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 static int AppendChar(char **buff, const char *buff_end, char c) {
  30   if (*buff < buff_end) {
  31     **buff = c;
  32     (*buff)++;
  33   }
  34   return 1;
  35 }
  36
  37 // Appends number in a given base to buffer. If its length is less than
  38 // |minimal_num_length|, it is padded with leading zeroes or spaces, depending
  39 // on the value of |pad_with_zero|.
  40 static int AppendNumber(char **buff, const char *buff_end, u64 absolute_value,
  41                         u8 base, u8 minimal_num_length, bool pad_with_zero,
  42                         bool negative, bool uppercase) {
  43   uptr const kMaxLen = 30;
  44   RAW_CHECK(base == 10 || base == 16);
  45   RAW_CHECK(base == 10 || !negative);
  46   RAW_CHECK(absolute_value || !negative);
  47   RAW_CHECK(minimal_num_length < kMaxLen);
  48   int result = 0;
  49   if (negative && minimal_num_length)
  50     --minimal_num_length;
  51   if (negative && pad_with_zero)
  52     result += AppendChar(buff, buff_end, '-');
  53   uptr num_buffer[kMaxLen];
  54   int pos = 0;
  55   do {
  56     RAW_CHECK_MSG((uptr)pos < kMaxLen, "AppendNumber buffer overflow");
  57     num_buffer[pos++] = absolute_value % base;
  58     absolute_value /= base;
  59   } while (absolute_value > 0);
  60   if (pos < minimal_num_length) {
  61     // Make sure compiler doesn't insert call to memset here.
  62     internal_memset(&num_buffer[pos], 0,
  63                     sizeof(num_buffer[0]) * (minimal_num_length - pos));
  64     pos = minimal_num_length;
  65   }
  66   RAW_CHECK(pos > 0);
  67   pos--;
  68   for (; pos >= 0 && num_buffer[pos] == 0; pos--) {
  69     char c = (pad_with_zero || pos == 0) ? '0' : ' ';
  70     result += AppendChar(buff, buff_end, c);
  71   }
  72   if (negative && !pad_with_zero) result += AppendChar(buff, buff_end, '-');
  73   for (; pos >= 0; pos--) {
  74     char digit = static_cast<char>(num_buffer[pos]);
  75     digit = (digit < 10) ? '0' + digit : (uppercase ? 'A' : 'a') + digit - 10;
  76     result += AppendChar(buff, buff_end, digit);
  77   }
  78   return result;
  79 }
  80
  81 static int AppendUnsigned(char **buff, const char *buff_end, u64 num, u8 base,
  82                           u8 minimal_num_length, bool pad_with_zero,
  83                           bool uppercase) {
  84   return AppendNumber(buff, buff_end, num, base, minimal_num_length,
  85                       pad_with_zero, false /* negative */, uppercase);
  86 }
  87
  88 static int AppendSignedDecimal(char **buff, const char *buff_end, s64 num,
  89                                u8 minimal_num_length, bool pad_with_zero) {
  90   bool negative = (num < 0);
  91   return AppendNumber(buff, buff_end, (u64)(negative ? -num : num), 10,
  92                       minimal_num_length, pad_with_zero, negative,
  93                       false /* uppercase */);
  94 }
  95
  96
  97 // Use the fact that explicitly requesting 0 width (%0s) results in UB and
  98 // interpret width == 0 as "no width requested":
  99 // width == 0 - no width requested
 100 // width  < 0 - left-justify s within and pad it to -width chars, if necessary
 101 // width  > 0 - right-justify s, not implemented yet
 102 static int AppendString(char **buff, const char *buff_end, int width,
 103                         int max_chars, const char *s) {
 104   if (!s)
 105     s = "<null>";
 106   int result = 0;
 107   for (; *s; s++) {
 108     if (max_chars >= 0 && result >= max_chars)
 109       break;
 110     result += AppendChar(buff, buff_end, *s);
 111   }
 112   // Only the left justified strings are supported.
