Re: [PATCH 10/23] getopt.3: Further clarification of optstring

["Alejandro Colomar (man-pages)" <alx.manpages@xxxxxxxxx>]

Hi Michael,

On 8/9/21 12:11 AM, Michael Kerrisk (man-pages) wrote:
> Thanks. The patch is good and I applied it
>
> @James: it would be helpful to explain in the commit
> message how you verified these details.
>
> @Alex: do not be shy of asking people to improve there commit
> messages in this way :-).

Yes, I should :-)


> See my modified commit message below.
>
> Cheers,
>
> Michael
>
>      getopt.3: Further clarification of optstring
>      
>      Explain that `optstring` cannot contain a semi-colon (`;`)
>      character.
>      [mtk: verfiried with a small test program; see also posix/getopt.c
>      in the glibc sources:
>      
>          if (temp == NULL || c == ':' || c == ';')
>            {
>              if (print_errors)
>                fprintf (stderr, _("%s: invalid option -- '%c'\n"), argv[0], c);
>              d->optopt = c;
>              return '?';
>            }
>      ]
>      
>      Also explain that `optstring` can include `+` as an option
>      character, possibly in addition to that character being used as
>      the first character in `optstring` to denote `POSIXLY_CORRECT`
>      behaviour.
>      [mtk: verified with a small test program.]
>      
>      Test program below. Example runs:
>      
>      $ ./a.out -+
>      opt = 43 (+); optind = 2
>      Got plus
>      $ ./a.out -';'
>      ./a.out: invalid option -- ';'
>      opt = 63 (?); optind = 2; optopt = 59 (;)
>      Unrecognized option (-;)
>      Usage: ./a.out [-p arg] [-x]
>      
>      Signed-off-by: James O. D. Hunt <jamesodhunt@xxxxxxxxx>
>      Signed-off-by: Alejandro Colomar <alx.manpages@xxxxxxxxx>
>      Signed-off-by: Michael Kerrisk <mtk.manpages@xxxxxxxxx>
>      
>      8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---8x---
>      #include <ctype.h>
>      #include <sys/types.h>
>      #include <stdio.h>
>      #include <stdlib.h>
>      #include <unistd.h>
>      
>      #define printable(ch) (isprint((unsigned char) ch) ? ch : '#')
>      
>      static void             /* Print "usage" message and exit */
>      usageError(char *progName, char *msg, int opt)
>      {
>          if (msg != NULL && opt != 0)
>              fprintf(stderr, "%s (-%c)\n", msg, printable(opt));
>          fprintf(stderr, "Usage: %s [-p arg] [-x]\n", progName);
>          exit(EXIT_FAILURE);
>      }
>      
>      int
>      main(int argc, char *argv[])
>      {
>          int opt, xfnd;
>          char *pstr;
>      
>          xfnd = 0;
>          pstr = NULL;
>      
>          while ((opt = getopt(argc, argv, "p:x+;")) != -1) {
>              printf("opt =%3d (%c); optind = %d", opt, printable(opt), optind);
>              if (opt == '?' || opt == ':')
>                  printf("; optopt =%3d (%c)", optopt, printable(optopt));
>              printf("\n");
>      
>              switch (opt) {
>              case 'p': pstr = optarg;                break;
>              case 'x': xfnd++;                       break;
>              case ';': printf("Got semicolon\n");    break;
>              case '+': printf("Got plus\n"); break;
>              case ':': usageError(argv[0], "Missing argument", optopt);
>              case '?': usageError(argv[0], "Unrecognized option", optopt);
>              default:
>                        printf("Unexpected case in switch()\n");
>                        exit(EXIT_FAILURE);
>              }
>          }
>
>          if (xfnd != 0)
>              printf("-x was specified (count=%d)\n", xfnd);
>          if (pstr != NULL)
>              printf("-p was specified with the value \"%s\"\n", pstr);
>          if (optind < argc)
>              printf("First nonoption argument is \"%s\" at argv[%d]\n",
>                      argv[optind], optind);
>          exit(EXIT_SUCCESS);
>      }

Nice!

Thanks,

Alex


--
Alejandro Colomar
Linux man-pages comaintainer; https://www.kernel.org/doc/man-pages/
http://www.alejandro-colomar.es/