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
  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 StaticSpinMutex CommonSanitizerReportMutex;
  31
  32 static 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|.
  43 static 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
  84 static 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
  90 static 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
  97 static int AppendString(char **buff, const char *buff_end, int precision,
  98                         const char *s) {
  99   if (s == 0)
 100     s = "<null>";
 101   int result = 0;
 102   for (; *s; s++) {
 103     if (precision >= 0 && result >= precision)
 104       break;
 105     result += AppendChar(buff, buff_end, *s);
 106   }
 107   return result;
 108 }
 109
 110 static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
 111   int result = 0;
 112   result += AppendString(buff, buff_end, -1, "0x");
 113   result += AppendUnsigned(buff, buff_end, ptr_value, 16,
 114                            SANITIZER_POINTER_FORMAT_LENGTH, true);
 115   return result;
 116 }
 117
 118 int VSNPrintf(char *buff, int buff_length,
 119               const char *format, va_list args) {
 120   static const char *kPrintfFormatsHelp =
 121     "Supported Printf formats: %([0-9]*)?(z|ll)?{d,u,x}; %p; %(\\.\\*)?s; %c\n";
 122   RAW_CHECK(format);
 123   RAW_CHECK(buff_length > 0);
 124   const char *buff_end = &buff[buff_length - 1];
 125   const char *cur = format;
 126   int result = 0;
 127   for (; *cur; cur++) {
 128     if (*cur != '%') {
 129       result += AppendChar(&buff, buff_end, *cur);
 130       continue;
 131     }
 132     cur++;
 133     bool have_width = (*cur >= '0' && *cur <= '9');
 134     bool pad_with_zero = (*cur == '0');
 135     int width = 0;
 136     if (have_width) {
 137       while (*cur >= '0' && *cur <= '9') {
 138         width = width * 10 + *cur++ - '0';
 139       }
 140     }
 141     bool have_precision = (cur[0] == '.' && cur[1] == '*');
 142     int precision = -1;
 143     if (have_precision) {
 144       cur += 2;
 145       precision = va_arg(args, int);
 146     }
 147     bool have_z = (*cur == 'z');
 148     cur += have_z;
 149     bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
 150     cur += have_ll * 2;
 151     s64 dval;
 152     u64 uval;
 153     bool have_flags = have_width | have_z | have_ll;
 154     // Only %s supports precision for now
 155     CHECK(!(precision >= 0 && *cur != 's'));
 156     switch (*cur) {
 157       case 'd': {
 158         dval = have_ll ? va_arg(args, s64)
 159              : have_z ? va_arg(args, sptr)
 160              : va_arg(args, int);
 161         result += AppendSignedDecimal(&buff, buff_end, dval, width,
 162                                       pad_with_zero);
 163         break;
 164       }
 165       case 'u':
 166       case 'x': {
 167         uval = have_ll ? va_arg(args, u64)
 168              : have_z ? va_arg(args, uptr)
 169              : va_arg(args, unsigned);
 170         result += AppendUnsigned(&buff, buff_end, uval,
 171                                  (*cur == 'u') ? 10 : 16, width, pad_with_zero);
 172         break;
 173       }
 174       case 'p': {
 175         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 176         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
 177         break;
 178       }
 179       case 's': {
 180         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 181         result += AppendString(&buff, buff_end, precision, va_arg(args, char*));
 182         break;
 183       }
 184       case 'c': {
 185         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 186         result += AppendChar(&buff, buff_end, va_arg(args, int));
 187         break;
 188       }
 189       case '%' : {
 190         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 191         result += AppendChar(&buff, buff_end, '%');
 192         break;
 193       }
 194       default: {
 195         RAW_CHECK_MSG(false, kPrintfFormatsHelp);
 196       }
 197     }
 198   }
 199   RAW_CHECK(buff <= buff_end);
 200   AppendChar(&buff, buff_end + 1, '\0');
 201   return result;
 202 }
 203
 204 static void (*PrintfAndReportCallback)(const char *);
 205 void SetPrintfAndReportCallback(void (*callback)(const char *)) {
 206   PrintfAndReportCallback = callback;
 207 }
 208
 209 // Can be overriden in frontend.
