lib/strutil/strescape.c

   1 /*
   2    Functions for escaping and unescaping strings
   3
   4    Copyright (C) 2009, 2011
   5    The Free Software Foundation, Inc.
   6
   7    Written by:
   8    Slava Zanko <slavazanko@gmail.com>, 2009;
   9    Patrick Winnertz <winnie@debian.org>, 2009
  10
  11    This file is part of the Midnight Commander.
  12
  13    The Midnight Commander is free software: you can redistribute it
  14    and/or modify it under the terms of the GNU General Public License as
  15    published by the Free Software Foundation, either version 3 of the License,
  16    or (at your option) any later version.
  17
  18    The Midnight Commander is distributed in the hope that it will be useful,
  19    but WITHOUT ANY WARRANTY; without even the implied warranty of
  20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  21    GNU General Public License for more details.
  22
  23    You should have received a copy of the GNU General Public License
  24    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  25  */
  26
  27 #include <config.h>
  28
  29 #include "lib/strescape.h"
  30
  31 /*** global variables ****************************************************************************/
  32
  33 /*** file scope macro definitions ****************************************************************/
  34
  35 /*** file scope type declarations ****************************************************************/
  36
  37 /*** file scope variables ************************************************************************/
  38
  39 static const char ESCAPE_SHELL_CHARS[] = " !#$%()&{}[]`?|<>;*\\\"'";
  40 static const char ESCAPE_REGEX_CHARS[] = "^!#$%()&{}[]`?|<>;*.\\";
  41 static const char ESCAPE_GLOB_CHARS[] = "$*\\?";
  42
  43 /*** file scope functions ************************************************************************/
  44
  45 /*** public functions ****************************************************************************/
  46
  47 char *
  48 strutils_escape (const char *src, gsize src_len, const char *escaped_chars,
  49                  gboolean escape_non_printable)
  50 {
  51     GString *ret;
  52     gsize curr_index;
  53     /* do NOT break allocation semantics */
  54     if (src == NULL)
  55         return NULL;
  56
  57     if (*src == '\0')
  58         return strdup ("");
  59
  60     ret = g_string_new ("");
  61
  62     if (src_len == (gsize) - 1)
  63         src_len = strlen (src);
  64
  65     for (curr_index = 0; curr_index < src_len; curr_index++)
  66     {
  67         if (escape_non_printable)
  68         {
  69             switch (src[curr_index])
  70             {
  71             case '\n':
  72                 g_string_append (ret, "\\n");
  73                 continue;
  74             case '\t':
  75                 g_string_append (ret, "\\t");
  76                 continue;
  77             case '\b':
  78                 g_string_append (ret, "\\b");
  79                 continue;
  80             case '\0':
  81                 g_string_append (ret, "\\0");
  82                 continue;
  83             }
  84         }
  85
  86         if (strchr (escaped_chars, (int) src[curr_index]))
  87             g_string_append_c (ret, '\\');
  88
  89         g_string_append_c (ret, src[curr_index]);
  90     }
  91     return g_string_free (ret, FALSE);
  92 }
  93
  94 /* --------------------------------------------------------------------------------------------- */
  95 char *
  96 strutils_unescape (const char *src, gsize src_len, const char *unescaped_chars,
  97                    gboolean unescape_non_printable)
  98 {
  99     GString *ret;
 100     gsize curr_index;
 101
 102     if (src == NULL)
 103         return NULL;
 104
 105     if (*src == '\0')
 106         return strdup ("");
 107
 108     ret = g_string_sized_new (16);
 109
 110     if (src_len == (gsize) (-1))
 111         src_len = strlen (src);
 112     src_len--;
 113
 114     for (curr_index = 0; curr_index < src_len; curr_index++)
 115     {
 116         if (src[curr_index] != '\\')
 117         {
 118             g_string_append_c (ret, src[curr_index]);
 119             continue;
 120         }
 121
 122         curr_index++;
 123
