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* make linking of thread-start with explicit scheduling conditionalRich Felker2018-05-093-28/+36
| | | | | | | the wrapper start function that performs scheduling operations is unreachable if pthread_attr_setinheritsched is never called, so move it there rather than the pthread_create source file, saving some code size for static-linked programs.
* improve design of thread-start with explicit scheduling attributesRich Felker2018-05-092-23/+39
| | | | | | | | | | | | eliminate the awkward startlock mechanism and corresponding fields of the pthread structure that were only used at startup. instead of having pthread_create perform the scheduling operations and having the new thread wait for them to be completed, start the new thread with a wrapper start function that performs its own scheduling, sending the result code back via a futex. this way the new thread can use storage from the calling thread's stack rather than permanent fields in the pthread structure.
* clean up and reduce size of internal pthread structureRich Felker2018-05-071-7/+9
| | | | | | | | | | | | | | | | | | | | | | | | | | over time the pthread structure has accumulated a lot of cruft taking up size. this commit removes unused fields and packs booleans and other small data more efficiently. changes which would also require changing code are not included at this time. non-volatile booleans are packed as unsigned char bitfield members. the canceldisable and cancelasync fields need volatile qualification due to how they're accessed from the cancellation signal handler and cancellable syscalls called from signal handlers. since volatile bitfield semantics are not clearly defined, discrete char objects are used instead. the pid field is completely removed; it has been unused since commit 83dc6eb087633abcf5608ad651d3b525ca2ec35e. the tid field's type is changed to int because its use is as a value in futexes, which are defined as plain int. it has no conceptual relationship to pid_t. also, its position is not ABI. startlock is reduced to a length-1 array. the second element was presumably intended as a waiter count, but it was never used and made no sense, since there is at most one waiter.
* improve joinable/detached thread state handlingRich Felker2018-05-056-24/+33
| | | | | | | | | | | | | | | | | previously, some accesses to the detached state (from pthread_join and pthread_getattr_np) were unsynchronized; they were harmless in programs with well-defined behavior, but ugly. other accesses (in pthread_exit and pthread_detach) were synchronized by a poorly named "exitlock", with an ad-hoc trylock operation on it open-coded in pthread_detach, whose only purpose was establishing protocol for which thread is responsible for deallocation of detached-thread resources. instead, use an atomic detach_state and unify it with the futex used to wait for thread exit. this eliminates 2 members from the pthread structure, gets rid of the hackish lock usage, and makes rigorous the trap added in commit 80bf5952551c002cf12d96deb145629765272db0 for catching attempts to join detached threads. it should also make attempt to detach an already-detached thread reliably trap.
* improve pthread_exit synchronization with functions targeting tidRich Felker2018-05-056-17/+18
| | | | | | | | | | | | | | | | if the last thread exited via pthread_exit, the logic that marked it dead did not account for the possibility of it targeting itself via atexit handlers. for example, an atexit handler calling pthread_kill(pthread_self(), SIGKILL) would return success (previously, ESRCH) rather than causing termination via the signal. move the release of killlock after the determination is made whether the exiting thread is the last thread. in the case where it's not, move the release all the way to the end of the function. this way we can clear the tid rather than spending storage on a dedicated dead-flag. clearing the tid is also preferable in that it hardens against inadvertent use of the value after the thread has terminated but before it is joined.
* remove incorrect ESRCH error from pthread_killRich Felker2018-05-041-1/+2
| | | | | | | | | | posix documents in the rationale and future directions for pthread_kill that, since the lifetime of the thread id for a joinable thread lasts until it is joined, ESRCH is not a correct error for pthread_kill to produce when the target thread has exited but not yet been joined, and that conforming applications cannot attempt to detect this state. future versions of the standard may explicitly require that ESRCH not be returned for this case.
