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From: "Michael Kerrisk (man-pages)" <mtk.manpages@gmail.com>
To: Alejandro Colomar <alx.manpages@gmail.com>
Cc: mtk.manpages@gmail.com,
	"James O. D. Hunt" <jamesodhunt@gmail.com>,
	linux-man@vger.kernel.org
Subject: Re: [PATCH 10/23] getopt.3: Further clarification of optstring
Date: Mon, 9 Aug 2021 00:11:37 +0200	[thread overview]
Message-ID: <eb5b8342-f6b6-86a2-7d0d-f7729996b128@gmail.com> (raw)
In-Reply-To: <20210808084133.734274-11-alx.manpages@gmail.com>

Hello James and Alex,

On 8/8/21 10:41 AM, Alejandro Colomar wrote:
> From: "James O. D. Hunt" <jamesodhunt@gmail.com>
> 
> Explain that `optstring` cannot contain a semi-colon (`;`) character.
> 
> 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.
> 
> Signed-off-by: James O. D. Hunt <jamesodhunt@gmail.com>
> Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
> ---
>  man3/getopt.3 | 10 +++++++++-
>  1 file changed, 9 insertions(+), 1 deletion(-)
> 
> diff --git a/man3/getopt.3 b/man3/getopt.3
> index ce4c28088..315224c64 100644
> --- a/man3/getopt.3
> +++ b/man3/getopt.3
> @@ -130,7 +130,7 @@ A legitimate option character is any visible one byte
>  .BR ascii (7)
>  character (for which
>  .BR isgraph (3)
> -would return nonzero) that is not \(aq\-\(aq or \(aq:\(aq.
> +would return nonzero) that is not \(aq\-\(aq, \(aq:\(aq  or \(aq;\(aq.
>  If such a
>  character is followed by a colon, the option requires an argument, so
>  .BR getopt ()
> @@ -166,6 +166,14 @@ If the first character of
>  .B POSIXLY_CORRECT
>  is set, then option processing stops as soon as a nonoption argument is
>  encountered.
> +If \(aq+\(aq is not the first character of
> +.IR optstring ,
> +it is treated as a normal option.
> +If
> +.B POSIXLY_CORRECT
> +behaviour is required in this case
> +.I optstring
> +will contain two \(aq+\(aq symbols.
>  If the first character of \fIoptstring\fP is \(aq\-\(aq, then
>  each nonoption \fIargv\fP-element is handled as if it were the argument of
>  an option with character code 1.  (This is used by programs that were

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 :-).

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@gmail.com>
    Signed-off-by: Alejandro Colomar <alx.manpages@gmail.com>
    Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>
    
    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);
    }

-- 
Michael Kerrisk
Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/
Linux/UNIX System Programming Training: http://man7.org/training/

  reply	other threads:[~2021-08-08 22:11 UTC|newest]

Thread overview: 60+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2021-08-08  8:41 [PATCH 00/23] More patches from others Alejandro Colomar
2021-08-08  8:41 ` [PATCH 01/23] pipe.7: also mention writev(2) in atomicity section Alejandro Colomar
2021-08-08 13:20   ` Alejandro Colomar (man-pages)
2021-08-08 20:06     ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 02/23] sigaction.2: Document SA_EXPOSE_TAGBITS and the flag support detection protocol Alejandro Colomar
2021-08-09  0:29   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 03/23] sigaction.2: Apply minor tweaks to Peter's patch Alejandro Colomar
2021-08-09  0:34   ` Michael Kerrisk (man-pages)
2021-08-09  6:36     ` Alejandro Colomar (man-pages)
2021-08-08  8:41 ` [PATCH 04/23] namespaces.7: ffix Alejandro Colomar
2021-08-08 20:08   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 05/23] unix.7: tfix Alejandro Colomar
2021-08-08 20:23   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 06/23] futex.2: Document FUTEX_LOCK_PI2 Alejandro Colomar
2021-08-09  0:06   ` Michael Kerrisk (man-pages)
2021-08-09  8:14     ` Kurt Kanzenbach
2021-08-09  9:01       ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 07/23] futex.2: Minor tweaks to Kurt's patch Alejandro Colomar
2021-08-09  0:05   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 08/23] man2: new page describing memfd_secret() system call Alejandro Colomar
2021-08-09  2:00   ` Michael Kerrisk (man-pages)
2021-08-10  8:53     ` Mike Rapoport
2021-08-08  8:41 ` [PATCH 09/23] termios.3: Document missing baudrate constants Alejandro Colomar
2021-08-08 20:30   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 10/23] getopt.3: Further clarification of optstring Alejandro Colomar
2021-08-08 22:11   ` Michael Kerrisk (man-pages) [this message]
2021-08-09  6:40     ` Alejandro Colomar (man-pages)
2021-08-08  8:41 ` [PATCH 11/23] getopt.3: Minor tweak to James's patch Alejandro Colomar
2021-08-08 22:12   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 12/23] termios.3: Use bold style for Bnn and EXTn macro constants Alejandro Colomar
2021-08-08 20:31   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 13/23] ioctl_tty.2: Document ioctls: TCGETS2, TCSETS2, TCSETSW2, TCSETSF2 Alejandro Colomar
2021-08-08 20:37   ` Michael Kerrisk (man-pages)
2021-08-08 20:56   ` Michael Kerrisk (man-pages)
2021-08-08 21:15     ` Pali Rohár
2021-08-08 21:30       ` Michael Kerrisk (man-pages)
2021-08-10 19:11     ` Pali Rohár
2021-08-10 20:40       ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 14/23] ioctl_tty.2: Update DTR example Alejandro Colomar
2021-08-08 20:12   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 15/23] termios.3: Add information how to set baud rate to any other value Alejandro Colomar
2021-08-08 20:34   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 16/23] man-pages.7: wfix Alejandro Colomar
2021-08-08 20:09   ` Michael Kerrisk (man-pages)
2021-10-17 19:42   ` Alejandro Colomar (man-pages)
2021-08-08  8:41 ` [PATCH 17/23] termios.3: ffix Alejandro Colomar
2021-08-08 20:35   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 18/23] termios.3: SPARC architecture has 4 different Bnnn constants Alejandro Colomar
2021-08-08 20:36   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 19/23] regex.3: wfix Alejandro Colomar
2021-08-08 20:11   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 20/23] mount_setattr.2: New manual page documenting the mount_setattr() system call Alejandro Colomar
2021-08-10  1:34   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 21/23] mount_setattr.2: Minor tweaks to Chirstian's patch Alejandro Colomar
2021-08-10  1:35   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 22/23] ldd.1: Fix example command Alejandro Colomar
2021-08-08 22:32   ` Michael Kerrisk (man-pages)
2021-08-08  8:41 ` [PATCH 23/23] close_range.2: Glibc added a wrapper recently Alejandro Colomar
2021-08-08 20:58   ` Michael Kerrisk (man-pages)
2021-08-10  1:39 ` [PATCH 00/23] More patches from others Michael Kerrisk (man-pages)

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