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2014-03-09fix incorrect rounding in printf floating point corner casesRich Felker-2/+2
the printf floating point formatting code contains an optimization to avoid computing digits that will be thrown away by rounding at the specified (or default) precision. while it was correctly retaining all places up to the last decimal place to be printed, it was not retaining enough precision to see the next nonzero decimal place in all cases. this could cause incorrect rounding down in round-to-even (default) rounding mode, for example, when printing 0.5+DBL_EPSILON with "%.0f". in the fix, LDBL_MANT_DIG/3 is a lazy (non-sharp) upper bound on the number of zeros between any two nonzero decimal digits.
2014-03-09fix buffer overflow in printf formatting of denormals with low bit setRich Felker-1/+2
empirically the overflow was an off-by-one, and it did not seem to be overwriting meaningful data. rather than simply increasing the buffer size by one, however, I have attempted to make the size obviously correct in terms of bounds on the number of iterations for the loops that fill the buffer. this still results in no more than a negligible size increase of the buffer on the stack (6-7 32-bit slots) and is a "safer" fix unless/until somebody wants to do the proof that a smaller buffer would suffice.
2014-02-07in fdopen, avoid setting O_APPEND flag if it's already setRich Felker-1/+2
this saves a syscall in the case where the underlying open already took place with O_APPEND, which is common because fopen with append modes sets O_APPEND at the time of open before passing the file descriptor to __fdopen.
2014-02-07fix ftello result for append streams with unflushed outputRich Felker-1/+4
when there is unflushed output, ftello (and ftell) compute the logical stream position as the underlying file descriptor's offset plus an adjustment for the amount of buffered data. however, this can give the wrong result for append-mode streams where the unflushed writes should adjust the logical position to be at the end of the file, as if a seek to end-of-file takes place before the write. the solution turns out to be a simple trick: when ftello (indirectly) calls lseek to determine the current file offset, use SEEK_END instead of SEEK_CUR if the stream is append-mode and there's unwritten buffered data. the ISO C rules regarding switching between reading and writing for a stream opened in an update mode, along with the POSIX rules regarding switching "active handles", conveniently leave undefined the hypothetical usage cases where this fix might lead to observably incorrect offsets. the bug being fixed was discovered via the test case for glibc issue
2014-01-08add __isoc99_vfscanf weak alias to vfscanfSzabolcs Nagy-0/+2
this glibc abi compatibility function was missed when the scanf aliases were added.
2013-12-12include cleanups: remove unused headers and add feature test macrosSzabolcs Nagy-9/+3
2013-10-07minor vfprintf and vfwprintf changes to please static code analyzersSzabolcs Nagy-6/+11
add missing va_end and remove some unnecessary code.
2013-10-04removed unused variable in vfwprintfRich Felker-2/+1
2013-09-01fix special-case breakage in popen due to reversed argument orderRich Felker-1/+1
2013-08-31fix invalid %m format crash in wide scanf variantsRich Felker-0/+2
the wide variant was missed in the previous commit.
2013-08-31avoid crash in scanf when invalid %m format is encounteredRich Felker-0/+2
invalid format strings invoke undefined behavior, so this is not a conformance issue, but it's nicer for scanf to report the error safely instead of calling free on a potentially-uninitialized pointer or a pointer to memory belonging to the caller.
2013-08-02protect against long double type mismatches (mainly powerpc for now)Rich Felker-0/+7
check in configure to be polite (failing early if we're going to fail) and in vfprintf.c since that is the point at which a mismatching type would be extremely dangerous.
2013-07-20fix uninitialized/stale use of alloc (%m modifier) flag in scanfRich Felker-0/+4
for conversion specifiers, alloc is always set when the specifier is parsed. however, if scanf stops due to mismatching literal text, either an uninitialized (if no conversions have been performed yet) or stale (from the previous conversion) of the flag will be used, possibly causing an invalid pointer to be passed to free when the function returns.
2013-06-22fix scanf %c conversion wrongly storing a terminating null byteRich Felker-4/+8
this seems to have been a regression from the refactoring which added the 'm' modifier.
2013-06-06implement 'm' modifier for wide scanf variantsRich Felker-7/+40
2013-06-05implement the 'm' (malloc) modifier for scanfRich Felker-22/+48
this commit only covers the byte-based scanf-family functions. the wide functions still lack support for the 'm' modifier.
