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2013-08-08block signals during forkRich Felker-0/+3
there are several reasons for this. some of them are related to race conditions that arise since fork is required to be async-signal-safe: if fork or pthread_create is called from a signal handler after the fork syscall has returned but before the subsequent userspace code has finished, inconsistent state could result. also, there seem to be kernel and/or strace bugs related to arrival of signals during fork, at least on some versions, and simply blocking signals eliminates the possibility of such bugs.
2013-08-08work around libraries with versioned symbols in dynamic linkerRich Felker-11/+14
this commit does not add versioning support; it merely fixes incorrect lookups of symbols in libraries that contain versioned symbols. previously, the version information was completely ignored, and empirically this seems to have resulted in the oldest version being chosen, but I am uncertain if that behavior was even reliable. the new behavior being introduced is to completely ignore symbols which are marked "hidden" (this seems to be the confusing nomenclature for non-current-version) when versioning is present. this should solve all problems related to libraries with symbol versioning as long as all binaries involved are up-to-date (compatible with the latest-version symbols), and it's the needed behavior for dlsym under all circumstances.
2013-08-07add Big5 charset support to iconvRich Felker-0/+1066
at this point, it is just the common base charset equivalent to Windows CP 950, with no further extensions. HKSCS and possibly other supersets will be added later. other aliases may need to be added too.
2013-08-07make fcvt decimal point location for zero make more senseRich Felker-1/+1
the (obsolete) standard allows either 0 or 1 for the decimal point location in this case, but since the number of zero digits returned in the output string (in this implementation) is one more than the number of digits the caller requested, it makes sense for the decimal point to be logically "after" the first digit. in a sense, this change goes with the previous commit which fixed the value of the decimal point location for non-zero inputs.
2013-08-07fix ecvt/fcvt decimal point position outputRich Felker-1/+1
these functions are obsolete and have no modern standard. the text in SUSv2 is highly ambiguous, specifying that "negative means to the left of the returned digits", which suggested to me that 0 would mean to the right of the first digit. however, this does not agree with historic practice, and the Linux man pages are more clear, specifying that a negative value means "that the decimal point is to the left of the start of the string" (in which case, 0 would mean the start of the string, in accordance with historic practice).
2013-08-05iconv support for legacy Korean encodingsRich Felker-0/+678
like for other character sets, stateful iso-2022 form is not supported yet but everything else should work. all charset aliases are treated the same, as Windows codepage 949, because reportedly the EUC-KR charset name is in widespread (mis?)usage in email and on the web for data which actually uses the extended characters outside the standard 93x94 grid. this could easily be changed if desired. the principle of this converter for handling the giant bulk of rare Hangul syllables outside of the standard KS X 1001 93x94 grid is the same as the GB18030 converter's treatment of non-explicitly-coded Unicode codepoints: sequences in the extension range are mapped to an integer index N, and the converter explicitly computes the Nth Hangul syllable not explicitly encoded in the character map. empirically, this requires at most 7 passes over the grid. this approach reduces the table size required for Korean legacy encodings from roughly 44k to 17k and should have minimal performance impact on real-world text conversions since the "slow" characters are rare. where it does have impact, the cost is merely a large constant time factor.
2013-08-03have new timer threads unblock their own SIGTIMERRich Felker-2/+2
unblocking it in the pthread_once init function is not sufficient, since multiple threads, some of them with the signal blocked, could already exist before this is called; timers started from such threads would be non-functional.
2013-08-03add system for resetting TLS to initial valuesRich Felker-14/+56
this is needed for reused threads in the SIGEV_THREAD timer notification system, and could be reused elsewhere in the future if needed, though it should be refactored for such use. for static linking, __init_tls.c is simply modified to export the TLS info in a structure with external linkage, rather than using statics. this perhaps makes the code more clear, since the statics were poorly named for statics. the new __reset_tls.c is only linked if it is used. for dynamic linking, the code is in dynlink.c. sharing code with __copy_tls is not practical since __reset_tls must also re-zero thread-local bss.
