path: root/include/limits.h
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2020-01-25move struct dirent to bits header, allow NAME_MAX to varyRich Felker-0/+2
this is not necessary for linux but is a simple, inexpensive change to make that facilitates ports to systems where NAME_MAX needs to be longer.
2019-10-17define LONG_MAX via arch alltypes.h, strip down bits/limits.hRich Felker-5/+11
LLONG_MAX is uniform for all archs we support and plenty of header and code level logic assumes it is, so it does not make sense for limits.h bits mechanism to pretend it's variable. LONG_BIT can be defined in terms of LONG_MAX; there's no reason to put it in bits. by moving LONG_MAX definition to __LONG_MAX in alltypes.h and moving LLONG_MAX out of bits, there are now no plain-C limits that are defined in the bits header, so the bits header only needs to be included in the POSIX or extended profiles. this allows the feature test macro logic to be removed from the bits header, facilitating a long-term goal of getting such logic out of bits. having __LONG_MAX in alltypes.h will allow further generalization of headers. archs without a constant PAGESIZE no longer need bits/limits.h at all.
2018-08-28fix dubious char signedness check in limits.hRich Felker-1/+1
commit 201995f382cc698ae19289623cc06a70048ffe7b introduced a hack utilizing the signedness of character constants at the preprocessor level to avoid depending on the gcc-specific __CHAR_UNSIGNED__ predef. while this trick works on gcc and presumably other compilers being used, it's not clear that the behavior it depends on is actually conforming. C11 ¶10 defines character constants as having type int, and 6.10.1 ¶4 defines preprocessor #if arithmetic to take place in intmax_t or uintmax_t, depending on the signedness of the integer operand types, and it is specified that "this includes interpreting character constants". if character literals had type char and just promoted to int, it would be clear that when char is unsigned they should behave as uintmax_t at the preprocessor level. however, as written the text of the standard seems to require that character constants always behave as intmax_t, corresponding to int, at the preprocessor level. since there is a good deal of ambiguity about the correct behavior and a risk that compilers will disagree or that an interpretation may mandate a change in the behavior, do not rely on it for defining CHAR_MIN and CHAR_MAX correctly. instead, use the signedness of the value (as opposed to the type) of '\xff', which will be positive if and only if plain char is unsigned. this behavior is clearly specified, and the specific case '\xff' is even used in an example, under of the standard.
2018-08-20remove erroneous SYMLINK_MAX definition from limits.h, pathconfRich Felker-1/+0
POSIX requires the symlink function to fail with ENAMETOOLONG if the link contents to be written exceed SYMLINK_MAX in length, but neither Linux nor our syscall wrapper code enforce this. the value 255 for SYMLINK_MAX is not meaningful and does not seem to have been motivated by anything except perhaps a wrong assumption that a definition was mandatory. it has been present (though moving through bits to top-level limits.h) since the beginning of the project history. [f]pathconf is entitled to return -1 as the limit for conf names for which there is no hard limit, with the usual POSIX note that an indefinite limit does not imply an infinite limit. in principle we might should report a limit for filesystems that impose one, but such functionality is not currently present for any of the pathconf limits, and adding it is beyond the scope of fixing the incorrect limit.
2018-03-10fix minor namespace issues in limits.hRich Felker-5/+10
2018-03-10reverse definition dependency between PAGESIZE and PAGE_SIZERich Felker-2/+2
PAGESIZE is actually the version defined in POSIX base, with PAGE_SIZE being in the XSI option. use PAGESIZE as the underlying definition to facilitate making exposure of PAGE_SIZE conditional.
2013-11-29increase TTY_NAME_MAX limit to 32Rich Felker-1/+1
the old value of 20 was reported by Laurent Bercot as being insufficient for a reasonable real-world usage case. actual problem was the internal buffer used by ttyname(), but the implementation of ttyname uses TTY_NAME_MAX, and for consistency it's best to increase both. the new value is aligned with glibc.
2013-10-20fix multiple minor namespace issues in headersRich Felker-1/+7
fcntl.h: AT_* is not a reserved namespace so extensions cannot be exposed by default. langinfo.h: YESSTR and NOSTR were removed from the standard. limits.h: NL_NMAX was removed from the standard. signal.h: the conditional for NSIG was wrongly checking _XOPEN_SOURCE rather than _BSD_SOURCE. this was purely a mistake; it doesn't even match the commit message from the commit that added it.
2013-09-15support configurable page size on mips, powerpc and microblazeSzabolcs Nagy-0/+2
PAGE_SIZE was hardcoded to 4096, which is historically what most systems use, but on several archs it is a kernel config parameter, user space can only know it at execution time from the aux vector. PAGE_SIZE and PAGESIZE are not defined on archs where page size is a runtime parameter, applications should use sysconf(_SC_PAGE_SIZE) to query it. Internally libc code defines PAGE_SIZE to libc.page_size, which is set to aux[AT_PAGESZ] in __init_libc and early in __dynlink as well. (Note that libc.page_size can be accessed without GOT, ie. before relocations are done) Some fpathconf settings are hardcoded to 4096, these should be actually queried from the filesystem using statfs.
