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* adapt setlocale to support possibility of failureRich Felker2018-10-202-12/+22
| | | | | | | introduce a new LOC_MAP_FAILED sentinel for errors, since null pointers for a category's locale map indicate the C locale. at this time, __get_locale does not fail, so there should be no functional change by this commit.
* adjust types in FILE struct to make line buffering check less expensiveRich Felker2018-10-181-4/+2
| | | | | | | | | | | | | | | | | the choice of signed char for lbf was a theoretically space-saving hack that was not helping, and was unwantedly expensive. while comparing bytes against a byte-sized member sounds easy, the trick here was that the byte to be compared was unsigned while the lbf member was signed, making it possible to set lbf negative to disable line buffering. however, this imposed a requirement to promote both operands, zero-extending one and sign-extending the other, in order to compare them. to fix this, repurpose the waiters count slot (unused since commit c21f750727515602a9e84f2a190ee8a0a2aeb2a1). while we're at it, switch mode (orientation) from signed char to int as well. this makes no semantic difference (its only possible values are -1, 0, and 1) but it might help on archs where byte access is awkward.
* optimize internal putc_unlocked macro used in putcRich Felker2018-10-181-1/+2
| | | | | | | | to check whether flush due to line buffering is needed, the int-type character argument must be truncated to unsigned char for comparison. if the original value is subsequently passed to __overflow, it must be preserved, adding to register pressure. since it doesn't matter, truncate all uses so the original value is no longer live.
* fix wrong result for putc variants due to operator precedenceRich Felker2018-10-181-1/+1
| | | | | | | the internal putc_unlocked macro was wrongly returning a meaningless boolean result rather than the written character or EOF. bug was found by reading (very surprising) asm.
* further optimize getc/putc when locking is neededRich Felker2018-10-182-10/+10
| | | | | | | | | | | | | | | check whether the lock is free before loading the calling thread's tid. if so, just use a dummy tid value that cannot compare equal to any actual thread id (because it's one bit wider). this also avoids the need to save the tid and pass it to locking_getc or locking_putc, reducing register pressure. this change might slightly hurt the case where the caller already holds the lock, but it does not affect the single-threaded case, and may significantly improve the multi-threaded case, especially on archs where loading the thread pointer is disproportionately expensive like early mips and arm ISA levels. but even on i386 it helps, at least on some machines; I measured roughly a 10-15% improvement.
* use prototype for function pointer in static link libc init barrierRich Felker2018-10-181-1/+1
| | | | | | this is not needed for correctness, but doesn't hurt, and in some cases the compiler may pessimize the call assuming the callee might be variadic when it lacks a prototype.
* fix error in constraints for static link libc init barrierRich Felker2018-10-181-1/+1
| | | | | | | commit 4390383b32250a941ec616e8bff6f568a801b1c0 inadvertently used "r" instead of "0" for the input constraint, which only happened to work for the configuration I tested it on because it usually makes sense for the compiler to choose the same input and output register.
* fix build regression due to missing file for putc changesRich Felker2018-10-181-0/+22
| | | | | commit d664061adb4d7f6647ab2059bc351daa394bf5da inadvertently omitted the new file putc.h.
* bypass indirection through pointer objects to access stdin/out/errRich Felker2018-10-184-9/+33
| | | | | | | | | | | | | | | | | by ABI, the public stdin/out/err macros use extern pointer objects, and this is necessary to avoid copy relocations that would be expensive and make the size of the FILE structure part of the ABI. however, internally it makes sense to access the underlying FILE objects directly. this avoids both an indirection through the GOT to find the address of the stdin/out/err pointer objects (which can't be computed PC-relative because they may have been moved to the main program by copy relocations) and an indirection through the resulting pointer object. in most places this is just a minor optimization, but in the case of getchar and putchar (and the unlocked versions thereof), ipa constant propagation makes all accesses to members of stdin/out PC-relative or GOT-relative, possibly reducing register pressure as well.
* optimize hot paths of putc with manual shrink-wrappingRich Felker2018-10-173-13/+8
| | | | | this is the analog of commit dd8f02b7dce53d6b1c4282439f1636a2d63bee01, but for putc.
