pidfile/lockfile handling bugfixes

pidfile/locking: log errors thru syslog, too

This works by replacing perror()/fprintf(stderr, ...)
by report() and strerror().

If the pidfile cannot be unlinked, truncate it.

Bump release version to 6.4.13.rc1, and move KNOWN BUGS section up in NEWS.

4 files changed, 48 insertions, 18 deletions

diff --git a/NEWS b/NEWS
index 7b9db2e7..727010c1 100644
--- a/NEWS
+++ b/NEWS
@@ -64,12 +64,22 @@ removed from a 6.5.0 or newer release.)
   for end-of-life OpenSSL versions may be removed even from patchlevel releases.
 
 ---------------------------------------------------------------------------------
-fetchmail-6.4.12 (released 2020-09-04, 27596 LoC):
+fetchmail-6.4.13 (work in progress):
 
 # BUG FIXES:
-* The README file is now the one from Git again. The makerelease.pl script
-  used to roll and upload the tarball sometimes clobbered the README file and
-  replaced its contents by a part of the NEWS file.
+* Errors about lock file (= pidfile) creation could be lost in daemon 
+  configurations (-d option, or set daemon) when using syslog. Now they are also 
+  logged to syslog.  Found verifying a pidfile creation issue on 6.4.12 that was 
+  previously reported by Alex Hall of Automatic Distributors.
+* If the lock file cannot be removed (no write permission on directory), try
+  to truncate it, and if that fails, report error.
+* If the pidfile was non-default, fetchmail -q or --quit would malfunction and
+  claim no other fetchmail were running, because it did not read the 
+  configuration files or merge the command line options, thus it would look for 
+  the PID in the wrong file.
+
+# CHANGES:
+* Lockfile (= pidfile) creation errors are now logged with filename and reason.
 
 # KNOWN BUGS AND WORKAROUNDS
   (This section floats upwards through the NEWS file so it stays with the
@@ -92,6 +102,14 @@ fetchmail-6.4.12 (released 2020-09-04, 27596 LoC):
   server to test against. Use GSSAPI.
 
 ---------------------------------------------------------------------------------
+fetchmail-6.4.12 (released 2020-09-04, 27596 LoC):
+
+# BUG FIXES:
+* The README file is now the one from Git again. The makerelease.pl script
+  used to roll and upload the tarball sometimes clobbered the README file and
+  replaced its contents by a part of the NEWS file.
+
+---------------------------------------------------------------------------------
 fetchmail-6.4.11 (released 2020-08-28, 27596 LoC):
 
 # REGRESSION FIX:
diff --git a/configure.ac b/configure.ac
index a547bee1..3328ba54 100644
--- a/configure.ac
+++ b/configure.ac
@@ -9,7 +9,7 @@ dnl Process this file with autoconf to produce a configure script.
 dnl
 
 dnl XXX - if bumping version here, check fetchmail.man, too!
-AC_INIT([fetchmail],[6.4.12],[fetchmail-users@lists.sourceforge.net])
+AC_INIT([fetchmail],[6.4.13.rc1],[fetchmail-users@lists.sourceforge.net])
 AC_CONFIG_SRCDIR([fetchmail.h])
 AC_CONFIG_HEADERS([config.h])
 AC_CONFIG_LIBOBJ_DIR([.])
diff --git a/fetchmail.c b/fetchmail.c
index fb1e6015..3619fd9b 100644
--- a/fetchmail.c
+++ b/fetchmail.c
@@ -329,9 +329,10 @@ int main(int argc, char **argv)
 	if (system("uname -a")) { /* NOOP to quench GCC complaint */ }
     }
 
