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// Copyright 1999-2005 The RE2 Authors. All Rights Reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
#include <stdarg.h>
#include <stdio.h>
#include "util/strutil.h"
#ifdef _WIN32
#define snprintf _snprintf
#define vsnprintf _vsnprintf
#endif
namespace re2 {
// ----------------------------------------------------------------------
// CEscapeString()
// Copies 'src' to 'dest', escaping dangerous characters using
// C-style escape sequences. 'src' and 'dest' should not overlap.
// Returns the number of bytes written to 'dest' (not including the \0)
// or (size_t)-1 if there was insufficient space.
// ----------------------------------------------------------------------
static size_t CEscapeString(const char* src, size_t src_len,
char* dest, size_t dest_len) {
const char* src_end = src + src_len;
size_t used = 0;
for (; src < src_end; src++) {
if (dest_len - used < 2) // space for two-character escape
return (size_t)-1;
unsigned char c = *src;
switch (c) {
case '\n': dest[used++] = '\\'; dest[used++] = 'n'; break;
case '\r': dest[used++] = '\\'; dest[used++] = 'r'; break;
case '\t': dest[used++] = '\\'; dest[used++] = 't'; break;
case '\"': dest[used++] = '\\'; dest[used++] = '\"'; break;
case '\'': dest[used++] = '\\'; dest[used++] = '\''; break;
case '\\': dest[used++] = '\\'; dest[used++] = '\\'; break;
default:
// Note that if we emit \xNN and the src character after that is a hex
// digit then that digit must be escaped too to prevent it being
// interpreted as part of the character code by C.
if (c < ' ' || c > '~') {
if (dest_len - used < 5) // space for four-character escape + \0
return (size_t)-1;
snprintf(dest + used, 5, "\\%03o", c);
used += 4;
} else {
dest[used++] = c; break;
}
}
}
if (dest_len - used < 1) // make sure that there is room for \0
return (size_t)-1;
dest[used] = '\0'; // doesn't count towards return value though
return used;
}
// ----------------------------------------------------------------------
// CEscape()
// Copies 'src' to result, escaping dangerous characters using
// C-style escape sequences. 'src' and 'dest' should not overlap.
// ----------------------------------------------------------------------
std::string CEscape(const StringPiece& src) {
const size_t dest_len = src.size() * 4 + 1; // Maximum possible expansion
char* dest = new char[dest_len];
const size_t used = CEscapeString(src.data(), src.size(),
dest, dest_len);
std::string s = std::string(dest, used);
delete[] dest;
return s;
}
void PrefixSuccessor(std::string* prefix) {
// We can increment the last character in the string and be done
// unless that character is 255, in which case we have to erase the
// last character and increment the previous character, unless that
// is 255, etc. If the string is empty or consists entirely of
// 255's, we just return the empty string.
while (!prefix->empty()) {
char& c = prefix->back();
if (c == '\xff') { // char literal avoids signed/unsigned.
prefix->pop_back();
} else {
++c;
break;
}
}
}
static void StringAppendV(std::string* dst, const char* format, va_list ap) {
// First try with a small fixed size buffer
char space[1024];
// It's possible for methods that use a va_list to invalidate
// the data in it upon use. The fix is to make a copy
// of the structure before using it and use that copy instead.
va_list backup_ap;
va_copy(backup_ap, ap);
int result = vsnprintf(space, sizeof(space), format, backup_ap);
va_end(backup_ap);
if ((result >= 0) && (static_cast<size_t>(result) < sizeof(space))) {
// It fit
dst->append(space, result);
return;
}
// Repeatedly increase buffer size until it fits
int length = sizeof(space);
while (true) {
if (result < 0) {
// Older behavior: just try doubling the buffer size
length *= 2;
} else {
// We need exactly "result+1" characters
length = result+1;
}
char* buf = new char[length];
// Restore the va_list before we use it again
va_copy(backup_ap, ap);
result = vsnprintf(buf, length, format, backup_ap);
va_end(backup_ap);
if ((result >= 0) && (result < length)) {
// It fit
dst->append(buf, result);
delete[] buf;
return;
}
delete[] buf;
}
}
std::string StringPrintf(const char* format, ...) {
va_list ap;
va_start(ap, format);
std::string result;
StringAppendV(&result, format, ap);
va_end(ap);
return result;
}
} // namespace re2
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