144 lines
4.3 KiB
C
144 lines
4.3 KiB
C
/*
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* Copyright (c) 1995-2013 Peter Simons <simons@cryp.to>
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* Copyright (c) 2000-2001 Cable & Wireless GmbH
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* Copyright (c) 1999-2000 CyberSolutions GmbH
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*
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* This program is free software: you can redistribute it and/or modify it under
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* the terms of the GNU General Public License as published by the Free Software
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* Foundation, either version 3 of the License, or (at your option) any later
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* version.
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*
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* This program is distributed in the hope that it will be useful, but WITHOUT
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* ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
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* FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
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* details.
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*
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* You should have received a copy of the GNU General Public License along with
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* this program. If not, see <http://www.gnu.org/licenses/>.
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*/
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#include <sys/types.h>
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#include <regex.h>
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#include "text.h"
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#ifndef MAX_TRANSFORM_ELEMENTS
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# define MAX_TRANSFORM_ELEMENTS 10
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#endif
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/* Do text-transformations using regular expressions.
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TransformText() is an easy interface to the regular expression
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routines included in most Unix kernels. It allows you to use text
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manipulation and replacing operations with a grace similar to
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sed(1) and perl(1).
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The regular expression language is described in the re_format(2)
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man file in great detail.
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RETURNS: TransformText() will return one of the following codes,
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indicating the success or failure of the transformation:
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TEXT_REGEX_OK: Success.
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TEXT_REGEX_ERROR: This error occurs if TransformText() failed to
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compile the given regular expression or if the regular expression
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didn't specify any submatches -- what is syntactically correct, but
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useless for this routine.
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TEXT_REGEX_TRANSFORM_DIDNT_MATCH: This returncode indicates that
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the provided regular expression did not match the text buffer.
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EXAMPLE:
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The following call will remove all whitespace at the begining and
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the end of the string contained in 'buf' and place the result back
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in the same variable:
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TransformText(buf, buf, "^[\t ]*(.*)[\t ]*$", "\\\\1");
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This practice is safe in this case, because the result string is
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guaranteed to be of equal length of shorter than the original. If
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this is not the case you must use a seperate target buffer or you
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will mess your string and buffers up badly.
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AUTHOR: Peter Simons <simons@rhein.de>
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*/
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int
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text_transform_text(char * dst_buffer, /* Where to save the resulting string. */
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const char * src_buffer, /* Text to transform. */
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const char * regex, /* Regex to describe what matches. */
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const char * rule) /* How the result should look. */
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{
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regex_t preg;
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regmatch_t pmatch[MAX_TRANSFORM_ELEMENTS];
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char error_msg[256];
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int rc;
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unsigned int i, j;
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const char * src_p;
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char * dst_p;
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/* Compile the regular expression. */
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rc = regcomp(&preg, regex, REG_EXTENDED | REG_ICASE);
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if (rc != 0) {
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regfree(&preg);
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return TEXT_REGEX_ERROR;
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}
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if (preg.re_nsub <= 0) {
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regfree(&preg);
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return TEXT_REGEX_ERROR;
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}
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/* Build the matching array. */
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rc = regexec(&preg, src_buffer, MAX_TRANSFORM_ELEMENTS, pmatch, 0);
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if (rc != 0) {
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if (rc == REG_NOMATCH) {
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regfree(&preg);
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return TEXT_REGEX_TRANSFORM_DIDNT_MATCH;
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}
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else {
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regerror(rc, &preg, error_msg, (size_t) sizeof(error_msg));
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regfree(&preg);
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return TEXT_REGEX_ERROR;
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}
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}
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/* Do the transformation. */
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src_p = rule;
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dst_p = dst_buffer;
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do {
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switch (*src_p) {
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case '\\': /* Handle backslash squences. */
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src_p++;
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switch (*src_p) {
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case '0': case '1': case '2':
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case '3': case '4': case '5':
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case '6': case '7': case '8':
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case '9': /* Substitute appropriate match. */
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i = *src_p - '0';
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for (j = pmatch[i].rm_so; j < pmatch[i].rm_eo; j++)
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*dst_p++ = src_buffer[j];
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src_p++;
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break;
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case '\\': /* Copy bashslash verbatim. */
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*dst_p++ = *src_p++;
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break;
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default: /* Copy verbatim and warn about unknown sequence. */
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*dst_p++ = *src_p++;
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}
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break;
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default:
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*dst_p++ = *src_p++;
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}
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} while (*src_p != '\0');
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*dst_p = '\0'; /* Terminate string. */
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regfree(&preg);
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return TEXT_REGEX_OK;
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}
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