platform_bionic/libc/include/unistd.h
Elliott Hughes b631ec7409 <unistd.h>: explain why getpagesize() is better than getauxval() as well as sysconf().
I thought we'd already done this, but apparently not.

Bug: http://b/315511637
Change-Id: I0581438a6f551be9750b6679a9f3ad06c83f1e9b
2024-06-03 19:19:22 +00:00

427 lines
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/*
* Copyright (C) 2008 The Android Open Source Project
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* * Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* * Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in
* the documentation and/or other materials provided with the
* distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
* FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
* COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
* INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
* BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS
* OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
* AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
* OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT
* OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*/
#pragma once
#include <stddef.h>
#include <sys/cdefs.h>
#include <sys/types.h>
#include <sys/select.h>
#include <bits/fcntl.h>
#include <bits/getentropy.h>
#include <bits/getopt.h>
#include <bits/ioctl.h>
#include <bits/lockf.h>
#include <bits/posix_limits.h>
#include <bits/seek_constants.h>
#include <bits/sysconf.h>
__BEGIN_DECLS
#define STDIN_FILENO 0
#define STDOUT_FILENO 1
#define STDERR_FILENO 2
#define F_OK 0
#define X_OK 1
#define W_OK 2
#define R_OK 4
#define _PC_FILESIZEBITS 0
#define _PC_LINK_MAX 1
#define _PC_MAX_CANON 2
#define _PC_MAX_INPUT 3
#define _PC_NAME_MAX 4
#define _PC_PATH_MAX 5
#define _PC_PIPE_BUF 6
#define _PC_2_SYMLINKS 7
#define _PC_ALLOC_SIZE_MIN 8
#define _PC_REC_INCR_XFER_SIZE 9
#define _PC_REC_MAX_XFER_SIZE 10
#define _PC_REC_MIN_XFER_SIZE 11
#define _PC_REC_XFER_ALIGN 12
#define _PC_SYMLINK_MAX 13
#define _PC_CHOWN_RESTRICTED 14
#define _PC_NO_TRUNC 15
#define _PC_VDISABLE 16
#define _PC_ASYNC_IO 17
#define _PC_PRIO_IO 18
#define _PC_SYNC_IO 19
extern char* _Nullable * _Nullable environ;
__noreturn void _exit(int __status);
/**
* [fork(2)](http://man7.org/linux/man-pages/man2/fork.2.html) creates a new
* process. fork() runs any handlers set by pthread_atfork().
*
* Returns 0 in the child, the pid of the child in the parent,
* and returns -1 and sets `errno` on failure.
*/
pid_t fork(void);
/**
* _Fork() creates a new process. _Fork() differs from fork() in that it does
* not run any handlers set by pthread_atfork(). In addition to any user-defined
* ones, bionic uses pthread_atfork() handlers to ensure consistency of its own
* state, so the child should only call
* [POSIX async-safe](https://man7.org/linux/man-pages/man7/signal-safety.7.html)
* functions.
*
* Returns 0 in the child, the pid of the child in the parent,
* and returns -1 and sets `errno` on failure.
*
* Available since API level 35.
*/
pid_t _Fork(void) __INTRODUCED_IN(35);
/**
* [vfork(2)](http://man7.org/linux/man-pages/man2/vfork.2.html) creates a new
* process. vfork() differs from fork() in that it does not run any handlers
* set by pthread_atfork(), and the parent is suspended until the child calls
* exec() or exits.
*
* Returns 0 in the child, the pid of the child in the parent,
* and returns -1 and sets `errno` on failure.
*/
pid_t vfork(void) __returns_twice;
/**
* [getpid(2)](http://man7.org/linux/man-pages/man2/getpid.2.html) returns
* the caller's process ID.
*
* Returns the caller's process ID.
*/
pid_t getpid(void);
/**
* [gettid(2)](http://man7.org/linux/man-pages/man2/gettid.2.html) returns
* the caller's thread ID.
*
* Returns the caller's thread ID.
