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libc.h was intended to be a header for access to global libc state and
related interfaces, but ended up included all over the place because
it was the way to get the weak_alias macro. most of the inclusions
removed here are places where weak_alias was needed. a few were
recently introduced for hidden. some go all the way back to when
libc.h defined CANCELPT_BEGIN and _END, and all (wrongly implemented)
cancellation points had to include it.
remaining spurious users are mostly callers of the LOCK/UNLOCK macros
and files that use the LFS64 macro to define the awful *64 aliases.
in a few places, new inclusion of libc.h is added because several
internal headers no longer implicitly include libc.h.
declarations for __lockfile and __unlockfile are moved from libc.h to
stdio_impl.h so that the latter does not need libc.h. putting them in
libc.h made no sense at all, since the macros in stdio_impl.h are
needed to use them correctly anyway.
the public flockfile interface is significantly heavier because it has
to handle the possibility of caller returning or thread exiting while
holding the lock.
the text of the specification for getopt's handling of options that
require an argument, which requires updating optarg and optind, does
not exclude the error case where the end of the argument list has been
reached. in that case, it is expected that optarg be assigned
argv[argc] (normally null) and optind be incremented by 2, resulting
in a value of argc+1.
the ':' in optstring has special meaning as a flag applying to the
previous option character, or to getopt's error handling behavior when
it appears at the beginning. don't also accept a "-:" option based on
getopt is only specified to modify optopt on error, and some software
apparently infers an error from optopt!=0.
getopt_long is changed analogously. the resulting behavior differs
slightly from the behavior of the GNU implementation of getopt_long,
which keeps an internal shadow copy of optopt and copies it to the
public one on return, but since the GNU implementation also exhibits
this shadow-copy behavior for plain getopt where is is non-conforming,
I think this can reasonably be considered a bug rather than an
intentional behavior that merits mimicing.
like fputs (see commit 10a17dfbad2c267d885817abc9c7589fc7ff630b), the
message printing code for getopt assumed that fwrite only returns 0 on
failure, but it can also happen on success if the total length to be
written is zero. programs with zero-length argv were affected.
commit 500c6886c654fd45e4926990fee2c61d816be197 introduced this
problem in getopt by fixing the fwrite behavior to conform to the
requirements of ISO C. previously the wrong expectations of the getopt
code were met by the fwrite implementation.
some related changes are also made to getopt, and the return value of
getopt_long in the case of missing arguments is fixed.
if writing the error message fails, POSIX requires that ferror(stderr)
be set. and as a function that operates on a stdio stream, getopt is
required to lock the stream it uses, stderr.
fwrite calls are used instead of fprintf since there is a demand from
some users not to pull in heavy stdio machinery via getopt. this
mimics the original code using write.
in the case where an initial '+' was passed in optstring (a
getopt_long feature to suppress argv permutation), getopt would fail
to see a possible subsequent ':', resulting in incorrect handling of
the previous hard-coded offsets of +1 and +2 contained a hidden
assumption that the option character matched was single-byte, despite
this implementation of getopt attempting to support multibyte option
characters. this patch reworks the matching logic to leave the final
index pointing just past the matched character so that fixed offsets
can be used to check for ':'.
this is a GNU extension, activated by including '-' as the first
character of the options string, whereby non-option arguments are
processed as if they were arguments to an option character '\1' rather
than ending option processing.
Processing an option character with optional argument fails if the
option is last on the command line. This happens because the
if (optind >= argc) check runs first before testing for optional
this extension is not incompatible with the standard behavior of the
function, not expensive, and avoids requiring a replacement getopt
with full GNU extensions for a few important apps including busybox's
sed with the -i option.
GNU used several extensions that were incompatible with C99 and POSIX,
so they used alternate names for the standard functions.
The result is that we need these to run standards-conformant programs
that were linked with glibc.
based on proposed patches by Daniel Cegiełka, with minor changes:
- use a weak symbol for optreset so it doesn't clash with namespace
- also reset optpos (position in multi-option arg like -lR)
- also make getopt_long support reset