121 lines
4.7 KiB
C
121 lines
4.7 KiB
C
#ifndef VLIBC_SYS_SELECT_H
|
|
#define VLIBC_SYS_SELECT_H
|
|
|
|
/*
|
|
* vlibc — <sys/select.h>.
|
|
*
|
|
* Synchronous I/O multiplexing: wait for readiness on file-descriptor sets
|
|
* with select() or pselect(). Both are thin wrappers over the SYS_pselect6
|
|
* kernel ABI, (nfds, readfds, writefds, exceptfds, struct timespec *,
|
|
* { sigset_t *, size_t } *): pselect passes its timespec and optional signal
|
|
* mask straight through, select converts its struct timeval timeout to a
|
|
* timespec and passes a NULL sigset pair.
|
|
*
|
|
* Level 1 (onlyposix): select, pselect, FD_* macros, fd_set, struct
|
|
* timeval.
|
|
*
|
|
* fd_set is the kernel's bitmap layout on x86_64: an array of unsigned long
|
|
* words, with descriptor d held in bit d % 64 of word d / 64. FD_SETSIZE
|
|
* caps the tracked descriptors at 1024 (16 words), so select()/pselect()
|
|
* must be called with nfds <= FD_SETSIZE and FD_SET() only ever receives
|
|
* descriptors below FD_SETSIZE. select() and pselect() report the number of
|
|
* ready descriptors, 0 on timeout, or -1 with errno set on error.
|
|
*
|
|
* The signal mask type is declared here under the shared guard; <signal.h>
|
|
* is its canonical POSIX home and will own the full sig* API.
|
|
*/
|
|
|
|
#include <vlibc/features.h>
|
|
|
|
#include <sys/types.h>
|
|
|
|
#include <time.h>
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
/* Maximum descriptors select()/pselect() track (fd_set's bit capacity). */
|
|
#define FD_SETSIZE 1024
|
|
|
|
/*
|
|
* A set of file descriptors, one bit per descriptor, stored in the kernel
|
|
* bitmap layout: an array of unsigned long words, bit d in word
|
|
* d / (8 * sizeof(unsigned long)). Descriptors 0..FD_SETSIZE-1 fit; no
|
|
* operation may touch a descriptor at or above FD_SETSIZE.
|
|
*/
|
|
typedef struct
|
|
{
|
|
unsigned long fds_bits[FD_SETSIZE / (8 * sizeof(unsigned long))];
|
|
} fd_set;
|
|
|
|
/* The word holding bit d of an fd_set, and that bit's mask within the word. */
|
|
#define VLIBC_FDS_WORD(d) ((d) / (8 * sizeof(unsigned long)))
|
|
#define VLIBC_FDS_MASK(d) (1UL << ((d) % (8 * sizeof(unsigned long))))
|
|
|
|
/* Clear every descriptor bit of set. */
|
|
#define FD_ZERO(set) \
|
|
do \
|
|
{ \
|
|
size_t fd_zero_i; \
|
|
for (fd_zero_i = 0; fd_zero_i < sizeof(fd_set) / sizeof(unsigned long); fd_zero_i++) \
|
|
{ \
|
|
(set)->fds_bits[fd_zero_i] = 0UL; \
|
|
} \
|
|
} while (0)
|
|
|
|
/* Add descriptor d to set. */
|
|
#define FD_SET(d, set) ((set)->fds_bits[VLIBC_FDS_WORD(d)] |= VLIBC_FDS_MASK(d))
|
|
|
|
/* Remove descriptor d from set. */
|
|
#define FD_CLR(d, set) ((set)->fds_bits[VLIBC_FDS_WORD(d)] &= ~VLIBC_FDS_MASK(d))
|
|
|
|
/* Nonzero when descriptor d is a member of set. */
|
|
#define FD_ISSET(d, set) ((set)->fds_bits[VLIBC_FDS_WORD(d)] & VLIBC_FDS_MASK(d))
|
|
|
|
#ifndef VLIBC_SIGSET_T_DEFINED
|
|
#define VLIBC_SIGSET_T_DEFINED
|
|
/*
|
|
* Signal mask type: a single 64-bit word — the x86_64 Linux sigset_t (see
|
|
* setjmp.h). pselect() and ppoll() only ever forward a pointer to the
|
|
* kernel, which reads the word directly. <signal.h> is the canonical POSIX
|
|
* home for sigset_t and builds the sig* API on this same layout; the
|
|
* typedef is repeated in <poll.h> under this guard so the two headers stay
|
|
* consistent.
|
|
*/
|
|
typedef unsigned long sigset_t;
|
|
#endif
|
|
|
|
/* Elapsed time in seconds and microseconds (see select()'s timeout). */
|
|
struct timeval
|
|
{
|
|
time_t tv_sec;
|
|
suseconds_t tv_usec;
|
|
};
|
|
|
|
/*
|
|
* Wait for readiness on the descriptors marked in readfds, writefds and
|
|
* exceptfds (each may be NULL), up to nfds descriptors (the highest
|
|
* descriptor in any set plus one). timeout is an upper bound on the wait; a
|
|
* NULL timeout blocks indefinitely, { 0, 0 } never blocks. On return each
|
|
* non-NULL set holds only its ready descriptors. Return the number of ready
|
|
* descriptors across the sets, 0 on timeout, or -1 with errno set.
|
|
*/
|
|
int
|
|
select(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds, struct timeval *timeout);
|
|
|
|
/*
|
|
* Like select(), but the timeout is a struct timespec and, when sigmask is
|
|
* not NULL, the given signal mask is atomically installed for the duration
|
|
* of the wait (the previous mask is restored before returning).
|
|
*/
|
|
int
|
|
pselect(int nfds, fd_set *readfds, fd_set *writefds, fd_set *exceptfds,
|
|
const struct timespec *timeout, const sigset_t *sigmask);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* VLIBC_SYS_SELECT_H */
|