-    /* avoid parsing the config file if all we're doing is killing a daemon */
-    if (!quitonly)
-	implicitmode = load_params(argc, argv, optind);
+    /* We used to avoid parsing the config file if all we're doing is killing 
+     * a daemon, under if (!quitonly) but since the pidfile can be configured 
+     * in the rcfile, this is no longer viable. */
+    implicitmode = load_params(argc, argv, optind);
 
     if (run.logfile) {
 	/* nodetach -> turn off logfile option */
diff --git a/lock.c b/lock.c
index 7f8b8667..9533e25f 100644
--- a/lock.c
+++ b/lock.c
@@ -60,7 +60,7 @@ static void unlockit(void)
 /* must-do actions for exit (but we can't count on being able to do malloc) */
 {
     if (lockfile && lock_acquired)
-	unlink(lockfile);
+	unlink(lockfile) && truncate(lockfile, (off_t)0);
 }
 
 void fm_lock_dispose(void)
@@ -84,7 +84,7 @@ int fm_lock_state(void)
 	bkgd = (args == 2);
 
 	if (ferror(lockfp)) {
-	    fprintf(stderr, GT_("fetchmail: error reading lockfile \"%s\": %s\n"),
+	    report(stderr, GT_("fetchmail: error reading lockfile \"%s\": %s\n"),
 		    lockfile, strerror(errno));
 	    fclose(lockfp); /* not checking should be safe, file mode was "r" */
 	    exit(PS_EXCLUDE);
@@ -95,10 +95,13 @@ int fm_lock_state(void)
 	    /* ^ could not read PID  || process does not exist */
 	    /* => lockfile is stale, unlink it */
 	    pid = 0;
-	    fprintf(stderr,GT_("fetchmail: removing stale lockfile\n"));
+	    report(stderr,GT_("fetchmail: removing stale lockfile \"%s\"\n"), lockfile);
 	    if (unlink(lockfile)) {
 	       if (errno != ENOENT) {
-		   perror(lockfile);
+		   if (outlevel >= O_VERBOSE) {
+		       report(stderr, GT_("fetchmail: cannot unlink lockfile \"%s\" (%s), trying to write to it\n"),
+			       lockfile, strerror(errno));
+		   }
 		   /* we complain but we don't exit; it might be
 		    * writable for us, but in a directory we cannot
 		    * write to. This means we can write the new PID to
@@ -110,7 +113,8 @@ int fm_lock_state(void)
 		       /* but if we cannot truncate the file either,
 			* assume that we cannot write to it later,
 			* complain and quit. */
-		       perror(lockfile);
+		       report(stderr, GT_("fetchmail: cannot write to lockfile \"%s\" either (%s), exiting\n"),
+			       strerror(errno), lockfile);
 		       exit(PS_EXCLUDE);
 		   }
 	       }
@@ -119,7 +123,7 @@ int fm_lock_state(void)
     } else {
 	pid = 0;
 	if (errno != ENOENT) {
-	    fprintf(stderr, GT_("fetchmail: error opening lockfile \"%s\": %s\n"),
+	    report(stderr, GT_("fetchmail: error opening lockfile \"%s\": %s\n"),
 		    lockfile, strerror(errno));
 	    exit(PS_EXCLUDE);
 	}
@@ -143,7 +147,11 @@ void fm_lock_or_die(void)
     if (!lock_acquired) {
 	int e = 0;
 
-	if ((fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, 0666)) != -1) {
+	fd = open(lockfile, O_WRONLY|O_CREAT|O_EXCL, 0666);
+	if (fd == -1 && EEXIST == errno) {
+		fd = open(lockfile, O_WRONLY|O_TRUNC, 0666);
+	}
+	if (-1 != fd) {
 	    ssize_t wr;
 
 	    snprintf(tmpbuf, sizeof(tmpbuf), "%ld\n", (long)getpid());
@@ -165,8 +173,7 @@ void fm_lock_or_die(void)
 	if (e == 0) {
 	    lock_acquired = TRUE;
 	} else {
-	    perror(lockfile);
-	    fprintf(stderr, GT_("fetchmail: lock creation failed.\n"));
+	    report(stderr, GT_("fetchmail: lock creation failed, pidfile \"%s\": %s\n"), lockfile, strerror(errno));
 	    exit(PS_EXCLUDE);
 	}
     }
@@ -175,6 +182,10 @@ void fm_lock_or_die(void)
 void fm_lock_release(void)
 /* release a lock on a given host */
 {
-    unlink(lockfile);
+    if (unlink(lockfile)) {
+	    if (truncate(lockfile, (off_t)0)) {
+		    report(stderr, GT_("fetchmail: cannot remove or truncate pidfile \"%s\": %s\n"), strerror(errno));
+	    }
+    }
 }
 /* lock.c ends here */