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ad1cd43a86645ba2d4f7c8747240452a349d6bc1
musl/src/internal/libc.h

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initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
#ifndef LIBC_H
#define LIBC_H
#include <stdlib.h>
#include <stdio.h>
support configurable page size on mips, powerpc and microblaze 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.
2013-09-15 02:00:32 +00:00
#include <limits.h>
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
implement locale file loading and state for remaining locale categories there is still no code which actually uses the loaded locale files, so the main observable effect of this commit is that calls to setlocale store and give back the names of the selected locales for the remaining categories (LC_TIME, LC_COLLATE, LC_MONETARY) if a locale file by the requested name could be loaded.
2014-07-24 03:23:11 -04:00
struct __locale_map;
add locale framework this commit adds non-stub implementations of setlocale, duplocale, newlocale, and uselocale, along with the data structures and minimal code needed for representing the active locale on a per-thread basis and optimizing the common case where thread-local locale settings are not in use. at this point, the data structures only contain what is necessary to represent LC_CTYPE (a single flag) and LC_MESSAGES (a name for use in finding message translation files). representation for the other categories will be added later; the expectation is that a single pointer will suffice for each. for LC_CTYPE, the strings "C" and "POSIX" are treated as special; any other string is accepted and treated as "C.UTF-8". for other categories, any string is accepted after being truncated to a maximum supported length (currently 15 bytes). for LC_MESSAGES, the name is kept regardless of whether libc itself can use such a message translation locale, since applications using catgets or gettext should be able to use message locales libc is not aware of. for other categories, names which are not successfully loaded as locales (which, at present, means all names) are treated as aliases for "C". setlocale never fails. locale settings are not yet used anywhere, so this commit should have no visible effects except for the contents of the string returned by setlocale.
2014-07-02 19:33:19 -04:00
struct __locale_struct {
overhaul locale internals to treat categories roughly uniformly previously, LC_MESSAGES was treated specially as the only category which could be set to a locale name without a definition file, in order to facilitate gettext message translations when no libc locale was available. LC_NUMERIC was completely un-settable, and LC_CTYPE stored a flag intended to be used for a possible future byte-based C locale, instead of storing a __locale_map pointer like the other categories use. this patch changes all categories to be represented by pointers to __locale_map structures, and allows locale names without definition files to be treated as valid locales with trivial definition when used in any category. outwardly visible functional changes should be minor, limited mainly to the strings read back from setlocale and the way gettext handles translations in categories other than LC_MESSAGES. various internal refactoring has also been performed, and improvements in const correctness have been made.
2015-05-27 03:22:52 -04:00
const struct __locale_map *volatile cat[6];
add locale framework this commit adds non-stub implementations of setlocale, duplocale, newlocale, and uselocale, along with the data structures and minimal code needed for representing the active locale on a per-thread basis and optimizing the common case where thread-local locale settings are not in use. at this point, the data structures only contain what is necessary to represent LC_CTYPE (a single flag) and LC_MESSAGES (a name for use in finding message translation files). representation for the other categories will be added later; the expectation is that a single pointer will suffice for each. for LC_CTYPE, the strings "C" and "POSIX" are treated as special; any other string is accepted and treated as "C.UTF-8". for other categories, any string is accepted after being truncated to a maximum supported length (currently 15 bytes). for LC_MESSAGES, the name is kept regardless of whether libc itself can use such a message translation locale, since applications using catgets or gettext should be able to use message locales libc is not aware of. for other categories, names which are not successfully loaded as locales (which, at present, means all names) are treated as aliases for "C". setlocale never fails. locale settings are not yet used anywhere, so this commit should have no visible effects except for the contents of the string returned by setlocale.
