path: root/src
AgeCommit message (Collapse)AuthorLines
2014-11-19overhaul ARM atomics/tls for performance and compatibilityRich Felker-12/+1
previously, builds for pre-armv6 targets hard-coded use of the "kuser helper" system for atomics and thread-pointer access, resulting in binaries that fail to run (crash) on systems where this functionality has been disabled (as a security/hardening measure) in the kernel. additionally, builds for armv6 hard-coded an outdated/deprecated memory barrier instruction which may require emulation (extremely slow) on future models. this overhaul replaces the behavior for all pre-armv7 builds (both of the above cases) to perform runtime detection of the appropriate mechanisms for barrier, atomic compare-and-swap, and thread pointer access. detection is based on information provided by the kernel in auxv: presence of the HWCAP_TLS bit for AT_HWCAP and the architecture version encoded in AT_PLATFORM. direct use of the instructions is preferred when possible, since probing for the existence of the kuser helper page would be difficult and would incur runtime cost. for builds targeting armv7 or later, the runtime detection code is not compiled at all, and much more efficient versions of the non-cas atomic operations are provided by using ldrex/strex directly rather than wrapping cas.
2014-11-19save auxv pointer into libc struct early in dynamic linker startupRich Felker-0/+1
this allows most code to assume it has already been saved, and is a prerequisite for upcoming changes for arm atomic/tls operations.
2014-11-15getopt: fix optional argument processingFelix Fietkau-2/+2
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 argument.
2014-11-15implement a private state for the uchar.h functionsJens Gustedt-0/+6
The C standard is imperative on that: 7.28.1 ... If ps is a null pointer, each function uses its own internal mbstate_t object instead, which is initialized at program startup to the initial conversion state; and these functions are also not supposed to implicitly use the state of the wchar.h functions: ... The implementation behaves as if no library function calls these functions with a null pointer for ps. Previously this resulted in two bugs. - The functions c16rtomb and mbrtoc16 would crash when called with ps set to null. - The function mbrtoc32 used the private state of mbrtowc, which it is not allowed to do.
2014-11-15fix behavior of printf with alt-form octal, zero precision, zero valueRich Felker-1/+1
in this case there are two conflicting rules in play: that an explicit precision of zero with the value zero produces no output, and that the '#' modifier for octal increases the precision sufficiently to yield a leading zero. ISO C ( paragraph 6 in C99+TC3) includes a parenthetical remark to clarify that the precision-increasing behavior takes precedence, but the corresponding text in POSIX off of which I based the implementation is missing this remark. this issue was covered in WG14 DR#151.
2014-11-05math: use fnstsw consistently instead of fstsw in x87 asmSzabolcs Nagy-11/+11
fnstsw does not wait for pending unmasked x87 floating-point exceptions and it is the same as fstsw when all exceptions are masked which is the only environment libc supports.
2014-11-05math: fix x86_64 and x32 asm not to use sahf instructionSzabolcs Nagy-28/+14
Some early x86_64 cpus (released before 2006) did not support sahf/lahf instructions so they should be avoided (intel manual says they are only supported if CPUID.80000001H:ECX.LAHF-SAHF[bit 0] = 1). The workaround simplifies exp2l and expm1l because fucomip can be used instead of the fucomp;fnstsw;sahf sequence copied from i386. In fmodl and remainderl sahf is replaced by a simple bit test.
2014-10-31fix uninitialized mode variable in openat functionRich Felker-1/+1
this was introduced in commit 2da3ab1382ca8e39eb1e4428103764a81fba73d3 as an oversight while making the variadic argument access conditional.