2013-06-05refactor wide-char scanf string handlingRich Felker-55/+32
this brings the wide version of the code into alignment with the byte-based version, in preparation for adding support for the m (malloc) modifier.
2013-06-04simplify some logic in scanf and remove redundant invalid-format checkRich Felker-18/+8
2013-06-04refactor scanf core to use common code path for all string formatsRich Felker-85/+52
the concept here is that %s and %c are essentially special-cases of %[, with some minimal additional special-casing. aside from simplifying the code and reducing the number of complex code-paths that would need changing to make optimizations later, the main purpose of this change is to simplify addition of the 'm' modifier which causes scanf to allocate storage for the string being read.
2013-04-06fix argument omission in ABI-compat weak_alias for fscanfRich Felker-1/+1
2013-04-05Add ABI compatability aliases.Isaac Dunham-0/+33
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.
2013-03-24rewrite popen to use posix_spawn instead of fragile vfork hacksRich Felker-41/+41
2012-12-10document self-synchronized destruction issue for stdio lockingRich Felker-0/+10
2012-11-09always add memory streams to stdio open file listRich Felker-18/+21
per interpretation for austin group issue #626, fflush(0) and exit() must block waiting for a lock if another thread has locked a memory stream with flockfile. this adds some otherwise-unnecessary synchronization cost to use of memory streams, but there was already a synchronization cost calling malloc anyway. previously the stream was only added to the open file list in single-threaded programs, so that upon subsequent call to pthread_create, locking could be turned on for the stream.
2012-11-08clean up sloppy nested inclusion from pthread_impl.hRich Felker-0/+4
this mirrors the stdio_impl.h cleanup. one header which is not strictly needed, errno.h, is left in pthread_impl.h, because since pthread functions return their error codes rather than using errno, nearly every single pthread function needs the errno constants. in a few places, rather than bringing in string.h to use memset, the memset was replaced by direct assignment. this seems to generate much better code anyway, and makes many functions which were previously non-leaf functions into leaf functions (possibly eliminating a great deal of bloat on some platforms where non-leaf functions require ugly prologue and/or epilogue).
2012-11-08clean up stdio_impl.hRich Felker-2/+83
this header evolved to facilitate the extremely lazy practice of omitting explicit includes of the necessary headers in individual stdio source files; not only was this sloppy, but it also increased build time. now, stdio_impl.h is only including the headers it needs for its own use; any further headers needed by source files are included directly where needed.
2012-11-01fix more unused variable warningsRich Felker-3/+2
some of these were coming from stdio functions locking files without unlocking them. I believe it's useful for this to throw a warning, so I added a new macro that's self-documenting that the file will never be unlocked to avoid the warning in the few places where it's wrong.
2012-10-27separate getc/putc from fgetc/fputcRich Felker-6/+25
for conformance, two functions should not have the same address. a conforming program could use the addresses of getc and fgetc in ways that assume they are distinct. normally i would just use a wrapper, but these functions are so small and performance-critical that an extra layer of function call could make the one that's a wrapper nearly twice as slow, so I'm just duplicating the code instead.
2012-10-24correct locking in stdio functions that tried to be lock-freeRich Felker-16/+36
these functions must behave as if they obtain the lock via flockfile to satisfy POSIX requirements. since another thread can provably hold the lock when they are called, they must wait to obtain the lock before they can return, even if the correct return value could be obtained without locking. in the case of fclose and freopen, failure to do so could cause correct (albeit obscure) programs to crash or otherwise misbehave; in the case of feof, ferror, and fwide, failure to obtain the lock could sometimes return incorrect results. in any case, having these functions proceed and return while another thread held the lock was wrong.
2012-10-24greatly improve freopen behaviorRich Felker-15/+27
1. don't open /dev/null just as a basis to copy flags; use shared __fmodeflags function to get the right file flags for the mode. 2. handle the case (probably invalid, but whatever) case where the original stream's file descriptor was closed; previously, the logic re-closed it. 3. accept the "e" mode flag for close-on-exec; update dup3 to fallback to using dup2 so we can simply call __dup3 instead of putting fallback logic in freopen itself.
