[Bug-gnulib] addition: sh-quote.c

[Bruno Haible]

Hi all,

While I intend to commit 'pipe' in a few days, here is another module
needed for spawning subprocesses. Quoting arguments for passing them
through /bin/sh. In gettext I'm making two uses of this module:

  - for passing arguments to multiword commands, such as $BROWSER or
    $EDITOR. ($BROWSER = "kfmclient openProfile webbrowsing",
    $EDITOR = "emacs -nw"). These are best called through /bin/sh,
    and the arguments passed to them must be quoted properly, in case
    they contain a space or similar.

  - for verbose display of commands executed through execv(), so that
    the user has a chance to copy&paste them into his shell and retry
    them if something goes wrong.

Similar stuff is already contained in clisp, groff and probably many
other programs.

Comments?

Bruno

============================== modules/sh-quote ==============================
Description:
Shell quoting.

Files:
lib/sh-quote.h
lib/sh-quote.c

Depends-on:
strpbrk
xalloc

configure.ac:

Makefile.am:
lib_SOURCES += sh-quote.h sh-quote.c

Include:
"sh-quote.h"

Maintainer:
Bruno Haible
============================== sh-quote.h ==============================
/* Shell quoting.
   Copyright (C) 2001-2002 Free Software Foundation, Inc.
   Written by Bruno Haible <address@hidden>, 2001.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

/* When passing a command to a shell, we must quote the program name and
   arguments, since Unix shells interpret characters like " ", "'", "<", ">",
   "$" etc. in a special way.  */

#include <stddef.h>

/* Returns the number of bytes needed for the quoted string.  */
extern size_t shell_quote_length (const char *string);

/* Copies the quoted string to p and returns the incremented p.  */
extern char * shell_quote_copy (char *p, const char *string);

/* Returns the freshly allocated quoted string.  */
extern char * shell_quote (const char *string);

/* Returns a freshly allocated string containing all argument strings, quoted,
   separated through spaces.  */
extern char * shell_quote_argv (char **argv);
============================== sh-quote.c ==============================
/* Shell quoting.
   Copyright (C) 2001-2003 Free Software Foundation, Inc.
   Written by Bruno Haible <address@hidden>, 2001.

   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2, or (at your option)
   any later version.

   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software Foundation,
   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif

/* Specification.  */
#include "sh-quote.h"

#include <string.h>

#include "strpbrk.h"
#include "xalloc.h"


/* Must quote the program name and arguments since Unix shells interpret
   characters like " ", "'", "<", ">", "$" etc. in a special way.  This
   kind of quoting should work unless the string contains "\n" and we call
   csh.  But we are lucky: only /bin/sh will be used.  */

#define SHELL_SPECIAL_CHARS "\t\n !\"#$&'()*;<=>?[\\]`{|}~"

/* Returns the number of bytes needed for the quoted string.  */
size_t
shell_quote_length (const char *string)
{
  if (string[0] == '\0')
    return 2;
  else if (strpbrk (string, SHELL_SPECIAL_CHARS) == NULL)
    return strlen (string);
  else
    {
      char qchar = '\0';        /* last quote character: none or ' or " */
      size_t length = 0;

      for (; *string != '\0'; string++)
        {
          char c = *string;
          char q = (c == '\'' ? '"' : '\'');

          if (qchar != q)
            {
              if (qchar)
                length++;
              qchar = q;
              length++;
            }
          length++;
        }
      if (qchar)
        length++;

      return length;
    }
}

/* Copies the quoted string to p and returns the incremented p.  */
char *
shell_quote_copy (char *p, const char *string)
{
  if (string[0] == '\0')
    {
      memcpy (p, "''", 2);
      return p + 2;
    }
  else if (strpbrk (string, SHELL_SPECIAL_CHARS) == NULL)
    {
      memcpy (p, string, strlen (string));
      return p + strlen (string);
    }
  else
    {
      char qchar = '\0';        /* last quote character: none or ' or " */

      for (; *string != '\0'; string++)
        {
          char c = *string;
          char q = (c == '\'' ? '"' : '\'');

          if (qchar != q)
            {
              if (qchar)
                *p++ = qchar;
              qchar = q;
              *p++ = qchar;
            }
          *p++ = c;
        }
      if (qchar)
        *p++ = qchar;

      return p;
    }
}

/* Returns the freshly allocated quoted string.  */
char *
shell_quote (const char *string)
{
  size_t length = shell_quote_length (string);
  char *quoted = (char *) xmalloc (length + 1);
  char *p = shell_quote_copy (quoted, string);
  *p = '\0';
  return quoted;
}

/* Returns a freshly allocated string containing all argument strings, quoted,
   separated through spaces.  */
char *
shell_quote_argv (char **argv)
{
  if (*argv != NULL)
    {
      char **argp;
      size_t length;
      char *command;
      char *p;

      length = 0;
      for (argp = argv; ; )
        {
          length += shell_quote_length (*argp) + 1;
          argp++;
          if (*argp == NULL)
            break;
        }

      command = (char *) xmalloc (length);

      p = command;
      for (argp = argv; ; )
        {
          p = shell_quote_copy (p, *argp);
          argp++;
          if (*argp == NULL)
            break;
          *p++ = ' ';
        }
      *p = '\0';

      return command;
    }
  else
    return xstrdup ("");
}