source: vendor/bash/3.1/lib/sh/shquote.c

/* 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 2, 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; see the file COPYING.  If not, write to the Free Software
   Foundation, 59 Temple Place, Suite 330, Boston, MA 02111 USA. */

#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>

/* **************************************************************** */
/*                                                                  */
/*       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)
     char *string;
{
  register int c;
  char *result, *r, *s;

  result = (char *)xmalloc (3 + (4 * strlen (string)));
  r = 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)
     char *string;
{
  register unsigned char c;
  char *result, *r, *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. */
char *
sh_backslash_quote (string)
     char *string;
{
  int c;
  char *result, *r, *s;

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

  for (r = result, s = string; s && (c = *s); s++)
    {
      switch (c)
        {
        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 */
        case ',':                               /* brace expansion */
          *r++ = '\\';
          *r++ = c;
          break;
#if 0
        case '~':                               /* tilde expansion */
          if (s == string || s[-1] == '=' || s[-1] == ':')
            *r++ = '\\';
          *r++ = c;
          break;

        case CTLESC: case CTLNUL:               /* internal quoting characters */
          *r++ = CTLESC;                        /* could be '\\'? */
          *r++ = c;
          break;
#endif

        case '#':                               /* comment char */
          if (s == string)
            *r++ = '\\';
          /* FALLTHROUGH */
        default:
          *r++ = c;
          break;
        }
    }

  *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);
}