sterm: Detect stale lock files

diff --git a/utils/sterm.c b/utils/sterm.c
index a3e9786ab82fd0e3e273b0e79f81f31e7183e7f7..e708a682cc049967e8801909b64f6d0594ceba1e 100644 (file)
--- a/utils/sterm.c
+++ b/utils/sterm.c
@@ -174,9 +174,21 @@ int main(int argc, char *argv[])
                CHECK(write(tmp, pid, strlen(pid)));
                close(tmp);
                snprintf(lockfile, sizeof(lockfile), "/var/lock/LCK..%s", dev + 5);
+       retry:
                if (link(template, lockfile) == -1) {
-                       perror(lockfile);
-                       exit(1);
+                       tmp = CHECK(open(lockfile, O_RDONLY));
+                       CHECK(read(tmp, pid, sizeof(pid)));
+                       close(tmp);
+                       int p = atoi(pid);
+                       char proc[50];
+                       snprintf(proc, sizeof(proc), "/proc/%d", p);
+                       if (access(proc, F_OK) == 0) {
+                               fprintf(stderr, "%s is used by PID %d\n", dev, p);
+                               exit(1);
+                       }
+                       fprintf(stderr, "Stale lock file %s (PID %d) - removing it!\n", lockfile, p);
+                       CHECK(unlink(lockfile));
+                       goto retry;
                }
                rm_file(0, template);
                on_exit(rm_file, lockfile);