* optimize hot paths of getc with manual shrink-wrappingRich Felker2018-10-174-15/+30
| | | | | | | | | | | | | | | | | | | | | | | | with these changes, in a program that has not created any threads besides the main thread and that has not called f[try]lockfile, getc performs indistinguishably from getc_unlocked. this was measured on several i386 and x86_64 models, and should hold on other archs too simply by the properties of the code generation. the case where the caller already holds the lock (via flockfile) is improved significantly as well (40-60% reduction in time on machines tested) and the case where locking is needed is improved somewhat (roughly 10%). the key technique used here is forcing the non-hot path out-of-line and enabling it to be a tail call. a static noinline function (conditional on __GNUC__) is used rather than the extern hiddens used elsewhere for this purpose, so that the compiler can choose non-default calling conventions, making it possible to tail-call to a callee that takes more arguments than the caller on archs where arguments are passed on the stack or must have space reserved on the stack for spilling the. the tid could just be reloaded via the thread pointer in locking_getc, but that would be ridiculously expensive on some archs where thread pointer load requires a trap or syscall.
* document and make explicit desired noinline property for __init_libcRich Felker2018-10-171-0/+6
| | | | | | | | | | | | | on multiple occasions I've started to flatten/inline the code in __init_libc, only to rediscover the reason it was not inlined: GCC fails to deallocate its stack (and now, with the changes in commit 4390383b32250a941ec616e8bff6f568a801b1c0, fails to produce a tail call to the stage 2 function; see PR #87639) before calling main if it was inlined. document this with a comment and use an explicit noinline attribute if __GNUC__ is defined so that even with CFLAGS that heavily favor inlining it won't get inlined.
* impose barrier between thread pointer setup and use for static linkingRich Felker2018-10-171-0/+13
| | | | | | | | | | | | this is the analog of commit 1c84c99913bf1cd47b866ed31e665848a0da84a2 for static linking. unlike with dynamic linking, we don't have symbolic lookup to use as a barrier. use a dummy (target-agnostic) degenerate inline asm fragment instead. this technique has precedent in commit 05ac345f895098657cf44d419b5d572161ebaf43 where it's used for explicit_bzero. if it proves problematic in any way, loading the address of the stage 2 function from a pointer object whose address leaks to kernelspace during thread pointer init could be used as an even stronger barrier.
* move stdio locking MAYBE_WAITERS definition to stdio_impl.hRich Felker2018-10-163-4/+2
| | | | don't repeat definition in two places.
* x86_64: add single instruction fmaSzabolcs Nagy2018-10-154-0/+92
| | | | | | | fma is only available on recent x86_64 cpus and it is much faster than a software fma, so this should be done with a runtime check, however that requires more changes, this patch just adds the code so it can be tested when musl is compiled with -mfma or -mfma4.
* arm: add single instruction fmaSzabolcs Nagy2018-10-152-0/+30
| | | | | | | | | | | | | | vfma is available in the vfpv4 fpu and above, the ACLE standard feature test for double precision hardware fma support is __ARM_FEATURE_FMA && __ARM_FP&8 we need further checks to work around clang bugs (fixed in clang >=7.0) && !__SOFTFP__ because __ARM_FP is defined even with -mfloat-abi=soft && !BROKEN_VFP_ASM to disable the single precision code when inline asm handling is broken. For runtime selection the HWCAP_ARM_VFPv4 hwcap flag can be used, but that requires further work.
* powerpc: add single instruction fabs, fabsf, fma, fmaf, sqrt, sqrtfSzabolcs Nagy2018-10-156-0/+90
| | | | | These are only available on hard float target and sqrt is not available in the base ISA, so further check is used.
* s390x: add single instruction fma and fmafSzabolcs Nagy2018-10-152-0/+14
| | | | These are available in the s390x baseline isa -march=z900.