2013-08-03fix multiple bugs in SIGEV_THREAD timersRich Felker-22/+36
1. the thread result field was reused for storing a kernel timer id, but would be overwritten if the application code exited or cancelled the thread. 2. low pointer values were used as the indicator that the timer id is a kernel timer id rather than a thread id. this is not portable, as mmap may return low pointers on some conditions. instead, use the fact that pointers must be aligned and kernel timer ids must be non-negative to map pointers into the negative integer space. 3. signals were not blocked until after the timer thread started, so a race condition could allow a signal handler to run in the timer thread when it's not supposed to exist. this is mainly problematic if the calling thread was the only thread where the signal was unblocked and the signal handler assumes it runs in that thread.
2013-08-03fix faccessat to support AT_EACCESS flagRich Felker-1/+46
this is another case of the kernel syscall failing to support flags where it needs to, leading to horrible workarounds in userspace. this time the workaround requires changing uid/gid, and that's not safe to do in the current process. in the worst case, kernel resource limits might prevent recovering the original values, and then there would be no way to safely return. so, use the safe but horribly inefficient alternative: forking. clone is used instead of fork to suppress signals from the child. fortunately this worst-case code is only needed when effective and real ids mismatch, which mainly happens in suid programs.
2013-08-03collapse euidaccess to a call to faccessatRich Felker-9/+1
it turns out Linux is buggy for faccessat, just like fchmodat: the kernel does not actually take a flags argument. so we're going to have to emulate it there.
2013-08-03add legacy euidaccess function and eaccess alias for itRich Felker-0/+18
this is mainly for ABI compat purposes.
2013-08-02make tdestroy allow null function pointer if no destructor is neededRich Felker-1/+1
this change is to align with a change in the glibc interface.
2013-08-02fix aliasing violations in tsearch functionsRich Felker-2/+10
patch by nsz. the actual object the caller has storing the tree root has type void *, so accessing it as struct node * is not valid. instead, simply access the value, move it to a temporary of the appropriate type and work from there, then move the result back.
2013-08-02protect against long double type mismatches (mainly powerpc for now)Rich Felker-0/+7
check in configure to be polite (failing early if we're going to fail) and in vfprintf.c since that is the point at which a mismatching type would be extremely dangerous.
2013-08-02add legacy function vallocRich Felker-0/+8
it was already declared in stdlib.h, but not defined anywhere.
2013-08-02add wcsftime_t aliasRich Felker-0/+3
this is a nonstandard extension.
2013-08-02make fchdir, fchmod, fchown, and fstat support O_PATH file descriptorsRich Felker-5/+37
on newer kernels, fchdir and fstat work anyway. this same fix should be applied to any other syscalls that are similarly affected. with this change, the current definitions of O_SEARCH and O_EXEC as O_PATH are mostly conforming to POSIX requirements. the main remaining issue is that O_NOFOLLOW has different semantics.
2013-08-02debloat code that depends on /proc/self/fd/%d with shared functionRich Felker-6/+26
I intend to add more Linux workarounds that depend on using these pathnames, and some of them will be in "syscall" functions that, from an anti-bloat standpoint, should not depend on the whole snprintf framework.
2013-08-02work around linux's lack of flags argument to fchmodat syscallRich Felker-1/+29
previously, the AT_SYMLINK_NOFOLLOW flag was ignored, giving dangerously incorrect behavior -- the target of the symlink had its modes changed to the modes (usually 0777) intended for the symlink). this issue was amplified by the fact that musl provides lchmod, as a wrapper for fchmodat, which some archival programs take as a sign that symlink modes are supported and thus attempt to use. emulating AT_SYMLINK_NOFOLLOW was a difficult problem, and I originally believed it could not be solved, at least not without depending on kernels newer than 3.5.x or so where O_PATH works halfway well. however, it turns out that accessing O_PATH file descriptors via their pseudo-symlink entries in /proc/self/fd works much better than trying to use the fd directly, and works even on older kernels. moreover, the kernel has permanently pegged these references to the inode obtained by the O_PATH open, so there should not be race conditions with the file being moved, deleted, replaced, etc.
