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lib/commonio: make lock failures more detailed

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This tweaks the database locking logic so that failures in the
link-checking paths are more detailed.
The rationale for this is that I've experienced a non-deterministic
bug which seems to be coming from this logic, and I'd like to get
more details about the actual failing condition.
This commit is contained in:
Luca BRUNO 2022-08-29 12:35:07 +00:00 committed by Serge Hallyn
parent cde221b858
commit 14e7caf6b2
1 changed files with 14 additions and 14 deletions
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28
lib/commonio.c
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@ -32,7 +32,7 @@
/* local function prototypes */
static int lrename (const char *, const char *);
static int check_link_count (const char *file);
static int check_link_count (const char *file, bool log);
static int do_lock_file (const char *file, const char *lock, bool log);
static /*@null@*/ /*@dependent@*/FILE *fopen_set_perms (
const char *name,
@ -93,15 +93,25 @@ int lrename (const char *old, const char *new)
return res;
}
static int check_link_count (const char *file)
static int check_link_count (const char *file, bool log)
{
struct stat sb;
if (stat (file, &sb) != 0) {
if (log) {
(void) fprintf (shadow_logfd,
"%s: %s file stat error: %s\n",
shadow_progname, file, strerror (errno));
}
return 0;
}
if (sb.st_nlink != 2) {
if (log) {
(void) fprintf (shadow_logfd,
"%s: %s: lock file already used (nlink: %u)\n",
shadow_progname, file, sb.st_nlink);
}
return 0;
}
@ -153,12 +163,7 @@ static int do_lock_file (const char *file, const char *lock, bool log)
close (fd);
if (link (file, lock) == 0) {
retval = check_link_count (file);
if ((0==retval) && log) {
(void) fprintf (shadow_logfd,
"%s: %s: lock file already used\n",
shadow_progname, file);
}
retval = check_link_count (file, log);
unlink (file);
return retval;
}
@ -219,12 +224,7 @@ static int do_lock_file (const char *file, const char *lock, bool log)
retval = 0;
if (link (file, lock) == 0) {
retval = check_link_count (file);
if ((0==retval) && log) {
(void) fprintf (shadow_logfd,
"%s: %s: lock file already used\n",
shadow_progname, file);
}
retval = check_link_count (file, log);
} else {
if (log) {
(void) fprintf (shadow_logfd,