* allow escaped path-separator slashes in globRich Felker2018-10-131-11/+22
| | | | | | | | | | | | | | | | | | previously (before and after rewrite), spurious escaping of path separators as \/ was not treated the same as /, but rather got split as an unpaired \ at the end of the fnmatch pattern and an unescaped /, resulting in a mismatch/error. for the case of \/ as part of the maximal literal prefix, remove the explicit rejection of it and move the handling of / below escape processing. for the case of \/ after a proper glob pattern, it's hard to parse the pattern, so don't. instead cheat and count repetitions of \ prior to the already-found / character. if there are an odd number, the last is escaping the /, so back up the split position by one. now the char clobbered by null termination is variable, so save it and restore as needed.
* rewrite core of the glob implementation for correctness & optimizationRich Felker2018-10-121-105/+112
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | this code has been long overdue for a rewrite, but the immediate cause that necessitated it was total failure to see past unreadable path components. for example, A/B/* would fail to match anything, even though it should succeed, when both A and A/B are searchable but only A/B is readable. this problem both was caught in conformance testing, and impacted users. the old glob implementation insisted on searching the listing of each path component for a match, even if the next component was a literal. it also used considerable stack space, up to length of the pattern, per recursion level, and relied on an artificial bound of the pattern length by PATH_MAX, which was incorrect because a pattern can be much longer than PATH_MAX while having matches shorter (for example, with necessarily long bracket expressions, or with redundancy). in the new implementation, each level of recursion starts by consuming the maximal literal (possibly escaped-literal) path prefix remaining in the pattern, and only opening a directory to read when there is a proper glob pattern in the next path component. it then recurses into each matching entry. the top-level glob function provided automatic storage (up to PATH_MAX) for construction of candidate/result strings, and allocates a duplicate of the pattern that can be modified in-place with temporary null-termination to pass to fnmatch. this allocation is not a big deal since glob already has to perform allocation, and has to link free to clean up if it experiences an allocation failure or other error after some results have already been allocated. care is taken to use the d_type field from iterated dirents when possible; stat is called only when there are literal path components past the last proper-glob component, or when needed to disambiguate symlinks for the purpose of GLOB_MARK. one peculiarity with the new implementation is the manner in which the error handling callback will be called. if attempting to match */B/C/D where a directory A exists that is inaccessible, the error reported will be a stat error for A/B/C/D rather than (previous and wrong implementation) an opendir error for A, or (likely on other implementations) a stat error for A/B. such behavior does not seem to be non-conforming, but if it turns out to be undesirable for any reason, backtracking could be done on error to report the first component producing it. also, redundant slashes are no longer normalized, but preserved as they appear in the pattern; this is probably more correct, and falls out naturally from the algorithm used. since trailing slashes (which force all matches to be directories) are preserved as well, the behavior of GLOB_MARK has been adjusted not to append an additional slash to results that already end in slash.
* combine arch ABI's DTP_OFFSET into DTV pointersRich Felker2018-10-124-17/+17
| | | | | | | | | | | | | | | | | | | | | | as explained in commit 6ba5517a460c6c438f64d69464fdfc3269a4c91a, some archs use an offset (typicaly -0x8000) with their DTPOFF relocations, which __tls_get_addr needs to invert. on affected archs, which lack direct support for large immediates, this can cost multiple extra instructions in the hot path. instead, incorporate the DTP_OFFSET into the DTV entries. this means they are no longer valid pointers, so store them as an array of uintptr_t rather than void *; this also makes it easier to access slot 0 as a valid slot count. commit e75b16cf93ebbc1ce758d3ea6b2923e8b2457c68 left behind cruft in two places, __reset_tls and __tls_get_new, from back when it was possible to have uninitialized gap slots indicated by a null pointer in the DTV. since the concept of null pointer is no longer meaningful with an offset applied, remove this cruft. presently there are no archs with both TLSDESC and nonzero DTP_OFFSET, but the dynamic TLSDESC relocation code is also updated to apply an inverted offset to its offset field, so that the offset DTV would not impose a runtime cost in TLSDESC resolver functions.
* fix redundant computations of strlen in glob append functionRich Felker2018-10-111-2/+5
| | | | | len was already passed as an argument, so don't use strcat, and use memcpy instead of strcpy.
