On Sun, Jan 15, 2023 at 11:01 PM Ammar Faizi wrote:
That is not the 'sigset_t' that the kernel wants. The kernel wants the 'sigset_t' that is in <asm-generic/signal.h>:
#define _NSIG 64 #define _NSIG_BPW __BITS_PER_LONG // this 64 on x86-64, but 32 on i386. #define _NSIG_WORDS (_NSIG / _NSIG_BPW) typedef struct { unsigned long sig[_NSIG_WORDS]; } sigset_t;The above struct is always 8 bytes in size. In other words:
_NSIG_WORDS == 2 on i386 _NSIG_WORDS == 1 on x86-64 sizeof(unsigned long) == 4 on i386 sizeof(unsigned long) == 8 on x86-64Therefore, sizeof(unsigned long [_NSIG_WORDS]) is always 8 on both architectures. That's the correct size.
I tried to #include <asm-generic/signal.h> but it conflicts with the other 'sigset_t' definition. So I can't do that.
Read the glibc sigaction implementation, it has different struct sigaction definitions for user and kernel too.
https://sourceware.org/git/?p=glibc.git%3Ba=blob%3Bf=sysdeps/unix/sysv/linux...
Since nolibc compiles everything in a single translation unit, you can't have a different sigset_t definition. You need to copy the definition to nolibc header and change the type name to something else for internal use only.
Why are there two different definitions of 'sigset_t'? I don't know.
I probably should read the story behind this syscall to get it implemented right. Let me ponder this again on Monday. But at least I tell what I have found so people can give some comments on it...
`man 2 rt_sigaction` tells the story. Here is the bedtime story, have a nice dream :-)
The original Linux system call was named sigaction(). However, with the addition of real-time signals in Linux 2.2, the fixed-size, 32-bit sigset_t type supported by that system call was no longer fit for purpose. Consequently, a new system call, rt_sigaction(), was added to support an enlarged sigset_t type. The new system call takes a fourth argument, size_t sigsetsize, which specifies the size in bytes of the signal sets in act.sa_mask and oldact.sa_mask. This argument is currently required to have the value sizeof(sigset_t) (or the error EINVAL results). The glibc sigaction() wrapper function hides these details from us, transpar‐ ently calling rt_sigaction() when the kernel provides it.