2012-10-24remove useless failure-check from freopen (can't happen)Rich Felker-2/+2
2012-10-21fix copy/paste error in popen changes that broke signalsRich Felker-1/+1
signal mask was not being restored after fork, but instead blocked again.
2012-10-19fix usage of locks with vforkRich Felker-1/+1
__release_ptc() is only valid in the parent; if it's performed in the child, the lock will be unlocked early then double-unlocked later, corrupting the lock state.
2012-10-18avoid raising spurious division-by-zero exception in printfRich Felker-1/+1
2012-10-18overhaul system() and popen() to use vfork; fix various related bugsRich Felker-24/+44
since we target systems without overcommit, special care should be taken that system() and popen(), like posix_spawn(), do not fail in processes whose commit charges are too high to allow ordinary forking. this in turn requires special precautions to ensure that the parent process's signal handlers do not end up running in the shared-memory child, where they could corrupt the state of the parent process. popen has also been updated to use pipe2, so it does not have a fd-leak race in multi-threaded programs. since pipe2 is missing on older kernels, (non-atomic) emulation has been added. some silly bugs in the old code should be gone too.
2012-09-29add 'e' modifier (close-on-exec) to fopen and fdopenRich Felker-2/+5
this feature will be in the next version of POSIX, and can be used internally immediately. there are many internal uses of fopen where close-on-exec is needed to fix bugs.
2012-09-29fix some more O_CLOEXEC/SOCK_CLOEXEC issuesRich Felker-1/+1
2012-09-06fix invalid implicit pointer conversion in gnulib-compat functionsRich Felker-1/+1
2012-09-06use restrict everywhere it's required by c99 and/or posix 2008Rich Felker-43/+43
to deal with the fact that the public headers may be used with pre-c99 compilers, __restrict is used in place of restrict, and defined appropriately for any supported compiler. we also avoid the form [restrict] since older versions of gcc rejected it due to a bug in the original c99 standard, and instead use the form *restrict.
2012-08-25implement "low hanging fruit" from C11Rich Felker-2/+2
based on Gregor's patch sent to the list. includes: - stdalign.h - removing gets in C11 mode - adding aligned_alloc and adjusting other functions to use it - adding 'x' flag to fopen for exclusive mode
2012-08-11add bsd fgetln functionRich Felker-0/+20
optimized to avoid allocation and return lines directly out of the stream buffer whenever possible.
2012-08-10minor but worthwhile optimization in printf: avoid expensive strspnRich Felker-4/+2
the strspn call was made for every format specifier and end-of-string, even though the expected return value was 1-2 for normal usage. replace with simple loop.
2012-08-10trivial optimization to printf: avoid wasted call frameRich Felker-1/+1
amusingly, this cuts more than 10% off the run time of printf("a"); on the machine i tested it on. sadly the same optimization is not possible for snprintf without duplicating all the pseudo-FILE setup code, which is not worth it.
2012-07-04putw is supposed to return 0 (not the value written) on successRich Felker-1/+1
this is not a standard but it's the traditional behavior and it's more useful because the caller can reliably detect errors.
2012-07-04make sure getw/putw agree with prototypes by defining _GNU_SOURCERich Felker-0/+2
2012-07-02fix missing function declarations for __stdio_exitRich Felker-0/+4
2012-06-20fix fwrite return value when full write does not succeedRich Felker-1/+1
2012-06-20avoid cancellation in pcloseRich Felker-3/+4
at the point pclose might receive and act on cancellation, it has already invalidated the FILE passed to it. thus, per musl's QOI guarantees about cancellation and resource allocation/deallocation, it's not a candidate for cancellation. if it were required to be a cancellation point by posix, we would have to switch the order of deallocation, but somehow still close the pipe in order to trigger the child process to exit. i looked into doing this, but the logic gets ugly, and i'm not sure the semantics are conformant, so i'd rather just leave it alone unless there's a need to change it.
2012-06-20fix invalid memory access in pcloseRich Felker-1/+2
2012-06-20make popen cancellation-safeRich Felker-0/+7
close was the only cancellation point called from popen, but it left popen with major resource leaks if any call to close got cancelled. the easiest, cheapest fix is just to use a non-cancellable close function.