Unix/Linux系統調用
accept()函數 Unix/Linux
access()函數 Unix/Linux
acct()函數 Unix/Linux
add_key()函數 Unix/Linux
adjtimex()函數 Unix/Linux
afs_syscall()函數 Unix/Linux
alarm()函數 Unix/Linux
alloc_hugepages()函數 Unix/Linux
arch_prctl()函數 Unix/Linux
bdflush()函數 Unix/Linux
bind()函數 Unix/Linux
break未實現 Unix/Linux
brk()函數 Unix/Linux
cacheflush()函數 Unix/Linux
chdir()函數 Unix/Linux
chmod()函數 Unix/Linux
chown()函數 Unix/Linux
chroot()函數 Unix/Linux
clone()函數 Unix/Linux
close()函數 Unix/Linux
connect()函數 Unix/Linux
create_module()函數 Unix/Linux
open()函數 Unix/Linux
dup2()函數 Unix/Linux
dup()函數 Unix/Linux
epoll_create()函數 Unix/Linux
epoll_ctl()函數 Unix/Linux
epoll_wait()函數 Unix/Linux
execve()函數 Unix/Linux
exit_group函數 Unix/Linux
_exit()函數 Unix/Linux
exit()函數 Unix/Linux
faccessat()函數 Unix/Linux
fattach()函數 Unix/Linux
fchdir()函數 Unix/Linux
fchmodat()函數 Unix/Linux
fchmod()函數 Unix/Linux
fchownat()函數 Unix/Linux
fchown()函數 Unix/Linux
fcntl()函數 Unix/Linux
fdatasync()函數 Unix/Linux
fdetach()函數 Unix/Linux
flock()函數 Unix/Linux
fork()函數 Unix/Linux
alloc_hugepages()函數 Unix/Linux
fstatat()函數 Unix/Linux
statfs()函數 Unix/Linux
stat()函數 Unix/Linux
statvfs()函數 Unix/Linux
fsync()函數 Unix/Linux
truncate()函數 Unix/Linux
futex()函數 Unix/Linux
futimesat()函數 Unix/Linux
getcontext()函數 Unix/Linux
getcwd()函數 Unix/Linux
getdents()函數 Unix/Linux
getdomainname()函數 Unix/Linux
getdtablesize()函數 Unix/Linux
getgid()函數 Unix/Linux
getuid()函數 Unix/Linux
getgroups()函數 Unix/Linux
getgroups()函數 Unix/Linux
gethostname()函數 Unix/Linux
getitimer()函數 Unix/Linux
get_kernel_syms()函數 Unix/Linux
unimplemented()函數 Unix/Linux
getpagesize()函數 Unix/Linux
getpeername()函數 Unix/Linux
setpgid()函數 Unix/Linux
getpgrp()函數 Unix/Linux
getpid()函數 Unix/Linux
getpmsg()函數 Unix/Linux
getppid()函數 Unix/Linux
getpriority()函數 Unix/Linux
getresuid()函數 Unix/Linux
getrlimit()函數 Unix/Linux
get_robust_list()函數 Unix/Linux
getrusage()函數 Unix/Linux
getsid()函數 Unix/Linux
getsockname()函數 Unix/Linux
getsockopt()函數 Unix/Linux
get_thread_area()函數 Unix/Linux
gettid()函數 Unix/Linux
gettimeofday()函數 Unix/Linux
getuid()函數 Unix/Linux
getunwind()函數 Unix/Linux
gtty()函數 Unix/Linux
idle()函數 Unix/Linux
outb()函數 Unix/Linux
inb_p()函數 Unix/Linux
inl()函數 Unix/Linux
inl_p()函數 Unix/Linux
inotify_add_watch()函數 Unix/Linux
inotify_init()函數 Unix/Linux
inotify_rm_watch()函數 Unix/Linux
outb()函數 Unix/Linux
insl()函數 Unix/Linux
insw()函數 Unix/Linux
intro()函數 Unix/Linux
inw()函數 Unix/Linux
inw_p()函數 Unix/Linux
io_cancel()函數 Unix/Linux
ioctl()函數 Unix/Linux
ioctl_list()函數 Unix/Linux
io_destroy()函數 Unix/Linux
io_getevents()函數 Unix/Linux
ioperm()函數 Unix/Linux
iopl()函數 Unix/Linux
ioprio_set()函數 Unix/Linux
