Re: [PATCH] crc: New optimised slice-by-8 implementation

[Bruno Haible via Gnulib discussion list]

Simon Josefsson wrote:
> I added another patch (attached)

Time for me to add another tweak:
We prepend a "DO NOT EDIT" line to generated files. Some editors react to this
line by asking the user whether they really want to edit the file. At the same
time, this is less annoying than doing a "chmod a-w" of the file.


2024-10-31  Bruno Haible  <br...@clisp.org>

        crc: Tweak generator.
        * lib/crc-generate-table.c (print_header): Don't emit a blank line at
        the end.
        (print_copyright_notice): Prepend a "DO NOT EDIT" line.
        (main): Fail if disk is full after we wrote part of the file.

diff --git a/lib/crc-generate-table.c b/lib/crc-generate-table.c
index 01f9ff77ed..314bf000ee 100644
--- a/lib/crc-generate-table.c
+++ b/lib/crc-generate-table.c
@@ -94,12 +94,13 @@ print_header (FILE * stream)
         fprintf (stream, ",");
       fprintf (stream, "\n");
     }
-  fprintf (stream, "};\n\n");
+  fprintf (stream, "};\n");
 }
 
 void
 print_copyright_notice (FILE * stream)
 {
+  fprintf (stream, "/* DO NOT EDIT! GENERATED AUTOMATICALLY! */\n");
   fprintf (stream, "/* crc.c -- cyclic redundancy checks\n");
   fprintf (stream,
            "Copyright (C) 2005-2006, 2009-2024 Free Software Foundation, 
Inc.\n");
@@ -134,17 +135,23 @@ main (int argc, char *argv[])
       fprintf (stderr, " Usage: %s crc-sliceby8.h\n", argv[0]);
       exit (1);
     }
-  FILE *stream;
 
-  stream = fopen (argv[1], "w");
+  const char *filename = argv[1];
+  FILE *stream = fopen (filename, "w");
   if (stream == NULL)
     {
-      fprintf (stderr, "cannot open '%s' for writing\n", argv[1]);
+      fprintf (stderr, "cannot open '%s' for writing\n", filename);
       exit (1);
     }
 
   print_copyright_notice (stream);
   print_header (stream);
 
+  if (ferror (stream) || fclose (stream))
+    {
+      fprintf (stderr, "error writing to '%s'\n", filename);
+      exit (1);
+    }
+
   return 0;
 }