2014-10-31math: use the rounding idiom consistentlySzabolcs Nagy-58/+89
the idiomatic rounding of x is n = x + toint - toint; where toint is either 1/EPSILON (x is non-negative) or 1.5/EPSILON (x may be negative and nearest rounding mode is assumed) and EPSILON is according to the evaluation precision (the type of toint is not very important, because single precision float can represent the 1/EPSILON of ieee binary128). in case of FLT_EVAL_METHOD!=0 this avoids a useless store to double or float precision, and the long double code became cleaner with 1/LDBL_EPSILON instead of ifdefs for toint. __rem_pio2f and __rem_pio2 functions slightly changed semantics: on i386 a double-rounding is avoided so close to half-way cases may get evaluated differently eg. as sin(pi/4-eps) instead of cos(pi/4+eps)
2014-10-31fix rint.c and rintf.c when FLT_EVAL_METHOD!=0Szabolcs Nagy-4/+22
The old code used the rounding idiom incorrectly: y = (double)(x + 0x1p52) - 0x1p52; the cast is useless if FLT_EVAL_METHOD==0 and causes a second rounding if FLT_EVAL_METHOD==2 which can give incorrect result in nearest rounding mode, so the correct idiom is to add/sub a power-of-2 according to the characteristics of double_t. This did not cause actual bug because only i386 is affected where rint is implemented in asm. Other rounding functions use a similar idiom, but they give correct results because they only rely on getting a neighboring integer result and the rounding direction is fixed up separately independently of the current rounding mode. However they should be fixed to use the idiom correctly too.
2014-10-30fix invalid access by openat to possibly-missing variadic mode argumentRich Felker-4/+8
the mode argument is only required to be present when the O_CREAT or O_TMPFILE flag is used.
2014-10-30fix failure of open to read variadic mode argument for O_TMPFILERich Felker-1/+1
2014-10-20manually "shrink wrap" fast path in pthread_onceRich Felker-8/+12
this change is a workaround for the inability of current compilers to perform "shrink wrapping" optimizations. in casual testing, it roughly doubled the performance of pthread_once when called on an already-finished once control object.
2014-10-13implement uchar.h (C11 UTF-16/32 conversion) interfacesRich Felker-0/+79
2014-10-13eliminate global waiters count in pthread_onceRich Felker-9/+13
2014-10-10fix missing barrier in pthread_once/call_once shortcut pathRich Felker-2/+6
these functions need to be fast when the init routine has already run, since they may be called very often from code which depends on global initialization having taken place. as such, a fast path bypassing atomic cas on the once control object was used to avoid heavy memory contention. however, on archs with weakly ordered memory, the fast path failed to ensure that the caller actually observes the side effects of the init routine. preliminary performance testing showed that simply removing the fast path was not practical; a performance drop of roughly 85x was observed with 20 threads hammering the same once control on a 24-core machine. so the new explicit barrier operation from atomic.h is used to retain the fast path while ensuring memory visibility. performance may be reduced on some archs where the barrier actually makes a difference, but the previous behavior was unsafe and incorrect on these archs. future improvements to the implementation of a_barrier should reduce the impact.
2014-10-09fix handling of negative offsets in timezone spec stringsRich Felker-10/+7
previously, the hours were considered as a signed quantity while minutes and seconds were always treated as positive offsets. however, semantically the '-' sign should negate the whole hh:mm:ss offset. this bug only affected timezones east of GMT with non-whole-hours offsets, such as those used in India and Nepal.
2014-10-08always provide __fpclassifyl and __signbitl definitionsRich Felker-1/+9
previously the external definitions of these functions were omitted on archs where long double is the same as double, since the code paths in the math.h macros which would call them are unreachable. however, even if they are unreachable, the definitions are still mandatory. omitting them is invalid C, and in the case of a non-optimizing compiler, will result in a link error.
2014-10-06ignore access mode bits of flags in mkostemps and functions that use itRich Felker-0/+1
per the text accepted for inclusion in POSIX, behavior is unspecified when any of the access mode bits are set. since it's impossible to consistently report this usage error (O_RDONLY could not be detected since its value happens to be zero), the most consistent way to handle them is just to ignore them. previously, if a caller erroneously passed O_WRONLY, the resulting access mode would be O_WRONLY|O_RDWR, which has the value 3, and this resulted in a file descriptor which rejects both read and write attempts when it is subsequently used.
2014-10-04fix handling of odd lengths in swab functionRich Felker-1/+1
this function is specified to leave the last byte with "unspecified disposition" when the length is odd, so for the most part correct programs should not be calling swab with odd lengths. however, doing so is permitted, and should not write past the end of the destination buffer.
