lib/sh/shquote.c

/* shquote - functions to quote and dequote strings */

/* Copyright (C) 1999 Free Software Foundation, Inc.

   This file is part of GNU Bash, the Bourne Again SHell.

   Bash 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 3 of the License, or
   (at your option) any later version.

   Bash 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 Bash.  If not, see <http://www.gnu.org/licenses/>.
*/

#include <config.h>

#if defined (HAVE_UNISTD_H)
#  ifdef _MINIX
#    include <sys/types.h>
#  endif
#  include <unistd.h>
#endif

#include <stdio.h>

#include "syntax.h"
#include <xmalloc.h>

/* Default set of characters that should be backslash-quoted in strings */
static const char bstab[256] =
  {
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 1, 1, 0, 0, 0, 0, 0,	/* TAB, NL */
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,

    1, 1, 1, 0, 1, 0, 1, 1,	/* SPACE, !, DQUOTE, DOL, AMP, SQUOTE */
    1, 1, 1, 0, 1, 0, 0, 0,	/* LPAR, RPAR, STAR, COMMA */
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1, 1, 0, 1, 1,	/* SEMI, LESSTHAN, GREATERTHAN, QUEST */

    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1, 1, 1, 1, 0,	/* LBRACK, BS, RBRACK, CARAT */

    1, 0, 0, 0, 0, 0, 0, 0,	/* BACKQ */
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 1, 1, 1, 0, 0,	/* LBRACE, BAR, RBRACE */

    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,

    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,

    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,

    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
    0, 0, 0, 0, 0, 0, 0, 0,
  };

/* **************************************************************** */
/*								    */
/*	 Functions for quoting strings to be re-read as input	    */
/*								    */
/* **************************************************************** */

/* Return a new string which is the single-quoted version of STRING.
   Used by alias and trap, among others. */
char *
sh_single_quote (string)
     const char *string;
{
  register int c;
  char *result, *r;
  const char *s;

  result = (char *)xmalloc (3 + (4 * strlen (string)));
  r = result;

  if (string[0] == '\'' && string[1] == 0)
    {
      *r++ = '\\';
      *r++ = '\'';
      *r++ = 0;
      return result;
    }

  *r++ = '\'';

  for (s = string; s && (c = *s); s++)
    {
      *r++ = c;

      if (c == '\'')
	{
	  *r++ = '\\';	/* insert escaped single quote */
	  *r++ = '\'';
	  *r++ = '\'';	/* start new quoted string */
	}
    }

  *r++ = '\'';
  *r = '\0';

  return (result);
}

/* Quote STRING using double quotes.  Return a new string. */
char *
sh_double_quote (string)
     const char *string;
{
  register unsigned char c;
  char *result, *r;
  const char *s;

  result = (char *)xmalloc (3 + (2 * strlen (string)));
  r = result;
  *r++ = '"';

  for (s = string; s && (c = *s); s++)
    {
      /* Backslash-newline disappears within double quotes, so don't add one. */
      if ((sh_syntaxtab[c] & CBSDQUOTE) && c != '\n')
	*r++ = '\\';
      else if (c == CTLESC || c == CTLNUL)
	*r++ = CTLESC;		/* could be '\\'? */

      *r++ = c;
    }

  *r++ = '"';
  *r = '\0';

  return (result);
}

/* Turn S into a simple double-quoted string.  If FLAGS is non-zero, quote
   double quote characters in S with backslashes. */
char *
sh_mkdoublequoted (s, slen, flags)
     const char *s;
     int slen, flags;
{
  char *r, *ret;
  int rlen;

  rlen = (flags == 0) ? slen + 3 : (2 * slen) + 1;
  ret = r = (char *)xmalloc (rlen);
  