2014-07-02 19:33:19 -04:00
};
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
struct __libc {
always initialize thread pointer at program start this is the first step in an overhaul aimed at greatly simplifying and optimizing everything dealing with thread-local state. previously, the thread pointer was initialized lazily on first access, or at program startup if stack protector was in use, or at certain random places where inconsistent state could be reached if it were not initialized early. while believed to be fully correct, the logic was fragile and non-obvious. in the first phase of the thread pointer overhaul, support is retained (and in some cases improved) for systems/situation where loading the thread pointer fails, e.g. old kernels. some notes on specific changes: - the confusing use of libc.main_thread as an indicator that the thread pointer is initialized is eliminated in favor of an explicit has_thread_pointer predicate. - sigaction no longer needs to ensure that the thread pointer is initialized before installing a signal handler (this was needed to prevent a situation where the signal handler caused the thread pointer to be initialized and the subsequent sigreturn cleared it again) but it still needs to ensure that implementation-internal thread-related signals are not blocked. - pthread tsd initialization for the main thread is deferred in a new manner to minimize bloat in the static-linked __init_tp code. - pthread_setcancelstate no longer needs special handling for the situation before the thread pointer is initialized. it simply fails on systems that cannot support a thread pointer, which are non-conforming anyway. - pthread_cleanup_push/pop now check for missing thread pointer and nop themselves out in this case, so stdio no longer needs to avoid the cancellable path when the thread pointer is not available. a number of cases remain where certain interfaces may crash if the system does not support a thread pointer. at this point, these should be limited to pthread interfaces, and the number of such cases should be fewer than before.
2014-03-24 16:57:11 -04:00
int can_do_threads;
clean up handling of thread/nothread mode, locking
2011-04-17 16:53:54 -04:00
int threaded;
security hardening: ensure suid programs have valid stdin/out/err this behavior (opening fds 0-2 for a suid program) is explicitly allowed (but not required) by POSIX to protect badly-written suid programs from clobbering files they later open. this commit does add some cost in startup code, but the availability of auxv and the security flag will be useful elsewhere in the future. in particular auxv is needed for static-linked vdso support, which is still waiting to be committed (sorry nik!)
2011-08-23 09:37:39 -04:00
int secure;
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
volatile int threads_minus_1;
remove remnants of support for running in no-thread-pointer mode since 1.1.0, musl has nominally required a thread pointer to be setup. most of the remaining code that was checking for its availability was doing so for the sake of being usable by the dynamic linker. as of commit 71f099cb7db821c51d8f39dfac622c61e54d794c, this is no longer necessary; the thread pointer is now valid before any libc code (outside of dynamic linker bootstrap functions) runs. this commit essentially concludes "phase 3" of the "transition path for removing lazy init of thread pointer" project that began during the 1.1.0 release cycle.
2015-04-13 19:24:51 -04:00
size_t *auxv;
support for TLS in dynamic-loaded (dlopen) modules unlike other implementations, this one reserves memory for new TLS in all pre-existing threads at dlopen-time, and dlopen will fail with no resources consumed and no new libraries loaded if memory is not available. memory is not immediately distributed to running threads; that would be too complex and too costly. instead, assurances are made that threads needing the new TLS can obtain it in an async-signal-safe way from a buffer belonging to the dynamic linker/new module (via atomic fetch-and-add based allocator). I've re-appropriated the lock that was previously used for __synccall (synchronizing set*id() syscalls between threads) as a general pthread_create lock. it's a "backwards" rwlock where the "read" operation is safe atomic modification of the live thread count, which multiple threads can perform at the same time, and the "write" operation is making sure the count does not increase during an operation that depends on it remaining bounded (__synccall or dlopen). in static-linked programs that don't use __synccall, this lock is a no-op and has no cost.
2012-10-05 11:51:50 -04:00
size_t tls_size;
support configurable page size on mips, powerpc and microblaze 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.
2013-09-15 02:00:32 +00:00
size_t page_size;
add locale framework this commit adds non-stub implementations of setlocale, duplocale, newlocale, and uselocale, along with the data structures and minimal code needed for representing the active locale on a per-thread basis and optimizing the common case where thread-local locale settings are not in use. at this point, the data structures only contain what is necessary to represent LC_CTYPE (a single flag) and LC_MESSAGES (a name for use in finding message translation files). representation for the other categories will be added later; the expectation is that a single pointer will suffice for each. for LC_CTYPE, the strings "C" and "POSIX" are treated as special; any other string is accepted and treated as "C.UTF-8". for other categories, any string is accepted after being truncated to a maximum supported length (currently 15 bytes). for LC_MESSAGES, the name is kept regardless of whether libc itself can use such a message translation locale, since applications using catgets or gettext should be able to use message locales libc is not aware of. for other categories, names which are not successfully loaded as locales (which, at present, means all names) are treated as aliases for "C". setlocale never fails. locale settings are not yet used anywhere, so this commit should have no visible effects except for the contents of the string returned by setlocale.
