llvm-project/compiler-rt/lib/sanitizer_common/sanitizer_printf.cc

//===-- sanitizer_printf.cc -----------------------------------------------===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This file is shared between AddressSanitizer and ThreadSanitizer.
//
// Internal printf function, used inside run-time libraries.
// We can't use libc printf because we intercept some of the functions used
// inside it.
//===----------------------------------------------------------------------===//


#include "sanitizer_common.h"
#include "sanitizer_libc.h"

#include <stdio.h>
#include <stdarg.h>

namespace __sanitizer {

static int AppendChar(char **buff, const char *buff_end, char c) {
  if (*buff < buff_end) {
    **buff = c;
    (*buff)++;
  }
  return 1;
}

// Appends number in a given base to buffer. If its length is less than
// "minimal_num_length", it is padded with leading zeroes.
static int AppendUnsigned(char **buff, const char *buff_end, u64 num,
                          u8 base, u8 minimal_num_length) {
  uptr const kMaxLen = 30;
  RAW_CHECK(base == 10 || base == 16);
  RAW_CHECK(minimal_num_length < kMaxLen);
  uptr num_buffer[kMaxLen];
  uptr pos = 0;
  do {
    RAW_CHECK_MSG(pos < kMaxLen, "appendNumber buffer overflow");
    num_buffer[pos++] = num % base;
    num /= base;
  } while (num > 0);
  while (pos < minimal_num_length) num_buffer[pos++] = 0;
  int result = 0;
  while (pos-- > 0) {
    uptr digit = num_buffer[pos];
    result += AppendChar(buff, buff_end, (digit < 10) ? '0' + digit
                                                      : 'a' + digit - 10);
  }
  return result;
}

static int AppendSignedDecimal(char **buff, const char *buff_end, s64 num) {
  int result = 0;
  if (num < 0) {
    result += AppendChar(buff, buff_end, '-');
    num = -num;
  }
  result += AppendUnsigned(buff, buff_end, (u64)num, 10, 0);
  return result;
}

static int AppendString(char **buff, const char *buff_end, const char *s) {
  if (s == 0)
    s = "<null>";
  int result = 0;
  for (; *s; s++) {
    result += AppendChar(buff, buff_end, *s);
  }
  return result;
}

static int AppendPointer(char **buff, const char *buff_end, u64 ptr_value) {
  int result = 0;
  result += AppendString(buff, buff_end, "0x");
  result += AppendUnsigned(buff, buff_end, ptr_value, 16,
                           (__WORDSIZE == 64) ? 12 : 8);
  return result;
}

int VSNPrintf(char *buff, int buff_length,
              const char *format, va_list args) {
  static const char *kPrintfFormatsHelp = "Supported Printf formats: "
                                          "%%[z]{d,u,x}; %%p; %%s\n";
  RAW_CHECK(format);
  RAW_CHECK(buff_length > 0);
  const char *buff_end = &buff[buff_length - 1];
  const char *cur = format;
  int result = 0;
  for (; *cur; cur++) {
    if (*cur != '%') {
      result += AppendChar(&buff, buff_end, *cur);
      continue;
    }
    cur++;
    bool have_z = (*cur == 'z');
    cur += have_z;
    s64 dval;
    u64 uval;
    switch (*cur) {
      case 'd': {
        dval = have_z ? va_arg(args, sptr)
                      : va_arg(args, int);
        result += AppendSignedDecimal(&buff, buff_end, dval);
        break;
      }
      case 'u':
      case 'x': {
        uval = have_z ? va_arg(args, uptr)
                      : va_arg(args, unsigned);
        result += AppendUnsigned(&buff, buff_end, uval,
                                 (*cur == 'u') ? 10 : 16, 0);
        break;
      }
      case 'p': {
        RAW_CHECK_MSG(!have_z, kPrintfFormatsHelp);
        result += AppendPointer(&buff, buff_end, va_arg(args, uptr));
        break;
      }
      case 's': {
        RAW_CHECK_MSG(!have_z, kPrintfFormatsHelp);
        result += AppendString(&buff, buff_end, va_arg(args, char*));
        break;
      }
      case '%' : {
        RAW_CHECK_MSG(!have_z, kPrintfFormatsHelp);
        result += AppendChar(&buff, buff_end, '%');
        break;
      }
      default: {
        RAW_CHECK_MSG(false, kPrintfFormatsHelp);
      }
    }
  }
  RAW_CHECK(buff <= buff_end);
  AppendChar(&buff, buff_end + 1, '\0');
  return result;
}

void Printf(const char *format, ...) {
  const int kLen = 1024 * 4;
  char *buffer = (char*)MmapOrDie(kLen, __FUNCTION__);
  va_list args;
  va_start(args, format);
  int needed_length = VSNPrintf(buffer, kLen, format, args);
  va_end(args);
  RAW_CHECK_MSG(needed_length < kLen, "Buffer in Printf is too short!\n");
  RawWrite(buffer);
  UnmapOrDie(buffer, kLen);
}

// Writes at most "length" symbols to "buffer" (including trailing '\0').
// Returns the number of symbols that should have been written to buffer
// (not including trailing '\0'). Thus, the string is truncated
// iff return value is not less than "length".
int internal_snprintf(char *buffer, uptr length, const char *format, ...) {
  va_list args;
  va_start(args, format);
  int needed_length = VSNPrintf(buffer, length, format, args);
  va_end(args);
  return needed_length;
}

// Like Printf, but prints the current PID before the output string.
void Report(const char *format, ...) {
  const int kLen = 1024 * 4;
  char *buffer = (char*)MmapOrDie(kLen, __FUNCTION__);
  int needed_length = internal_snprintf(buffer, kLen, "==%d== ", GetPid());
  RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
  va_list args;
  va_start(args, format);
  needed_length += VSNPrintf(buffer + needed_length, kLen - needed_length,
                             format, args);
  va_end(args);
  RAW_CHECK_MSG(needed_length < kLen, "Buffer in Report is too short!\n");
  RawWrite(buffer);
  UnmapOrDie(buffer, kLen);
}

}  // namespace __sanitizer