linux: Consolidate fxstat{64}

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

The LFS support is implemented on fxstat64.c, instead of fxstat.c for 64-bit architectures. The fxstat.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 issuess __NR_fstat64 plus handle the overflow on 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_fstat, otherwise it calls __NR_fstat64 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 sysissues 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. 64-bit kABI (aarch64, ia64, powerpc64*, s390x, riscv64, and x86_64): it issuess __NR_fstat for _STAT_VER_KERNEL or _STAT_VER_LINUX.

1.2. Old 64-bit kABI with defines __NR_fstat64 instead of __NR_fstat (sparc64): it issues __NR_fstat for _STAT_VER_KERNEL or __NR_fstat64 and convert to struct stat64.

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

2. Old ABIs with XSTAT_IS_XSTAT64 being 0 (arm, csky, i386, hppa, m68k, microblaze, mips32, nios2, sh, powerpc32, and sparc32): it issues __NR_fstat64.

Also, two special cases requires specific implementations:

1. alpha: it requires to handle _STAT_VER_KERNEL64 to issues __NR_fstat64 and use the kernel_stat with __NR_fstat otherwise.

2. mips64: as for non-LFS implementation its ABIs differ from glibc exported one, which requires an 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.

5febe6a38f linux: Consolidate fxstat{64}
.../unix/sysv/linux/alpha/{fxstat.c => fxstat64.c} | 48 +++++++----------
sysdeps/unix/sysv/linux/arm/fxstat.c | 1 -
sysdeps/unix/sysv/linux/fxstat.c | 62 +++++++++++-----------
sysdeps/unix/sysv/linux/fxstat64.c | 53 ++++++++++++------
.../unix/sysv/linux/generic/wordsize-32/fxstat.c | 57 --------------------
.../unix/sysv/linux/generic/wordsize-32/fxstat64.c | 36 -------------
sysdeps/unix/sysv/linux/hppa/fxstat.c | 1 -
sysdeps/unix/sysv/linux/i386/fxstat.c | 59 --------------------
sysdeps/unix/sysv/linux/m68k/fxstat.c | 1 -
sysdeps/unix/sysv/linux/microblaze/fxstat.c | 1 -
.../unix/sysv/linux/{wordsize-64 => mips}/fxstat.c | 37 ++++++-------
sysdeps/unix/sysv/linux/mips/mips64/fxstat64.c | 13 +----
sysdeps/unix/sysv/linux/powerpc/powerpc32/fxstat.c | 1 -
sysdeps/unix/sysv/linux/s390/s390-32/fxstat.c | 1 -
sysdeps/unix/sysv/linux/sh/fxstat.c | 1 -
sysdeps/unix/sysv/linux/sparc/sparc32/fxstat.c | 1 -
sysdeps/unix/sysv/linux/sparc/sparc64/fxstat.c | 1 -
sysdeps/unix/sysv/linux/wordsize-64/fxstat64.c | 1 -
18 files changed, 107 insertions(+), 268 deletions(-)


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