Also move up the signature for rt_sigprocmask, similar to the way this is done in clone.2. Due to the history of sigprocmask, there are various notions of what sigset_t refers to. This attempts to clarify the man page, by giving the major instances different names: - sigset_t is the glibc sigset_t (1024 bits) - kernel_sigset_t is the kernel's sigset_t (64 bits) - old_kernel_sigset_t is the pre-rt kernel's sigset_t (32 bits) and explaining their difference in the NOTES. Even though the sources do not refer to the various sigset_t's by these names, I think it is important to be explicit, esp since sizeof(sigset_t) would give an incorrect value for `sigsetsize` if written in a source file that includes the libc headers. Lastly, move the note on an incorrect `sigsetsize` causing EINVAL up to the ERRORS section, so everything is in one place. --- man2/sigprocmask.2 | 49 +++++++++++++++++++++++++++++++++++++++---------- 1 file changed, 39 insertions(+), 10 deletions(-) diff --git a/man2/sigprocmask.2 b/man2/sigprocmask.2 index 51f7933..907061f 100644 --- a/man2/sigprocmask.2 +++ b/man2/sigprocmask.2 @@ -32,8 +32,19 @@ sigprocmask, rt_sigprocmask \- examine and change blocked signals .SH SYNOPSIS .B #include <signal.h> .sp -.BI "int sigprocmask(int " how ", const sigset_t *" set , -.BI "sigset_t *" oldset ); +.nf +/* Prototype for the glibc wrapper function */ +.BI "int sigprocmask(int " how ", const sigset_t *" set ", sigset_t *" oldset ); + +/* Prototype for the underlying system call */ +.BI "int rt_sigprocmask(int " how ", const kernel_sigset_t *" set , +.BI " kernel_sigset_t *" oldset, " size_t " sigsetsize ); + +/* Prototype for the legacy system call (deprecated) */ +.BI "int sigprocmask(int " how ", const old_kernel_sigset_t *" set , +.BI " old_kernel_sigset_t *" oldset ); " +.fi + .sp .in -4n Feature Test Macro Requirements for glibc (see @@ -111,9 +122,10 @@ or argument points outside the process's allocated address space. .TP .B EINVAL -The value specified in +Either the value specified in .I how -was invalid. +was invalid or the kernel does not support the size passed in +.I sigsetsize. .SH CONFORMING TO POSIX.1-2001, POSIX.1-2008. .SH NOTES @@ -148,6 +160,16 @@ See for details on manipulating signal sets. .\" .SS C library/kernel differences + +The kernel's definition of +.IR sigset_t +differs in size from that used +by the C library. In this man page the former is referred to as +.I kernel_sigset_t +(it is still named +.I sigset_t +in the kernel sources). + The glibc wrapper function for .BR sigprocmask () silently ignores attempts to block the two real-time signals that @@ -161,23 +183,30 @@ The original Linux system call was named However, with the addition of real-time signals in Linux 2.2, the fixed-size, 32-bit .IR sigset_t +(referred to as +.IR old_kernel_sigset_t +in this man page) type supported by that system call was no longer fit for purpose. Consequently, a new system call, .BR rt_sigprocmask (), was added to support an enlarged .IR sigset_t -type. +type +(referred to as +.IR kernel_sigset_t +in this man page +). The new system call takes a fourth argument, .IR "size_t sigsetsize" , which specifies the size in bytes of the signal sets in .IR set and .IR oldset . -This argument is currently required to have the value -.IR sizeof(sigset_t) -(or the error -.B EINVAL -results). +This argument is currently required to have the value 8 +( +.IR sizeof(kernel_sigset_t) +). + The glibc .BR sigprocmask () wrapper function hides these details from us, transparently calling -- 2.8.1 -- To unsubscribe from this list: send the line "unsubscribe linux-man" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
