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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 "SandboxLogging.h"
#ifdef ANDROID
# include <android/log.h>
#endif
#include <algorithm>
#include <stdio.h>
#include <string.h>
#include <sys/uio.h>
#include <unistd.h>
#include "base/posix/eintr_wrapper.h"
namespace mozilla {
// Alters an iovec array to remove the first `toDrop` bytes. This
// complexity is necessary because writev can return a short write
// (e.g., if stderr is a pipe and the buffer is almost full).
static void IOVecDrop(struct iovec* iov, int iovcnt, size_t toDrop) {
while (toDrop > 0 && iovcnt > 0) {
size_t toDropHere = std::min(toDrop, iov->iov_len);
iov->iov_base = static_cast<char*>(iov->iov_base) + toDropHere;
iov->iov_len -= toDropHere;
toDrop -= toDropHere;
++iov;
--iovcnt;
}
}
void SandboxLogError(const char* message) {
#ifdef ANDROID
// This uses writev internally and appears to be async signal safe.
__android_log_write(ANDROID_LOG_ERROR, "Sandbox", message);
#endif
static const char logPrefix[] = "Sandbox: ", logSuffix[] = "\n";
struct iovec iovs[3] = {
{const_cast<char*>(logPrefix), sizeof(logPrefix) - 1},
{const_cast<char*>(message), strlen(message)},
{const_cast<char*>(logSuffix), sizeof(logSuffix) - 1},
};
while (iovs[2].iov_len > 0) {
ssize_t written = HANDLE_EINTR(writev(STDERR_FILENO, iovs, 3));
if (written <= 0) {
break;
}
IOVecDrop(iovs, 3, static_cast<size_t>(written));
}
}
} // namespace mozilla
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