12d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// Copyright 1999-2005 The RE2 Authors. All Rights Reserved. 22d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// Use of this source code is governed by a BSD-style 32d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// license that can be found in the LICENSE file. 42d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 52d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines#include "util/util.h" 62d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines#include "re2/stringpiece.h" 72d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 82d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hinesnamespace re2 { 92d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 102d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// ---------------------------------------------------------------------- 112d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// CEscapeString() 122d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// Copies 'src' to 'dest', escaping dangerous characters using 132d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// C-style escape sequences. 'src' and 'dest' should not overlap. 142d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// Returns the number of bytes written to 'dest' (not including the \0) 152d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// or -1 if there was insufficient space. 162d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// ---------------------------------------------------------------------- 172d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hinesint CEscapeString(const char* src, int src_len, char* dest, 182d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines int dest_len) { 192d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines const char* src_end = src + src_len; 202d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines int used = 0; 212d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 222d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines for (; src < src_end; src++) { 232d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines if (dest_len - used < 2) // Need space for two letter escape 242d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines return -1; 252d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 262d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines unsigned char c = *src; 272d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines switch (c) { 282d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\n': dest[used++] = '\\'; dest[used++] = 'n'; break; 292d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\r': dest[used++] = '\\'; dest[used++] = 'r'; break; 302d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\t': dest[used++] = '\\'; dest[used++] = 't'; break; 312d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break; 322d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\'': dest[used++] = '\\'; dest[used++] = '\''; break; 332d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break; 342d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines default: 352d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines // Note that if we emit \xNN and the src character after that is a hex 362d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines // digit then that digit must be escaped too to prevent it being 372d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines // interpreted as part of the character code by C. 382d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines if (c < ' ' || c > '~') { 392d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines if (dest_len - used < 4) // need space for 4 letter escape 402d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines return -1; 412d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines sprintf(dest + used, "\\%03o", c); 422d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines used += 4; 432d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines } else { 442d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines dest[used++] = c; break; 452d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines } 462d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines } 472d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines } 482d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 492d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines if (dest_len - used < 1) // make sure that there is room for \0 502d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines return -1; 512d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 522d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines dest[used] = '\0'; // doesn't count towards return value though 532d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines return used; 542d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines} 552d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 562d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 572d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// ---------------------------------------------------------------------- 582d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// CEscape() 592d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// Copies 'src' to result, escaping dangerous characters using 602d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// C-style escape sequences. 'src' and 'dest' should not overlap. 612d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines// ---------------------------------------------------------------------- 622d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hinesstring CEscape(const StringPiece& src) { 632d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines const int dest_length = src.size() * 4 + 1; // Maximum possible expansion 642d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines char* dest = new char[dest_length]; 652d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines const int len = CEscapeString(src.data(), src.size(), 662d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines dest, dest_length); 672d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines string s = string(dest, len); 682d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines delete[] dest; 692d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines return s; 702d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines} 712d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hines 722d1fdb26e458c4ddc04155c1d421bced3ba90cd0Stephen Hinesstring PrefixSuccessor(const StringPiece& prefix) { 73 // We can increment the last character in the string and be done 74 // unless that character is 255, in which case we have to erase the 75 // last character and increment the previous character, unless that 76 // is 255, etc. If the string is empty or consists entirely of 77 // 255's, we just return the empty string. 78 bool done = false; 79 string limit(prefix.data(), prefix.size()); 80 int index = limit.length() - 1; 81 while (!done && index >= 0) { 82 if ((limit[index]&255) == 255) { 83 limit.erase(index); 84 index--; 85 } else { 86 limit[index]++; 87 done = true; 88 } 89 } 90 if (!done) { 91 return ""; 92 } else { 93 return limit; 94 } 95} 96 97} // namespace re2 98