if pidfile turned out to be !regular file, do not unlink it.

It's most probably the /dev/null.

1 files changed, 16 insertions, 8 deletions

diff --git a/libbb/pidfile.c b/libbb/pidfile.c
index 64e67c322..cafa7891f 100644
--- a/libbb/pidfile.c
+++ b/libbb/pidfile.c
@@ -11,22 +11,30 @@
 #define WANT_PIDFILE 1
 #include "libbb.h"
 
-int write_pidfile(const char *path)
+smallint wrote_pidfile;
+
+void write_pidfile(const char *path)
 {
         int pid_fd;
         char *end;
         char buf[sizeof(int)*3 + 2];
+        struct stat sb;
 
         if (!path)
-                return 1;
+                return;
         /* we will overwrite stale pidfile */
         pid_fd = open(path, O_WRONLY|O_CREAT|O_TRUNC, 0666);
         if (pid_fd < 0)
-                return 0;
-        /* few bytes larger, but doesn't use stdio */
-        end = utoa_to_buf(getpid(), buf, sizeof(buf));
-        *end = '\n';
-        full_write(pid_fd, buf, end - buf + 1);
+                return;
+
+        /* path can be "/dev/null"! Test for such cases */
+        wrote_pidfile = (fstat(pid_fd, &sb) == 0) && S_ISREG(sb.st_mode);
+
+        if (wrote_pidfile) {
+                /* few bytes larger, but doesn't use stdio */
+                end = utoa_to_buf(getpid(), buf, sizeof(buf));
+                *end = '\n';
+                full_write(pid_fd, buf, end - buf + 1);
+        }
         close(pid_fd);
-        return 1;
 }