* fix invalid substitute of [1] for flexible array member in globRich Felker2018-10-111-2/+2
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* fix fesetround error checkingSzabolcs Nagy2018-10-101-6/+5
| | | | Rounding modes are not bit flags, but arbitrary non-negative integers.
* fix build regression on armhf in tlsdesc asmRich Felker2018-10-091-0/+1
| | | | | | | | | | | when invoking the assembler, arm gcc does not always pass the right flags to enable use of vfp instruction mnemonics. for C code it produces, it emits the .fpu directive, but this does not help when building asm source files, which tlsdesc needs to be. to fix, use an explicit directive here. commit 0beb9dfbecad38af9759b1e83eeb007e28b70abb introduced this regression. it has not appeared in any release.
* allow freeaddrinfo of arbitrary sublists of addrinfo listRich Felker2018-10-043-8/+25
| | | | | | | | | | | | | | | | | | | | | | | the specification for freeaddrinfo allows it to be used to free "arbitrary sublists" of the list returned by getaddrinfo. it's not clearly stated how such sublists come into existence, but the interpretation seems to be that the application can edit the ai_next pointers to cut off a portion of the list and then free it. actual freeing of individual list slots is contrary to the design of our getaddrinfo implementation, which has no failure paths after making a single allocation, so that light callers can avoid linking realloc/free. freeing individual slots is also incompatible with sharing the string for ai_canonname, which the current implementation does despite no requirement that it be present except on the first result. so, rather than actually freeing individual slots, provide a way to find the start of the allocated array, and reference-count it, freeing the memory all at once after the last slot has been freed. since the language in the spec is "arbitrary sublists", no provision for handling other constructs like multiple lists glued together, circular links, etc. is made. presumably passing such a construct to freeaddrinfo produces undefined behavior.
* inline cp15 thread pointer load in arm dynamic TLSDESC asm when possibleRich Felker2018-10-011-0/+9
| | | | | | | | | | | | the indirect function call is a significant portion of the code path for the dynamic case, and most users are probably building for ISA levels where it can be omitted. we could drop at least one register save/restore (lr) with this change, and possibly another (ip) with some clever shuffling, but it's not clear whether there's a way to do it that's not more expensive, or whether avoiding the save/restore would have any practical effect, so in the interest of avoiding complexity it's omitted for now.
* add TLSDESC support for 32-bit armRich Felker2018-10-011-0/+62
| | | | | | | | | | | | | | | unlike other asm where the baseline ISA is used, these functions are hot paths and use ISA-level specializations. call-clobbered vfp registers are saved before calling __tls_get_new, since there is no guarantee it won't use them. while setjmp/longjmp have to use hwcap to decide whether to the fpu is in use, since application code could be using vfp registers even if libc was compiled as pure softfloat, __tls_get_new is part of libc and can be assumed not to have access to vfp registers if tlsdesc.S does not. thus it suffices just to check the predefined preprocessor macros. the check for __ARM_PCS_VFP is redundant; !__SOFTFP__ must always be true if the target ISA level includes fpu instructions/registers.
* fix aliasing-based undefined behavior in string functionsRich Felker2018-09-268-19/+46
| | | | | | | | | use the GNU C may_alias attribute if available, and fallback to naive byte-by-byte loops if __GNUC__ is not defined. this patch has been written to minimize changes so that history remains reviewable; it does not attempt to bring the affected code into a more consistent or elegant form.
* optimize nop case of wmemmoveRich Felker2018-09-231-0/+1
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* fix undefined pointer comparison in wmemmoveRich Felker2018-09-231-1/+2
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* fix undefined pointer comparison in memmoveRich Felker2018-09-231-1/+1
| | | | | | | | | | | | | | | the comparison must take place in the address space model as an integer type, since comparing pointers that are not pointing into the same array is undefined. the subsequent d<s comparison however is valid, because it's only reached in the case where the source and dest overlap, in which case they are necessarily pointing to parts of the same array. to make the comparison, use an unsigned range check for dist(s,d)>=n, algebraically !(-n<s-d<n). subtracting n yields !(-2*n<s-d-n<0), which mapped into unsigned modular arithmetic is !(-2*n<s-d-n) or rather -2*n>=s-d-n.