2014-07-02 19:33:19 -04:00
struct __locale_struct global_locale;
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
};
support configurable page size on mips, powerpc and microblaze 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.
2013-09-15 02:00:32 +00:00
#ifndef PAGE_SIZE
#define PAGE_SIZE libc.page_size
#endif
cleanup and work around visibility bug in gcc 3 that affects x86_64 in gcc 3, the visibility attribute must be placed on both the declaration and on the definition. if it's omitted from the definition, the compiler fails to emit the ".hidden" directive in the assembly, and the linker will either generate textrels (if supported, such as on i386) or refuse to link (on targets where certain types of textrels are forbidden or impossible without further assumptions about memory layout, such as on x86_64). this patch also unifies the decision about when to use visibility into libc.h and makes the visibility in the utf-8 state machine tables based on libc.h rather than a duplicate test.
2012-02-23 21:24:56 -05:00
#ifdef __PIC__
fix trailing whitespace issues that crept in here and there
2012-12-07 16:16:44 -05:00
#define ATTR_LIBC_VISIBILITY __attribute__((visibility("hidden")))
cleanup and work around visibility bug in gcc 3 that affects x86_64 in gcc 3, the visibility attribute must be placed on both the declaration and on the definition. if it's omitted from the definition, the compiler fails to emit the ".hidden" directive in the assembly, and the linker will either generate textrels (if supported, such as on i386) or refuse to link (on targets where certain types of textrels are forbidden or impossible without further assumptions about memory layout, such as on x86_64). this patch also unifies the decision about when to use visibility into libc.h and makes the visibility in the utf-8 state machine tables based on libc.h rather than a duplicate test.
2012-02-23 21:24:56 -05:00
#else
#define ATTR_LIBC_VISIBILITY
#endif
extern struct __libc __libc ATTR_LIBC_VISIBILITY;
use an accessor function for __libc data pointer when compiled as PIC prior to this change, a large portion of libc was unusable prior to relocation by the dynamic linker, due to dependence on the global data in the __libc structure and the need to obtain its address through the GOT. with this patch, the accessor function __libc_loc is now able to obtain the address of __libc via PC-relative addressing without using the GOT. this means the majority of libc functionality is now accessible right away. naturally, the above statements all depend on having an architecture where PC-relative addressing and jumps/calls are feasible, and a compiler that generates the appropriate code.
2011-02-20 22:30:06 -05:00
#define libc __libc
various changes in preparation for dynamic linking support prefer using visibility=hidden for __libc internal data, rather than an accessor function, if the compiler has visibility. optimize with -O3 for PIC targets (shared library). without heavy inlining, reloading the GOT register in small functions kills performance. 20-30% size increase for a single libc.so is not a big deal, compared to comparaible size increase in every static binaries. use -Bsymbolic-functions, not -Bsymbolic. global variables are subject to COPY relocations, and thus binding their addresses in the library at link time will cause library functions to read the wrong (original) copies instead of the copies made in the main program's bss section. add entry point, _start, for dynamic linker.
2011-02-24 16:37:21 -05:00
fix inconsistent visibility for __hwcap and __sysinfo symbols these are used as hidden by asm files (and such use is the whole reason they exist), but their actual definitions were not hidden.
2015-04-22 02:53:41 -04:00
extern size_t __hwcap ATTR_LIBC_VISIBILITY;
extern size_t __sysinfo ATTR_LIBC_VISIBILITY;
extern char *__progname, *__progname_full;
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
/* Designed to avoid any overhead in non-threaded processes */
use explicit visibility to optimize a few hot-path function calls on x86 and some other archs, functions which make function calls which might go through a PLT incur a significant overhead cost loading the GOT register prior to making the call. this load is utterly useless in musl, since all calls are bound at library-creation time using -Bsymbolic-functions, but the compiler has no way of knowing this, and attempts to set the default visibility to protected have failed due to bugs in GCC and binutils. this commit simply manually assigns hidden/protected visibility, as appropriate, to a few internal-use-only functions which have many callers, or which have callers that are hot paths like getc/putc. it shaves about 5k off the i386 libc.so with -Os. many of the improvements are in syscall wrappers, where the benefit is just size and performance improvement is unmeasurable noise amid the syscall overhead. however, stdio may be measurably faster. if in the future there are toolchains that can do the same thing globally without introducing linking bugs, it might be worth considering removing these workarounds.
