linux: Consolidate lxstat{64}

System Internals / glibc - Adhemerval Zanella [] - 11 September 2020 17:35 UTC

The LFS support is implemented on lxstat64.c, instead of lxstat.c for 64-bit architectures. The xstat.c implements the non-LFS and it is a no-op for !XSTAT_IS_XSTAT64.

The generic non-LFS implementation handles two cases:

1. New kABIs which uses generic pre 64-bit time Linux ABI (csky and nios): it issues __NR_fstat64 with AT_SYMLINK_NOFOLLOW plus handles the possible overflow off st_ino, st_size, or st_blocks. It only handles _STAT_VER_KERNEL.

2. Old KABIs with old non-LFS support (arm, i386, hppa, m68k, microblaze, s390, sh, powerpc, and sparc32). For _STAT_VER_KERNEL it issues __NR_lstat, otherwise it isseus __NR_lstat64 and convert to non-LFS stat struct and handle possible overflows on st_ino, st_size, or st_blocks.

Also non-LFS mips is an outlier and it has its own implementation since _STAT_VER_LINUX requires a different conversion function (it uses the kernel_stat as the syscall argument since its exported ABI is different than the kernel one for both non-LFS and LFS implementation).

The generic LFS implementation handles multiple cases:

1. XSTAT_IS_XSTAT64 being 1:

1.1. Old 64-bit kABI (ia64, powerpc64*, s390x, sparc64, x86_64): it issues __NR_lstat for _STAT_VER_KERNEL or _STAT_VER_LINUX.

1.2. Old 64-bit kABI with defines __NR_lstat64 instead of __NR_lstat (sparc64): it issues __NR_lstat for _STAT_VER_KERNEL or __NR_lstat64 and convert to struct stat64.

1.3. New kABIs which uses generic 64-bit Linux ABI (aarch64 and riscv64): it issues __NR_newfstatat with AT_SYMLINK_NOFOLLOW and only for _STAT_VER_KERNEL.

1.4. New 32-bit kABIs with only 64-bit time_t support (arc and riscv32): it issues __NR_statx and covert to struct stat64.

2. Old ABIs with XSTAT_IS_XSTAT64 being 0:

2.1. New kABIs which uses generic pre 64-bit time Linux ABI (csky and nios2): it issues __NR_fstatat64 for _STAT_VER_KERNEL.

2.2. Old kABIs with old non-LFS support (arm, i386, hppa, m68k, microblaze, s390, sh, mips32, powerpc32, and sparc32): it issues __NR_lstat64.

Also, two special cases requires specific LFS implementations:

1. alpha: it requires to handle _STAT_VER_KERNEL64 to issue __NR_lstat64 and use the kernel_stat with __NR_lstat otherwise.

2. mips64: as for non-LFS implementation its ABIs differ from glibc exported one, which requires a specific conversion function to handle the kernel_stat.

Checked with a build for all affected ABIs. I also checked on x86_64, i686, powerpc, powerpc64le, sparcv9, sparc64, s390, and s390x.

4f40e6adc4 linux: Consolidate lxstat{64}
sysdeps/unix/sysv/linux/alpha/lxstat.c | 57 ------------------
.../linux/{generic/lxstat.c => alpha/lxstat64.c} | 47 +++++++--------
sysdeps/unix/sysv/linux/arm/lxstat.c | 1 -
.../unix/sysv/linux/generic/wordsize-32/lxstat.c | 55 -----------------
.../unix/sysv/linux/generic/wordsize-32/lxstat64.c | 66 ---------------------
sysdeps/unix/sysv/linux/hppa/lxstat.c | 1 -
sysdeps/unix/sysv/linux/i386/lxstat.c | 60 -------------------
sysdeps/unix/sysv/linux/lxstat.c | 64 ++++++++++----------
sysdeps/unix/sysv/linux/lxstat64.c | 68 +++++++++++++++++++---
sysdeps/unix/sysv/linux/m68k/lxstat.c | 1 -
sysdeps/unix/sysv/linux/microblaze/lxstat.c | 1 -
.../unix/sysv/linux/{wordsize-64 => mips}/lxstat.c | 37 ++++++------
sysdeps/unix/sysv/linux/mips/mips64/lxstat64.c | 14 +----
sysdeps/unix/sysv/linux/powerpc/powerpc32/lxstat.c | 2 -
sysdeps/unix/sysv/linux/s390/s390-32/lxstat.c | 1 -
sysdeps/unix/sysv/linux/sh/lxstat.c | 2 -
sysdeps/unix/sysv/linux/sparc/sparc32/lxstat.c | 2 -
sysdeps/unix/sysv/linux/sparc/sparc64/lxstat.c | 1 -
sysdeps/unix/sysv/linux/wordsize-64/lxstat64.c | 1 -
19 files changed, 136 insertions(+), 345 deletions(-)


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