[pfbtops]: Fix code style and diagnostic nits.

* src/utils/pfbtops/pfbtops.c (error): Exit with `EXIT_FAILURE` status
  (from standard C library) instead of status 2.

  (main): Exit with `EXIT_SUCCESS` status when writing version or help
  information.  Exit with status 2 when dying due to usage error.  Use
  `fprintf()` and `strerror()` to construct error message when dying due
  to inability to open input file instead of using `perror()`, which
  anonymizes its caller and thus should never be used in serious work.
  Avoid it like `gets()`.

* NEWS: Add item for exit status changes.

Continues the long process of fixing Savannah #52463.

Also update editor aid comments.

1 files changed, 21 insertions, 11 deletions

diff --git a/src/utils/pfbtops/pfbtops.c b/src/utils/pfbtops/pfbtops.c
index 81edee422..8fbe44a79 100644
--- a/src/utils/pfbtops/pfbtops.c
+++ b/src/utils/pfbtops/pfbtops.c
@@ -24,8 +24,10 @@ along with this program.  If not, see <http://www.gnu.org/licenses/>. */
 
 #define __GETOPT_PREFIX groff_
 
+#include <errno.h> // errno
 #include <stdio.h>
-#include <stdlib.h>
+#include <stdlib.h> // exit(), EXIT_FAILURE, EXIT_SUCCESS
+#include <string.h> // strerror()
 #include <limits.h>
 
 #include <getopt.h>
@@ -43,8 +45,8 @@ static char *program_name;
 
 static void error(const char *s)
 {
-  fprintf(stderr, "%s: %s\n", program_name, s);
-  exit(2);
+  fprintf(stderr, "%s: error: %s\n", program_name, s);
+  exit(EXIT_FAILURE);
 }
 
 static void usage(FILE *stream)
@@ -181,26 +183,28 @@ int main(int argc, char **argv)
     switch (opt) {
     case 'v':
       printf("GNU pfbtops (groff) version %s\n", Version_string);
-      exit(0);
+      exit(EXIT_SUCCESS);
       break;
     case CHAR_MAX + 1: /* --help */
       usage(stdout);
-      exit(0);
+      exit(EXIT_SUCCESS);
       break;
     case '?':
       usage(stderr);
-      exit(1);
+      exit(2);
       break;
     }
   }
 
   if (argc - optind > 1) {
     usage(stderr);
-    exit(1);
+    exit(2);
   }
-  if (argc > optind && !freopen(argv[optind], "r", stdin)) {
-    perror(argv[optind]);
-    exit(1);
+  const char *file = argv[optind];
+  if (argc > optind && !freopen(file, "r", stdin)) {
+    fprintf(stderr, "%s: error: unable to open file '%s': %s\n",
+	    program_name, file, strerror(errno));
+    exit(EXIT_FAILURE);
   }
   SET_BINARY(fileno(stdin));
   for (;;) {
@@ -229,5 +233,11 @@ int main(int argc, char **argv)
     else
       get_binary(n);
   }
-  exit(0);
+  exit(EXIT_SUCCESS);
 }
+
+// Local Variables:
+// fill-column: 72
+// mode: C
+// End:
+// vim: set cindent noexpandtab shiftwidth=2 textwidth=72: