libsanitizer/sanitizer_common/sanitizer_printf.cc

   1 //===-- sanitizer_printf.cc -----------------------------------------------===//
   2 //
   3 // This file is distributed under the University of Illinois Open Source
   4 // License. See LICENSE.TXT for details.
   5 //
   6 //===----------------------------------------------------------------------===//
   7 //
   8 // This file is shared between AddressSanitizer and ThreadSanitizer.
   9 //
  10 // Internal printf function, used inside run-time libraries.
  11 // We can't use libc printf because we intercept some of the functions used
  12 // inside it.
  13 //===----------------------------------------------------------------------===//
  14
  15 #include "sanitizer_common.h"
  16 #include "sanitizer_flags.h"
  17 #include "sanitizer_libc.h"
  18
  19 #include <stdio.h>
  20 #include <stdarg.h>
  21
  22 #if SANITIZER_WINDOWS && defined(_MSC_VER) && _MSC_VER < 1800 &&               \
  23       !defined(va_copy)
  24 # define va_copy(dst, src) ((dst) = (src))
  25 #endif
  26
  27 namespace __sanitizer {
  28
  29 StaticSpinMutex CommonSanitizerReportMutex;
  30
  31 static int AppendChar(char **buff, const char *buff_end, char c) {
  32   if (*buff < buff_end) {
  33     **buff = c;
  34     (*buff)++;
  35   }
  36   return 1;
  37 }
  38
  39 // Appends number in a given base to buffer. If its length is less than
  40 // |minimal_num_length|, it is padded with leading zeroes or spaces, depending
  41 // on the value of |pad_with_zero|.
  42 static int AppendNumber(char **buff, const char *buff_end, u64 absolute_value,
  43                         u8 base, u8 minimal_num_length, bool pad_with_zero,
  44                         bool negative) {
  45   uptr const kMaxLen = 30;
  46   RAW_CHECK(base == 10 || base == 16);
  47   RAW_CHECK(base == 10 || !negative);
  48   RAW_CHECK(absolute_value || !negative);
  49   RAW_CHECK(minimal_num_length < kMaxLen);
  50   int result = 0;
  51   if (negative && minimal_num_length)
  52     --minimal_num_length;
  53   if (negative && pad_with_zero)
  54     result += AppendChar(buff, buff_end, '-');
  55   uptr num_buffer[kMaxLen];
  56   int pos = 0;
  57   do {
  58     RAW_CHECK_MSG((uptr)pos < kMaxLen, "AppendNumber buffer overflow");
  59     num_buffer[pos++] = absolute_value % base;
  60     absolute_value /= base;
  61   } while (absolute_value > 0);
  62   if (pos < minimal_num_length) {
  63     // Make sure compiler doesn't insert call to memset here.
  64     internal_memset(&num_buffer[pos], 0,
  65                     sizeof(num_buffer[0]) * (minimal_num_length - pos));
  66     pos = minimal_num_length;
  67   }
  68   RAW_CHECK(pos > 0);
  69   pos--;
  70   for (; pos >= 0 && num_buffer[pos] == 0; pos--) {
  71     char c = (pad_with_zero || pos == 0) ? '0' : ' ';
  72     result += AppendChar(buff, buff_end, c);
  73   }
  74   if (negative && !pad_with_zero) result += AppendChar(buff, buff_end, '-');
  75   for (; pos >= 0; pos--) {
  76     char digit = static_cast<char>(num_buffer[pos]);
  77     result += AppendChar(buff, buff_end, (digit < 10) ? '0' + digit
  78                                                       : 'a' + digit - 10);
  79   }
  80   return result;
  81 }
  82
  83 static int AppendUnsigned(char **buff, const char *buff_end, u64 num, u8 base,
  84                           u8 minimal_num_length, bool pad_with_zero) {
  85   return AppendNumber(buff, buff_end, num, base, minimal_num_length,
  86                       pad_with_zero, false /* negative */);
  87 }
  88
  89 static int AppendSignedDecimal(char **buff, const char *buff_end, s64 num,
  90                                u8 minimal_num_length, bool pad_with_zero) {
  91   bool negative = (num < 0);
  92   return AppendNumber(buff, buff_end, (u64)(negative ? -num : num), 10,
  93                       minimal_num_length, pad_with_zero, negative);
  94 }
  95
  96 static int AppendString(char **buff, const char *buff_end, int precision,
  97                         const char *s) {
  98   if (!s)
  99     s = "<null>";
 100   int result = 0;
 101   for (; *s; s++) {
 102     if (precision >= 0 && result >= precision)
 103       break;
 104     result += AppendChar(buff, buff_end, *s);
 105   }
 106   return result;
 107 }
 108
 109 static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
 110   int result = 0;
 111   result += AppendString(buff, buff_end, -1, "0x");
 112   result += AppendUnsigned(buff, buff_end, ptr_value, 16,
 113                            SANITIZER_POINTER_FORMAT_LENGTH, true);
 114   return result;
 115 }
 116
 117 int VSNPrintf(char *buff, int buff_length,
 118               const char *format, va_list args) {
 119   static const char *kPrintfFormatsHelp =
 120     "Supported Printf formats: %([0-9]*)?(z|ll)?{d,u,x}; %p; %(\\.\\*)?s; %c\n";
 121   RAW_CHECK(format);
 122   RAW_CHECK(buff_length > 0);
 123   const char *buff_end = &buff[buff_length - 1];
 124   const char *cur = format;
 125   int result = 0;
 126   for (; *cur; cur++) {
 127     if (*cur != '%') {
 128       result += AppendChar(&buff, buff_end, *cur);
 129       continue;
 130     }
 131     cur++;
 132     bool have_width = (*cur >= '0' && *cur <= '9');
 133     bool pad_with_zero = (*cur == '0');
 134     int width = 0;
 135     if (have_width) {
 136       while (*cur >= '0' && *cur <= '9') {
 137         width = width * 10 + *cur++ - '0';
 138       }
 139     }
 140     bool have_precision = (cur[0] == '.' && cur[1] == '*');
 141     int precision = -1;
 142     if (have_precision) {
 143       cur += 2;
 144       precision = va_arg(args, int);
 145     }
 146     bool have_z = (*cur == 'z');
 147     cur += have_z;
 148     bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
 149     cur += have_ll * 2;
 150     s64 dval;
 151     u64 uval;
 152     bool have_flags = have_width | have_z | have_ll;
 153     // Only %s supports precision for now
 154     CHECK(!(precision >= 0 && *cur != 's'));
 155     switch (*cur) {
 156       case 'd': {
 157         dval = have_ll ? va_arg(args, s64)
 158              : have_z ? va_arg(args, sptr)
 159              : va_arg(args, int);
 160         result += AppendSignedDecimal(&buff, buff_end, dval, width,
 161                                       pad_with_zero);
 162         break;
 163       }
 164       case 'u':
 165       case 'x': {
 166         uval = have_ll ? va_arg(args, u64)
 167              : have_z ? va_arg(args, uptr)
 168              : va_arg(args, unsigned);
 169         result += AppendUnsigned(&buff, buff_end, uval,
 170                                  (*cur == 'u') ? 10 : 16, width, pad_with_zero);
 171         break;
 172       }
 173       case 'p': {
 174         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 175         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
 176         break;
 177       }
 178       case 's': {
 179         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 180         result += AppendString(&buff, buff_end, precision, va_arg(args, char*));
 181         break;
 182       }
 183       case 'c': {
 184         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 185         result += AppendChar(&buff, buff_end, va_arg(args, int));
 186         break;
 187       }
 188       case '%' : {
 189         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 190         result += AppendChar(&buff, buff_end, '%');
 191         break;
 192       }
 193       default: {
 194         RAW_CHECK_MSG(false, kPrintfFormatsHelp);
 195       }
 196     }
 197   }
 198   RAW_CHECK(buff <= buff_end);
 199   AppendChar(&buff, buff_end + 1, '\0');
 200   return result;
 201 }
 202
 203 static void (*PrintfAndReportCallback)(const char *);
 204 void SetPrintfAndReportCallback(void (*callback)(const char *)) {
 205   PrintfAndReportCallback = callback;
 206 }
 207
 208 // Can be overriden in frontend.
