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27dd121d14
git-subtree-dir: outside/re2 git-subtree-mainline: f94738bfd171ae447133e0964843addbb497894f git-subtree-split: 539b44fc4c5a49c3453b80e3af85d297f4cab4bf
98 lines
3.3 KiB
C++
98 lines
3.3 KiB
C++
// Copyright 1999-2005 The RE2 Authors. All Rights Reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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#include "util/util.h"
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#include "re2/stringpiece.h"
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namespace re2 {
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// ----------------------------------------------------------------------
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// CEscapeString()
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// Copies 'src' to 'dest', escaping dangerous characters using
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// C-style escape sequences. 'src' and 'dest' should not overlap.
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// Returns the number of bytes written to 'dest' (not including the \0)
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// or -1 if there was insufficient space.
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// ----------------------------------------------------------------------
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int CEscapeString(const char* src, int src_len, char* dest,
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int dest_len) {
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const char* src_end = src + src_len;
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int used = 0;
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for (; src < src_end; src++) {
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if (dest_len - used < 2) // Need space for two letter escape
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return -1;
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unsigned char c = *src;
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switch (c) {
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case '\n': dest[used++] = '\\'; dest[used++] = 'n'; break;
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case '\r': dest[used++] = '\\'; dest[used++] = 'r'; break;
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case '\t': dest[used++] = '\\'; dest[used++] = 't'; break;
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case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break;
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case '\'': dest[used++] = '\\'; dest[used++] = '\''; break;
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case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break;
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default:
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// Note that if we emit \xNN and the src character after that is a hex
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// digit then that digit must be escaped too to prevent it being
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// interpreted as part of the character code by C.
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if (c < ' ' || c > '~') {
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if (dest_len - used < 4) // need space for 4 letter escape
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return -1;
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sprintf(dest + used, "\\%03o", c);
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used += 4;
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} else {
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dest[used++] = c; break;
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}
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}
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}
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if (dest_len - used < 1) // make sure that there is room for \0
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return -1;
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dest[used] = '\0'; // doesn't count towards return value though
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return used;
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}
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// ----------------------------------------------------------------------
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// CEscape()
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// Copies 'src' to result, escaping dangerous characters using
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// C-style escape sequences. 'src' and 'dest' should not overlap.
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// ----------------------------------------------------------------------
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string CEscape(const StringPiece& src) {
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const int dest_length = src.size() * 4 + 1; // Maximum possible expansion
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char* dest = new char[dest_length];
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const int len = CEscapeString(src.data(), src.size(),
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dest, dest_length);
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string s = string(dest, len);
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delete[] dest;
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return s;
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}
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string PrefixSuccessor(const StringPiece& prefix) {
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// We can increment the last character in the string and be done
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// unless that character is 255, in which case we have to erase the
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// last character and increment the previous character, unless that
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// is 255, etc. If the string is empty or consists entirely of
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// 255's, we just return the empty string.
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bool done = false;
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string limit(prefix.data(), prefix.size());
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int index = limit.length() - 1;
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while (!done && index >= 0) {
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if ((limit[index]&255) == 255) {
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limit.erase(index);
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index--;
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} else {
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limit[index]++;
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done = true;
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}
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}
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if (!done) {
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return "";
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} else {
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return limit;
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}
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}
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} // namespace re2
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