: %m");
e = secure_getenv("SYSTEMD_IN_INITRD");
if (e) {
if (streq(e, "lenient"))
lenient = true;
else if (!streq(e, "auto")) {
r = parse_boolean(e);
if (r >= 0) {
saved_in_initrd = r > 0;
return saved_in_initrd;
}
log_debug_errno(r, "Failed to parse $SYSTEMD_IN_INITRD, ignoring: %m");
}
}
if (!lenient) {
r = path_is_temporary_fs("/");
if (r < 0)
log_debug_errno(r, "Couldn't determine if / is a temporary file system: %m");
if (r >= 0)
saved_in_initrd = r > 0;
else
saved_in_initrd = access("/etc/initrd-release", F_OK) >= 0 &&
statfs("/", &s) >= 0 &&
is_temporary_fs(&s);
}
r = access("/etc/initrd-release", F_OK);
if (r >= 0) {
if (saved_in_initrd == 0)
log_debug("/etc/initrd-release exists, but it's not an initrd.");
else
saved_in_initrd = 1;
} else {
if (errno != ENOENT)
log_debug_errno(errno, "Failed to test if /etc/initrd-release exists: %m");
saved_in_initrd = 0;
}
return saved_in_initrd;
}