Ian Lance Taylor <i...@golang.org> wrote:
> Given that pretty much every one of these musl patches has led to
> problems on some glibc systems, it would be very nice if you could do
> some testing with glibc. Thanks.
Sorry, my bad.
I just tested this on Arch Linux and it compiles fine with the patch.
> Can you expand on the st_atim issue?
The st_atim issue is simply that struct stat contains additional struct
fields on 32-bit musl architectures (__st_{a,m,c}tim32) in addition to
st_{a,m,c}tim [1]. The sed expression currently only replaces the first
occurrence (i.e. __st_{a,m,c}tim32) from gen-sysinfo.go:
$ grep 'st_[acm]tim' sysinfo.go
type _stat struct { st_dev uint64; __st_dev_padding int32;
__st_ino_truncated int32; st_mode uint32; st_nlink uint32; st_uid uint32;
st_gid uint32; st_rdev uint64; __st_rdev_padding int32; st_size int64;
st_blksize int32; st_blocks int64; __st_atim32 struct { tv_sec int32; tv_nsec
int32; }; __st_mtim32 struct { tv_sec int32; tv_nsec int32; }; __st_ctim32
struct { tv_sec int32; tv_nsec int32; }; st_ino uint64; st_atim Timespec;
st_mtim Timespec; st_ctim Timespec; }
type Stat_t struct { Dev uint64; __st_dev_padding int32;
__Ino_truncated int32; Mode uint32; Nlink uint32; Uid uint32; Gid uint32; Rdev
uint64; __st_rdev_padding int32; Size int64; Blksize int32; Blocks int64;
__Atim32 struct { tv_sec int32; tv_nsec int32; }; __Mtim32 struct { tv_sec
int32; tv_nsec int32; }; __Ctim32 struct { tv_sec int32; tv_nsec int32; }; Ino
uint64; st_atim Timespec; st_mtim Timespec; st_ctim Timespec; }
This causes the following build error on 32-bit musl architectures:
stat_atim.go: error: reference to undefined field or method 'Mtim'
17 | fs.modTime = timespecToTime(fs.sys.Mtim)
| ^
stat_atim.go: error: reference to undefined field or method 'Atim'
52 | return timespecToTime(fi.Sys().(*syscall.Stat_t).Atim)
| ^
This is fixed by the proposed patch by replacing both members in struct stat.
> What does the musl type look like in gen-sysinfo.go?
$ grep 'st_[acm]tim' gen-sysinfo.go
// unknowndefine st_atime st_atim.tv_sec
// unknowndefine st_mtime st_mtim.tv_sec
// unknowndefine st_ctime st_ctim.tv_sec
type _stat struct { st_dev uint64; __st_dev_padding int32;
__st_ino_truncated int32; st_mode uint32; st_nlink uint32; st_uid uint32;
st_gid uint32; st_rdev uint64; __st_rdev_padding int32; st_size int64;
st_blksize int32; st_blocks int64; __st_atim32 struct { tv_sec int32; tv_nsec
int32; }; __st_mtim32 struct { tv_sec int32; tv_nsec int32; }; __st_ctim32
struct { tv_sec int32; tv_nsec int32; }; st_ino uint64; st_atim _timespec;
st_mtim _timespec; st_ctim _timespec; }
> What is the value of SYS_SECCOMP in musl? Is it a system call number?
SYS_SECCOMP is a macro defined in signal.h which can be used to check
the si_code member of siginfo_t for SIGSYS, see the SECCOMP_RET_TRAP
description in seccomp(2). As such, it is not a system call number.
The value of SYS_SECCOMP is simply 1 [2].
> What does it look like in gen-sysinfo.go?
Defined in gen-sysinfo.go as follows:
4688:const _SYS_seccomp = 317
4775:const _SYS_SECCOMP = 1
where the former is the syscall and the latter is the expanded
SYS_SECCOMP macro constant. When generating sysinfo.go the name seems to
be uppercased, thus resulting in a compilation failure. The generated
sysinfo.go contains the following lines:
3067:const _SYS_seccomp = 317
3154:const _SYS_SECCOMP = 1
6600:const SYS_SECCOMP = _SYS_seccomp
6606:const SYS_SECCOMP = _SYS_SECCOMP
Build error:
sysinfo.go:6606:7: error: redefinition of 'SYS_SECCOMP'
6606 | const SYS_SECCOMP = _SYS_SECCOMP
| ^
sysinfo.go:6600:7: note: previous definition of 'SYS_SECCOMP' was here
6600 | const SYS_SECCOMP = _SYS_seccomp
| ^
This is fixed by the patch by only extracting _SYS_seccomp, not _SYS_SECCOMP.
If you need more information, just let me know :)
Greetings,
Sören
[1]: https://git.musl-libc.org/cgit/musl/tree/arch/i386/bits/stat.h
[2]:
https://git.musl-libc.org/cgit/musl/commit/?id=3dcbd896907d9d474da811b7c6b769342abaf651