*/
pid_t gettid(void);
pid_t getpgid(pid_t __pid);
int setpgid(pid_t __pid, pid_t __pgid);
pid_t getppid(void);
pid_t getpgrp(void);
int setpgrp(void);
pid_t getsid(pid_t __pid);
pid_t setsid(void);
int execv(const char* _Nonnull __path, char* _Nullable const* _Nullable __argv);
int execvp(const char* _Nonnull __file, char* _Nullable const* _Nullable __argv);
int execvpe(const char* _Nonnull __file, char* _Nullable const* _Nullable __argv, char* _Nullable const* _Nullable __envp);
int execve(const char* _Nonnull __file, char* _Nullable const* _Nullable __argv, char* _Nullable const* _Nullable __envp);
int execl(const char* _Nonnull __path, const char* _Nullable __arg0, ...) __attribute__((__sentinel__));
int execlp(const char* _Nonnull __file, const char* _Nullable __arg0, ...) __attribute__((__sentinel__));
int execle(const char* _Nonnull __path, const char* _Nullable __arg0, ... /*, char* const* __envp */)
__attribute__((__sentinel__(1)));
int fexecve(int __fd, char* _Nullable const* _Nullable __argv, char* _Nullable const* _Nullable __envp) __INTRODUCED_IN(28);
int nice(int __incr);
/**
* [setegid(2)](http://man7.org/linux/man-pages/man2/setegid.2.html) sets
* the effective group ID.
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setegid(gid_t __gid);
/**
* [seteuid(2)](http://man7.org/linux/man-pages/man2/seteuid.2.html) sets
* the effective user ID.
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int seteuid(uid_t __uid);
/**
* [setgid(2)](http://man7.org/linux/man-pages/man2/setgid.2.html) sets
* the group ID.
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setgid(gid_t __gid);
/**
* [setregid(2)](http://man7.org/linux/man-pages/man2/setregid.2.html) sets
* the real and effective group IDs (use -1 to leave an ID unchanged).
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setregid(gid_t __rgid, gid_t __egid);
/**
* [setresgid(2)](http://man7.org/linux/man-pages/man2/setresgid.2.html) sets
* the real, effective, and saved group IDs (use -1 to leave an ID unchanged).
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setresgid(gid_t __rgid, gid_t __egid, gid_t __sgid);
/**
* [setresuid(2)](http://man7.org/linux/man-pages/man2/setresuid.2.html) sets
* the real, effective, and saved user IDs (use -1 to leave an ID unchanged).
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setresuid(uid_t __ruid, uid_t __euid, uid_t __suid);
/**
* [setreuid(2)](http://man7.org/linux/man-pages/man2/setreuid.2.html) sets
* the real and effective group IDs (use -1 to leave an ID unchanged).
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setreuid(uid_t __ruid, uid_t __euid);
/**
* [setuid(2)](http://man7.org/linux/man-pages/man2/setuid.2.html) sets
* the user ID.