* new tsearch implementationSzabolcs Nagy2018-09-207-213/+200
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | Rewrote the AVL tree implementation: - It is now non-recursive with fixed stack usage (large enough for worst case tree height). twalk and tdestroy are still recursive as that's smaller/simpler. - Moved unrelated interfaces into separate translation units. - The node structure is changed to use indexed children instead of left/right pointers, this simplifies the balancing logic. - Using void * pointers instead of struct node * in various places, because this better fits the api (node address is passed in a void** argument, so it is tempting to incorrectly cast it to struct node **). - As a further performance improvement the rebalancing now stops when it is not needed (subtree height is unchanged). Otherwise the behaviour should be the same as before (checked over generated random inputs that the resulting tree shape is equivalent). - Removed the old copyright notice (including prng related one: it should be licensed under the same terms as the rest of the project). .text size of pic tsearch + tfind + tdelete + twalk: x86_64 i386 aarch64 arm mips powerpc ppc64le sh4 m68k s390x old 941 899 1220 1068 1852 1400 1600 1008 1008 1488 new 857 881 1040 976 1564 1192 1360 736 820 1408
* fix getaddrinfo regression with AI_ADDRCONFIG on some configurationsRich Felker2018-09-191-1/+10
| | | | | | | | | | | | | | | | | | | | despite not being documented to do so in the standard or Linux documentation, attempts to udp connect to 127.0.0.1 or ::1 generate EADDRNOTAVAIL when the loopback device is not configured and there is no default route for IPv6. this caused getaddrinfo with AI_ADDRCONFIG to fail with EAI_SYSTEM and EADDRNOTAVAIL on some no-IPv6 configurations, rather than the intended behavior of detecting IPv6 as unsuppported and producing IPv4-only results. previously, only EAFNOSUPPORT was treated as unavailability of the address family being probed. instead, treat all errors related to inability to get an address or route as conclusive that the family being probed is unsupported, and only fail with EAI_SYSTEM on other errors. further improvements may be desirable, such as reporting EAI_AGAIN instead of EAI_SYSTEM for errors which are expected to be transient, but this patch should suffice to fix the serious regression.
* support setting of default thread stack size via PT_GNU_STACK headerRich Felker2018-09-181-0/+5
| | | | | | | | | | | | | | | | | | | | | | | | this facilitates building software that assumes a large default stack size without any patching to call pthread_setattr_default_np or pthread_attr_setstacksize at each thread creation site, using just LDFLAGS. normally the PT_GNU_STACK header is used only to reflect whether executable stack is desired, but with GNU ld at least, passing -Wl,-z,stack-size=N will set a size on the program header. with this patch, that size will be incorporated into the default stack size (subject to increase-only rule and DEFAULT_STACK_MAX limit). both static and dynamic linking honor the program header. for dynamic linking, all libraries loaded at program start, including preloaded ones, are considered. dlopened libraries are not considered, for several reasons. extra logic would be needed to defer processing until the load of the new library is commited, synchronization woud be needed since other threads may be running concurrently, and the effectiveness woud be limited since the larger size would not apply to threads that already existed at the time of dlopen. programs that will dlopen code expecting a large stack need to declare the requirement themselves, or pthread_setattr_default_np can be used.
* increase default thread stack/guard sizeRich Felker2018-09-181-2/+2
| | | | | | | | | | | | stack size default is increased from 80k to 128k. this coincides with Linux's hard-coded default stack for the main thread (128k is initially committed; growth beyond that up to ulimit is contingent on additional allocation succeeding) and GNU ld's default PT_GNU_STACK size for FDPIC, at least on sh. guard size default is increased from 4k to 8k to reduce the risk of guard page jumping on overflow, since use of just over 4k of stack is common (PATH_MAX buffers, etc.).
