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Verify file modifications by other programs

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* src/filelock.c (lock_file): Check whether the file was modified
since it was visited even if 'create-lockfiles' is nil.  (Bug#18828)
This commit is contained in:
Eli Zaretskii 2015-05-08 12:20:16 +03:00
parent 0d0a4d06ef
commit 25fde89819
1 changed files with 25 additions and 24 deletions
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49
src/filelock.c
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@ -669,10 +669,6 @@ lock_file (Lisp_Object fn)
struct gcpro gcpro1;
USE_SAFE_ALLOCA;
/* Don't do locking if the user has opted out. */
if (! create_lockfiles)
return;
/* Don't do locking while dumping Emacs.
Uncompressing wtmp files uses call-process, which does not work
in an uninitialized Emacs. */
@ -690,9 +686,6 @@ lock_file (Lisp_Object fn)
#endif
encoded_fn = ENCODE_FILE (fn);
/* Create the name of the lock-file for file fn */
MAKE_LOCK_NAME (lfname, encoded_fn);
/* See if this file is visited and has changed on disk since it was
visited. */
{
@ -707,27 +700,35 @@ lock_file (Lisp_Object fn)
}
/* Try to lock the lock. */
if (0 < lock_if_free (&lock_info, lfname))
/* Don't do locking if the user has opted out. */
if (create_lockfiles)
{
/* Someone else has the lock. Consider breaking it. */
Lisp_Object attack;
char *dot = lock_info.dot;
ptrdiff_t pidlen = lock_info.colon - (dot + 1);
static char const replacement[] = " (pid ";
int replacementlen = sizeof replacement - 1;
memmove (dot + replacementlen, dot + 1, pidlen);
strcpy (dot + replacementlen + pidlen, ")");
memcpy (dot, replacement, replacementlen);
attack = call2 (intern ("ask-user-about-lock"), fn,
build_string (lock_info.user));
/* Take the lock if the user said so. */
if (!NILP (attack))
lock_file_1 (lfname, 1);
/* Create the name of the lock-file for file fn */
MAKE_LOCK_NAME (lfname, encoded_fn);
/* Try to lock the lock. */
if (0 < lock_if_free (&lock_info, lfname))
{
/* Someone else has the lock. Consider breaking it. */
Lisp_Object attack;
char *dot = lock_info.dot;
ptrdiff_t pidlen = lock_info.colon - (dot + 1);
static char const replacement[] = " (pid ";
int replacementlen = sizeof replacement - 1;
memmove (dot + replacementlen, dot + 1, pidlen);
strcpy (dot + replacementlen + pidlen, ")");
memcpy (dot, replacement, replacementlen);
attack = call2 (intern ("ask-user-about-lock"), fn,
build_string (lock_info.user));
/* Take the lock if the user said so. */
if (!NILP (attack))
lock_file_1 (lfname, 1);
}
SAFE_FREE ();
}
UNGCPRO;
SAFE_FREE ();
}
void