md5sum,sha*sum: fix --ignore-missing with checksums starting with 00

* NEWS: Mention the fix.
* src/md5sum.c (digest_file): Add a new MISSING parameter to
return whether the file was missing, separately from the digest.
* tests/misc/md5sum.pl: Add a test case.
Fixes http://bugs.gnu.org/24795

1 files changed, 12 insertions, 8 deletions

diff --git a/src/md5sum.c b/src/md5sum.c
index 5a39a4f05..6e85cb150 100644
--- a/src/md5sum.c
+++ b/src/md5sum.c
@@ -463,15 +463,19 @@ print_filename (char const *file, bool escape)
    text because it was a terminal.
 
    Put the checksum in *BIN_RESULT, which must be properly aligned.
+   Put true in *MISSING if the file can't be opened due to ENOENT.
    Return true if successful.  */
 
 static bool
-digest_file (const char *filename, int *binary, unsigned char *bin_result)
+digest_file (const char *filename, int *binary, unsigned char *bin_result,
+             bool *missing)
 {
   FILE *fp;
   int err;
   bool is_stdin = STREQ (filename, "-");
 
+  *missing = false;
+
   if (is_stdin)
     {
       have_read_stdin = true;
@@ -491,7 +495,7 @@ digest_file (const char *filename, int *binary, unsigned char *bin_result)
         {
           if (ignore_missing && errno == ENOENT)
             {
-              *bin_result = '\0';
+              *missing = true;
               return true;
             }
           error (0, errno, "%s", quotef (filename));
@@ -604,14 +608,14 @@ digest_check (const char *checkfile_name)
                                           '8', '9', 'a', 'b',
                                           'c', 'd', 'e', 'f' };
           bool ok;
+          bool missing;
           /* Only escape in the edge case producing multiple lines,
              to ease automatic processing of status output.  */
           bool needs_escape = ! status_only && strchr (filename, '\n');
 
           properly_formatted_lines = true;
 
-          *bin_buffer = '\1'; /* flag set to 0 for ignored missing files.  */
-          ok = digest_file (filename, &binary, bin_buffer);
+          ok = digest_file (filename, &binary, bin_buffer, &missing);
 
           if (!ok)
             {
@@ -624,10 +628,9 @@ digest_check (const char *checkfile_name)
                   printf (": %s\n", _("FAILED open or read"));
                 }
             }
-          else if (ignore_missing && ! *bin_buffer)
+          else if (ignore_missing && missing)
             {
-              /* Treat an empty buffer as meaning a missing file,
-                 which is ignored with --ignore-missing.  */
+              /* Ignore missing files with --ignore-missing.  */
               ;
             }
           else
@@ -878,8 +881,9 @@ main (int argc, char **argv)
       else
         {
           int file_is_binary = binary;
+          bool missing;
 
-          if (! digest_file (file, &file_is_binary, bin_buffer))
+          if (! digest_file (file, &file_is_binary, bin_buffer, &missing))
             ok = false;
           else
             {