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Diffstat (limited to 'man2/sigaction.2')
| -rw-r--r-- | man2/sigaction.2 | 160 |
1 files changed, 81 insertions, 79 deletions
diff --git a/man2/sigaction.2 b/man2/sigaction.2 index c352da8b5c..6c241561b3 100644 --- a/man2/sigaction.2 +++ b/man2/sigaction.2 @@ -942,35 +942,63 @@ This will also be generated if an attempt is made to change the action for .BR SIGKILL " or " SIGSTOP , which cannot be caught or ignored. +.SH VERSIONS +.SS C library/kernel differences +The glibc wrapper function for +.BR sigaction () +gives an error +.RB ( EINVAL ) +on attempts to change the disposition of the two real-time signals +used internally by the NPTL threading implementation. +See +.BR nptl (7) +for details. +.PP +On architectures where the signal trampoline resides in the C library, +the glibc wrapper function for +.BR sigaction () +places the address of the trampoline code in the +.I act.sa_restorer +field and sets the +.B SA_RESTORER +flag in the +.I act.sa_flags +field. +See +.BR sigreturn (2). +.PP +The original Linux system call was named +.BR sigaction (). +However, with the addition of real-time signals in Linux 2.2, +the fixed-size, 32-bit +.I sigset_t +type supported by that system call was no longer fit for purpose. +Consequently, a new system call, +.BR rt_sigaction (), +was added to support an enlarged +.I sigset_t +type. +The new system call takes a fourth argument, +.IR "size_t sigsetsize" , +which specifies the size in bytes of the signal sets in +.I act.sa_mask +and +.IR oldact.sa_mask . +This argument is currently required to have the value +.I sizeof(sigset_t) +(or the error +.B EINVAL +results). +The glibc +.BR sigaction () +wrapper function hides these details from us, transparently calling +.BR rt_sigaction () +when the kernel provides it. .SH STANDARDS -POSIX.1-2001, POSIX.1-2008, SVr4. +POSIX.1-2008. +.SH HISTORY +POSIX.1-2001, SVr4. .\" SVr4 does not document the EINTR condition. -.SH NOTES -A child created via -.BR fork (2) -inherits a copy of its parent's signal dispositions. -During an -.BR execve (2), -the dispositions of handled signals are reset to the default; -the dispositions of ignored signals are left unchanged. -.PP -According to POSIX, the behavior of a process is undefined after it -ignores a -.BR SIGFPE , -.BR SIGILL , -or -.B SIGSEGV -signal that was not generated by -.BR kill (2) -or -.BR raise (3). -Integer division by zero has undefined result. -On some architectures it will generate a -.B SIGFPE -signal. -(Also dividing the most negative integer by \-1 may generate -.BR SIGFPE .) -Ignoring this signal might lead to an endless loop. .PP POSIX.1-1990 disallowed setting the action for .B SIGCHLD @@ -1018,6 +1046,32 @@ allowed the receipt of any signal, not just the one we are installing (effectively overriding any .I sa_mask settings). +.SH NOTES +A child created via +.BR fork (2) +inherits a copy of its parent's signal dispositions. +During an +.BR execve (2), +the dispositions of handled signals are reset to the default; +the dispositions of ignored signals are left unchanged. +.PP +According to POSIX, the behavior of a process is undefined after it +ignores a +.BR SIGFPE , +.BR SIGILL , +or +.B SIGSEGV +signal that was not generated by +.BR kill (2) +or +.BR raise (3). +Integer division by zero has undefined result. +On some architectures it will generate a +.B SIGFPE +signal. +(Also dividing the most negative integer by \-1 may generate +.BR SIGFPE .) +Ignoring this signal might lead to an endless loop. .PP .BR sigaction () can be called with a NULL second argument to query the current signal @@ -1040,58 +1094,6 @@ See for a list of the async-signal-safe functions that can be safely called inside from inside a signal handler. .\" -.SS C library/kernel differences -The glibc wrapper function for -.BR sigaction () -gives an error -.RB ( EINVAL ) -on attempts to change the disposition of the two real-time signals -used internally by the NPTL threading implementation. -See -.BR nptl (7) -for details. -.PP -On architectures where the signal trampoline resides in the C library, -the glibc wrapper function for -.BR sigaction () -places the address of the trampoline code in the -.I act.sa_restorer -field and sets the -.B SA_RESTORER -flag in the -.I act.sa_flags -field. -See -.BR sigreturn (2). -.PP -The original Linux system call was named -.BR sigaction (). -However, with the addition of real-time signals in Linux 2.2, -the fixed-size, 32-bit -.I sigset_t -type supported by that system call was no longer fit for purpose. -Consequently, a new system call, -.BR rt_sigaction (), -was added to support an enlarged -.I sigset_t -type. -The new system call takes a fourth argument, -.IR "size_t sigsetsize" , -which specifies the size in bytes of the signal sets in -.I act.sa_mask -and -.IR oldact.sa_mask . -This argument is currently required to have the value -.I sizeof(sigset_t) -(or the error -.B EINVAL -results). -The glibc -.BR sigaction () -wrapper function hides these details from us, transparently calling -.BR rt_sigaction () -when the kernel provides it. -.\" .SS Undocumented Before the introduction of .BR SA_SIGINFO , |