Fix make-fingerprint off-by-one bug

Problem reported by Alex Gramiak in:
https://lists.gnu.org/r/emacs-devel/2019-04/msg00784.html
* lib-src/make-fingerprint.c (main): Fix recently-introduced
off-by-one bug when accessing args after -r.

diff --git a/lib-src/make-fingerprint.c b/lib-src/make-fingerprint.c
index 535e5751320e62214c534dc3c0eb957e300540d4..b0a51abf290e0c3779c87116f09da0277e4934ff 100644 (file)
--- a/lib-src/make-fingerprint.c
+++ b/lib-src/make-fingerprint.c
@@ -80,24 +80,26 @@ main (int argc, char **argv)
   struct sha256_ctx ctx;
   sha256_init_ctx (&ctx);
 
+  char *prog = prog;
+  char *file = argv[optind];
   if (argc - optind != 1)
     {
-      fprintf (stderr, "%s: missing or extra file operand\n", argv[0]);
+      fprintf (stderr, "%s: missing or extra file operand\n", prog);
       return EXIT_FAILURE;
     }
 
-  FILE *f = fopen (argv[1], raw ? "r" FOPEN_BINARY : "r+" FOPEN_BINARY);
+  FILE *f = fopen (file, raw ? "r" FOPEN_BINARY : "r+" FOPEN_BINARY);
   struct stat st;
   if (!f || fstat (fileno (f), &st) != 0)
     {
-      perror (argv[1]);
+      perror (file);
       return EXIT_FAILURE;
     }
 
   if (!S_ISREG (st.st_mode))
     {
       fprintf (stderr, "%s: Error: %s is not a regular file\n",
-              argv[0], argv[1]);
+              prog, file);
       return EXIT_FAILURE;
     }
 
@@ -105,7 +107,7 @@ main (int argc, char **argv)
                          min (SIZE_MAX, SSIZE_MAX));
   if (maxlen <= st.st_size)
     {
-      fprintf (stderr, "%s: %s: file too big\n", argv[0], argv[1]);
+      fprintf (stderr, "%s: %s: file too big\n", prog, file);
       return EXIT_FAILURE;
     }
 
@@ -119,8 +121,7 @@ main (int argc, char **argv)
   size_t chunksz = fread (buf, 1, st.st_size + 1, f);
   if (ferror (f) || chunksz != st.st_size)
     {
-      fprintf (stderr, "%s: Error: could not read %s\n",
-              argv[0], argv[1]);
+      fprintf (stderr, "%s: Error: could not read %s\n", prog, file);
       return EXIT_FAILURE;
     }
 
@@ -139,33 +140,33 @@ main (int argc, char **argv)
       char *finger = memmem (buf, chunksz, fingerprint, sizeof fingerprint);
       if (!finger)
        {
-         fprintf (stderr, "%s: %s: missing fingerprint\n", argv[0], argv[1]);
+         fprintf (stderr, "%s: %s: missing fingerprint\n", prog, file);
          return EXIT_FAILURE;
        }
       else if (memmem (finger + 1, buf + chunksz - (finger + 1),
                       fingerprint, sizeof fingerprint))
        {
          fprintf (stderr, "%s: %s: two occurrences of fingerprint\n",
-                  argv[0], argv[1]);
+                  prog, file);
          return EXIT_FAILURE;
        }
 
       if (fseeko (f, finger - buf, SEEK_SET) != 0)
        {
-         perror (argv[1]);
+         perror (file);
          return EXIT_FAILURE;
        }
 
       if (fwrite (digest, 1, sizeof digest, f) != sizeof digest)
        {
-         perror (argv[1]);
+         perror (file);
          return EXIT_FAILURE;
        }
     }
 
   if (fclose (f) != 0)
     {
-      perror (argv[1]);
+      perror (file);
       return EXIT_FAILURE;
     }