io_setup()函數 Unix/Linux
io_submit()函數 Unix/Linux
ipc()函數 Unix/Linux
isastream()函數 Unix/Linux
kexec_load()函數 Unix/Linux
keyctl()函數 Unix/Linux
kill()函數 Unix/Linux
killpg()函數 Unix/Linux
lchown()函數 Unix/Linux
linkat()函數 Unix/Linux
link()函數 Unix/Linux
listen()函數 Unix/Linux
_llseek()函數 Unix/Linux
llseek()函數 Unix/Linux
lock()函數 Unix/Linux
lookup_dcookie()函數 Unix/Linux
lseek()函數 Unix/Linux
lstat()函數 Unix/Linux
madvise()函數 Unix/Linux
mincore()函數 Unix/Linux
mkdirat()函數 Unix/Linux
mkdir()函數 Unix/Linux
mknod()函數 Unix/Linux
mlockall()函數 Unix/Linux
mlock()函數 Unix/Linux
mmap2()函數 Unix/Linux
mmap()函數 Unix/Linux
modify_ldt()函數 Unix/Linux
mount()函數 Unix/Linux
move_pages()函數 Unix/Linux
mprotect()函數 Unix/Linux
mpx()函數 Unix/Linux
mq_getsetattr()函數 Unix/Linux
mremap()函數 Unix/Linux
msgctl()函數 Unix/Linux
msgget()函數 Unix/Linux
msgop()函數 Unix/Linux
msgsnd()函數 Unix/Linux
msync()函數 Unix/Linux
multiplexer()函數 Unix/Linux
munlockall()函數 Unix/Linux
munlock()函數 Unix/Linux
munmap()函數 Unix/Linux
nanosleep()函數 Unix/Linux
_newselect()函數 Unix/Linux
nfsservctl()函數 Unix/Linux
nice()函數 Unix/Linux
obsolete()函數 Unix/Linux
oldfstat()函數 Unix/Linux
oldlstat()函數 Unix/Linux
oldolduname()函數 Unix/Linux
oldstat()函數 Unix/Linux
olduname()函數 Unix/Linux
openat()函數 Unix/Linux
open()函數 Unix/Linux
outb()函數 Unix/Linux
outb_p()函數 Unix/Linux
outsb()函數 Unix/Linux
outsl()函數 Unix/Linux
outsw()函數 Unix/Linux
outw()函數 Unix/Linux
outw_p()函數 Unix/Linux
path_resolution()函數 Unix/Linux
pause()函數 Unix/Linux
perfmonctl()函數 Unix/Linux
personality()函數 Unix/Linux
pipe()函數 Unix/Linux
pivot_root()函數 Unix/Linux
poll()函數 Unix/Linux
posix_fadvise()函數 Unix/Linux
ppoll()函數 Unix/Linux
prctl()函數 Unix/Linux
pread()函數 Unix/Linux
prof()函數 Unix/Linux
pselect()函數 Unix/Linux
ptrace()函數 Unix/Linux
putmsg()函數 Unix/Linux
putpmsg()函數 Unix/Linux
pwrite()函數 Unix/Linux
query_module()函數 Unix/Linux
quotactl()函數 Unix/Linux
readahead()函數 Unix/Linux
readdir()函數 Unix/Linux
read()函數 Unix/Linux
readlinkat()函數 Unix/Linux
readlink()函數 Unix/Linux
readv()函數 Unix/Linux
reboot()函數 Unix/Linux
recvfrom()函數 Unix/Linux
recv()函數 Unix/Linux
recvmsg()函數 Unix/Linux
remap_file_pages()函數 Unix/Linux
renameat()函數 Unix/Linux
rename()函數 Unix/Linux
request_key()函數 Unix/Linux
rmdir()函數 Unix/Linux
sbrk()函數 Unix/Linux
sched_setaffinity()函數 Unix/Linux
sched_getparam()函數 Unix/Linux
sched_get_priority_max()函數 Unix/Linux
sched_get_priority_min()函數 Unix/Linux
sched_setscheduler()函數 Unix/Linux
sched_rr_get_interval()函數 Unix/Linux
sched_setparam()函數 Unix/Linux
sched_yield()函數 Unix/Linux
security()函數 Unix/Linux
select()函數 Unix/Linux
select_tut()函數 Unix/Linux
semctl()函數 Unix/Linux

