sanitizer_printf.cc revision 6f2741c6325e0112f52b537444e1aaac8e746f85 
1//===-- sanitizer_printf.cc -----------------------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10// This file is shared between AddressSanitizer and ThreadSanitizer.
11//
12// Internal printf function, used inside run-time libraries.
13// We can't use libc printf because we intercept some of the functions used
14// inside it.
15//===----------------------------------------------------------------------===//
16
17
18#include "sanitizer_common.h"
19#include "sanitizer_libc.h"
20
21#include <stdio.h>
22#include <stdarg.h>
23
24#if SANITIZER_WINDOWS && !defined(va_copy)
25# define va_copy(dst, src) ((dst) = (src))
26#endif
27
28namespace __sanitizer {
29
30StaticSpinMutex CommonSanitizerReportMutex;
31
32static int AppendChar(char **buff, const char *buff_end, char c) {
33  if (*buff < buff_end) {
34    **buff = c;
35    (*buff)++;
36  }
37  return 1;
38}
39
40// Appends number in a given base to buffer. If its length is less than
41// |minimal_num_length|, it is padded with leading zeroes or spaces, depending
42// on the value of |pad_with_zero|.
43static int AppendNumber(char **buff, const char *buff_end, u64 absolute_value,
44                        u8 base, u8 minimal_num_length, bool pad_with_zero,
45                        bool negative) {
46  uptr const kMaxLen = 30;
47  RAW_CHECK(base == 10 || base == 16);
48  RAW_CHECK(base == 10 || !negative);
49  RAW_CHECK(absolute_value || !negative);
50  RAW_CHECK(minimal_num_length < kMaxLen);
51  int result = 0;
52  if (negative && minimal_num_length)
53    --minimal_num_length;
54  if (negative && pad_with_zero)
55    result += AppendChar(buff, buff_end, '-');
56  uptr num_buffer[kMaxLen];
57  int pos = 0;
58  do {
59    RAW_CHECK_MSG((uptr)pos < kMaxLen, "AppendNumber buffer overflow");
60    num_buffer[pos++] = absolute_value % base;
61    absolute_value /= base;
62  } while (absolute_value > 0);
63  if (pos < minimal_num_length) {
64    // Make sure compiler doesn't insert call to memset here.
65    internal_memset(&num_buffer[pos], 0,
66                    sizeof(num_buffer[0]) * (minimal_num_length - pos));
67    pos = minimal_num_length;
68  }
69  RAW_CHECK(pos > 0);
70  pos--;
71  for (; pos >= 0 && num_buffer[pos] == 0; pos--) {
72    char c = (pad_with_zero || pos == 0) ? '0' : ' ';
73    result += AppendChar(buff, buff_end, c);
74  }
75  if (negative && !pad_with_zero) result += AppendChar(buff, buff_end, '-');
76  for (; pos >= 0; pos--) {
77    char digit = static_cast<char>(num_buffer[pos]);
78    result += AppendChar(buff, buff_end, (digit < 10) ? '0' + digit
79                                                      : 'a' + digit - 10);
80  }
81  return result;
82}
83
84static int AppendUnsigned(char **buff, const char *buff_end, u64 num, u8 base,
85                          u8 minimal_num_length, bool pad_with_zero) {
86  return AppendNumber(buff, buff_end, num, base, minimal_num_length,
87                      pad_with_zero, false /* negative */);
88}
89
90static int AppendSignedDecimal(char **buff, const char *buff_end, s64 num,
91                               u8 minimal_num_length, bool pad_with_zero) {
92  bool negative = (num < 0);
93  return AppendNumber(buff, buff_end, (u64)(negative ? -num : num), 10,
94                      minimal_num_length, pad_with_zero, negative);
95}
96
97static int AppendString(char **buff, const char *buff_end, const char *s) {
98  if (s == 0)
99    s = "<null>";
100  int result = 0;
101  for (; *s; s++) {
102    result += AppendChar(buff, buff_end, *s);
103  }
104  return result;
105}
106
107static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
108  int result = 0;
109  result += AppendString(buff, buff_end, "0x");
110  result += AppendUnsigned(buff, buff_end, ptr_value, 16,
111                           (SANITIZER_WORDSIZE == 64) ? 12 : 8, true);
112  return result;
113}
114
115int VSNPrintf(char *buff, int buff_length,
116              const char *format, va_list args) {
117  static const char *kPrintfFormatsHelp =
118    "Supported Printf formats: %([0-9]*)?(z|ll)?{d,u,x}; %p; %s; %c\n";
119  RAW_CHECK(format);
120  RAW_CHECK(buff_length > 0);
121  const char *buff_end = &buff[buff_length - 1];
122  const char *cur = format;
123  int result = 0;
124  for (; *cur; cur++) {
125    if (*cur != '%') {
126      result += AppendChar(&buff, buff_end, *cur);
127      continue;
128    }
129    cur++;
130    bool have_width = (*cur >= '0' && *cur <= '9');
131    bool pad_with_zero = (*cur == '0');
132    int width = 0;
133    if (have_width) {
134      while (*cur >= '0' && *cur <= '9') {
135        width = width * 10 + *cur++ - '0';
136      }
137    }
138    bool have_z = (*cur == 'z');
139    cur += have_z;
140    bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
141    cur += have_ll * 2;
142    s64 dval;
143    u64 uval;
144    bool have_flags = have_width | have_z | have_ll;
145    switch (*cur) {
146      case 'd': {
147        dval = have_ll ? va_arg(args, s64)
148             : have_z ? va_arg(args, sptr)
