On 2/14/21 12:30 AM, Alejandro Colomar (man-pages) wrote: > On 2/13/21 5:05 PM, Michael Kerrisk (man-pages) wrote: >> Hi Alex, >> >> On 2/12/21 4:28 PM, Alejandro Colomar (man-pages) wrote: >>> Hi Michael, >>> >>> AFAICT, the syscalls [rt_]sigprocmask use '[old_]sigset_t' (there's the >>> '__user' modifier too), so 'kernel_' should be removed from the types, >>> shouldn't it? >> >> Looks like you're right. Will you send a patch? >> >> Thanks, >> >> Michael > > Hi Michael, > > I was wrong! D'oh! I should read the manual page! Cheers, Michael > [[ > C library/kernel differences > The kernel's definition of sigset_t differs in size from > that used by the C library. In this manual page, the for‐ > mer is referred to as kernel_sigset_t (it is nevertheless > named sigset_t in the kernel sources). > > The glibc wrapper function for sigprocmask() silently ig‐ > nores attempts to block the two real-time signals that are > used internally by the NPTL threading implementation. See > nptl(7) for details. > > The original Linux system call was named sigprocmask(). > However, with the addition of real-time signals in Linux > 2.2, the fixed-size, 32-bit sigset_t (referred to as > old_kernel_sigset_t in this manual page) type supported by > that system call was no longer fit for purpose. Conse‐ > quently, a new system call, rt_sigprocmask(), was added to > support an enlarged sigset_t type (referred to as ker‐ > nel_sigset_t in this manual page). The new system call > takes a fourth argument, size_t sigsetsize, which specifies > the size in bytes of the signal sets in set and oldset. > This argument is currently required to have a fixed archi‐ > tecture specific value (equal to sizeof(kernel_sigset_t)). > > The glibc sigprocmask() wrapper function hides these de‐ > tails from us, transparently calling rt_sigprocmask() when > the kernel provides it. > ]] > > > -- Michael Kerrisk Linux man-pages maintainer; http://www.kernel.org/doc/man-pages/ Linux/UNIX System Programming Training: http://man7.org/training/