*
* On Android, this function only affects the calling thread, not all threads
* in the process.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int setuid(uid_t __uid);
uid_t getuid(void);
uid_t geteuid(void);
gid_t getgid(void);
gid_t getegid(void);
int getgroups(int __size, gid_t* _Nullable __list);
int setgroups(size_t __size, const gid_t* _Nullable __list);
int getresuid(uid_t* _Nonnull __ruid, uid_t* _Nonnull __euid, uid_t* _Nonnull __suid);
int getresgid(gid_t* _Nonnull __rgid, gid_t* _Nonnull __egid, gid_t* _Nonnull __sgid);
char* _Nullable getlogin(void);
int getlogin_r(char* _Nonnull __buffer, size_t __buffer_size) __INTRODUCED_IN(28);
long fpathconf(int __fd, int __name);
long pathconf(const char* _Nonnull __path, int __name);
int access(const char* _Nonnull __path, int __mode);
int faccessat(int __dirfd, const char* _Nonnull __path, int __mode, int __flags);
int link(const char* _Nonnull __old_path, const char* _Nonnull __new_path);
int linkat(int __old_dir_fd, const char* _Nonnull __old_path, int __new_dir_fd, const char* _Nonnull __new_path, int __flags);
int unlink(const char* _Nonnull __path);
int unlinkat(int __dirfd, const char* _Nonnull __path, int __flags);
int chdir(const char* _Nonnull __path);
int fchdir(int __fd);
int rmdir(const char* _Nonnull __path);
int pipe(int __fds[_Nonnull 2]);
#if defined(__USE_GNU)
int pipe2(int __fds[_Nonnull 2], int __flags);
#endif
int chroot(const char* _Nonnull __path);
int symlink(const char* _Nonnull __old_path, const char* _Nonnull __new_path);
int symlinkat(const char* _Nonnull __old_path, int __new_dir_fd, const char* _Nonnull __new_path);
ssize_t readlink(const char* _Nonnull __path, char* _Nonnull __buf, size_t __buf_size);
ssize_t readlinkat(int __dir_fd, const char* _Nonnull __path, char* _Nonnull __buf, size_t __buf_size);
int chown(const char* _Nonnull __path, uid_t __owner, gid_t __group);
int fchown(int __fd, uid_t __owner, gid_t __group);
int fchownat(int __dir_fd, const char* _Nonnull __path, uid_t __owner, gid_t __group, int __flags);
int lchown(const char* _Nonnull __path, uid_t __owner, gid_t __group);
char* _Nullable getcwd(char* _Nullable __buf, size_t __size);
void sync(void);
#if defined(__USE_GNU)
int syncfs(int __fd) __INTRODUCED_IN(28);
#endif
int close(int __fd);
/**
* [read(2)](https://man7.org/linux/man-pages/man2/read.2.html) reads
* up to `__count` bytes from file descriptor `__fd` into `__buf`.
*
* Note: `__buf` is not normally nullable, but may be null in the
* special case of a zero-length read(), which while not generally
* useful may be meaningful to some device drivers.
*
* Returns the number of bytes read on success, and returns -1 and sets `errno` on failure.
*/
ssize_t read(int __fd, void* __BIONIC_COMPLICATED_NULLNESS __buf, size_t __count);
/**
* [write(2)](https://man7.org/linux/man-pages/man2/write.2.html) writes
* up to `__count` bytes to file descriptor `__fd` from `__buf`.
*
* Note: `__buf` is not normally nullable, but may be null in the
* special case of a zero-length write(), which while not generally
* useful may be meaningful to some device drivers.
*
* Returns the number of bytes written on success, and returns -1 and sets `errno` on failure.
*/
ssize_t write(int __fd, const void* __BIONIC_COMPLICATED_NULLNESS __buf, size_t __count);
int dup(int __old_fd);
int dup2(int __old_fd, int __new_fd);
int dup3(int __old_fd, int __new_fd, int __flags);
int fsync(int __fd);
int fdatasync(int __fd);
/* See https://android.googlesource.com/platform/bionic/+/main/docs/32-bit-abi.md */
#if defined(__USE_FILE_OFFSET64)
int truncate(const char* _Nonnull __path, off_t __length) __RENAME(truncate64);
off_t lseek(int __fd, off_t __offset, int __whence) __RENAME(lseek64);
ssize_t pread(int __fd, void* _Nonnull __buf, size_t __count, off_t __offset) __RENAME(pread64);