2014-09-22fix incorrect sequence generation in *rand48 prng functionsRich Felker-2/+2
patch by Jens Gustedt. this fixes a bug reported by Nadav Har'El. the underlying issue was that a left-shift by 16 bits after promotion of unsigned short to int caused integer overflow. while some compilers define this overflow case as "shifting into the sign bit", doing so doesn't help; the sign bit then gets extended through the upper bits in subsequent arithmetic as unsigned long long. this patch imposes a promotion to unsigned prior to the shift, so that the result is well-defined and matches the specified behavior.
2014-09-19fix linked list corruption in flockfile listsRich Felker-0/+1
commit 5345c9b884e7c4e73eb2c8bb83b8d0df20f95afb added a linked list to track the FILE streams currently locked (via flockfile) by a thread. due to a failure to fully link newly added members, removal from the list could leave behind references which could later result in writes to already-freed memory and possibly other memory corruption. implicit stdio locking was unaffected; the list is only used in conjunction with explicit flockfile locking. this bug was not present in any releases; it was introduced and fixed during the same release cycle. patch by Timo Teräs, who discovered and tracked down the bug.
2014-09-18math: fix exp10 not to raise invalid exception on NaNSzabolcs Nagy-4/+13
This was not caught earlier because gcc incorrectly generates quiet relational operators that never raise exceptions.
2014-09-16fix overflow corner case in strtoul-family functionsRich Felker-0/+1
incorrect behavior occurred only in cases where the input overflows unsigned long long, not just the (possibly lower) range limit for the result type. in this case, processing of the '-' sign character was not suppressed, and the function returned a value of 1 despite setting errno to ERANGE.
2014-09-13rewrite the regex pattern parser in regcompSzabolcs Nagy-1081/+634
The new code is a bit simpler and the generated code is about 1KB smaller (on i386). The basic design was kept including internal interfaces, TNFA generation was not touched. The old tre parser had various issues: [^aa-z] negated overlapping ranges in a bracket expression were handled incorrectly (eg [^aa-z] was handled as [^a] instead of [^a-z]) a{,2} missing lower bound in a counted repetition should be an error, but it was accepted with broken semantics: a{,2} was treated as a{0,3}, the new parser rejects it a{999,} large min count was not rejected (a{5000,} failed with REG_ESPACE due to reaching a stack limit), the new parser enforces the RE_DUP_MAX limit \xff regcomp used to accept a pattern with illegal sequences in it (treated them as empty expression so p\xffq matched pq) the new parser rejects such patterns with REG_BADPAT or REG_ERANGE [^b-fD-H] with REG_ICASE old parser turned this into [^b-fB-F] because of the negated overlapping range issue (see above), the new parser treats it as [^b-hB-H], POSIX seems to require [^d-fD-F], but practical implementations do case-folding first and negate the character set later instead of the other way around. (Supporting the posix way efficiently would require significant changes so it was left as is, it is unclear if any application actually expects the posix behaviour, this issue is raised on the austingroup tracker: ). another case-insensitive matching issue is that unicode case folding rules can group more than two characters together while towupper and towlower can only work for a pair of upper and lower case characters, this is a limitation of POSIX so it is not fixed. invalid bracket and brace expressions may return different error codes now (REG_ERANGE instead of REG_EBRACK or REG_BADBR instead of REG_EBRACE) otherwise the new parser should be compatible with the old one. regcomp should be able to handle arbitrary pattern input if the pattern length is limited, the only exception is the use of large repetition counts (eg. (a{255}){255}) which require exp amount of memory and there is no easy workaround.
2014-09-08fix exp10l.c to include float.hSzabolcs Nagy-0/+1
the previous commit was a no op in exp10l because LDBL_* macros were implicitly 0 (the preprocessor does not warn about undefined symbols).
2014-09-08prune math code on archs with binary64 long doubleSzabolcs Nagy-0/+10
__polevll, __p1evll and exp10l were provided on archs when long double is the same as double. The first two were completely unused and exp10l can be a wrapper around exp10.