* limit the configurable default stack/guard size for threadsRich Felker2018-09-183-8/+15
| | | | | | | | | | limit to 8MB/1MB, repectively. since the defaults cannot be reduced once increased, excessively large settings would lead to an unrecoverably broken state. this change is in preparation to allow defaults to be increased via program headers at the linker level. creation of threads that really need larger sizes needs to be done with an explicit attribute.
* remove redundant declarations of __default_stacksize, __default_guardsizeRich Felker2018-09-183-8/+0
| | | | these are now declared in pthread_impl.h.
* fix benign data race in pthread_attr_initRich Felker2018-09-181-0/+2
| | | | access to defaults should be protected against concurrent changes.
* fix deletion of pthread tsd keys that still have non-null values storedRich Felker2018-09-183-18/+104
| | | | | | | | | | | | | | | | | | | | | | | | | per POSIX, deletion of a key for which some threads still have values stored is permitted, and newly created keys must initially hold the null value in all threads. these properties were not met by our implementation; if a key was deleted with values left and a new key was created in the same slot, the old values were still visible. moreover, due to lack of any synchronization in pthread_key_delete, there was a TOCTOU race whereby a concurrent pthread_exit could attempt to call a null destructor pointer for the newly orphaned value. this commit introduces a solution based on __synccall, stopping the world to zero out the values for deleted keys, but only does so lazily when all key slots have been exhausted. pthread_key_delete is split off into a separate translation unit so that static-linked programs which only create keys but never delete them will not pull in the __synccall machinery. a global rwlock is added to synchronize creation and deletion of keys with dtor execution. since the dtor execution loop now has to release and retake the lock around its call to each dtor, checks are made not to call the nodtor dummy function for keys which lack a dtor.
* fix race condition in file lockingKaarle Ritvanen2018-09-181-6/+6
| | | | | | | | | | | | | | | | | | | | | The condition occurs when - thread #1 is holding the lock - thread #2 is waiting for it on __futexwait - thread #1 is about to release the lock and performs a_swap - thread #3 enters the __lockfile function and manages to grab the lock before thread #1 calls __wake, resetting the MAYBE_WAITERS flag - thread #1 calls __wake - thread #2 wakes up but goes again to __futexwait as the lock is held by thread #3 - thread #3 releases the lock but does not call __wake as the MAYBE_WAITERS flag is not set This condition results in thread #2 not being woken up. This patch fixes the problem by making the woken up thread ensure that the flag is properly set before going to sleep again. Mainainer's note: This fixes a regression introduced in commit c21f750727515602a9e84f2a190ee8a0a2aeb2a1.
* getdelim: only grow buffer when necessary, improve OOM behaviorRich Felker2018-09-161-10/+17
| | | | | | | | | | | | | | | | | | | | | | | | | | commit b114190b29417fff6f701eea3a3b3b6030338280 introduced spurious realloc of the output buffer in cases where the result would exactly fit in the caller-provided buffer. this is contrary to a strict reading of the spec, which only allows realloc when the provided buffer is "of insufficient size". revert the adjustment of the realloc threshold, and instead push the byte read by getc_unlocked (for which the adjustment was made) back into the stdio buffer if it does not fit in the output buffer, to be read in the next loop iteration. in order not to leave a pushed-back byte in the stdio buffer if realloc fails (which would violate the invariant that logical FILE position and underlying open file description offset match for unbuffered FILEs), the OOM code path must be changed. it would suffice move just one byte in this case, but from a QoI perspective, in the event of ENOMEM the entire output buffer (up to the allocated length reported via *n) should contain bytes read from the FILE stream. otherwise the caller has no way to distinguish trunated data from uninitialized buffer space. the SIZE_MAX/2 check is removed since the sum of disjoint object sizes is assumed not to be able to overflow, leaving just one OOM code path.
