libsanitizer/sanitizer_common/sanitizer_printf.cpp

   1 //===-- sanitizer_printf.cpp ----------------------------------------------===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file is shared between AddressSanitizer and ThreadSanitizer.
  10 //
  11 // Internal printf function, used inside run-time libraries.
  12 // We can't use libc printf because we intercept some of the functions used
  13 // inside it.
  14 //===----------------------------------------------------------------------===//
  15
  16 #include "sanitizer_common.h"
  17 #include "sanitizer_flags.h"
  18 #include "sanitizer_libc.h"
  19
  20 #include <stdio.h>
  21 #include <stdarg.h>
  22
  23 #if SANITIZER_WINDOWS && defined(_MSC_VER) && _MSC_VER < 1800 &&               \
  24       !defined(va_copy)
  25 # define va_copy(dst, src) ((dst) = (src))
  26 #endif
  27
  28 namespace __sanitizer {
  29
  30 static int AppendChar(char **buff, const char *buff_end, char c) {
  31   if (*buff < buff_end) {
  32     **buff = c;
  33     (*buff)++;
  34   }
  35   return 1;
  36 }
  37
  38 // Appends number in a given base to buffer. If its length is less than
  39 // |minimal_num_length|, it is padded with leading zeroes or spaces, depending
  40 // on the value of |pad_with_zero|.
  41 static int AppendNumber(char **buff, const char *buff_end, u64 absolute_value,
  42                         u8 base, u8 minimal_num_length, bool pad_with_zero,
  43                         bool negative, bool uppercase) {
  44   uptr const kMaxLen = 30;
  45   RAW_CHECK(base == 10 || base == 16);
  46   RAW_CHECK(base == 10 || !negative);
  47   RAW_CHECK(absolute_value || !negative);
  48   RAW_CHECK(minimal_num_length < kMaxLen);
  49   int result = 0;
  50   if (negative && minimal_num_length)
  51     --minimal_num_length;
  52   if (negative && pad_with_zero)
  53     result += AppendChar(buff, buff_end, '-');
  54   uptr num_buffer[kMaxLen];
  55   int pos = 0;
  56   do {
  57     RAW_CHECK_MSG((uptr)pos < kMaxLen, "AppendNumber buffer overflow");
  58     num_buffer[pos++] = absolute_value % base;
  59     absolute_value /= base;
  60   } while (absolute_value > 0);
  61   if (pos < minimal_num_length) {
  62     // Make sure compiler doesn't insert call to memset here.
  63     internal_memset(&num_buffer[pos], 0,
  64                     sizeof(num_buffer[0]) * (minimal_num_length - pos));
  65     pos = minimal_num_length;
  66   }
  67   RAW_CHECK(pos > 0);
  68   pos--;
  69   for (; pos >= 0 && num_buffer[pos] == 0; pos--) {
  70     char c = (pad_with_zero || pos == 0) ? '0' : ' ';
  71     result += AppendChar(buff, buff_end, c);
  72   }
  73   if (negative && !pad_with_zero) result += AppendChar(buff, buff_end, '-');
  74   for (; pos >= 0; pos--) {
  75     char digit = static_cast<char>(num_buffer[pos]);
  76     digit = (digit < 10) ? '0' + digit : (uppercase ? 'A' : 'a') + digit - 10;
  77     result += AppendChar(buff, buff_end, digit);
  78   }
  79   return result;
  80 }
  81
  82 static int AppendUnsigned(char **buff, const char *buff_end, u64 num, u8 base,
  83                           u8 minimal_num_length, bool pad_with_zero,
  84                           bool uppercase) {
  85   return AppendNumber(buff, buff_end, num, base, minimal_num_length,
  86                       pad_with_zero, false /* negative */, uppercase);
  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                       false /* uppercase */);
  95 }
  96
  97
  98 // Use the fact that explicitly requesting 0 width (%0s) results in UB and
  99 // interpret width == 0 as "no width requested":
 100 // width == 0 - no width requested
 101 // width  < 0 - left-justify s within and pad it to -width chars, if necessary
 102 // width  > 0 - right-justify s, not implemented yet
 103 static int AppendString(char **buff, const char *buff_end, int width,
 104                         int max_chars, const char *s) {
 105   if (!s)
 106     s = "<null>";
 107   int result = 0;
 108   for (; *s; s++) {
 109     if (max_chars >= 0 && result >= max_chars)
 110       break;
 111     result += AppendChar(buff, buff_end, *s);
 112   }
 113   // Only the left justified strings are supported.