 209 #if SANITIZER_SUPPORTS_WEAK_HOOKS
 210 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 211 void OnPrint(const char *str) {
 212   (void)str;
 213 }
 214 #elif defined(SANITIZER_GO) && defined(TSAN_EXTERNAL_HOOKS)
 215 void OnPrint(const char *str);
 216 #else
 217 void OnPrint(const char *str) {
 218   (void)str;
 219 }
 220 #endif
 221
 222 static void CallPrintfAndReportCallback(const char *str) {
 223   OnPrint(str);
 224   if (PrintfAndReportCallback)
 225     PrintfAndReportCallback(str);
 226 }
 227
 228 static void SharedPrintfCode(bool append_pid, const char *format,
 229                              va_list args) {
 230   va_list args2;
 231   va_copy(args2, args);
 232   const int kLen = 16 * 1024;
 233   // |local_buffer| is small enough not to overflow the stack and/or violate
 234   // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
 235   // hand, the bigger the buffer is, the more the chance the error report will
 236   // fit into it.
 237   char local_buffer[400];
 238   int needed_length;
 239   char *buffer = local_buffer;
 240   int buffer_size = ARRAY_SIZE(local_buffer);
 241   // First try to print a message using a local buffer, and then fall back to
 242   // mmaped buffer.
 243   for (int use_mmap = 0; use_mmap < 2; use_mmap++) {
 244     if (use_mmap) {
 245       va_end(args);
 246       va_copy(args, args2);
 247       buffer = (char*)MmapOrDie(kLen, "Report");
 248       buffer_size = kLen;
 249     }
 250     needed_length = 0;
 251     // Check that data fits into the current buffer.
 252 #   define CHECK_NEEDED_LENGTH \
 253       if (needed_length >= buffer_size) { \
 254         if (!use_mmap) continue; \
 255         RAW_CHECK_MSG(needed_length < kLen, \
 256                       "Buffer in Report is too short!\n"); \
 257       }
 258     if (append_pid) {
 259       int pid = internal_getpid();
 260       const char *exe_name = GetProcessName();
 261       if (common_flags()->log_exe_name && exe_name) {
 262         needed_length += internal_snprintf(buffer, buffer_size,
 263                                            "==%s", exe_name);
 264         CHECK_NEEDED_LENGTH
 265       }
 266       needed_length += internal_snprintf(buffer + needed_length,
 267                                          buffer_size - needed_length,
 268                                          "==%d==", pid);
 269       CHECK_NEEDED_LENGTH
 270     }
 271     needed_length += VSNPrintf(buffer + needed_length,
 272                                buffer_size - needed_length, format, args);
 273     CHECK_NEEDED_LENGTH
 274     // If the message fit into the buffer, print it and exit.
 275     break;
 276 #   undef CHECK_NEEDED_LENGTH
 277   }
 278   RawWrite(buffer);
 279   if (common_flags()->log_to_syslog)
 280     WriteToSyslog(buffer);
 281   CallPrintfAndReportCallback(buffer);
 282   // If we had mapped any memory, clean up.
 283   if (buffer != local_buffer)
 284     UnmapOrDie((void *)buffer, buffer_size);
 285   va_end(args2);
 286 }
 287
 288 FORMAT(1, 2)
 289 void Printf(const char *format, ...) {
 290   va_list args;
 291   va_start(args, format);
 292   SharedPrintfCode(false, format, args);
 293   va_end(args);
 294 }
 295
 296 // Like Printf, but prints the current PID before the output string.
 297 FORMAT(1, 2)
 298 void Report(const char *format, ...) {
 299   va_list args;
 300   va_start(args, format);
 301   SharedPrintfCode(true, format, args);
 302   va_end(args);
 303 }
 304
 305 // Writes at most "length" symbols to "buffer" (including trailing '\0').
 306 // Returns the number of symbols that should have been written to buffer
 307 // (not including trailing '\0'). Thus, the string is truncated
 308 // iff return value is not less than "length".
 309 FORMAT(3, 4)
 310 int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 311   va_list args;
 312   va_start(args, format);
 313   int needed_length = VSNPrintf(buffer, length, format, args);
 314   va_end(args);
 315   return needed_length;
 316 }
 317
 318 FORMAT(2, 3)
 319 void InternalScopedString::append(const char *format, ...) {
 320   CHECK_LT(length_, size());
 321   va_list args;
 322   va_start(args, format);
 323   VSNPrintf(data() + length_, size() - length_, format, args);
 324   va_end(args);
 325   length_ += internal_strlen(data() + length_);
 326   CHECK_LT(length_, size());
 327 }
 328
 329 } // namespace __sanitizer