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//===-- Linux implementation of getcwd ------------------------------------===//
//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//
#include "src/unistd/getcwd.h"
#include "src/__support/OSUtil/syscall.h" // For internal syscall function.
#include "src/__support/common.h"
#include "src/string/allocating_string_utils.h" // For strdup.
#include "src/errno/libc_errno.h"
#include <linux/limits.h> // This is safe to include without any name pollution.
#include <stdlib.h>
#include <sys/syscall.h> // For syscall numbers.
namespace __llvm_libc {
namespace {
bool getcwd_syscall(char *buf, size_t size) {
int ret = __llvm_libc::syscall_impl<int>(SYS_getcwd, buf, size);
if (ret < 0) {
libc_errno = -ret;
return false;
} else if (ret == 0 || buf[0] != '/') {
libc_errno = ENOENT;
return false;
}
return true;
}
} // anonymous namespace
LLVM_LIBC_FUNCTION(char *, getcwd, (char *buf, size_t size)) {
if (buf == nullptr) {
// We match glibc's behavior here and return the cwd in a malloc-ed buffer.
// We will allocate a static buffer of size PATH_MAX first and fetch the cwd
// into it. This way, if the syscall fails, we avoid unnecessary malloc
// and free.
char pathbuf[PATH_MAX];
if (!getcwd_syscall(pathbuf, PATH_MAX))
return nullptr;
auto cwd = internal::strdup(pathbuf);
if (!cwd) {
libc_errno = ENOMEM;
return nullptr;
}
return *cwd;
} else if (size == 0) {
libc_errno = EINVAL;
return nullptr;
}
// TODO: When buf is not sufficient, evaluate the full cwd path using
// alternate approaches.
if (!getcwd_syscall(buf, size))
return nullptr;
return buf;
}
} // namespace __llvm_libc
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