tools/include/nolibc/sys/select.h

Source file repositories/reference/linux-study-clean/tools/include/nolibc/sys/select.h

File Facts

System
Linux kernel
Corpus path
tools/include/nolibc/sys/select.h
Extension
.h
Size
2388 bytes
Lines
95
Domain
Support Tooling And Documentation
Bucket
tools
Inferred role
Support Tooling And Documentation: implementation source
Status
source implementation candidate

Why This File Exists

Repository support layer: documentation, build tooling, samples, user-space helper tools, generated initramfs support, licenses, and validation utilities.

Dependency Surface

Detected Declarations

Annotated Snippet

#include "../nolibc.h"

#ifndef _NOLIBC_SYS_SELECT_H
#define _NOLIBC_SYS_SELECT_H

#include <linux/time.h>
#include <linux/unistd.h>

/* commonly an fd_set represents 256 FDs */
#ifndef FD_SETSIZE
#define FD_SETSIZE     256
#endif

#define FD_SETIDXMASK (8 * sizeof(unsigned long))
#define FD_SETBITMASK (8 * sizeof(unsigned long)-1)

/* for select() */
typedef struct {
	unsigned long fds[(FD_SETSIZE + FD_SETBITMASK) / FD_SETIDXMASK];
} fd_set;

#define FD_CLR(fd, set) do {						\
		fd_set *__set = (set);					\
		int __fd = (fd);					\
		if (__fd >= 0)						\
			__set->fds[__fd / FD_SETIDXMASK] &=		\
				~(1U << (__fd & FD_SETBITMASK));	\
	} while (0)

#define FD_SET(fd, set) do {						\
		fd_set *__set = (set);					\
		int __fd = (fd);					\
		if (__fd >= 0)						\
			__set->fds[__fd / FD_SETIDXMASK] |=		\
				1 << (__fd & FD_SETBITMASK);		\
	} while (0)

#define FD_ISSET(fd, set) ({						\
			fd_set *__set = (set);				\
			int __fd = (fd);				\
		int __r = 0;						\
		if (__fd >= 0)						\
			__r = !!(__set->fds[__fd / FD_SETIDXMASK] &	\
1U << (__fd & FD_SETBITMASK));						\
		__r;							\
	})

#define FD_ZERO(set) do {						\
		fd_set *__set = (set);					\
		int __idx;						\
		int __size = (FD_SETSIZE+FD_SETBITMASK) / FD_SETIDXMASK;\
		for (__idx = 0; __idx < __size; __idx++)		\
			__set->fds[__idx] = 0;				\
	} while (0)

/*
 * int select(int nfds, fd_set *read_fds, fd_set *write_fds,
 *            fd_set *except_fds, struct timeval *timeout);
 */

static __attribute__((unused))
int _sys_select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *timeout)
{
#if defined(__NR_pselect6_time64)
	struct __kernel_timespec t;

	if (timeout) {
		t.tv_sec  = timeout->tv_sec;
		t.tv_nsec = (uint32_t)timeout->tv_usec * 1000;
	}
	return __nolibc_syscall6(__NR_pselect6_time64, nfds, rfds, wfds, efds,
				 timeout ? &t : NULL, NULL);
#else
	struct __kernel_old_timespec t;

	if (timeout) {
		t.tv_sec  = timeout->tv_sec;
		t.tv_nsec = (uint32_t)timeout->tv_usec * 1000;
	}
	return __nolibc_syscall6(__NR_pselect6, nfds, rfds, wfds, efds,
				 timeout ? &t : NULL, NULL);
#endif
}

static __attribute__((unused))
int select(int nfds, fd_set *rfds, fd_set *wfds, fd_set *efds, struct timeval *timeout)
{
	return __sysret(_sys_select(nfds, rfds, wfds, efds, timeout));
}

Annotation

Implementation Notes