1// Copyright 2002 and onwards Google Inc.
2
3#include <stdarg.h> // For va_list and related operations
4#include <stdio.h> // MSVC requires this for _vsnprintf
5#include <vector>
6using std::vector;
7
8#include <string>
9using std::string;
10#include "stringprintf.h"
11#include "base/logging.h"
12// Max arguments supported by StringPrintVector
13const int kStringPrintfVectorMaxArgs = 32;
14
15// An empty block of zero for filler arguments. This is const so that if
16// printf tries to write to it (via %n) then the program gets a SIGSEGV
17// and we can fix the problem or protect against an attack.
18static const char string_printf_empty_block [256] = { '\0' };
19
20string StringPrintfVector(const char* format, const vector<string>& v) {
21 CHECK_LE(v.size(), kStringPrintfVectorMaxArgs)
22 << "StringPrintfVector currently only supports up to "
23 << kStringPrintfVectorMaxArgs << " arguments. "
24 << "Feel free to add support for more if you need it.";
25
26 // Add filler arguments so that bogus format+args have a harder time
27 // crashing the program, corrupting the program (%n),
28 // or displaying random chunks of memory to users.
29
30 const char* cstr[kStringPrintfVectorMaxArgs];
31 for (int i = 0; i < v.size(); ++i) {
32 cstr[i] = v[i].c_str();
33 }
34 for (int i = v.size(); i < arraysize(cstr); ++i) {
35 cstr[i] = &string_printf_empty_block[0];
36 }
37
38 // I do not know any way to pass kStringPrintfVectorMaxArgs arguments,
39 // or any way to build a va_list by hand, or any API for printf
40 // that accepts an array of arguments. The best I can do is stick
41 // this COMPILE_ASSERT right next to the actual statement.
42
43 COMPILE_ASSERT(kStringPrintfVectorMaxArgs == 32, arg_count_mismatch);
44 return StringPrintf(format,
45 cstr[0], cstr[1], cstr[2], cstr[3], cstr[4],
46 cstr[5], cstr[6], cstr[7], cstr[8], cstr[9],
47 cstr[10], cstr[11], cstr[12], cstr[13], cstr[14],
48 cstr[15], cstr[16], cstr[17], cstr[18], cstr[19],
49 cstr[20], cstr[21], cstr[22], cstr[23], cstr[24],
50 cstr[25], cstr[26], cstr[27], cstr[28], cstr[29],
51 cstr[30], cstr[31]);
52}
53