previously, it was pretty much random which one of these trees a given
function appeared in. they have now been organized into:
src/linux: non-POSIX linux syscalls (possibly shard with other nixen)
src/legacy: various obsolete/legacy functions, mostly wrappers
src/misc: still mostly uncategorized; some misc POSIX, some nonstd
src/crypt: crypt hash functions
further cleanup will be done later.
note that POSIX does not specify these functions as _Noreturn, because
POSIX is aligned with C99, not the new C11 standard. when POSIX is
eventually updated to C11, it will almost surely give these functions
the _Noreturn attribute. for now, the actual _Noreturn keyword is not
used anyway when compiling with a c99 compiler, which is what POSIX
requires; the GCC __attribute__ is used instead if it's available,
however.
in a few places, I've added infinite for loops at the end of _Noreturn
functions to silence compiler warnings. presumably
__buildin_unreachable could achieve the same thing, but it would only
work on newer GCCs and would not be portable. the loops should have
near-zero code size cost anyway.
like the previous _Noreturn commit, this one is based on patches
contributed by philomath.
some minor changes to how hard-coded sets for thread-related purposes
are handled were also needed, since the old object sizes were not
necessarily sufficient. things have gotten a bit ugly in this area,
and i think a cleanup is in order at some point, but for now the goal
is just to get the code working on all supported archs including mips,
which was badly broken by linux rejecting syscalls with the wrong
sigset_t size.
based on patches by orc and Isaac Dunham, with some fixes. sys/io.h
exists and contains prototypes for these functions regardless of
whether the target arch has them; this is a bit unorthodox but I don't
think it will break anything. the function definitions do not exist
unless the appropriate SYS_* syscall number macro is defined, which
should make sure configure scripts looking for these functions don't
find them on other systems.
presently, sys/io.h does not have the inb/outb/etc. port io
macros/functions. I'd be surprised if ioperm/iopl are useful without
them, so they probably need to be added at some point in appropriate
bits/io.h files...
these are not exposed publicly in any header, but the few programs
that use them (modutils/kmod, etc.) are declaring the functions
themselves rather than making the syscalls directly, and it doesn't
really hurt to have them (same as the capset junk).
these were left in glibc for binary compatibility after the public
part of the interface was removed, and libcap kept using them (with
its own copy of the header files) rather than just making the syscalls
directly. might as well add them since they're so small...
- add the rest of the junk traditionally in sys/param.h
- add prototypes for some nonstandard functions
- add _GNU_SOURCE to their source files so the compiler can check proto
the changes to syscall_ret are mostly no-ops in the generated code,
just cleanup of type issues and removal of some implementation-defined
behavior. the one exception is the change in the comparison value,
which is fixed so that 0xf...f000 (which in principle could be a valid
return value for mmap, although probably never in reality) is not
treated as an error return.
it should be noted that flock does not mix well with standard fcntl
locking, but nonetheless some applications will attempt to use flock
instead of fcntl if both exist. options to configure or small patches
may be needed. debian maintainers have plenty of experience with this
unfortunate situation...
note that unlike the originals, these do not print the program
name/argv[0] because we have not saved it anywhere. this could be
changed in __libc_start_main if desired.
this commit shuffles around the location of syscall definitions so
that we can make a syscall() library function with both SYS_* and
__NR_* style syscall names available to user applications, provides
the syscall() library function, and optimizes the code that performs
the actual inline syscalls in the library itself.
previously on i386 when built as PIC (shared library), syscalls were
incurring bus lock (lock prefix) overhead at entry and exit, due to
the way the ebx register was being loaded (xchg instruction with a
memory operand). now the xchg takes place between two registers.
further cleanup to arch/$(ARCH)/syscall.h is planned.
this was originally written for an early draft of the library where
non-standard functions would reside in a static library separate from
the shared libc.so, which would implement a pure standard. the idea
was not to depend on an implementation-dependent __syscall_ret
function in the main libc. but it turned out to be better to put
everything in a single library for both static and dynamic linking
uses, and thus the (incomplete) remnants of this feature were just
enlarging the source and binary.
- hide all the legacy xxxxxx32 name cruft in syscall.h so the actual
source files can be clean and uniform across all archs.
- cleanup llseek/lseek and mmap2/mmap handling for 32/64 bit systems
- alternate implementation for nice if the target lacks nice syscall
Rich Felker
nsz