  *r++ = '"';
  while (*s)
    {
      if (flags && *s == '"')
	*r++ = '\\';
      *r++ = *s++;
    }
  *r++ = '"';
  *r = '\0';

  return ret;
}

/* Remove backslashes that are quoting characters that are special between
   double quotes.  Return a new string.  XXX - should this handle CTLESC
   and CTLNUL? */
char *
sh_un_double_quote (string)
     char *string;
{
  register int c, pass_next;
  char *result, *r, *s;

  r = result = (char *)xmalloc (strlen (string) + 1);

  for (pass_next = 0, s = string; s && (c = *s); s++)
    {
      if (pass_next)
	{
	  *r++ = c;
	  pass_next = 0;
	  continue;
	}
      if (c == '\\' && (sh_syntaxtab[(unsigned char) s[1]] & CBSDQUOTE))
	{
	  pass_next = 1;
	  continue;
	}
      *r++ = c;
    }

  *r = '\0';
  return result;
}

/* Quote special characters in STRING using backslashes.  Return a new
   string.  NOTE:  if the string is to be further expanded, we need a
   way to protect the CTLESC and CTLNUL characters.  As I write this,
   the current callers will never cause the string to be expanded without
   going through the shell parser, which will protect the internal
   quoting characters.  TABLE, if set, points to a map of the ascii code
   set with char needing to be backslash-quoted if table[char]==1.  FLAGS,
   if 1, causes tildes to be quoted as well. */
   
char *
sh_backslash_quote (string, table, flags)
     char *string;
     char *table;
     int flags;
{
  int c;
  char *result, *r, *s, *backslash_table;

  result = (char *)xmalloc (2 * strlen (string) + 1);

  backslash_table = table ? table : (char *)bstab;
  for (r = result, s = string; s && (c = *s); s++)
    {
      if (backslash_table[c] == 1)
	*r++ = '\\';
      else if (c == '#' && s == string)			/* comment char */
	*r++ = '\\';
      else if ((flags&1) && c == '~' && (s == string || s[-1] == ':' || s[-1] == '='))
        /* Tildes are special at the start of a word or after a `:' or `='
	   (technically unquoted, but it doesn't make a difference in practice) */
	*r++ = '\\';
      *r++ = c;
    }

  *r = '\0';
  return (result);
}

#if defined (PROMPT_STRING_DECODE)
/* Quote characters that get special treatment when in double quotes in STRING
   using backslashes.  Return a new string. */
char *
sh_backslash_quote_for_double_quotes (string)
     char *string;
{
  unsigned char c;
  char *result, *r, *s;

  result = (char *)xmalloc (2 * strlen (string) + 1);

  for (r = result, s = string; s && (c = *s); s++)
    {
      if (sh_syntaxtab[c] & CBSDQUOTE)
	*r++ = '\\';
      /* I should probably add flags for these to sh_syntaxtab[] */
      else if (c == CTLESC || c == CTLNUL)
	*r++ = CTLESC;		/* could be '\\'? */

      *r++ = c;
    }

  *r = '\0';
  return (result);
}
#endif /* PROMPT_STRING_DECODE */

int
sh_contains_shell_metas (string)
     char *string;
{
  char *s;

  for (s = string; s && *s; s++)
    {
      switch (*s)
	{
	case ' ': case '\t': case '\n':		/* IFS white space */
	case '\'': case '"': case '\\':		/* quoting chars */
	case '|': case '&': case ';':		/* shell metacharacters */
	case '(': case ')': case '<': case '>':
	case '!': case '{': case '}':		/* reserved words */
	case '*': case '[': case '?': case ']':	/* globbing chars */
	case '^':
	case '$': case '`':			/* expansion chars */
	  return (1);
	case '~':				/* tilde expansion */
	  if (s == string || s[-1] == '=' || s[-1] == ':')
	    return (1);
	  break;
	case '#':
	  if (s == string)			/* comment char */
	    return (1);
	  /* FALLTHROUGH */
	default:
	  break;
	}
    }

  return (0);
}

int
sh_contains_quotes (string)
     char *string;
{
  char *s;

  for (s = string; s && *s; s++)
    {
      if (*s == '\'' || *s == '"' || *s == '\\')
	return 1;
    }
  return 0;
}