poll()函數 Unix/Linux

poll, ppoll - 等待上一個文件描述符某些事件

內容簡介

#include <poll.h>

int poll(struct pollfd **fds*, nfds_t nfds**, int** timeout**);**

#define _GNU_SOURCE #include <poll.h>

int ppoll(struct pollfd **fds*, nfds_t nfds**,** const struct timespec **timeout*, const sigset_t **sigmask*);

描述

poll () performs a similar task to  select (2): it waits for one of a set of file descriptors to become ready to perform I/O.

The set of file descriptors to be monitored is specified in the fds argument, which is an array of nfds structures of the following form:

struct pollfd {
int fd; /* file descriptor */
short events; /* requested events */
short revents; /* returned events */
};

The field  fd  contains a file descriptor for an open file.

The field events is an input parameter, a bitmask specifying the events the application is interested in.

The field revents is an output parameter, filled by the kernel with the events that actually occurred. The bits returned in revents can include any of those specified inevents, or one of the values POLLERRPOLLHUP, or POLLNVAL. (These three bits are meaningless in the events field, and will be set in the revents field whenever the corresponding condition is true.)

If none of the events requested (and no error) has occurred for any of the file descriptors, then poll() blocks until one of the events occurs.

The timeout argument specifies an upper limit on the time for which poll() will block, in milliseconds. Specifying a negative value in timeout means an infinite timeout.

The bits that may be set/returned in events and revents are defined in <poll.h>:

標籤

描述

POLLIN

There is data to read.

POLLPRI

 

There is urgent data to read (e.g., out-of-band data on TCP socket; pseudo-terminal master in packet mode has seen state change in slave).

POLLOUT

 

Writing now will not block.

POLLRDHUP (since Linux 2.6.17)

 

Stream socket peer closed connection, or shut down writing half of connection. The _GNU_SOURCE feature test macro must be defined in order to obtain this definition.

POLLERR

 

Error condition (output only).

POLLHUP

 

Hang up (output only).

POLLNVAL

 

Invalid request: fd not open (output only).

When compiling with _XOPEN_SOURCE defined, one also has the following, which convey no further information beyond the bits listed above:

標籤

描述

POLLRDNORM

 

Equivalent to POLLIN.

POLLRDBAND

 

Priority band data can be read (generally unused on Linux).

POLLWRNORM

 

Equivalent to POLLOUT.

POLLWRBAND

 

Priority data may be written.

Linux also knows about, but does not use POLLMSG.

ppoll()

The relationship between  poll () and  ppoll () is analogous to the relationship between select () and  pselect (): like  pselect (),  ppoll () allows an application to safely wait until either a file descriptor becomes ready or until a signal is caught.

Other than the difference in the timeout argument, the following ppoll() call:

ready = ppoll(&fds, nfds, timeout, &sigmask);

相當於原子執行以下調用:

sigset_t origmask;

sigprocmask(SIG_SETMASK, &sigmask, &origmask); ready = ppoll(&fds, nfds, timeout); sigprocmask(SIG_SETMASK, &origmask, NULL);

See the description of pselect(2) for an explanation of why ppoll() is necessary.

The timeout argument specifies an upper limit on the amount of time that ppoll() will block. This argument is a pointer to a structure of the following form:

struct timespec {
long tv_sec; /* seconds */
long tv_nsec; /* nanoseconds */
};

If timeout is specified as NULL, then ppoll() can block indefinitely.

返回值

On success, a positive number is returned; this is the number of structures which have non-zero  revents  fields (in other words, those descriptors with events or errors reported). A value of 0 indicates that the call timed out and no file descriptors were ready. On error, -1 is returned, and  errno  is set appropriately.

錯誤

標籤

描述

EBADF

An invalid file descriptor was given in one of the sets.

EFAULT

The array given as argument was not contained in the calling program’s address space.

EINTR

A signal occurred before any requested event.

EINVAL

The nfds value exceeds the RLIMIT_NOFILE value.

ENOMEM

There was no space to allocate file descriptor tables.

LINUX 注意

The Linux  ppoll () system call modifies its  timeout  argument. However, the glibc wrapper function hides this behaviour by using a local variable for the timeout argument that is passed to the system call. Thus, the glibc  ppoll () function does not modify its  timeout argument.

BUGS

See the discussion of spurious readiness notifications under the BUGS section of select (2).

遵循於

poll () conforms to POSIX.1-2001.  ppoll () is Linux specific.

版本

The  poll () system call was introduced in Linux 2.1.23. The  poll () library call was introduced in libc 5.4.28 (and provides emulation using select() if your kernel does not have a  poll () system call).

The ppoll() system call was added to Linux in kernel 2.6.16. The ppoll() library call was added in glibc 2.4.

注意

Some implementations define the non-standard constant  INFTIM  with the value -1 for use as a  timeout . This constant is not provided in glibc.

另請參閱

  • select (2)

  • select_tut (2)