2014-09-07add C11 thread creation and related thread functionsRich Felker-7/+84
based on patch by Jens Gustedt. the main difficulty here is handling the difference between start function signatures and thread return types for C11 threads versus POSIX threads. pointers to void are assumed to be able to represent faithfully all values of int. the function pointer for the thread start function is cast to an incorrect type for passing through pthread_create, but is cast back to its correct type before calling so that the behavior of the call is well-defined. changes to the existing threads implementation were kept minimal to reduce the risk of regressions, and duplication of code that carries implementation-specific assumptions was avoided for ease and safety of future maintenance.
2014-09-06add C11 condition variable functionsJens Gustedt-0/+57
Because of the clear separation for private pthread_cond_t these interfaces are quite simple and direct.
2014-09-06add C11 mutex functionsJens Gustedt-0/+69
2014-09-06add C11 thread functions operating on tss_t and once_flagJens Gustedt-0/+42
These all have POSIX equivalents, but aside from tss_get, they all have minor changes to the signature or return value and thus need to exist as separate functions.
2014-09-06use weak symbols for the POSIX functions that will be used by C threadsJens Gustedt-29/+76
The intent of this is to avoid name space pollution of the C threads implementation. This has two sides to it. First we have to provide symbols that wouldn't pollute the name space for the C threads implementation. Second we have to clean up some internal uses of POSIX functions such that they don't implicitly drag in such symbols.
2014-09-06add C11 timespec_get function, with associated time.h changes for C11Rich Felker-0/+12
based on patch by Jens Gustedt for inclusion with C11 threads implementation, but committed separately since it's independent of threads.
2014-09-06fix non-static dummy function that slipped in with locale implementationRich Felker-1/+1
2014-09-05add missing legacy LFS *64 symbol aliasesSzabolcs Nagy-0/+23
versionsort64, aio*64 and lio*64 symbols were missing, they are only needed for glibc ABI compatibility, on the source level dirent.h and aio.h already redirect them.
2014-09-05fix memory leak in regexec when input contains illegal sequenceSzabolcs Nagy-5/+6
2014-09-05fix off-by-one in bounds check in fpathconfRich Felker-1/+1
this error resulted in an out-of-bounds read, as opposed to a reported error, when calling the function with an argument one greater than the max valid index.
2014-09-05fix potential read past end of buffer in getnameinfo service name lookupRich Felker-1/+1
if the loop stopped due to reaching the end of the string, the subsequent increment could possibly move the position one past the end of the buffer. no further writes happen, the reads cannot fault anyway unless the stack completely lacks any zero bytes, and reading junk should not yield an incorrect result from the function either. nonetheless the code was wrong and needs to be fixed.
2014-09-05remove incorrect and useless check in network service name lookup codeRich Felker-1/+0
the condition was probably intended to be !*p rather than !p, but neither is needed here. the subsequent code naturally handles the case where it's already at end of string.
2014-09-05fix case mapping for U+00DF (ß)Rich Felker-2/+1
U+00DF ('ß') has had an uppercase form (U+1E9E) available since Unicode 5.1, but Unicode lacks the case mappings for it due to stability policy. when I added support for the new character in commit 1a63a9fc30e7a1f1239e3cedcb5041e5ec1c5351, I omitted the mapping in the lowercase-to-uppercase direction. this choice was not based on any actual information, only assumptions. this commit adds bidirectional case mappings between U+00DF and U+1E9E, and removes the special-case hack that allowed U+00DF to be identified as lowecase despite lacking a mapping. aside from strong evidence that this is the "right" behavior for real-world usage of these characters, several factors informed this decision: - the other "potentially correct" mapping, to "SS", is not representable in the C case-mapping system anyway. - leaving one letter in lowercase form when transforming a string to uppercase is obviously wrong. - having a character which is nominally lowercase but which is fixed under case mapping violates reasonable invariants.
2014-09-05make non-waiting paths of sem_[timed]wait and pthread_join cancelableRich Felker-0/+3
per POSIX these functions are both cancellation points, so they must act on any cancellation request which is pending prior to the call. previously, only the code path where actual waiting took place could act on cancellation.