* use a dedicated futex object for pthread_join instead of tid fieldRich Felker2018-05-024-5/+8
| | | | | | | | | | | | | | | | | | the tid field in the pthread structure is not volatile, and really shouldn't be, so as not to limit the compiler's ability to reorder, merge, or split loads in code paths that may be relevant to performance (like controlling lock ownership). however, use of objects which are not volatile or atomic with futex wait is inherently broken, since the compiler is free to transform a single load into multiple loads, thereby using a different value for the controlling expression of the loop and the value passed to the futex syscall, leading the syscall to block instead of returning. reportedly glibc's pthread_join was actually affected by an equivalent issue in glibc on s390. add a separate, dedicated join_futex object for pthread_join to use.
* optimize sigisemptysetRich Felker2018-05-011-2/+3
| | | | | | | | the static const zero set ended up getting put in bss instead of rodata, wasting writable memory, and the call to memcmp was size-inefficient. generally for nonstandard extension functions we try to avoid poking at any internals directly, but the way the zero set was setup was arguably already doing so.
* avoid excessive stack usage in getcwdRich Felker2018-05-011-2/+2
| | | | | | | | | | | to support the GNU extension of allocating a buffer for getcwd's result when a null pointer is passed without incurring a link dependency on free, we use a PATH_MAX-sized buffer on the stack and only duplicate it to allocated storage after the operation succeeds. unfortunately this imposed excessive stack usage on all callers, including those not making use of the GNU extension. instead, use a VLA to make stack allocation conditional.
* getopt_long_only: don't prefix-match long-options that match short onesRich Felker2018-04-271-2/+15
| | | | | | | | | | | | | | | | | for getopt_long, partial (prefix) matches of long options always begin with "--" and thus can never be ambiguous with a short option. for getopt_long_only, though, a single-character option can match both a short option and as a prefix for a long option. in this case, we wrongly interpreted it as a prefix for the long option. introduce a new pass, only in long-only mode, to check the prefix match against short options before accepting it. the only reason there's a slightly nontrivial loop being introduced rather than strchr is that our getopt already supports multibyte short options, and getopt_long_long should handle them consistently. a temp buffer and strstr could have been used, but the code to set it up would be just as large as what's introduced here and it would unnecessarily pull in relatively large code for strstr.
* reintroduce hardening against partially-replaced allocatorRich Felker2018-04-193-5/+13
| | | | | | | | | | | | | | commit 618b18c78e33acfe54a4434e91aa57b8e171df89 removed the previous detection and hardening since it was incorrect. commit 72141795d4edd17f88da192447395a48444afa10 already handled all that remained for hardening the static-linked case. in the dynamic-linked case, have the dynamic linker check whether malloc was replaced and make that information available. with these changes, the properties documented in commit c9f415d7ea2dace5bf77f6518b6afc36bb7a5732 are restored: if calloc is not provided, it will behave as malloc+memset, and any of the memalign-family functions not provided will fail with ENOMEM.
* return chunks split off by memalign using __bin_chunk instead of freeRich Felker2018-04-193-7/+8
| | | | | | | | | | | | | | | this change serves multiple purposes: 1. it ensures that static linking of memalign-family functions will pull in the system malloc implementation, thereby causing link errors if an attempt is made to link the system memalign functions with a replacement malloc (incomplete allocator replacement). 2. it eliminates calls to free that are unpaired with allocations, which are confusing when setting breakpoints or tracing execution. as a bonus, making __bin_chunk external may discourage aggressive and unnecessary inlining of it.
* using malloc implementation types/macros/idioms for memalignRich Felker2018-04-191-20/+22
| | | | | | | | | the generated code should be mostly unchanged, except for explicit use of C_INUSE in place of copying the low bits from existing chunk headers/footers. these changes also remove mild UB due to dubious arithmetic on pointers into imaginary size_t[] arrays.
* move malloc implementation types and macros to an internal headerRich Felker2018-04-192-37/+40
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* revert detection of partially-replaced allocatorRich Felker2018-04-193-15/+6
| | | | | | | | | | | | | | | | | | | | | commit c9f415d7ea2dace5bf77f6518b6afc36bb7a5732 included checks to make calloc fallback to memset if used with a replaced malloc that didn't also replace calloc, and the memalign family fail if free has been replaced. however, the checks gave false positives for replacement whenever malloc or free resolved to a PLT entry in the main program. for now, disable the checks so as not to leave libc in a broken state. this means that the properties documented in the above commit are no longer satisfied; failure to replace calloc and the memalign family along with malloc is unsafe if they are ever called. the calloc checks were correct but useless for static linking. in both cases (simple or full malloc), calloc and malloc are in a source file together, so replacement of one but not the other would give linking errors. the memalign-family check was useful for static linking, but broken for dynamic as described above, and can be replaced with a better link-time check.