 113   while (width < -result)
 114     result += AppendChar(buff, buff_end, ' ');
 115   return result;
 116 }
 117
 118 static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
 119   int result = 0;
 120   result += AppendString(buff, buff_end, 0, -1, "0x");
 121   result += AppendUnsigned(buff, buff_end, ptr_value, 16,
 122                            SANITIZER_POINTER_FORMAT_LENGTH,
 123                            true /* pad_with_zero */, false /* uppercase */);
 124   return result;
 125 }
 126
 127 int VSNPrintf(char *buff, int buff_length,
 128               const char *format, va_list args) {
 129   static const char *kPrintfFormatsHelp =
 130       "Supported Printf formats: %([0-9]*)?(z|ll)?{d,u,x,X}; %p; "
 131       "%[-]([0-9]*)?(\\.\\*)?s; %c\n";
 132   RAW_CHECK(format);
 133   RAW_CHECK(buff_length > 0);
 134   const char *buff_end = &buff[buff_length - 1];
 135   const char *cur = format;
 136   int result = 0;
 137   for (; *cur; cur++) {
 138     if (*cur != '%') {
 139       result += AppendChar(&buff, buff_end, *cur);
 140       continue;
 141     }
 142     cur++;
 143     bool left_justified = *cur == '-';
 144     if (left_justified)
 145       cur++;
 146     bool have_width = (*cur >= '0' && *cur <= '9');
 147     bool pad_with_zero = (*cur == '0');
 148     int width = 0;
 149     if (have_width) {
 150       while (*cur >= '0' && *cur <= '9') {
 151         width = width * 10 + *cur++ - '0';
 152       }
 153     }
 154     bool have_precision = (cur[0] == '.' && cur[1] == '*');
 155     int precision = -1;
 156     if (have_precision) {
 157       cur += 2;
 158       precision = va_arg(args, int);
 159     }
 160     bool have_z = (*cur == 'z');
 161     cur += have_z;
 162     bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
 163     cur += have_ll * 2;
 164     s64 dval;
 165     u64 uval;
 166     const bool have_length = have_z || have_ll;
 167     const bool have_flags = have_width || have_length;
 168     // At the moment only %s supports precision and left-justification.
 169     CHECK(!((precision >= 0 || left_justified) && *cur != 's'));
 170     switch (*cur) {
 171       case 'd': {
 172         dval = have_ll ? va_arg(args, s64)
 173              : have_z ? va_arg(args, sptr)
 174              : va_arg(args, int);
 175         result += AppendSignedDecimal(&buff, buff_end, dval, width,
 176                                       pad_with_zero);
 177         break;
 178       }
 179       case 'u':
 180       case 'x':
 181       case 'X': {
 182         uval = have_ll ? va_arg(args, u64)
 183              : have_z ? va_arg(args, uptr)
 184              : va_arg(args, unsigned);
 185         bool uppercase = (*cur == 'X');
 186         result += AppendUnsigned(&buff, buff_end, uval, (*cur == 'u') ? 10 : 16,
 187                                  width, pad_with_zero, uppercase);
 188         break;
 189       }
 190       case 'p': {
 191         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 192         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
 193         break;
 194       }
 195       case 's': {
 196         RAW_CHECK_MSG(!have_length, kPrintfFormatsHelp);
 197         // Only left-justified width is supported.
 198         CHECK(!have_width || left_justified);
 199         result += AppendString(&buff, buff_end, left_justified ? -width : width,
 200                                precision, va_arg(args, char*));
 201         break;
 202       }
 203       case 'c': {
 204         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 205         result += AppendChar(&buff, buff_end, va_arg(args, int));
 206         break;
 207       }
 208       case '%' : {
 209         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 210         result += AppendChar(&buff, buff_end, '%');
 211         break;
 212       }
 213       default: {
 214         RAW_CHECK_MSG(false, kPrintfFormatsHelp);
 215       }
 216     }
 217   }
 218   RAW_CHECK(buff <= buff_end);
 219   AppendChar(&buff, buff_end + 1, '\0');
 220   return result;
 221 }
 222
 223 static void (*PrintfAndReportCallback)(const char *);
 224 void SetPrintfAndReportCallback(void (*callback)(const char *)) {
 225   PrintfAndReportCallback = callback;
 226 }
 227
 228 // Can be overriden in frontend.
 229 #if SANITIZER_GO && defined(TSAN_EXTERNAL_HOOKS)
 230 // Implementation must be defined in frontend.
 231 extern "C" void OnPrint(const char *str);
 232 #else
 233 SANITIZER_INTERFACE_WEAK_DEF(void, OnPrint, const char *str) {
 234   (void)str;
 235 }
 236 #endif
 237
 238 static void CallPrintfAndReportCallback(const char *str) {
 239   OnPrint(str);
 240   if (PrintfAndReportCallback)
 241     PrintfAndReportCallback(str);
 242 }
 243
 244 static void NOINLINE SharedPrintfCodeNoBuffer(bool append_pid,
 245                                               char *local_buffer,
 246                                               int buffer_size,
 247                                               const char *format,
 248                                               va_list args) {
 249   va_list args2;
 250   va_copy(args2, args);
 251   const int kLen = 16 * 1024;
 252   int needed_length;
 253   char *buffer = local_buffer;
 254   // First try to print a message using a local buffer, and then fall back to
 255   // mmaped buffer.