2013-08-02move RPATH search after LD_LIBRARY_PATH searchRich Felker-2/+2
this is the modern way, and the only way that makes any sense. glibc has this complicated mechanism with RPATH and RUNPATH that controls whether RPATH is processed before or after LD_LIBRARY_PATH, presumably to support legacy binaries, but there is no compelling reason to support this, and better behavior is obtained by just fixing the search order.
2013-08-02if map_library has allocated a buffer for phdrs, free it on success tooRich Felker-0/+1
this fixes an oversight in the previous commit.
2013-08-02improve error handling in map_library and support long phdrsRich Felker-12/+21
previously, errno could be meaningless when the caller wrote it to the dlerror string or stderr. try to make it meaningful. also, fix incorrect check for over-long program headers and instead actually support them by allocating memory if needed.
2013-08-02fix uninitialized dyn variable in map_libraryRich Felker-1/+1
this can only happen for invalid library files, but they were not detected reliably because the variable was uninitialized.
2013-08-02fix (deprecated) mktemp logic and update it to match other temp functionsRich Felker-4/+11
the access function cannot be used to check for existence, because it operates using real uid/gid rather than effective to determine accessibility; this matters for the non-final path components. instead, use stat. failure of stat is success if only the final component is missing (ENOENT) and otherwise is failure.
2013-08-02remove (no longer useful) namespace-protected __mktemp symbolRich Felker-4/+1
2013-08-02make mkdtemp and mkstemp family leave template unchanged on failRich Felker-13/+18
also refactor mkdtemp based on new shared temp code, removing dependency on the deprecated mktemp, whose behavior made this logic more difficult.
2013-08-01optimized memset asm for i386 and x86_64Rich Felker-0/+88
the concept of both versions is the same; they differ only in details. for long runs, they use "rep movsl" or "rep movsq", and for small runs, they use a trick, writing from both ends towards the middle, that reduces the number of branches needed. in addition, if memset is called multiple times with the same length, all branches will be predicted; there are no loops. for larger runs, there are likely faster approaches than "rep", at least on some cpu models. for 32-bit, it's unlikely that there is any faster approach that does not require non-baseline instructions; doing anything fancier would require inspecting cpu capabilities. for 64-bit, there may very well be faster versions that work on all models; further optimization could be explored in the future. with these changes, memset is anywhere between 50% faster and 6 times faster, depending on the cpu model and the length and alignment of the destination buffer.
2013-07-31in pthread_getattr_np, use mremap rather than madvise to measure stackRich Felker-1/+2
the original motivation for this patch was that qemu (and possibly other syscall emulators) nop out madvise, resulting in an infinite loop. however, there is another benefit to this change: madvise may actually undo an explicit madvise the application intended for its stack, whereas the mremap operation is a true nop. the logic here is that mremap must fail if it cannot resize the mapping in-place, and the caller knows that it cannot resize in-place because it knows the next page of virtual memory is already occupied.
2013-07-31fix theoretical out-of-bound access in dynamic linkerRich Felker-1/+1
one of the arguments to memcmp may be shorter than the length l-3, and memcmp is under no obligation not to access past the first byte that differs. instead use strncmp which conveys the correct semantics. the performance difference is negligible here and since the code is only use for shared libc, both functions are already linked anyway.
2013-07-31prevent passing PT_INTERP name to dlopen from double-loading libcRich Felker-6/+11
the dev/inode for the main app and the dynamic linker ("interpreter") are not available, so the subsequent checks don't work. in general we don't want to make exact string matches to existing libraries prevent loading new ones, since this breaks loading upgraded modules in module-loading systems. so instead, special-case it. the motivation for this fix is that calling dlopen on the names returned by dl_iterate_phdr or walking the link map (obtained by dlinfo) seem to be the only methods available to an application to actually get a list of open dso handles.
