path: root/tools/include/nolibc/sys.h

/* SPDX-License-Identifier: LGPL-2.1 OR MIT */
/*
 * Syscall definitions for NOLIBC (those in man(2))
 * Copyright (C) 2017-2021 Willy Tarreau <w@1wt.eu>
 */

#ifndef _NOLIBC_SYS_H
#define _NOLIBC_SYS_H

#include "std.h"

/* system includes */
#include <asm/unistd.h>
#include <asm/signal.h>  /* for SIGCHLD */
#include <asm/ioctls.h>
#include <asm/mman.h>
#include <linux/fs.h>
#include <linux/loop.h>
#include <linux/time.h>
#include <linux/auxvec.h>
#include <linux/fcntl.h> /* for O_* and AT_* */
#include <linux/stat.h>  /* for statx() */
#include <linux/prctl.h>
#include <linux/resource.h>

#include "arch.h"
#include "errno.h"
#include "stdarg.h"
#include "types.h"


/* Syscall return helper: takes the syscall value in argument and checks for an
 * error in it. This may only be used with signed returns (int or long), but
 * not with pointers. An error is any value < 0. When an error is encountered,
 * -ret is set into errno and -1 is returned. Otherwise the returned value is
 * passed as-is with its type preserved.
 */

#define __sysret(arg)							\
({									\
	__typeof__(arg) __sysret_arg = (arg);				\
	(__sysret_arg < 0)                              /* error ? */	\
		? (({ SET_ERRNO(-__sysret_arg); }), -1) /* ret -1 with errno = -arg */ \
		: __sysret_arg;                         /* return original value */ \
})

/* Syscall ENOSYS helper: Avoids unused-parameter warnings and provides a
 * debugging hook.
 */

static __inline__ int __nolibc_enosys(const char *syscall, ...)
{
	(void)syscall;
	return -ENOSYS;
}


/* Functions in this file only describe syscalls. They're declared static so
 * that the compiler usually decides to inline them while still being allowed
 * to pass a pointer to one of their instances. Each syscall exists in two
 * versions:
 *   - the "internal" ones, which matches the raw syscall interface at the
 *     kernel level, which may sometimes slightly differ from the documented
 *     libc-level ones. For example most of them return either a valid value
 *     or -errno. All of these are prefixed with "sys_". They may be called
 *     by non-portable applications if desired.
 *
 *   - the "exported" ones, whose interface must closely match the one
 *     documented in man(2), that applications are supposed to expect. These
 *     ones rely on the internal ones, and set errno.
 *
 * Each syscall will be defined with the two functions, sorted in alphabetical
 * order applied to the exported names.
 *
 * In case of doubt about the relevance of a function here, only those which
 * set errno should be defined here. Wrappers like those appearing in man(3)
 * should not be placed here.
 */


/*
 * int brk(void *addr);
 * void *sbrk(intptr_t inc)
 */

static __attribute__((unused))
void *sys_brk(void *addr)
{
	return (void *)my_syscall1(__NR_brk, addr);
}

static __attribute__((unused))
int brk(void *addr)
{
	void *ret = sys_brk(addr);

	if (!ret) {
		SET_ERRNO(ENOMEM);
		return -1;
	}
	return 0;
}

static __attribute__((unused))
void *sbrk(intptr_t inc)
{
	/* first call to find current end */
	void *ret = sys_brk(0);

	if (ret && sys_brk(ret + inc) == ret + inc)
		return ret + inc;

	SET_ERRNO(ENOMEM);
	return (void *)-1;
}


/*
 * int chdir(const char *path);
 */

static __attribute__((unused))
int sys_chdir(const char *path)
{
	return my_syscall1(__NR_chdir, path);
}

static __attribute__((unused))
int chdir(const char *path)
{
	return __sysret(sys_chdir(path));
}


/*
 * int chmod(const char *path, mode_t mode);
 */

static __attribute__((unused))
int sys_chmod(const char *path, mode_t mode)
{
#ifdef __NR_fchmodat
	return my_syscall4(__NR_fchmodat, AT_FDCWD, path, mode, 0);
#elif defined(__NR_chmod)
	return my_syscall2(__NR_chmod, path, mode);
#else
	return __nolibc_enosys(__func__, path, mode);
#endif
}

static __attribute__((unused))
int chmod(const char *path, mode_t mode)
{
	return __sysret(sys_chmod(path, mode));
}


/*
 * int chown(const char *path, uid_t owner, gid_t group);
 */

static __attribute__((unused))
int sys_chown(const char *path, uid_t owner, gid_t group)
{
#ifdef __NR_fchownat
	return my_syscall5(__NR_fchownat, AT_FDCWD, path