 124         if (unescaped_chars == ESCAPE_SHELL_CHARS && src[curr_index] == '$')
 125         {
 126             /* special case: \$ is used to disallow variable substitution */
 127             g_string_append_c (ret, '\\');
 128         }
 129         else
 130         {
 131             if (unescape_non_printable)
 132             {
 133                 switch (src[curr_index])
 134                 {
 135                 case 'n':
 136                     g_string_append_c (ret, '\n');
 137                     continue;
 138                 case 't':
 139                     g_string_append_c (ret, '\t');
 140                     continue;
 141                 case 'b':
 142                     g_string_append_c (ret, '\b');
 143                     continue;
 144                 case '0':
 145                     g_string_append_c (ret, '\0');
 146                     continue;
 147                 }
 148             }
 149
 150             if (strchr (unescaped_chars, (int) src[curr_index]) == NULL)
 151                 g_string_append_c (ret, '\\');
 152         }
 153
 154         g_string_append_c (ret, src[curr_index]);
 155     }
 156     g_string_append_c (ret, src[curr_index]);
 157
 158     return g_string_free (ret, FALSE);
 159 }
 160
 161 /* --------------------------------------------------------------------------------------------- */
 162
 163 /**
 164  * To be compatible with the general posix command lines we have to escape
 165  * strings for the command line
 166  *
 167  * @param src string for escaping
 168  *
 169  * @returns escaped string (which needs to be freed later) or NULL when NULL string is passed.
 170  */
 171
 172 char *
 173 strutils_shell_escape (const char *src)
 174 {
 175     return strutils_escape (src, -1, ESCAPE_SHELL_CHARS, FALSE);
 176 }
 177
 178 /* --------------------------------------------------------------------------------------------- */
 179
 180 char *
 181 strutils_glob_escape (const char *src)
 182 {
 183     return strutils_escape (src, -1, ESCAPE_GLOB_CHARS, TRUE);
 184 }
 185
 186 /* --------------------------------------------------------------------------------------------- */
 187
 188 char *
 189 strutils_regex_escape (const char *src)
 190 {
 191     return strutils_escape (src, -1, ESCAPE_REGEX_CHARS, TRUE);
 192 }
 193
 194 /* --------------------------------------------------------------------------------------------- */
 195
 196 /**
 197  * Unescape paths or other strings for e.g the internal cd
 198  * shell-unescape within a given buffer (writing to it!)
 199  *
 200  * @param text string for unescaping
 201  *
 202  * @returns unescaped string (which needs to be freed)
 203  */
 204
 205 char *
 206 strutils_shell_unescape (const char *text)
 207 {
 208     return strutils_unescape (text, -1, ESCAPE_SHELL_CHARS, TRUE);
 209 }
 210
 211 /* --------------------------------------------------------------------------------------------- */
 212
 213 char *
 214 strutils_glob_unescape (const char *text)
 215 {
 216     return strutils_unescape (text, -1, ESCAPE_GLOB_CHARS, TRUE);
 217 }
 218
 219 /* --------------------------------------------------------------------------------------------- */
 220 char *
 221 strutils_regex_unescape (const char *text)
 222 {
 223     return strutils_unescape (text, -1, ESCAPE_REGEX_CHARS, TRUE);
 224 }
 225
 226 /* --------------------------------------------------------------------------------------------- */
 227
 228 /**
 229  * Check if char in pointer contain escape'd chars
 230  *
 231  * @param start string for checking
 232  * @param current pointer to checked character
 233  *
 234  * @returns TRUE if string contain escaped chars otherwise return FALSE
 235  */
 236
 237 gboolean
 238 strutils_is_char_escaped (const char *start, const char *current)
 239 {
 240     int num_esc = 0;
 241
 242     if (start == NULL || current == NULL || current <= start)
 243         return FALSE;
 244
 245     current--;
 246     while (current >= start && *current == '\\')
 247     {
 248         num_esc++;
 249         current--;
 250     }
 251     return (gboolean) num_esc % 2;
 252 }
 253
 254 /* --------------------------------------------------------------------------------------------- */