crashpad/util/misc/paths_linux.cc
Mark Mentovai 6278690abe Update copyright boilerplate, 2022 edition (Crashpad)
sed -i '' -E -e 's/Copyright (.+) The Crashpad Authors\. All rights reserved\.$/Copyright \1 The Crashpad Authors/' $(git grep -El 'Copyright (.+) The Crashpad Authors\. All rights reserved\.$')

Bug: chromium:1098010
Change-Id: I8d6138469ddbe3d281a5d83f64cf918ec2491611
Reviewed-on: https://chromium-review.googlesource.com/c/crashpad/crashpad/+/3878262
Reviewed-by: Joshua Peraza <jperaza@chromium.org>
Commit-Queue: Mark Mentovai <mark@chromium.org>
2022-09-06 23:54:07 +00:00

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// Copyright 2016 The Crashpad Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
#include "util/misc/paths.h"
#include <limits.h>
#include <unistd.h>
#include <algorithm>
#include <string>
#include "base/logging.h"
namespace crashpad {
// static
bool Paths::Executable(base::FilePath* path) {
// Linux does not provide a straightforward way to size the buffer before
// calling readlink(). Normally, the st_size field returned by lstat() could
// be used, but this is usually zero for things in /proc.
//
// The /proc filesystem does not provide any way to read “exe” links for
// pathnames longer than a page. See linux-4.9.20/fs/proc/base.c
// do_proc_readlink(), which allocates a single page to receive the path
// string. Coincidentally, the page size and PATH_MAX are normally the same
// value, although neither is strictly a limit on the length of a pathname.
//
// On Android, the smaller of the page size and PATH_MAX actually does serve
// as an effective limit on the length of an executables pathname. See
// Android 7.1.1 bionic/linker/linker.cpp get_executable_path(), which aborts
// via __libc_fatal() if the “exe” link cant be read into a PATH_MAX-sized
// buffer.
std::string exe_path(std::max(getpagesize(), PATH_MAX),
std::string::value_type());
ssize_t exe_path_len =
readlink("/proc/self/exe", &exe_path[0], exe_path.size());
if (exe_path_len < 0) {
PLOG(ERROR) << "readlink";
return false;
} else if (static_cast<size_t>(exe_path_len) >= exe_path.size()) {
LOG(ERROR) << "readlink";
return false;
}
exe_path.resize(exe_path_len);
*path = base::FilePath(exe_path);
return true;
}
} // namespace crashpad