* setvbuf: minor comment typo fixWill Dietz2018-04-191-1/+1
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* remove a_ctz_l from arch specific atomic_arch.hAndre McCurdy2018-04-191-19/+23
| | | | | | | | Update atomic.h to provide a_ctz_l in all cases (atomic_arch.h should now only provide a_ctz_32 and/or a_ctz_64). The generic version of a_ctz_32 now takes advantage of a_clz_32 if available and the generic a_ctz_64 now makes use of a_ctz_32.
* fix out of bounds write for zero length buffer in gethostnameMarc André Tanner2018-04-191-1/+1
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* add support for caller-provided buffers to setvbufRich Felker2018-04-181-11/+14
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* clean up allocation/setup logic for open_[w]memstreamRich Felker2018-04-182-38/+50
| | | | | bring these functions up to date with the current idioms we use/prefer in fmemopen and fopencookie.
* clean up allocation/setup logic for fmemopenRich Felker2018-04-181-21/+31
| | | | | | rather than manually performing pointer arithmetic to carve multiple objects out of one allocation, use a containing struct that encompasses them all.
* minor cleanup in fopencookieRich Felker2018-04-181-5/+2
| | | | | assign entire struct rather than member-at-a-time. don't repeat buffer sizes; always use sizeof to ensure consistency.
* allow interposition/replacement of allocator (malloc)Rich Felker2018-04-184-23/+30
| | | | | | | | | | | | | | | | | | | | | | | replacement is subject to conditions on the replacement functions. they may only call functions which are async-signal-safe, as specified either by POSIX or as an implementation-defined extension. if any allocator functions are replaced, at least malloc, realloc, and free must be provided. if calloc is not provided, it will behave as malloc+memset. any of the memalign-family functions not provided will fail with ENOMEM. in order to implement the above properties, calloc and __memalign check that they are using their own malloc or free, respectively. choice to check malloc or free is based on considerations of supporting __simple_malloc. in order to make this work, calloc is split into separate versions for __simple_malloc and full malloc; commit ba819787ee93ceae94efd274f7849e317c1bff58 already did most of the split anyway, and completing it saves an extra call frame. previously, use of -Bsymbolic-functions made dynamic interposition impossible. now, we are using an explicit dynamic-list, so add allocator functions to the list. most are not referenced anyway, but all are added for completeness.
* refactor flockfile not to duplicate lock mechanism logicRich Felker2018-04-182-12/+14
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* fix stdio lock dependency on read-after-free not faultingRich Felker2018-04-183-20/+24
| | | | | | | instead of using a waiters count, add a bit to the lock field indicating that the lock may have waiters. threads which obtain the lock after contending for it will perform a potentially-spurious wake when they release the lock.
* remove unused __brk function/source fileRich Felker2018-04-171-7/+0
| | | | | commit e3bc22f1eff87b8f029a6ab31f1a269d69e4b053 removed all references to __brk.
* comment __malloc_donate overflow logicRich Felker2018-04-171-0/+3
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* ldso, malloc: implement reclaim_gaps via __malloc_donateAlexander Monakov2018-04-171-18/+43
| | | | | Split 'free' into unmap_chunk and bin_chunk, use the latter to introduce __malloc_donate and use it in reclaim_gaps instead of calling 'free'.
* malloc: fix an over-allocation bugAlexander Monakov2018-04-171-4/+4
| | | | | Fix an instance where realloc code would overallocate by OVERHEAD bytes amount. Manually arrange for reuse of memcpy-free-return exit sequence.
* fix return value of nice functionRich Felker2018-04-171-5/+9
| | | | | | | the Linux SYS_nice syscall is unusable because it does not return the newly set priority. always use SYS_setpriority. also avoid overflows in addition of inc by handling large inc values directly without examining the old nice value.