 114   while (width < -result)
 115     result += AppendChar(buff, buff_end, ' ');
 116   return result;
 117 }
 118
 119 static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
 120   int result = 0;
 121   result += AppendString(buff, buff_end, 0, -1, "0x");
 122   result += AppendUnsigned(buff, buff_end, ptr_value, 16,
 123                            SANITIZER_POINTER_FORMAT_LENGTH,
 124                            true /* pad_with_zero */, false /* uppercase */);
 125   return result;
 126 }
 127
 128 int VSNPrintf(char *buff, int buff_length,
 129               const char *format, va_list args) {
 130   static const char *kPrintfFormatsHelp =
 131       "Supported Printf formats: %([0-9]*)?(z|ll)?{d,u,x,X}; %p; "
 132       "%[-]([0-9]*)?(\\.\\*)?s; %c\n";
 133   RAW_CHECK(format);
 134   RAW_CHECK(buff_length > 0);
 135   const char *buff_end = &buff[buff_length - 1];
 136   const char *cur = format;
 137   int result = 0;
 138   for (; *cur; cur++) {
 139     if (*cur != '%') {
 140       result += AppendChar(&buff, buff_end, *cur);
 141       continue;
 142     }
 143     cur++;
 144     bool left_justified = *cur == '-';
 145     if (left_justified)
 146       cur++;
 147     bool have_width = (*cur >= '0' && *cur <= '9');
 148     bool pad_with_zero = (*cur == '0');
 149     int width = 0;
 150     if (have_width) {
 151       while (*cur >= '0' && *cur <= '9') {
 152         width = width * 10 + *cur++ - '0';
 153       }
 154     }
 155     bool have_precision = (cur[0] == '.' && cur[1] == '*');
 156     int precision = -1;
 157     if (have_precision) {
 158       cur += 2;
 159       precision = va_arg(args, int);
 160     }
 161     bool have_z = (*cur == 'z');
 162     cur += have_z;
 163     bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
 164     cur += have_ll * 2;
 165     s64 dval;
 166     u64 uval;
 167     const bool have_length = have_z || have_ll;
 168     const bool have_flags = have_width || have_length;
 169     // At the moment only %s supports precision and left-justification.
 170     CHECK(!((precision >= 0 || left_justified) && *cur != 's'));
 171     switch (*cur) {
 172       case 'd': {
 173         dval = have_ll ? va_arg(args, s64)
 174              : have_z ? va_arg(args, sptr)
 175              : va_arg(args, int);
 176         result += AppendSignedDecimal(&buff, buff_end, dval, width,
 177                                       pad_with_zero);
 178         break;
 179       }
 180       case 'u':
 181       case 'x':
 182       case 'X': {
 183         uval = have_ll ? va_arg(args, u64)
 184              : have_z ? va_arg(args, uptr)
 185              : va_arg(args, unsigned);
 186         bool uppercase = (*cur == 'X');
 187         result += AppendUnsigned(&buff, buff_end, uval, (*cur == 'u') ? 10 : 16,
 188                                  width, pad_with_zero, uppercase);
 189         break;
 190       }
 191       case 'p': {
 192         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 193         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
 194         break;
 195       }
 196       case 's': {
 197         RAW_CHECK_MSG(!have_length, kPrintfFormatsHelp);
 198         // Only left-justified width is supported.
 199         CHECK(!have_width || left_justified);
 200         result += AppendString(&buff, buff_end, left_justified ? -width : width,
 201                                precision, va_arg(args, char*));
 202         break;
 203       }
 204       case 'c': {
 205         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 206         result += AppendChar(&buff, buff_end, va_arg(args, int));
 207         break;
 208       }
 209       case '%' : {
 210         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 211         result += AppendChar(&buff, buff_end, '%');
 212         break;
 213       }
 214       default: {
 215         RAW_CHECK_MSG(false, kPrintfFormatsHelp);
 216       }
 217     }
 218   }
 219   RAW_CHECK(buff <= buff_end);
 220   AppendChar(&buff, buff_end + 1, '\0');
 221   return result;
 222 }
 223
 224 static void (*PrintfAndReportCallback)(const char *);
 225 void SetPrintfAndReportCallback(void (*callback)(const char *)) {
 226   PrintfAndReportCallback = callback;
 227 }
 228
 229 // Can be overriden in frontend.
 230 #if SANITIZER_GO && defined(TSAN_EXTERNAL_HOOKS)
 231 // Implementation must be defined in frontend.
