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* 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.
* work around arm gcc's rejection of r7 asm constraints in thumb modeRich Felker2018-05-011-14/+39
| | | | | | | | | | | | | | | | | | | | | | | in thumb mode, r7 is the ABI frame pointer register, and unless frame pointer is disabled, gcc insists on treating it as a fixed register, refusing to spill it to satisfy constraints. unfortunately, r7 is also used in the syscall ABI for passing the syscall number. up til now we just treated this as a requirement to disable frame pointer when generating code as thumb, but it turns out gcc forcibly enables frame pointer, and the fixed register constraint that goes with it, for functions which contain VLAs. this produces an unacceptable arch-specific constraint that (non-arm-specific) source files making syscalls cannot use VLAs. as a workaround, avoid r7 register constraints when producing thumb code and instead save/restore r7 in a temp register as part of the asm block. at some point we may want/need to support armv6-m/thumb1, so the asm has been tweaked to be thumb1-compatible while also near-optimal for thumb2: it allows the temp and/or syscall number to be in high registers (necessary since r0-r5 may all be used for syscalll args) and in thumb2 mode allows the syscall number to be an 8-bit immediate.
* 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 Felker2018-04-194-5/+22
| | | | | | | | | | | | | | 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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* arm: use a_ll/a_sc atomics when building for ARMv6T2Andre McCurdy2018-04-191-1/+1
| | | | | ARMv6 cores with support for Thumb2 can take advantage of the "ldrex" and "strex" based implementations of a_ll and a_sc.
* arm: respect both __ARM_ARCH_6KZ__ and __ARM_ARCH_6ZK__ macrosAndre McCurdy2018-04-192-2/+2
| | | | | | | | | | | | __ARM_ARCH_6ZK__ is a gcc specific historical typo which may not be defined by other compilers. https://gcc.gnu.org/ml/gcc-patches/2015-07/msg02237.html To avoid unexpected results when building for ARMv6KZ with clang, the correct form of the macro (ie 6KZ) needs to be tested. The incorrect form of the macro (ie 6ZK) still needs to be tested for compatibility with pre-2015 versions of gcc.
* provide optimized a_ctz_32 for armAndre McCurdy2018-04-191-0/+12
| | | | | | Provide an ARM specific a_ctz_32 helper function for architecture versions for which it can be implemented efficiently via the "rbit" instruction (ie all Thumb-2 capable versions of ARM v6 and above).
* remove a_ctz_l from arch specific atomic_arch.hAndre McCurdy2018-04-193-24/+28
| | | | | | | | 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 Felker2018-04-185-23/+39
| | | | | | | | | | | | | | | | | | | | | | | 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.
* enable reclaim_gaps for fdpicRich Felker2018-04-171-2/+18
| | | | | | | | | | | | | | | | | | the existing laddr function for fdpic cannot translate ELF virtual addresses outside of the LOAD segments to runtime addresses because the fdpic loadmap only covers the logically-mapped part. however the whole point of reclaim_gaps is to recover the slack space up to the page boundaries, so it needs to work with such addresses. add a new laddr_pg function that accepts any address in the page range for the LOAD segment by expanding the loadmap records out to page boundaries. only use the new version for reclaim_gaps, so as not to impact performance of other address lookups. also, only use laddr_pg for the start address of a gap; the end address lies one byte beyond the end, potentially in a different page where it would get mapped differently. instead of mapping end, apply the length (end-start) to the mapped value of start.
* comment __malloc_donate overflow logicRich Felker2018-04-171-0/+3
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* ldso, malloc: implement reclaim_gaps via __malloc_donateAlexander Monakov2018-04-172-30/+47
| | | | | 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.