ssize_t pwrite(int __fd, const void* _Nonnull __buf, size_t __count, off_t __offset) __RENAME(pwrite64);
int ftruncate(int __fd, off_t __length) __RENAME(ftruncate64);
#else
int truncate(const char* _Nonnull __path, off_t __length);
off_t lseek(int __fd, off_t __offset, int __whence);
ssize_t pread(int __fd, void* _Nonnull __buf, size_t __count, off_t __offset);
ssize_t pwrite(int __fd, const void* _Nonnull __buf, size_t __count, off_t __offset);
int ftruncate(int __fd, off_t __length);
#endif
int truncate64(const char* _Nonnull __path, off64_t __length);
off64_t lseek64(int __fd, off64_t __offset, int __whence);
ssize_t pread64(int __fd, void* _Nonnull __buf, size_t __count, off64_t __offset);
ssize_t pwrite64(int __fd, const void* _Nonnull __buf, size_t __count, off64_t __offset);
int ftruncate64(int __fd, off64_t __length);
int pause(void);
unsigned int alarm(unsigned int __seconds);
unsigned int sleep(unsigned int __seconds);
int usleep(useconds_t __microseconds);
int gethostname(char* _Nonnull _buf, size_t __buf_size);
int sethostname(const char* _Nonnull __name, size_t __n) __INTRODUCED_IN(23);
int brk(void* _Nonnull __addr);
void* _Nullable sbrk(ptrdiff_t __increment);
int isatty(int __fd);
char* _Nullable ttyname(int __fd);
int ttyname_r(int __fd, char* _Nonnull __buf, size_t __buf_size);
int acct(const char* _Nullable __path);
/**
* [getpagesize(2)](https://man7.org/linux/man-pages/man2/getpagesize.2.html)
* returns the system's page size. This is slightly faster than going via
* sysconf(), and avoids the linear search in getauxval().
*
* Returns the system's page size in bytes.
*/
int getpagesize(void) __attribute_const__;
long syscall(long __number, ...);
int daemon(int __no_chdir, int __no_close);
#if defined(__arm__)
/**
* New code should use __builtin___clear_cache() instead, which works on
* all architectures.
*/
int cacheflush(long __addr, long __nbytes, long __cache);
#endif
pid_t tcgetpgrp(int __fd);
int tcsetpgrp(int __fd, pid_t __pid);
/* Used to retry syscalls that can return EINTR. */
#define TEMP_FAILURE_RETRY(exp) ({ \
__typeof__(exp) _rc; \
do { \
_rc = (exp); \
} while (_rc == -1 && errno == EINTR); \
_rc; })
int getdomainname(char* _Nonnull __buf, size_t __buf_size) __INTRODUCED_IN(26);
int setdomainname(const char* _Nonnull __name, size_t __n) __INTRODUCED_IN(26);
/**
* [copy_file_range(2)](https://man7.org/linux/man-pages/man2/copy_file_range.2.html) copies
* a range of data from one file descriptor to another.
*
* Available since API level 34.
*
* Returns the number of bytes copied on success, and returns -1 and sets
* `errno` on failure.
*/
ssize_t copy_file_range(int __fd_in, off64_t* _Nullable __off_in, int __fd_out, off64_t* _Nullable __off_out, size_t __length, unsigned int __flags) __INTRODUCED_IN(34);
#if __ANDROID_API__ >= 28
void swab(const void* _Nonnull __src, void* _Nonnull __dst, ssize_t __byte_count) __INTRODUCED_IN(28);
#endif
/**
* [close_range(2)](https://man7.org/linux/man-pages/man2/close_range.2.html)
* performs an action (which depends on value of flags) on an inclusive range
* of file descriptors.
*
* Available since API level 34.
*
* Note: there is no emulation on too old kernels, hence this will fail with
* -1/ENOSYS on pre-5.9 kernels, -1/EINVAL for unsupported flags. In particular
* CLOSE_RANGE_CLOEXEC requires 5.11, though support was backported to Android
* Common Kernel 5.10-T.
*
* Returns 0 on success, and returns -1 and sets `errno` on failure.
*/
int close_range(unsigned int __min_fd, unsigned int __max_fd, int __flags) __INTRODUCED_IN(34);
#if defined(__BIONIC_INCLUDE_FORTIFY_HEADERS)
#define _UNISTD_H_
#include <bits/fortify/unistd.h>
#undef _UNISTD_H_
#endif
__END_DECLS
#include <android/legacy_unistd_inlines.h>