 256   for (int use_mmap = 0; use_mmap < 2; use_mmap++) {
 257     if (use_mmap) {
 258       va_end(args);
 259       va_copy(args, args2);
 260       buffer = (char*)MmapOrDie(kLen, "Report");
 261       buffer_size = kLen;
 262     }
 263     needed_length = 0;
 264     // Check that data fits into the current buffer.
 265 #   define CHECK_NEEDED_LENGTH \
 266       if (needed_length >= buffer_size) { \
 267         if (!use_mmap) continue; \
 268         RAW_CHECK_MSG(needed_length < kLen, \
 269                       "Buffer in Report is too short!\n"); \
 270       }
 271     // Fuchsia's logging infrastructure always keeps track of the logging
 272     // process, thread, and timestamp, so never prepend such information.
 273     if (!SANITIZER_FUCHSIA && append_pid) {
 274       int pid = internal_getpid();
 275       const char *exe_name = GetProcessName();
 276       if (common_flags()->log_exe_name && exe_name) {
 277         needed_length += internal_snprintf(buffer, buffer_size,
 278                                            "==%s", exe_name);
 279         CHECK_NEEDED_LENGTH
 280       }
 281       needed_length += internal_snprintf(
 282           buffer + needed_length, buffer_size - needed_length, "==%d==", pid);
 283       CHECK_NEEDED_LENGTH
 284     }
 285     needed_length += VSNPrintf(buffer + needed_length,
 286                                buffer_size - needed_length, format, args);
 287     CHECK_NEEDED_LENGTH
 288     // If the message fit into the buffer, print it and exit.
 289     break;
 290 #   undef CHECK_NEEDED_LENGTH
 291   }
 292   RawWrite(buffer);
 293
 294   // Remove color sequences from the message.
 295   RemoveANSIEscapeSequencesFromString(buffer);
 296   CallPrintfAndReportCallback(buffer);
 297   LogMessageOnPrintf(buffer);
 298
 299   // If we had mapped any memory, clean up.
 300   if (buffer != local_buffer)
 301     UnmapOrDie((void *)buffer, buffer_size);
 302   va_end(args2);
 303 }
 304
 305 static void NOINLINE SharedPrintfCode(bool append_pid, const char *format,
 306                                       va_list args) {
 307   // |local_buffer| is small enough not to overflow the stack and/or violate
 308   // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
 309   // hand, the bigger the buffer is, the more the chance the error report will
 310   // fit into it.
 311   char local_buffer[400];
 312   SharedPrintfCodeNoBuffer(append_pid, local_buffer, ARRAY_SIZE(local_buffer),
 313                            format, args);
 314 }
 315
 316 FORMAT(1, 2)
 317 void Printf(const char *format, ...) {
 318   va_list args;
 319   va_start(args, format);
 320   SharedPrintfCode(false, format, args);
 321   va_end(args);
 322 }
 323
 324 // Like Printf, but prints the current PID before the output string.
 325 FORMAT(1, 2)
 326 void Report(const char *format, ...) {
 327   va_list args;
 328   va_start(args, format);
 329   SharedPrintfCode(true, format, args);
 330   va_end(args);
 331 }
 332
 333 // Writes at most "length" symbols to "buffer" (including trailing '\0').
 334 // Returns the number of symbols that should have been written to buffer
 335 // (not including trailing '\0'). Thus, the string is truncated
 336 // iff return value is not less than "length".
 337 FORMAT(3, 4)
 338 int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 339   va_list args;
 340   va_start(args, format);
 341   int needed_length = VSNPrintf(buffer, length, format, args);
 342   va_end(args);
 343   return needed_length;
 344 }
 345
 346 FORMAT(2, 3)
 347 void InternalScopedString::append(const char *format, ...) {
 348   CHECK_LT(length_, size());
 349   va_list args;
 350   va_start(args, format);
 351   VSNPrintf(data() + length_, size() - length_, format, args);
 352   va_end(args);
 353   length_ += internal_strlen(data() + length_);
 354   CHECK_LT(length_, size());
 355 }
 356
 357 } // namespace __sanitizer