* use explicit dynamic-list rather than symbolic-functions for linkingRich Felker2018-04-172-4/+41
| | | | | | | | | | | | | | | | | | | | | we have always bound symbols at libc.so link time rather than runtime to minimize startup-time relocations and overhead of calls through the PLT, and possibly also to preclude interposition that would not work correctly anyway if allowed. historically, binding at link-time was also necessary for the dynamic linker to work, but the dynamic linker bootstrap overhaul in commit f3ddd173806fd5c60b3f034528ca24542aecc5b9 made it unnecessary. our use of -Bsymbolic-functions, rather than -Bsymbolic, was chosen because the latter is incompatible with public global data; it makes it incompatible with copy relocations in the main program. however, not all global data needs to be public. by using --dynamic-list instead with an explicit list, we can reduce the number of symbolic relocations left for runtime. this change will also allow us to permit interposition of specific functions (e.g. the allocator) if/when we want to, by adding them to the dynamic list.
* 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 default feature profile in tar.hRich Felker2018-03-281-0/+2
| | | | | | | commit d93c0740d86aaf7043e79b942a6c0b3f576af4c8 added use of feature test macros without including features.h, causing a definition that should be exposed in the default profile, TSVTX, to appear only when _XOPEN_SOURCE or higher is explicitly defined.
* adjust makefile target-specific CFLAGS rules to be more robust & completeRich Felker2018-03-241-11/+8
| | | | | | | | | | | | | | previously, MEMOPS_SRCS failed to include arch-specific replacement files for memcpy, etc., omitting CFLAGS_MEMOPS and thereby potentially causing build failure if an arch provided C (rather than asm) replacements for these files. instead of trying to explicitly include all the files that might have arch replacements, which is prone to human error, extract final names to be used out of $(LIBC_OBJS), where the rules for arch replacements have already been applied. do the same for NOSSP_OBJS, using CRT_OBJS and LDSO_OBJS rather than repeating ourselves with $(wildcard...) and explicit pathnames again.
* fix out-of-tree build of crt files with stack protector enabledRich Felker2018-03-241-1/+1
| | | | | the makefile logic for these files was wrong in the out-of-tree case, but it likely only affected the "all" level of stack protector.
* explicitly use signed keyword to define intNN_t and derivative typesRich Felker2018-03-121-4/+4
| | | | | | | | | | | | | | | | | | | | standing alone, both the signed and int keywords identify the same type, a (signed) int. however the C language has an exception where, when the lone keyword int is used to declare a bitfield, it's implementation-defined whether the bitfield is signed or unsigned. C11 footnote 125 extends this implementation-definedness to typedefs, and DR#315 extends it to other integer types (for which support with bitfields is implementation-defined). while reasonable ABIs (all the ones we support) define bitfields as signed by default, GCC and compatible compilers offer an option -funsigned-bitfields to change the default. while any signed types defined without explicit use of the signed keyword are affected, the stdint.h types, especially intNN_t, have a natural use in bitfields. ensure that bitfields defined with these types always have the correct signedness regardless of compiler & flags used. see also GCC PR 83294.
* fix minor namespace issues in termios.hRich Felker2018-03-106-0/+12
| | | | | | | | | | the output delay features (NL*, CR*, TAB*, BS*, and VT*) are XSI-shaded. VT* is in the V* namespace reservation but the rest need to be suppressed in base POSIX namespace. unfortunately this change introduces feature test macro checks into another bits header. at some point these checks should be simplified by having features.h handle the "FTM X implies Y" relationships.
* remove spurious const keyword in sigqueue declarationRich Felker2018-03-101-1/+1
| | | | | | this must have been taken from POSIX without realizing that it was meaningless. the resolution to Austin Group issue #844 removed it from the standard.
* fix minor namespace issue in unistd.hRich Felker2018-03-101-2/+1
| | | | | | the F_* macros associated with the lockf function are XSI-shaded (like the lockf function itself) and should only be exposed when the function is.
* fix minor namespace issue in tar.hRich Felker2018-03-101-0/+2
| | | | TSVTX is XSI-shaded.
* fix minor namespace issues in limits.hRich Felker2018-03-101-5/+10
| | | | PAGE_SIZE, NZERO, and NL_LANGMAX are XSI-shaded.
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