this commit preserves ABI fully for existing interface boundaries
between libc and libc consumers (applications or libraries), by
retaining existing symbol names for the legacy 32-bit interfaces and
redirecting sources compiled against the new headers to alternate
symbol names. this does not necessarily, however, preserve the
pairwise ABI of libc consumers with one another; where they use
time_t-derived types in their interfaces with one another, it may be
necessary to synchronize updates with each other.
the intent is that ABI resulting from this commit already be stable
and permanent, but it will not be officially so until a release is
made. changes to some header-defined types that do not play any role
in the ABI between libc and its consumers may still be subject to
change.
mechanically, the changes made by this commit for each 32-bit arch are
as follows:
- _REDIR_TIME64 is defined to activate the symbol redirections in
public headers
- COMPAT_SRC_DIRS is defined in arch.mak to activate build of ABI
compat shims to serve as definitions for the original symbol names
- time_t and suseconds_t definitions are changed to long long (64-bit)
- IPC_STAT definition is changed to add the IPC_TIME64 bit (0x100),
triggering conversion of semid_ds, shmid_ds, and msqid_ds split
low/high time bits into new time_t members
- structs semid_ds, shmid_ds, msqid_ds, and stat are modified to add
new 64-bit time_t/timespec members at the end, maintaining existing
layout of other members.
- socket options (SO_*) and ioctl (sockios) command macros are
redefined to use the kernel's "_NEW" values.
in addition, on archs where vdso clock_gettime is used, the
VDSO_CGT_SYM macro definition in syscall_arch.h is changed to use a
new time64 vdso function if available, and a new VDSO_CGT32_SYM macro
is added for use as fallback on kernels lacking time64.
there are more archs sharing the generic 64-bit version of the struct,
which is uniform and much more reasonable, than sharing the current
"generic" one, and depending on how time64 sysvipc is done for 32-bit
archs, even more may be sharing the "64-bit version" in the future.
so, duplicate the current generic to all archs using it (arm, i386,
m68k, microblaze, or1k) so that the generic can be changed freely.
this is recorded as its own commit mainly as a hint to git tooling, to
assist in copy/move tracking.
all bits headers that were identical for a number of 'clean' archs are
moved to the new arch/generic tree. in addition, a few headers that
differed only cosmetically from the new generic version are removed.
additional deduplication may be possible in mman.h and in several
headers (limits.h, posix.h, stdint.h) that mostly depend on whether
the arch is 32- or 64-bit, but they are left alone for now because
greater gains are likely possible with more invasive changes to header
logic, which is beyond the scope of this commit.
some of these definitions were just plain wrong, others based on
outdated ancient "non-64" versions of the kernel interface.
as much as possible has now been moved out of bits/*
these changes break abi (the old abi for these functions was wrong),
but since they were not working anyway it can hardly matter.
Rich Felker
rofl0r