utmpdump: cleanup file descriptor usage

 - don't support --follow for stdin at all
 - inotify based implementation closes the file, so don't close it in
   main() again

Signed-off-by: Karel Zak <kzak@redhat.com>

diff --git a/login-utils/utmpdump.c b/login-utils/utmpdump.c
index a61dfa1a55bbfea9e2e1cd9a0f3ab3224ac7faf9..8af333a8033940013101fef1ef5a46f0a343537f 100644 (file)
--- a/login-utils/utmpdump.c
+++ b/login-utils/utmpdump.c
@@ -120,10 +120,8 @@ static void roll_file(const char *filename, off_t *size)
        if (fstat(fileno(fp), &st) == -1)
                err(EXIT_FAILURE, _("%s: stat failed"), filename);
 
-       if (st.st_size == *size) {
-               fclose(fp);
-               return;
-       }
+       if (st.st_size == *size)
+               goto done;
 
        if (fseek(fp, *size, SEEK_SET) != (off_t) -1) {
                while (fread(&ut, sizeof(ut), 1, fp) == 1)
@@ -137,6 +135,7 @@ static void roll_file(const char *filename, off_t *size)
         */
        *size = (pos != -1 && pos != *size) ? pos : st.st_size;
 
+done:
        fclose(fp);
 }
 
@@ -189,7 +188,7 @@ static int follow_by_inotify(FILE *fp, const char *filename)
 }
 #endif /* HAVE_INOTIFY_INIT */
 
-static void dump(FILE *fp, const char *filename, int follow)
+static FILE *dump(FILE *fp, const char *filename, int follow)
 {
        struct utmp ut;
 
@@ -200,9 +199,12 @@ static void dump(FILE *fp, const char *filename, int follow)
                print_utline(ut);
 
        if (!follow)
-               return;
+               return fp;
+
 #ifdef HAVE_INOTIFY_INIT
-       if (follow_by_inotify(fp, filename) != 0)
+       if (follow_by_inotify(fp, filename) == 0)
+               return NULL;                            /* file already closed */
+       else
 #endif
                /* fallback for systems without inotify or with non-free
                 * inotify instances */
@@ -211,6 +213,8 @@ static void dump(FILE *fp, const char *filename, int follow)
                                print_utline(ut);
                        sleep(1);
                }
+
+       return fp;
 }
 
 
@@ -295,8 +299,8 @@ static void __attribute__((__noreturn__)) usage(FILE *out)
 int main(int argc, char **argv)
 {
        int c;
-       FILE *fp;
-       int reverse = 0, forever = 0;
+       FILE *fp = NULL;
+       int reverse = 0, follow = 0;
        const char *filename = NULL;
 
        static const struct option longopts[] = {
@@ -319,7 +323,7 @@ int main(int argc, char **argv)
                        break;
 
                case 'f':
-                       forever = 1;
+                       follow = 1;
                        break;
 
                case 'h':
@@ -339,9 +343,9 @@ int main(int argc, char **argv)
                if (!fp)
                        err(EXIT_FAILURE, _("%s: open failed"), filename);
        } else {
+               if (follow)
+                       errx(EXIT_FAILURE, _("following standard input is unsupported"));
                filename = "/dev/stdin";
-               if (forever)
-                       warnx(_("warning: following standard input indefinitely is ineffective"));
                fp = stdin;
        }
 
@@ -350,10 +354,10 @@ int main(int argc, char **argv)
                undump(fp);
        } else {
                fprintf(stderr, _("Utmp dump of %s\n"), filename);
-               dump(fp, filename, forever);
+               fp = dump(fp, filename, follow);
        }
 
-       if (fp != stdin)
+       if (fp && fp != stdin)
                fclose(fp);
 
        return EXIT_SUCCESS;