2013-04-04eliminate gcc dependency for testing char signedness in limits.hRich Felker-1/+1
2013-02-01pthread stack treatment overhaul for application-provided stacks, etc.Rich Felker-2/+2
the main goal of these changes is to address the case where an application provides a stack of size N, but TLS has size M that's a significant portion of the size N (or even larger than N), thus giving the application less stack space than it expected or no stack at all! the new strategy pthread_create now uses is to only put TLS on the application-provided stack if TLS is smaller than 1/8 of the stack size or 2k, whichever is smaller. this ensures that the application always has "close enough" to what it requested, and the threshold is chosen heuristically to make sure "sane" amounts of TLS still end up in the application-provided stack. if TLS does not fit the above criteria, pthread_create uses mmap to obtain space for TLS, but still uses the application-provided stack for actual call frame stack. this is to avoid wasting memory, and for the sake of supporting ugly hacks like garbage collection based on assumptions that the implementation will use the provided stack range. in order for the above heuristics to ever succeed, the amount of TLS space wasted on POSIX TSD (pthread_key_create based) needed to be reduced. otherwise, these changes would preclude any use of pthread_create without mmap, which would have serious memory usage and performance costs for applications trying to create huge numbers of threads using pre-allocated stack space. the new value of PTHREAD_KEYS_MAX is the minimum allowed by POSIX, 128. this should still be plenty more than real-world applications need, especially now that C11/gcc-style TLS is now supported in musl, and most apps and libraries choose to use that instead of POSIX TSD when available. at the same time, PTHREAD_STACK_MIN has been decreased. it was originally set to PAGE_SIZE back when there was no support for TLS or application-provided stacks, and requests smaller than a whole page did not make sense. now, there are two good reasons to support requests smaller than a page: (1) applications could provide pre-allocated stacks smaller than a page, and (2) with smaller stack sizes, stack+TLS+TSD can all fit in one page, making it possible for applications which need huge numbers of threads with minimal stack needs to allocate exactly one page per thread. the new value of PTHREAD_STACK_MIN, 2k, is aligned with the minimum size for sigaltstack.
2012-11-26fix missing limits when only _BSD_SOURCE is definedRich Felker-1/+1
the missing check did not affect the default profile, since it has both _XOPEN_SOURCE and _BSD_SOURCE defined, but it did break programs which explicitly define _BSD_SOURCE, causing it to be the only feature test macro present.
2012-09-07default features: make musl usable without feature test macrosRich Felker-0/+2
the old behavior of exposing nothing except plain ISO C can be obtained by defining __STRICT_ANSI__ or using a compiler option (such as -std=c99) that predefines it. the new default featureset is POSIX with XSI plus _BSD_SOURCE. any explicit feature test macros will inhibit the default. installation docs have also been updated to reflect this change.
2012-05-14missing limit LOGIN_NAME_MAXRich Felker-0/+1
2012-03-20limits.h: support gcc's -funsigned-charRich Felker-2/+10
some software apparently uses this and breaks with musl due to mismatching definitions...
2011-06-25move all limits that don't vary out of bits/limits.h, into main limits.hRich Felker-0/+22
2011-06-07define MQ_PRIO_MAXRich Felker-0/+1
2011-03-29implement POSIX timersRich Felker-0/+1
this implementation is superior to the glibc/nptl implementation, in that it gives true realtime behavior. there is no risk of timer expiration events being lost due to failed thread creation or failed malloc, because the thread is created as time creation time, and reused until the timer is deleted.
2011-03-10fix sem_open and sem_close to obey posix semanticsRich Felker-0/+1
multiple opens of the same named semaphore must return the same pointer, and only the last close can unmap it. thus the ugly global state keeping track of mappings. the maximum number of distinct named semaphores that can be opened is limited sufficiently small that the linear searches take trivial time, especially compared to the syscall overhead of these functions.
2011-03-03preliminaries to adding POSIX semaphoresRich Felker-0/+1
2011-02-14extensive header cleanup for standards conformance & correctnessRich Felker-2/+3
thanks to Peter Mazinger (psm) for pointing many of these issues out and submitting a patch on which this commit is loosely based
2011-02-14begin namespace-cleanup of standard C headersRich Felker-1/+7
2011-02-13reorganize thread exit code, make pthread_exit call cancellation handlers (pt2)Rich Felker-1/+2
2011-02-12initial check-in, version 0.5.0v0.5.0Rich Felker-0/+101