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_libc.h"
  18
  19 #include <stdio.h>
  20 #include <stdarg.h>
  21
  22 namespace __sanitizer {
  23
  24 static int AppendChar(char **buff, const char *buff_end, char c) {
  25   if (*buff < buff_end) {
  26     **buff = c;
  27     (*buff)++;
  28   }
  29   return 1;
  30 }
  31
  32 // Appends number in a given base to buffer. If its length is less than
  33 // "minimal_num_length", it is padded with leading zeroes.
  34 static int AppendUnsigned(char **buff, const char *buff_end, u64 num,
  35                           u8 base, u8 minimal_num_length) {
  36   uptr const kMaxLen = 30;
  37   RAW_CHECK(base == 10 || base == 16);
  38   RAW_CHECK(minimal_num_length < kMaxLen);
  39   uptr num_buffer[kMaxLen];
  40   uptr pos = 0;
  41   do {
  42     RAW_CHECK_MSG(pos < kMaxLen, "appendNumber buffer overflow");
  43     num_buffer[pos++] = num % base;
  44     num /= base;
  45   } while (num > 0);
  46   if (pos < minimal_num_length) {
  47     // Make sure compiler doesn't insert call to memset here.
  48     internal_memset(&num_buffer[pos], 0,
  49                     sizeof(num_buffer[0]) * (minimal_num_length - pos));
  50     pos = minimal_num_length;
  51   }
  52   int result = 0;
  53   while (pos-- > 0) {
  54     uptr digit = num_buffer[pos];
  55     result += AppendChar(buff, buff_end, (digit < 10) ? '0' + digit
  56                                                       : 'a' + digit - 10);
  57   }
  58   return result;
  59 }
  60
  61 static int AppendSignedDecimal(char **buff, const char *buff_end, s64 num,
  62                                u8 minimal_num_length) {
  63   int result = 0;
  64   if (num < 0) {
  65     result += AppendChar(buff, buff_end, '-');
  66     num = -num;
  67     if (minimal_num_length)
  68       --minimal_num_length;
  69   }
  70   result += AppendUnsigned(buff, buff_end, (u64)num, 10, minimal_num_length);
  71   return result;
  72 }
  73
  74 static int AppendString(char **buff, const char *buff_end, const char *s) {
  75   if (s == 0)
  76     s = "<null>";
  77   int result = 0;
  78   for (; *s; s++) {
  79     result += AppendChar(buff, buff_end, *s);
  80   }
  81   return result;
  82 }
  83
  84 static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
  85   int result = 0;
  86   result += AppendString(buff, buff_end, "0x");
  87   result += AppendUnsigned(buff, buff_end, ptr_value, 16,
  88                            (SANITIZER_WORDSIZE == 64) ? 12 : 8);
  89   return result;
  90 }
  91
  92 int VSNPrintf(char *buff, int buff_length,
  93               const char *format, va_list args) {
  94   static const char *kPrintfFormatsHelp =
  95     "Supported Printf formats: %(0[0-9]*)?(z|ll)?{d,u,x}; %p; %s; %c\n";
  96   RAW_CHECK(format);
  97   RAW_CHECK(buff_length > 0);
  98   const char *buff_end = &buff[buff_length - 1];
  99   const char *cur = format;
 100   int result = 0;
 101   for (; *cur; cur++) {
 102     if (*cur != '%') {
 103       result += AppendChar(&buff, buff_end, *cur);
 104       continue;
 105     }
 106     cur++;
 107     bool have_width = (*cur == '0');
 108     int width = 0;
 109     if (have_width) {
 110       while (*cur >= '0' && *cur <= '9') {
 111         have_width = true;
 112         width = width * 10 + *cur++ - '0';
 113       }
 114     }
 115     bool have_z = (*cur == 'z');
 116     cur += have_z;
 117     bool have_ll = !have_z && (cur[0] == 'l' && cur[1] == 'l');
 118     cur += have_ll * 2;
 119     s64 dval;
 120     u64 uval;
 121     bool have_flags = have_width | have_z | have_ll;
 122     switch (*cur) {
 123       case 'd': {
 124         dval = have_ll ? va_arg(args, s64)
 125              : have_z ? va_arg(args, sptr)
 126              : va_arg(args, int);
 127         result += AppendSignedDecimal(&buff, buff_end, dval, width);
 128         break;
 129       }
 130       case 'u':
 131       case 'x': {
 132         uval = have_ll ? va_arg(args, u64)
 133              : have_z ? va_arg(args, uptr)
 134              : va_arg(args, unsigned);
 135         result += AppendUnsigned(&buff, buff_end, uval,
 136                                  (*cur == 'u') ? 10 : 16, width);
 137         break;
 138       }
 139       case 'p': {
 140         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 141         result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
 142         break;
 143       }
 144       case 's': {
 145         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 146         result += AppendString(&buff, buff_end, va_arg(args, char*));
 147         break;
 148       }
 149       case 'c': {
 150         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 151         result += AppendChar(&buff, buff_end, va_arg(args, int));
 152         break;
 153       }
 154       case '%' : {
 155         RAW_CHECK_MSG(!have_flags, kPrintfFormatsHelp);
 156         result += AppendChar(&buff, buff_end, '%');
 157         break;
 158       }
 159       default: {
 160         RAW_CHECK_MSG(false, kPrintfFormatsHelp);
 161       }
 162     }
 163   }
 164   RAW_CHECK(buff <= buff_end);
 165   AppendChar(&buff, buff_end + 1, '\0');
 166   return result;
 167 }
 168
 169 static void (*PrintfAndReportCallback)(const char *);
 170 void SetPrintfAndReportCallback(void (*callback)(const char *)) {
 171   PrintfAndReportCallback = callback;
 172 }
 173
 174 void Printf(const char *format, ...) {
 175   const int kLen = 16 * 1024;
 176   InternalScopedBuffer<char> buffer(kLen);
 177   va_list args;
 178   va_start(args, format);
 179   int needed_length = VSNPrintf(buffer.data(), kLen, format, args);
 180   va_end(args);
 181   RAW_CHECK_MSG(needed_length < kLen, "Buffer in Printf is too short!\n");
 182   RawWrite(buffer.data());
 183   if (PrintfAndReportCallback)
 184     PrintfAndReportCallback(buffer.data());
 185 }
 186
 187 // Writes at most "length" symbols to "buffer" (including trailing '\0').
 188 // Returns the number of symbols that should have been written to buffer
 189 // (not including trailing '\0'). Thus, the string is truncated
 190 // iff return value is not less than "length".
 191 int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
 192   va_list args;
 193   va_start(args, format);
 194   int needed_length = VSNPrintf(buffer, length, format, args);
 195   va_end(args);
 196   return needed_length;
 197 }
 198
 199 // Like Printf, but prints the current PID before the output string.
 200 void Report(const char *format, ...) {
 201   const int kLen = 16 * 1024;
 202   InternalScopedBuffer<char> buffer(kLen);
 203   int needed_length = internal_snprintf(buffer.data(),
 204                                         kLen, "==%d== ", GetPid());
 205   RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
 206   va_list args;
 207   va_start(args, format);
 208   needed_length += VSNPrintf(buffer.data() + needed_length,
 209                              kLen - needed_length, format, args);
 210   va_end(args);
 211   RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
 212   RawWrite(buffer.data());
 213   if (PrintfAndReportCallback)
 214     PrintfAndReportCallback(buffer.data());
 215 }
 216
 217 }  // namespace __sanitizer