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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
* License, v. 2.0. If a copy of the MPL was not distributed with this
* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
#include <cstdarg>
#ifdef _WIN32
# include <windows.h>
#else
# include <unistd.h>
#endif
#include <cmath>
#include <cstring>
#include "mozilla/Assertions.h"
#include "mozilla/Unused.h"
#include "FdPrintf.h"
/* Template class allowing a limited number of increments on a value */
template <typename T>
class CheckedIncrement {
public:
CheckedIncrement(T aValue, size_t aMaxIncrement)
: mValue(aValue), mMaxIncrement(aMaxIncrement) {}
T operator++(int) {
if (!mMaxIncrement) {
MOZ_CRASH("overflow detected");
}
mMaxIncrement--;
return mValue++;
}
T& operator++() {
(*this)++;
return mValue;
}
void advance(T end) {
// Only makes sense if T is a pointer type.
size_t diff = end - mValue;
if (diff > mMaxIncrement) {
MOZ_CRASH("overflow detected");
}
mMaxIncrement -= diff;
mValue = end;
};
void rewind(T pos) {
size_t diff = mValue - pos;
mMaxIncrement += diff;
mValue = pos;
}
operator T() { return mValue; }
T value() { return mValue; }
private:
T mValue;
size_t mMaxIncrement;
};
template <typename T>
static unsigned NumDigits(T n) {
if (n < 1) {
// We want one digit, it will be 0.
return 1;
}
double l = log10(static_cast<double>(n));
double cl = ceil(l);
return l == cl ? unsigned(cl) + 1 : unsigned(cl);
}
static void LeftPad(CheckedIncrement<char*>& b, size_t pad) {
while (pad-- > 0) {
*(b++) = ' ';
}
}
// Write the digits into the buffer.
static void WriteDigits(CheckedIncrement<char*>& b, size_t i,
size_t num_digits) {
size_t x = pow(10, double(num_digits - 1));
do {
*(b++) = "0123456789"[(i / x) % 10];
x /= 10;
} while (x > 0);
}
void FdPrintf(intptr_t aFd, const char* aFormat, ...) {
if (aFd == 0) {
return;
}
char buf[256];
CheckedIncrement<char*> b(buf, sizeof(buf));
CheckedIncrement<const char*> f(aFormat, strlen(aFormat) + 1);
va_list ap;
va_start(ap, aFormat);
while (true) {
switch (*f) {
case '\0':
goto out;
case '%': {
// The start of the format specifier is used if this specifier is
// invalid.
const char* start = f;
// Read the field width
f++;
char* end = nullptr;
size_t width = strtoul(f, &end, 10);
// If strtol can't find a number that's okay, that means 0 in our
// case, but we must advance f).
f.advance(end);
switch (*f) {
case 'z': {
if (*(++f) == 'u') {
size_t i = va_arg(ap, size_t);
size_t num_digits = NumDigits(i);
LeftPad(b, width > num_digits ? width - num_digits : 0);
WriteDigits(b, i, num_digits);
} else {
// If the format specifier is unknown then write out '%' and
// rewind to the beginning of the specifier causing it to be
// printed normally.
*(b++) = '%';
f.rewind(start);
}
break;
}
case 'p': {
intptr_t ptr = va_arg(ap, intptr_t);
*(b++) = '0';
*(b++) = 'x';
int x = sizeof(intptr_t) * 8;
bool wrote_msb = false;
do {
x -= 4;
size_t hex_digit = ptr >> x & 0xf;
if (hex_digit || wrote_msb) {
*(b++) = "0123456789abcdef"[hex_digit];
wrote_msb = true;
}
} while (x > 0);
if (!wrote_msb) {
*(b++) = '0';
}
break;
}
case 's': {
const char* str = va_arg(ap, const char*);
size_t len = strlen(str);
LeftPad(b, width > len ? width - len : 0);
while (*str) {
*(b++) = *(str++);
}
break;
}
case '%':
// Print a single raw '%'.
*(b++) = '%';
break;
default:
// If the format specifier is unknown then write out '%' and
// rewind to the beginning of the specifier causing it to be
// printed normally.
*(b++) = '%';
f.rewind(start);
break;
}
break;
}
default:
*(b++) = *f;
break;
}
f++;
}
out:
#ifdef _WIN32
// See comment in FdPrintf.h as to why WriteFile is used.
DWORD written;
WriteFile(reinterpret_cast<HANDLE>(aFd), buf, b - buf, &written, nullptr);
#else
MOZ_UNUSED(write(aFd, buf, b - buf));
#endif
va_end(ap);
}
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