The 'bitset' module accesses an undefined errno in two situations: 1) After calling fread() that reads fewer elements than requested, and after calling ferror(), the value of errno is undefined.[1][2] 2) After calling fclose() on native Windows, the value of errno is undefined. [3][4][5]
[1] https://pubs.opengroup.org/onlinepubs/9699919799/functions/fread.html [2] https://pubs.opengroup.org/onlinepubs/9699919799/functions/ferror.html [3] https://pubs.opengroup.org/onlinepubs/9699919799/functions/fclose.html [4] https://www.gnu.org/software/gnulib/manual/html_node/fclose.html [5] https://learn.microsoft.com/en-us/cpp/c-runtime-library/reference/fclose-fcloseall This patch fixes it. 2024-02-25 Bruno Haible <br...@clisp.org> bitset: Don't access errno when it's not set. * lib/bitset/stats.c (bitset_stats_read): Don't use errno after neither fread() nor ferror() has set it. On native Windows, don't use errno after fclose(). diff --git a/lib/bitset/stats.c b/lib/bitset/stats.c index 5c40fc9466..c06a450f7c 100644 --- a/lib/bitset/stats.c +++ b/lib/bitset/stats.c @@ -261,12 +261,19 @@ bitset_stats_read (const char *file_name) 1, file) != 1) { if (ferror (file)) - perror (_("cannot read stats file")); + fprintf (stderr, "%s\n", _("cannot read stats file")); else fprintf (stderr, "%s\n", _("bad stats file size")); } if (fclose (file) != 0) - perror (_("cannot read stats file")); + { +#if defined _WIN32 && !defined __CYGWIN__ + fprintf (stderr, "%s\n", _("cannot read stats file")); +#else + /* fclose() sets errno. */ + perror (_("cannot read stats file")); +#endif + } } bitset_stats_info_data.runs++; }