149             : va_arg(args, int);
150        result += AppendSignedDecimal(&buff, buff_end, dval, width,
151                                      pad_with_zero);
152        break;
153      }
154      case 'u':
155      case 'x': {
156        uval = have_ll ? va_arg(args, u64)
157             : have_z ? va_arg(args, uptr)
158             : va_arg(args, unsigned);
159        result += AppendUnsigned(&buff, buff_end, uval,
160                                 (*cur == 'u') ? 10 : 16, width, pad_with_zero);
161        break;
162      }
163      case 'p': {
164        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
165        result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
166        break;
167      }
168      case 's': {
169        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
170        result += AppendString(&buff, buff_end, va_arg(args, char*));
171        break;
172      }
173      case 'c': {
174        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
175        result += AppendChar(&buff, buff_end, va_arg(args, int));
176        break;
177      }
178      case '%' : {
179        RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
180        result += AppendChar(&buff, buff_end, '%');
181        break;
182      }
183      default: {
184        RAW_CHECK_MSG(false, kPrintfFormatsHelp);
185      }
186    }
187  }
188  RAW_CHECK(buff <= buff_end);
189  AppendChar(&buff, buff_end + 1, '\0');
190  return result;
191}
192
193static void (*PrintfAndReportCallback)(const char *);
194void SetPrintfAndReportCallback(void (*callback)(const char *)) {
195  PrintfAndReportCallback = callback;
196}
197
198// Can be overriden in frontend.
199#if SANITIZER_SUPPORTS_WEAK_HOOKS
200SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
201void OnPrint(const char *str) {
202  (void)str;
203}
204#elif defined(SANITIZER_GO) && defined(TSAN_EXTERNAL_HOOKS)
205void OnPrint(const char *str);
206#else
207void OnPrint(const char *str) {
208  (void)str;
209}
210#endif
211
212static void CallPrintfAndReportCallback(const char *str) {
213  OnPrint(str);
214  if (PrintfAndReportCallback)
215    PrintfAndReportCallback(str);
216}
217
218static void SharedPrintfCode(bool append_pid, const char *format,
219                             va_list args) {
220  va_list args2;
221  va_copy(args2, args);
222  const int kLen = 16 * 1024;
223  // |local_buffer| is small enough not to overflow the stack and/or violate
224  // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
225  // hand, the bigger the buffer is, the more the chance the error report will
226  // fit into it.
227  char local_buffer[400];
228  int needed_length;
229  char *buffer = local_buffer;
230  int buffer_size = ARRAY_SIZE(local_buffer);
231  // First try to print a message using a local buffer, and then fall back to
232  // mmaped buffer.
233  for (int use_mmap = 0; use_mmap < 2; use_mmap++) {
234    if (use_mmap) {
235      va_end(args);
236      va_copy(args, args2);
237      buffer = (char*)MmapOrDie(kLen, "Report");
238      buffer_size = kLen;
239    }
240    needed_length = 0;
241    if (append_pid) {
242      int pid = internal_getpid();
243      needed_length += internal_snprintf(buffer, buffer_size, "==%d==", pid);
244      if (needed_length >= buffer_size) {
245        // The pid doesn't fit into the current buffer.
246        if (!use_mmap)
247          continue;
248        RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
249      }
250    }
251    needed_length += VSNPrintf(buffer + needed_length,
252                               buffer_size - needed_length, format, args);
253    if (needed_length >= buffer_size) {
254      // The message doesn't fit into the current buffer.
255      if (!use_mmap)
256        continue;
257      RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
258    }
259    // If the message fit into the buffer, print it and exit.
260    break;
261  }
262  RawWrite(buffer);
263  CallPrintfAndReportCallback(buffer);
264  // If we had mapped any memory, clean up.
265  if (buffer != local_buffer)
266    UnmapOrDie((void *)buffer, buffer_size);
267  va_end(args2);
268}
269
270void Printf(const char *format, ...) {
271  va_list args;
272  va_start(args, format);
273  SharedPrintfCode(false, format, args);
274  va_end(args);
275}
276
277// Like Printf, but prints the current PID before the output string.
278void Report(const char *format, ...) {
279  va_list args;
280  va_start(args, format);
281  SharedPrintfCode(true, format, args);
282  va_end(args);
283}
284
285// Writes at most "length" symbols to "buffer" (including trailing '\0').
286// Returns the number of symbols that should have been written to buffer
287// (not including trailing '\0'). Thus, the string is truncated
288// iff return value is not less than "length".
289int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
290  va_list args;
291  va_start(args, format);
292  int needed_length = VSNPrintf(buffer, length, format, args);
293  va_end(args);
294  return needed_length;
295}
296
297}  // namespace __sanitizer
298