* optimize malloc0Alexander Monakov2018-04-111-6/+23
| | | | | | | | | | | | | Implementation of __malloc0 in malloc.c takes care to preserve zero pages by overwriting only non-zero data. However, malloc must have already modified auxiliary heap data just before and beyond the allocated region, so we know that edge pages need not be preserved. For allocations smaller than one page, pass them immediately to memset. Otherwise, use memset to handle partial pages at the head and tail of the allocation, and scan complete pages in the interior. Optimize the scanning loop by processing 16 bytes per iteration and handling rest of page via memset as soon as a non-zero byte is found.
* fix incorrect results for catan with some inputsRich Felker2018-04-111-13/+1
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | the catan implementation from OpenBSD includes a FIXME-annotated "overflow" branch that produces a meaningless and incorrect large-magnitude result. it was reachable via three paths, corresponding to gotos removed by this commit, in order: 1. pure imaginary argument with imaginary component greater than 1 in magnitude. this case does not seem at all exceptional and is handled (at least with the quality currently expected from our complex math functions) by the existing non-exceptional code path. 2. arguments on the unit circle, including the pure-real argument 1.0. these are not exceptional except for ±i, which should produce results with infinite imaginary component and which lead to computation of atan2(±0,0) in the existing non-exceptional code path. such calls to atan2() however are well-defined by POSIX. 3. the specific argument +i. this route should be unreachable due to the above (2), but subtle rounding effects might have made it possible in rare cases. continuing on the non-exceptional code path in this case would lead to computing the (real) log of an infinite argument, then producing a NAN when multiplying it by I. for now, remove the exceptional code paths entirely. replace the multiplication by I with construction of a complex number using the CMPLX macro so that the NAN issue (3) prevented cannot arise. with these changes, catan should give reasonably correct results for real arguments, and should no longer give completely-wrong results for pure-imaginary arguments outside the interval (-i,+i).
* fix wrong result in casin and many related complex functionsRich Felker2018-04-093-3/+6
| | | | | | | | | | | the factor of -i noted in the comment at the top of casin.c was omitted from the actual code, yielding a result rotated 90 degrees and propagating into errors in other functions defined in terms of casin. implement multiplication by -i as a rotation of the real and imaginary parts of the result, rather than by actual multiplication, since the latter cannot be optimized without knowledge that the operand is finite. here, the rotation is the actual intent, anyway.
* implement wcsftime padding specifier extensionsSamuel Holland2018-04-071-3/+5
| | | | | | | | | | | | | | Commit 8a6bd7307da3fc4d08dd6a9277b611ccb4971354 added support for padding specifier extensions to strftime, but did not modify wcsftime. In the process, it added a parameter to __strftime_fmt_1 in strftime.c, but failed to update the prototype in wcsftime.c. This was found by compiling musl with LTO: src/time/wcsftime.c:7:13: warning: type of '__strftime_fmt_1' does \ not match original declaration [-Wlto-type-mismatch] Fix the prototype of __strftime_fmt_1 in wcsftime.c, and generate the 'pad' argument the same way as it is done in strftime.
* prevent bypass of guarantee that suids start with fd 0/1/2 openRich Felker2018-04-051-0/+2
| | | | | | | | | | | | | | | it was reported by Erik Bosman that poll fails without setting revents when the nfds argument exceeds the current value for RLIMIT_NOFILE, causing the subsequent open calls to be bypassed. if the rlimit is either 1 or 2, this leaves fd 0 and 1 potentially closed but openable when the application code is reached. based on a brief reading of the poll syscall documentation and code, it may be possible for poll to fail under other attacker-controlled conditions as well. if it turns out these are reasonable conditions that may happen in the real world, we may have to go back and implement fallbacks to probe each fd individually if poll fails, but for now, keep things simple and treat all poll failures as fatal.