2013-07-31add some sanity checks in dynamic loader codeRich Felker-0/+10
reject elf files which are not ET_EXEC/ET_DYN type as bad exec format, and reject ET_EXEC files when they cannot be loaded at the correct address, since they are not relocatable at runtime. the main practical benefit of this is to make dlopen of the main program fail rather than producing an unsafe-to-use handle.
2013-07-31fix bug where read error was treated as success reading library headersRich Felker-1/+1
2013-07-31don't call null pointer if DT_INIT/DT_FINI are nullRich Felker-2/+2
it's not clear to me why the linker even outputs these headers if they are null, but apparently it does so. with the default startfiles, they will never be null anyway, but this patch allows eliminating crti, crtn, crtbegin, and crtend (leaving only crt1) if the toolchain is using init_array/fini_array (or for a C-only, no-ctor environment).
2013-07-30use separate sigaction buffers for old and new dataTimo Teräs-8/+8
in signal() it is needed since __sigaction uses restrict in parameters and sharing the buffer is technically an aliasing error. do the same for the syscall, as at least qemu-user does not handle it properly.
2013-07-28add missing erfcl wrapper for archs where long double is plain doubleRich Felker-0/+4
2013-07-28fix semantically incorrect use of LC_GLOBAL_LOCALERich Felker-7/+7
LC_GLOBAL_LOCALE refers to the global locale, controlled by setlocale, not the thread-local locale in effect which these functions should be using. neither LC_GLOBAL_LOCALE nor 0 has an argument to the *_l functions has behavior defined by the standard, but 0 is a more logical choice for requesting the callee to lookup the current locale. in the future I may move the current locale lookup the the caller (the non-_l-suffixed wrapper). at this point, all of the locale logic is dummied out, so no harm was done, but it should at least avoid misleading usage.
2013-07-27fix indention-with-spacesRich Felker-1/+1
2013-07-27reorder strftime to eliminate the incorrect indention levelRich Felker-5/+5
this change is in preparation for possibly adding support for the field width and padding specifiers added in POSIX 2008.
2013-07-27a few more fixes for unistd/sysconf feature reportingRich Felker-7/+7
2013-07-26report presence of ADV and MSG options in unistd.h and sysconfRich Felker-2/+2
2013-07-26report that posix_spawn is supported in unistd.h and sysconfRich Felker-1/+1
2013-07-26add ABI symbols for strtol family functionsRich Felker-0/+8
these odd names are actually generated by mess in glibc's stdlib.h, so any glibc-linked program using strtol needs them to run against musl.
2013-07-26make ldd report the libc/dynamic linker itselfRich Felker-0/+22
2013-07-26fix computation of entry point and main app phdrs when invoking via ldsoRich Felker-3/+1
entry point was wrong for PIE. e_entry was being treated as an absolute value, whereas it's actually relative to the load address (which is zero for non-PIE). phdr pointer was wrong for non-PIE. e_phoff was being treated as load-address-relative, whereas it's actually a file offset in the ELF file. in any case, map_library was already computing it correctly, and the incorrect code in __dynlink was overwriting it with junk.
2013-07-25fix undefined strcpy call in inet_ntopRich Felker-1/+1
source and dest arguments for strcpy cannot overlap, so memmove must be used here. the length is already known from the above loop.
2013-07-25make inet_ntop format v4-mapped ipv6 addresses properlyRich Felker-8/+14
based on a patch by orc. POSIX actually fails to specify the format of the ntop conversion; presumably, any output that will correctly round-trip back via the (well-specified) pton operation is acceptable. the new behavior is much more convenient than the old, however. this patch also affects getnameinfo, which is implemented in terms of inet_ntop and which is the preferred interface for performing this conversion. I've also removed some inexplicable cruft (filling the buffer with 'x' before doing anything) whose origin I was unable to track down.
2013-07-24rework langinfo code for ABI compat and for use by time codeRich Felker-17/+17
2013-07-24update strxfrm/wcsxfrm for future LC_COLLATE support and ABI compatRich Felker-14/+20
2013-07-24add ABI compat aliases for a number of locale_t functionsRich Felker-0/+24