2012-10-25 15:40:58 -04:00
void __lock(volatile int *) ATTR_LIBC_VISIBILITY;
void __unlock(volatile int *) ATTR_LIBC_VISIBILITY;
int __lockfile(FILE *) ATTR_LIBC_VISIBILITY;
void __unlockfile(FILE *) ATTR_LIBC_VISIBILITY;
fix potential deadlock bug in libc-internal locking logic if a multithreaded program became non-multithreaded (i.e. all other threads exited) while one thread held an internal lock, the remaining thread would fail to release the lock. the the program then became multithreaded again at a later time, any further attempts to obtain the lock would deadlock permanently. the underlying cause is that the value of libc.threads_minus_1 at unlock time might not match the value at lock time. one solution would be returning a flag to the caller indicating whether the lock was taken and needs to be unlocked, but there is a simpler solution: using the lock itself as such a flag. note that this flag is not needed anyway for correctness; if the lock is not held, the unlock code is harmless. however, the memory synchronization properties associated with a_store are costly on some archs, so it's best to avoid executing the unlock code when it is unnecessary.
2013-09-20 02:00:27 -04:00
#define LOCK(x) __lock(x)
#define UNLOCK(x) __unlock(x)
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
new attempt at making set*id() safe and robust changing credentials in a multi-threaded program is extremely difficult on linux because it requires synchronizing the change between all threads, which have their own thread-local credentials on the kernel side. this is further complicated by the fact that changing the real uid can fail due to exceeding RLIMIT_NPROC, making it possible that the syscall will succeed in some threads but fail in others. the old __rsyscall approach being replaced was robust in that it would report failure if any one thread failed, but in this case, the program would be left in an inconsistent state where individual threads might have different uid. (this was not as bad as glibc, which would sometimes even fail to report the failure entirely!) the new approach being committed refuses to change real user id when it cannot temporarily set the rlimit to infinity. this is completely POSIX conformant since POSIX does not require an implementation to allow real-user-id changes for non-privileged processes whatsoever. still, setting the real uid can fail due to memory allocation in the kernel, but this can only happen if there is not already a cached object for the target user. thus, we forcibly serialize the syscalls attempts, and fail the entire operation on the first failure. this *should* lead to an all-or-nothing success/failure result, but it's still fragile and highly dependent on kernel developers not breaking things worse than they're already broken. ideally linux will eventually add a CLONE_USERCRED flag that would give POSIX conformant credential changes without any hacks from userspace, and all of this code would become redundant and could be removed ~10 years down the line when everyone has abandoned the old broken kernels. i'm not holding my breath...
2011-07-29 22:59:44 -04:00
void __synccall(void (*)(void *), void *);
int __setxid(int, int, int, int);
move rsyscall out of pthread_create module this is something of a tradeoff, as now set*id() functions, rather than pthread_create, are what pull in the code overhead for dealing with linux's refusal to implement proper POSIX thread-vs-process semantics. my motivations are: 1. it's cleaner this way, especially cleaner to optimize out the rsyscall locking overhead from pthread_create when it's not needed. 2. it's expected that only a tiny number of core system programs will ever use set*id() functions, whereas many programs may want to use threads, and making thread overhead tiny is an incentive for "light" programs to try threads.
2011-04-06 20:27:07 -04:00
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
extern char **__environ;
#undef weak_alias
#define weak_alias(old, new) \
extern __typeof(old) new __attribute__((weak, alias(#old)))
#undef LFS64_2
enable LARGEFILE64 aliases these will NOT be used when compiling with -D_LARGEFILE64_SOURCE on musl; instead, they exist in the hopes of eventually being able to run some glibc-linked apps with musl sitting in place of glibc. also remove the (apparently incorrect) fcntl alias.
2012-05-31 23:12:31 -04:00
#define LFS64_2(x, y) weak_alias(x, y)
initial check-in, version 0.5.0
2011-02-12 00:22:29 -05:00
#undef LFS64
#define LFS64(x) LFS64_2(x, x##64)
#endif
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