mxq_reaper: Retry on spool file write errors

If we can't write the spool file for any reason, do not write to stderr,
as this is the users stderr of the mxq job. Just wait and retry until
success.

mxq_reaper.c

@@ -73,38 +73,54 @@ int main(int argc, char **argv) {
         sleep(wait);
     }
 
-    char *tmpfilename;
-    if (asprintf(&tmpfilename, "%s.tmp", spoolfilename) == -1)
-        die("%m\n");
+    while (1) {
+        // if anything fails, do not write to stderr, as this is the users
+        // stderr, just wait and retry.
+
+        char *tmpfilename;
+        if (asprintf(&tmpfilename, "%s.tmp", spoolfilename) == -1)
+            goto retry_1;
 
-    FILE *out = fopen(tmpfilename,"w");
-    if (out == NULL)
-        die("%s: %m\n", tmpfilename);
-    fprintf(out,"1 %d %d %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n",
-        getpid(),
-        user_status,
-        user_time.tv_sec, user_time.tv_usec,
-        user_rusage.ru_utime.tv_sec, user_rusage.ru_utime.tv_usec,
-        user_rusage.ru_stime.tv_sec, user_rusage.ru_stime.tv_usec,
-        user_rusage.ru_maxrss,
-        user_rusage.ru_ixrss,
-        user_rusage.ru_idrss,
-        user_rusage.ru_isrss,
-        user_rusage.ru_minflt,
-        user_rusage.ru_majflt,
-        user_rusage.ru_nswap,
-        user_rusage.ru_inblock,
-        user_rusage.ru_oublock,
-        user_rusage.ru_msgsnd,
-        user_rusage.ru_msgrcv,
-        user_rusage.ru_nsignals,
-        user_rusage.ru_nvcsw,
-        user_rusage.ru_nivcsw
-    );
-    fflush(out);
-    fsync(fileno(out));
-    fclose(out);
-    if (rename(tmpfilename, spoolfilename) == -1)
-        die("%s: %m\n", spoolfilename);
+        FILE *out = fopen(tmpfilename, "w");
+        if (out == NULL)
+            goto retry_2;
+        if (fprintf(out,"1 %d %d %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld %ld\n",
+                getpid(),
+                user_status,
+                user_time.tv_sec, user_time.tv_usec,
+                user_rusage.ru_utime.tv_sec, user_rusage.ru_utime.tv_usec,
+                user_rusage.ru_stime.tv_sec, user_rusage.ru_stime.tv_usec,
+                user_rusage.ru_maxrss,
+                user_rusage.ru_ixrss,
+                user_rusage.ru_idrss,
+                user_rusage.ru_isrss,
+                user_rusage.ru_minflt,
+                user_rusage.ru_majflt,
+                user_rusage.ru_nswap,
+                user_rusage.ru_inblock,
+                user_rusage.ru_oublock,
+                user_rusage.ru_msgsnd,
+                user_rusage.ru_msgrcv,
+                user_rusage.ru_nsignals,
+                user_rusage.ru_nvcsw,
+                user_rusage.ru_nivcsw) < 0)
+            goto retry_3;
+        if (fflush(out) == EOF)
+            goto retry_3;
+        if (fsync(fileno(out)) == -1)
+            goto retry_3;
+        if (fclose(out) == EOF)
+            goto retry_2;
+        if (rename(tmpfilename, spoolfilename) == -1)
+            goto retry_2;
+        break;
+
+retry_3:
+        fclose(out);
+retry_2:
+        free(tmpfilename);
+retry_1:
+        sleep(10);
+    }
     return 0;
 }