 232 extern "C" void OnPrint(const char *str);
 233 #else
 234 SANITIZER_INTERFACE_WEAK_DEF(void, OnPrint, const char *str) {
 235   (void)str;
 236 }
 237 #endif
 238
 239 static void CallPrintfAndReportCallback(const char *str) {
 240   OnPrint(str);
 241   if (PrintfAndReportCallback)
 242     PrintfAndReportCallback(str);
 243 }
 244
 245 static void NOINLINE SharedPrintfCodeNoBuffer(bool append_pid,
 246                                               char *local_buffer,
 247                                               int buffer_size,
 248                                               const char *format,
 249                                               va_list args) {
 250   va_list args2;
 251   va_copy(args2, args);
 252   const int kLen = 16 * 1024;
 253   int needed_length;
 254   char *buffer = local_buffer;
 255   // First try to print a message using a local buffer, and then fall back to
 256   // mmaped buffer.
 257   for (int use_mmap = 0; use_mmap < 2; use_mmap++) {
 258     if (use_mmap) {
 259       va_end(args);
 260       va_copy(args, args2);
 261       buffer = (char*)MmapOrDie(kLen, "Report");
 262       buffer_size = kLen;
 263     }
 264     needed_length = 0;
 265     // Check that data fits into the current buffer.
 266 #   define CHECK_NEEDED_LENGTH \
 267       if (needed_length >= buffer_size) { \
 268         if (!use_mmap) continue; \
 269         RAW_CHECK_MSG(needed_length < kLen, \
 270                       "Buffer in Report is too short!\n"); \
 271       }
 272     // Fuchsia's logging infrastructure always keeps track of the logging
 273     // process, thread, and timestamp, so never prepend such information.
 274     if (!SANITIZER_FUCHSIA && append_pid) {
 275       int pid = internal_getpid();
 276       const char *exe_name = GetProcessName();
 277       if (common_flags()->log_exe_name && exe_name) {
 278         needed_length += internal_snprintf(buffer, buffer_size,
 279                                            "==%s", exe_name);
 280         CHECK_NEEDED_LENGTH
 281       }
 282       needed_length += internal_snprintf(
 283           buffer + needed_length, buffer_size - needed_length, "==%d==", pid);
 284       CHECK_NEEDED_LENGTH
 285     }
 286     needed_length += VSNPrintf(buffer + needed_length,
 287                                buffer_size - needed_length, format, args);
 288     CHECK_NEEDED_LENGTH
 289     // If the message fit into the buffer, print it and exit.
 290     break;
 291 #   undef CHECK_NEEDED_LENGTH
 292   }
 293   RawWrite(buffer);
 294
 295   // Remove color sequences from the message.
 296   RemoveANSIEscapeSequencesFromString(buffer);
 297   CallPrintfAndReportCallback(buffer);
 298   LogMessageOnPrintf(buffer);
 299
 300   // If we had mapped any memory, clean up.
 301   if (buffer != local_buffer)
 302     UnmapOrDie((void *)buffer, buffer_size);
 303   va_end(args2);
 304 }
 305
 306 static void NOINLINE SharedPrintfCode(bool append_pid, const char *format,
 307                                       va_list args) {
 308   // |local_buffer| is small enough not to overflow the stack and/or violate
 309   // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
 310   // hand, the bigger the buffer is, the more the chance the error report will
 311   // fit into it.
 312   char local_buffer[400];
 313   SharedPrintfCodeNoBuffer(append_pid, local_buffer, ARRAY_SIZE(local_buffer),
 314                            format, args);
 315 }
 316
 317 FORMAT(1, 2)
 318 void Printf(const char *format, ...) {
 319   va_list args;
 320   va_start(args, format);
 321   SharedPrintfCode(false, format, args);
 322   va_end(args);
 323 }
 324
 325 // Like Printf, but prints the current PID before the output string.
 326 FORMAT(1, 2)
 327 void Report(const char *format, ...) {
 328   va_list args;
 329   va_start(args, format);
 330   SharedPrintfCode(true, format, args);
 331   va_end(args);
 332 }
 333
 334 // Writes at most "length" symbols to "buffer" (including trailing '\0').
 335 // Returns the number of symbols that should have been written to buffer
 336 // (not including trailing '\0'). Thus, the string is truncated
 337 // iff return value is not less than "length".
 338 FORMAT(3, 4)
 339 int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 340   va_list args;
 341   va_start(args, format);
 342   int needed_length = VSNPrintf(buffer, length, format, args);
 343   va_end(args);
 344   return needed_length;
 345 }
 346
 347 FORMAT(2, 3)
 348 void InternalScopedString::append(const char *format, ...) {
 349   CHECK_LT(length_, size());
 350   va_list args;
 351   va_start(args, format);
 352   VSNPrintf(data() + length_, size() - length_, format, args);
 353   va_end(args);
 354   length_ += internal_strlen(data() + length_);
 355   CHECK_LT(length_, size());
 356 }
 357
 358 } // namespace __sanitizer