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/**************************************************************/
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/* tpax: a topological pax implementation */
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/* Copyright (C) 2020--2024 SysDeer Technologies, LLC */
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/* Released under GPLv2 and GPLv3; see COPYING.TPAX. */
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/**************************************************************/
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#include <regex.h>
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#include <stdlib.h>
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#include <string.h>
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#include <errno.h>
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#include <tpax/tpax.h>
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#include "tpax_driver_impl.h"
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static int tpax_backref_idx(const char c)
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{
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return ((c >= '1') && (c <= '9')) ? c - '0' : 0;
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}
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int tpax_util_path_replstr(
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char * dstpath,
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const char * srcpath,
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const char * replstr,
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const regex_t * regex,
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size_t buflen,
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int flags)
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{
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int ret;
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int idx;
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regoff_t ro;
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const char * ch;
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char * dst;
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size_t explen;
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regmatch_t pmatch[11];
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/* attempt to match */
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switch (regexec(regex,srcpath,11,pmatch,0)) {
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case 0:
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break;
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case REG_NOMATCH:
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return 0;
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default:
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return -1;
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}
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/* copy bytes leading up to match */
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if (buflen <= (explen = pmatch[0].rm_so)) {
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errno = ENOBUFS;
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return -1;
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}
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for (ro=0,dst=dstpath; ro
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*dst++ = srcpath[ro];
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buflen -= explen;
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/* copy replacement string */
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for (ch=replstr,ret=0; buflen && *ch; ch++) {
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/* <ampersand> stands for the entire matched string */
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if (ch[0] == '&') {
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idx = 0;
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/* back-reference semantics: a matched subexpression or an empty string */
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} else if ((ch[0] == '\\') && (idx = tpax_backref_idx(ch[1]))) {
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if (pmatch[idx].rm_so < 0)
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idx = -1;
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ch++;
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/* all other escaped characters */
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} else if (ch[0] == '\\') {
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*dst++ = *++ch;
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idx = -1;
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buflen--;
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/* all other characters */
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} else {
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*dst++ = *ch;
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idx = -1;
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buflen--;
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}
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/* copy matched string or matched subexpression, if any */
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if (idx >= 0) {
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if (buflen <= (explen = (pmatch[idx].rm_eo - pmatch[idx].rm_so))) {
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errno = ENOBUFS;
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return -1;
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}
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for (ro=pmatch[idx].rm_so; ro
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*dst++ = srcpath[ro];
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buflen -= explen;
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}
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}
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/* replace further occurrences as needed */
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if ((flags & TPAX_REPL_GLOBAL) && srcpath[pmatch[0].rm_eo])
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ret = tpax_util_path_replstr(
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dst,&srcpath[pmatch[0].rm_eo],replstr,
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regex,buflen,flags);
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if (ret < 0)
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return -1;
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/* copy remaining, non-matching bytes as needed */
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if (ret == 0) {
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for (ch=&srcpath[pmatch[0].rm_eo]; *ch; ch++)
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*dst++ = *ch;
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*dst = '\0';
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}
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/* all done */
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ret += (dst - dstpath);
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return ret;
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}
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