 210 #if SANITIZER_SUPPORTS_WEAK_HOOKS
 211 SANITIZER_INTERFACE_ATTRIBUTE SANITIZER_WEAK_ATTRIBUTE
 212 void OnPrint(const char *str) {
 213   (void)str;
 214 }
 215 #elif defined(SANITIZER_GO) && defined(TSAN_EXTERNAL_HOOKS)
 216 void OnPrint(const char *str);
 217 #else
 218 void OnPrint(const char *str) {
 219   (void)str;
 220 }
 221 #endif
 222
 223 static void CallPrintfAndReportCallback(const char *str) {
 224   OnPrint(str);
 225   if (PrintfAndReportCallback)
 226     PrintfAndReportCallback(str);
 227 }
 228
 229 static void SharedPrintfCode(bool append_pid, const char *format,
 230                              va_list args) {
 231   va_list args2;
 232   va_copy(args2, args);
 233   const int kLen = 16 * 1024;
 234   // |local_buffer| is small enough not to overflow the stack and/or violate
 235   // the stack limit enforced by TSan (-Wframe-larger-than=512). On the other
 236   // hand, the bigger the buffer is, the more the chance the error report will
 237   // fit into it.
 238   char local_buffer[400];
 239   int needed_length;
 240   char *buffer = local_buffer;
 241   int buffer_size = ARRAY_SIZE(local_buffer);
 242   // First try to print a message using a local buffer, and then fall back to
 243   // mmaped buffer.
 244   for (int use_mmap = 0; use_mmap < 2; use_mmap++) {
 245     if (use_mmap) {
 246       va_end(args);
 247       va_copy(args, args2);
 248       buffer = (char*)MmapOrDie(kLen, "Report");
 249       buffer_size = kLen;
 250     }
 251     needed_length = 0;
 252     if (append_pid) {
 253       int pid = internal_getpid();
 254       needed_length += internal_snprintf(buffer, buffer_size, "==%d==", pid);
 255       if (needed_length >= buffer_size) {
 256         // The pid doesn't fit into the current buffer.
 257         if (!use_mmap)
 258           continue;
 259         RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
 260       }
 261     }
 262     needed_length += VSNPrintf(buffer + needed_length,
 263                                buffer_size - needed_length, format, args);
 264     if (needed_length >= buffer_size) {
 265       // The message doesn't fit into the current buffer.
 266       if (!use_mmap)
 267         continue;
 268       RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
 269     }
 270     // If the message fit into the buffer, print it and exit.
 271     break;
 272   }
 273   RawWrite(buffer);
 274   AndroidLogWrite(buffer);
 275   CallPrintfAndReportCallback(buffer);
 276   // If we had mapped any memory, clean up.
 277   if (buffer != local_buffer)
 278     UnmapOrDie((void *)buffer, buffer_size);
 279   va_end(args2);
 280 }
 281
 282 FORMAT(1, 2)
 283 void Printf(const char *format, ...) {
 284   va_list args;
 285   va_start(args, format);
 286   SharedPrintfCode(false, format, args);
 287   va_end(args);
 288 }
 289
 290 // Like Printf, but prints the current PID before the output string.
 291 FORMAT(1, 2)
 292 void Report(const char *format, ...) {
 293   va_list args;
 294   va_start(args, format);
 295   SharedPrintfCode(true, format, args);
 296   va_end(args);
 297 }
 298
 299 // Writes at most "length" symbols to "buffer" (including trailing '\0').
 300 // Returns the number of symbols that should have been written to buffer
 301 // (not including trailing '\0'). Thus, the string is truncated
 302 // iff return value is not less than "length".
 303 FORMAT(3, 4)
 304 int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 305   va_list args;
 306   va_start(args, format);
 307   int needed_length = VSNPrintf(buffer, length, format, args);
 308   va_end(args);
 309   return needed_length;
 310 }
 311
 312 FORMAT(2, 3)
 313 void InternalScopedString::append(const char *format, ...) {
 314   CHECK_LT(length_, size());
 315   va_list args;
 316   va_start(args, format);
 317   VSNPrintf(data() + length_, size() - length_, format, args);
 318   va_end(args);
 319   length_ += internal_strlen(data() + length_);
 320   CHECK_LT(length_, size());
 321 }
 322
 323 }  // namespace __sanitizer