| //===-- 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 LIBC_NAMESPACE { |
| |
| namespace { |
| |
| bool getcwd_syscall(char *buf, size_t size) { |
| int ret = LIBC_NAMESPACE::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 LIBC_NAMESPACE |