diff options
| -rw-r--r-- | man7/signal.7 | 173 |
1 files changed, 155 insertions, 18 deletions
diff --git a/man7/signal.7 b/man7/signal.7 index 6a407b7094..bce203bcde 100644 --- a/man7/signal.7 +++ b/man7/signal.7 @@ -35,7 +35,7 @@ .\" 2006-04-24, mtk, Added text on changing signal dispositions, .\" signal mask, and pending signals. .\" -.TH SIGNAL 7 2008-06-02 "Linux" "Linux Programmer's Manual" +.TH SIGNAL 7 2008-07-04 "Linux" "Linux Programmer's Manual" .SH NAME signal \- list of available signals .SH DESCRIPTION @@ -471,6 +471,143 @@ waitpid() write() .fi .in +.SS Interruption of System Calls and Library Functions by Signal Handlers +If a signal handler is invoked while a system call or library function +call is blocked, then the system call may fail with the error +.BR EINTR . +The details depend on the interface +(in particular, whether the genealogy of the interface is System V or BSD) +and whether or not the signal handler was established using the +.BR SA_RESTART +flag (see +.BR sigaction (2)). +The details vary across Unix systems. + +For the following interfaces, +if the +.BR SA_RESTART +flag was used, +then a blocked call will be restarted after being interrupted +by a signal handler; +otherwise the call will fail with the error +.BR EINTR : +.\" The following system calls use ERESTARTSYS, +.\" so that they are restartable +.RS 4 +.IP * 2 +.BR read (2), +.BR readv (2), +.BR write (2), +.BR writev (2), +and +.BR ioctl (2) +calls on "slow" devices. +A "slow" device is one where the I/O call may block for an indefinite time, +for example, a terminal, pipe, or socket. +(A disk is not a slow device according to this definition.) +If an I/O call on a slow device has already transferred some data by the +time it is interrupted by a signal handler, +then the call will return a success status +(normally, the number of bytes transferred). +.IP * +.BR open (2), +if it can block (e.g., for a FIFO; see +.BR fifo (7)). +.IP * +.BR wait (2), +.BR wait3 (2), +.BR wait4 (2), +.BR waitid (2), +and +.BR waitpid (2). +.IP * +Socket interfaces: +.\" If a timeout i(setsockopt()) is in effect on the socket, then these +.\" system calls switch to using EINTR. Consequently, they and are not +.\" automatically restarted, and they show the stop/cont behavior +.\" described below. (Verified from 2.6.26 source, and by experiment; mtk) +.BR accept (2), +.BR connect (2), +.BR recv (2), +.BR recvfrom (2), +.BR recvmsg (2), +.BR send (2), +.BR sendto (2), +and +.BR sendmsg (2). +.IP * +File locking interfaces: +.BR flock (2) +and +.BR fcntl (2) +.BR F_SETLKW . +.IP * +POSIX message queue interfaces: +.BR mq_receive (), +.BR mq_timedreceive (), +.BR mq_send (), +and +.BR mq_timedsend (). +.IP * +.BR futex (2) +.B FUTEX_WAIT +(since Linux 2.6.22; beforehand, always failed with +.BR EINTR ). +.IP * +POSIX semaphore interfaces: +.BR sem_wait (3) +and +.BR sem_timedwait (3) +(since Linux 2.6.22; beforehand, always failed with +.BR EINTR ). +.RE +.PP +The following interfaces are never restarted after +being interrupted by a signal handler, +regardless of the use of +.BR SA_RESTART : +.\" These are the system calls that give EINTR or ERESTARTNOHAND +.\" on interruption by a signal handler. +.RS 4 +.IP * 2 +Interfaces used to wait for signals: +.BR pause (2), +.BR sigsuspend (2), +.BR sigtimedwat (2), +and +.BR sigwaitinfo (2). +.IP * +File descriptor multiplexing interfaces: +.BR epoll_wait (2), +.BR epoll_pwait (2), +.BR poll (2), +.BR ppoll (2), +.BR select (2), +and +.BR pselect (2). +.IP * +System V IPC calls: +.\" On some other systems, SA_RESTART does restart these system calls +.BR msgrcv (2), +.BR msgsnd (2), +.BR semop (2), +and +.BR semtimedop (2). +.IP * +Sleep interfaces: +.BR clock_nanosleep (2), +.BR nanosleep (2), +.BR sleep (3), +and +.BR usleep (3). +.IP * +.BR read (2) +from an +.BR inotify (7) +file descriptor. +.IP * +.BR io_getevents (2). +.RE .SH "CONFORMING TO" POSIX.1 .SH BUGS @@ -480,30 +617,30 @@ and have the same value. The latter is commented out in the kernel source, but the build process of some software still thinks that -signal 29 is +Lsignal 29 is .BR SIGLOST . .SH "SEE ALSO" .BR kill (1), .BR kill (2), -.BR kill\%pg (2), -.BR set\%itimer (2), -.BR set\%rlimit (2), -.BR sget\%mask (2), -.BR sig\%action (2), -.BR sig\%nal (2), +.BR killpg (2), +.BR setitimer (2), +.BR setrlimit (2), +.BR sgetmask (2), +.BR sigaction (2), +.BR signal (2), .BR signalfd (2), -.BR sig\%pend\%ing (2), -.BR sig\%proc\%mask (2), -.BR sig\%queue (2), -.BR sig\%suspend (2), -.BR sig\%waitinfo (2), -.BR bsd\%_signal (3), +.BR sigpending (2), +.BR sigprocmask (2), +.BR sigqueue (2), +.BR sigsuspend (2), +.BR sigwaitinfo (2), +.BR bsd_signal (3), .BR raise (3), -.BR sig\%vec (3), -.BR sig\%set (3), +.BR sigvec (3), +.BR sigset (3), .BR sigwait (3), -.BR str\%signal (3), -.BR sysv\%_signal (3), +.BR strsignal (3), +.BR sysv_signal (3), .BR core (5), .BR proc (5), .BR pthreads (7) |