* fix null pointer subtraction and comparison in stdioRich Felker2018-09-1614-31/+41
| | | | | | | | | | | | | | | | | | | | morally, for null pointers a and b, a-b, a<b, and a>b should all be defined as 0; however, C does not define any of them. the stdio implementation makes heavy use of such pointer comparison and subtraction for buffer logic, and also uses null pos/base/end pointers to indicate that the FILE is not in the corresponding (read or write) mode ready for accesses through the buffer. all of the comparisons are fixed trivially by using != in place of the relational operators, since the opposite relation (e.g. pos>end) is logically impossible. the subtractions have been reviewed to check that they are conditional the stream being in the appropriate reading- or writing-through-buffer mode, with checks added where needed. in fgets and getdelim, the checks added should improve performance for unbuffered streams by avoiding a do-nothing call to memchr, and should be negligible for buffered streams.
* fix failure of getdelim to set stream orientation on errorRich Felker2018-09-161-0/+2
| | | | | if EINVAL or ENOMEM happened before the first getc_unlocked, it was possible that the stream orientation had not yet been set.
* check for kernel support before allowing robust mutex creationRich Felker2018-09-151-1/+17
| | | | | | | | | | | | | | | | on some archs, linux support for futex operations (including robust_list processing) that depend on kernelspace CAS is conditional on a runtime check. as of linux 4.18, this check fails unconditionally on nommu archs that perform it, and spurious failure on powerpc64 was observed but not explained. it's also possible that futex support is omitted entirely, or that the kernel is older than 2.6.17. for most futex ops, ENOSYS does not yield hard breakage; userspace will just spin at 100% cpu load. but for robust mutexes, correct behavior depends on the kernel functionality. use the get_robust_list syscall to probe for support at the first call to pthread_mutexattr_setrobust, and block creation of robust mutexes with a reportable error if they can't be supported.
* always reset DST rules during tzsetBenjamin Peterson2018-09-151-1/+2
| | | | | do_tzset() did't always reset the DST transition rules r0 and r1. That means the rules from older TZ settings could leak into newer ones.
* fix undefined behavior in strto* via FILE buffer pointer abuseRich Felker2018-09-154-20/+43
| | | | | | | | | | | | | | | | | | | | | | | | | | | | in order to produce FILE objects to pass to the intscan/floatscan backends without any (prohibitively costly) extra buffering layer, the strto* functions set the FILE's rend (read end) buffer pointer to an invalid value at the end of the address space, or SIZE_MAX/2 past the beginning of the string. this led to undefined behavior comparing and subtracting the end pointer with the buffer position pointer (rpos). the comparison issue is easily eliminated by using != instead of <. however the subtractions require nontrivial changes: previously, f->shcnt stored the count that would have been read if consuming the whole buffer, which required an end pointer for the buffer. the purpose for this was that it allowed reading it and adding rpos-rend at any time to get the actual count so far, and required no adjustment at the time of __shgetc (actual function call) since the call would only happen when reaching the end of the buffer. to get rid of the dependency on rend, instead offset shcnt by buf-rpos (start of buffer) at the time of last __shlim/__shgetc call. this makes for slightly more work in __shgetc the function, but for the inline macro it's still just as easy to compute the current count. since the scan helper interfaces used here are a big hack, comments are added to document their contracts and what's going on with their implementations.
* improve error handling of ttyname_r and isattyBenjamin Peterson2018-09-152-2/+6
| | | | | | | | | POSIX allows ttyname(_r) and isatty to return EBADF if passed file descriptor is invalid. maintainer's note: these are optional ("may fail") errors, but it's non-conforming for ttyname_r to return ENOTTY when it failed for a different reason.
* add hidden version of &errno accessor functionRich Felker2018-09-142-0/+13
| | | | | | | | | | | this significantly improves codegen in functions that need to access errno but otherwise have no need for a GOT pointer. we could probably improve it much more by including an inline version of the &errno accessor function, but that depends on having the definitions of struct __pthread and __pthread_self(), which at present would expose a lot more than is appropriate. moving them to a small tls.h later might make this more reasonable.
* fix build regression in sysconf for archs with variable page sizeRich Felker2018-09-141-0/+1
| | | | | | commit 5ce3737931bb411a8d167356d4d0287b53b0cbdc removed the inclusion of libc.h from this file as spurious, but it's needed to get PAGE_SIZE on archs where PAGE_SIZE is not a constant defined by limits.h.