* fix fmaf wrong resultSzabolcs Nagy2018-04-021-1/+1
| | | | | | | | | | | | | if double precision r=x*y+z is not a half way case between two single precision floats or it is an exact result then fmaf returns (float)r. however the exactness check was wrong when |x*y| < |z| and could cause incorrectly rounded result in nearest rounding mode when r is a half way case. fmaf(-0x1.26524ep-54, -0x1.cb7868p+11, 0x1.d10f5ep-29) was incorrectly rounded up to 0x1.d117ap-29 instead of 0x1.d1179ep-29. (exact result is 0x1.d1179efffffffecp-29, r is 0x1.d1179fp-29)
* fix nl_langinfo_l(CODESET, loc) reporting wrong locale's valueRich Felker2018-03-071-1/+1
| | | | | | use of MB_CUR_MAX encoded a hidden dependency on the currently active locale for the calling thread, whereas nl_langinfo_l is supposed to report for the locale passed as an argument.
* add public interface headers to implementation filesRich Felker2018-02-256-0/+11
| | | | | | | | | general policy is that all source files defining a public API or an ABI mechanism referenced by a public header should include the public header that declares the interface, so that the compiler or analysis tools can check the consistency of the declarations. Alexander Monakov pointed out a number of violations of this principle a few years back. fix them now.
* fix aliasing violations in fgetpos/fsetposRich Felker2018-02-242-2/+2
| | | | | | | | | | | | | add a member of appropriate type to the fpos_t union so that accesses are well-defined. use long long instead of off_t since off_t is not always exposed in stdio.h and there's no namespace-clean alias for it. access is still performed using pointer casts rather than by naming the union member as a matter of style; to the extent possible, the naming of fields in opaque types defined in the public headers is not treated as an API contract with the implementation. access via the pointer cast is valid as long as the union has a member of matching type.
* use idiomatic safe form for FUNLOCK macroRich Felker2018-02-241-1/+1
| | | | | | | previously this macro used an odd if/else form instead of the more idiomatic do/while(0), making it unsafe against omission of trailing semicolon. the omission would make the following statement conditional instead of producing an error.
* in vswprintf, initialize the FILE rather than memset-and-assignRich Felker2018-02-241-9/+8
| | | | | this is the idiom that's used elsewhere and should be more efficient or at least no worse.
* remove unused MIN macro from getdelim source fileRich Felker2018-02-241-2/+0
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* remove useless null check before call to free in fcloseRich Felker2018-02-241-1/+1
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* remove useless and confusing parentheses in stdio __towrite functionRich Felker2018-02-241-1/+1
| | | | | | they seem to be relics of e3cd6c5c265cd481db6e0c5b529855d99f0bda30 where this code was refactored from a check that previously masked against (F_ERR|F_NOWR) instead of just F_NOWR.
* avoid use of readv syscall in __stdio_read backend when not neededRich Felker2018-02-241-1/+2
| | | | | | | | formally, calling readv with a zero-length first iov component should behave identically to calling read on just the second component, but presence of a zero-length iov component has triggered bugs in some kernels and performs significantly worse than a simple read on some file types.
* consistently return number of bytes read from stdio read backendRich Felker2018-02-242-2/+2
| | | | | | | | | | the stdio FILE read backend's return type is size_t, not ssize_t, and all of the special (non-fd-backed) FILE types already return the number of bytes read (zero) on error or eof. only __stdio_read leaked a syscall error return into its return value. fread had a workaround for this behavior going all the way back to the original check-in. remove the workaround since it's no longer needed.
* remove obfuscated flags bit-twiddling logic in __stdio_readRich Felker2018-02-241-1/+1
| | | | | replace with simple conditional that doesn't rely on assumption that cnt is either 0 or -1.
* fix getopt wrongly treating colons in optstring as valid option charsRich Felker2018-02-241-1/+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 its presence.
* add getentropy functionRich Felker2018-02-231-0/+31
| | | | | | | based loosely on patch by Hauke Mehrtens; converted to wrap the public API of the underlying getrandom function rather than direct syscalls, so that if/when a fallback implementation of getrandom is added it will automatically get picked up by getentropy too.
* add getrandom syscall wrapperHauke Mehrtens2018-02-221-0/+7
| | | | | This syscall is available since Linux 3.17 and was also implemented in glibc in version 2.25 using the same interfaces.