2014-09-05remove an extra layer of buffer copying in getnameinfo reverse dnsRich Felker-3/+2
the outer getnameinfo function already has a properly-sized temporary buffer for storing the reverse dns (ptr) result. there is no reason for the callback to use a secondary buffer and copy it on success, and doing so potentially expanded the impact of the dn_expand bug that was fixed in commit 49d2c8c6bcf8c926e52c7f510033b6adc31355f5. this change reduces the code size by a small amount, and also reduces the run-time stack space requirements by about 256 bytes.
2014-09-04fix multiple stdio functions' behavior on zero-length operationsRich Felker-9/+7
previously, fgets, fputs, fread, and fwrite completely omitted locking and access to the FILE object when their arguments yielded a zero length read or write operation independent of the FILE state. this optimization was invalid; it wrongly skipped marking the stream as byte-oriented (a C conformance bug) and exposed observably missing synchronization (a POSIX conformance bug) where one of these functions could wrongly complete despite another thread provably holding the lock.
2014-09-04suppress null termination when fgets reads EOF with no dataRich Felker-1/+1
the C standard requires that "the contents of the array remain unchanged" in this case. this patch also changes the behavior on read errors, but in that case "the array contents are indeterminate", so the application cannot inspect them anyway.
2014-09-04fix dn_expand empty name handling and offsets to 0Szabolcs Nagy-6/+9
Empty name was rejected in dn_expand since commit 56b57f37a46dab432247bf29d96fcb11fbd02a6d which is a regression as reported by Natanael Copa. Furthermore if an offset pointer in a compressed name pointed to a terminating 0 byte (instead of a label) the returned name was not null terminated.
2014-08-25add malloc_usable_size function and non-stub malloc.hRich Felker-0/+17
this function is needed for some important practical applications of ABI compatibility, and may be useful for supporting some non-portable software at the source level too. I was hesitant to add a function which imposes any constraints on malloc internals; however, it turns out that any malloc implementation which has realloc must already have an efficient way to determine the size of existing allocations, so no additional constraint is imposed. for now, some internal malloc definitions are duplicated in the new source file. if/when malloc is refactored to put them in a shared internal header file, these could be removed. since malloc_usable_size is conventionally declared in malloc.h, the empty stub version of this file was no longer suitable. it's updated to provide the standard allocator functions, nonstandard ones (even if stdlib.h would not expose them based on the feature test macros in effect), and any malloc-extension functions provided (currently, only malloc_usable_size).
2014-08-25refrain from spinning on locks when there is already a waiterRich Felker-5/+5
if there is already a waiter for a lock, spinning on the lock is essentially an attempt to steal it from whichever waiter would obtain it via any priority rules in place, and is therefore undesirable. in the current implementation, there is always an inherent race window at unlock during which a newly-arriving thread may steal the lock from the existing waiters, but we should aim to keep this window minimal rather than enlarging it.
2014-08-25spin before waiting on futex in mutex and rwlock lock operationsRich Felker-0/+20
2014-08-25spin in sem_[timed]wait before performing futex waitRich Felker-0/+5
empirically, this increases the maximum rate of wait/post operations between two threads by 20-150 times on machines I tested, including x86 and arm. conceptually, it makes sense to do some spinning because semaphores are intended to be usable as a notification mechanism between threads, not just as locks, and low-latency notification is a valuable property to have.
2014-08-25sanitize number of spins in userspace before futex waitRich Felker-2/+2
the previous spin limit of 10000 was utterly unreasonable. empirically, it could consume up to 200000 cycles, whereas a failed futex wait (EAGAIN) typically takes 1000 cycles or less, and even a true wait/wake round seems much less expensive. the new counts (100 for general wait, 200 in barrier) were simply chosen to be in the range of what's reasonable without having adverse effects on casual micro-benchmark tests I have been running. they may still be too high, from a standpoint of not wasting cpu cycles, but at least they're a lot better than before. rigorous testing across different archs and cpu models should be performed at some point to determine whether further adjustments should be made.