musl - musl - an implementation of the standard library for Linux-based systems

Age	Commit message (Collapse)	Author	Lines
2023-06-01	fix public clone function to be safe and usable by applications	Rich Felker	-6/+50
	the clone() function has been effectively unusable since it was added, due to producing a child process with inconsistent state. in particular, the child process's thread structure still contains the tid, thread list pointers, thread count, and robust list for the parent. this will cause malfunction in interfaces that attempt to use the tid or thread list, some of which are specified to be async-signal-safe. this patch attempts to make clone() consistent in a _Fork-like sense. as in _Fork, when the parent process is multi-threaded, the child process inherits an async-signal context where it cannot call AS-unsafe functions, but its context is now intended to be safe for calling AS-safe functions. making clone fork-like would also be a future option, if it turns out that this is what makes sense to applications, but it's not done at this time because the changes would be more invasive. in the case where the CLONE_VM flag is used, clone is only vfork-like, not _Fork-like. in particular, the child will see itself as having the parent's tid, and cannot safely call any libc functions but one of the exec family or _exit. handling of flags and variadic arguments is also changed so that arguments are only consumed with flags that indicate their presence, and so that flags which produce an inconsistent state are disallowed (reported as EINVAL). in particular, all libc functions carry a contract that they are only callable with ABI requirements met, which includes having a valid thread pointer to a thread structure that's unique within the process, and whose contents are opaque and only able to be setup internally by the implementation. the only way for an application to use flags that violate these requirements without executing any libc code is to perform the syscall from application-provided asm.
2018-09-12	fix issues from public functions defined without declaration visible	Rich Felker	-0/+2
	policy is that all public functions which have a public declaration should be defined in a context where that public declaration is visible, to avoid preventable type mismatches. an audit performed using GCC's -Wmissing-declarations turned up the violations corrected here. in some cases the public header had not been included; in others, a feature test macro needed to make the declaration visible had been omitted. in the case of gethostent and getnetent, the omission seems to have been intentional, as a hack to admit a single stub definition for both functions. this kind of hack is no longer acceptable; it's UB and would not fly with LTO or advanced toolchains. the hack is undone to make exposure of the declarations possible.
2014-02-09	clone: make clone a wrapper around __clone	Bobby Bingham	-0/+19
	The architecture-specific assembly versions of clone did not set errno on failure, which is inconsistent with glibc. __clone still returns the error via its return value, and clone is now a wrapper that sets errno as needed. The public clone has also been moved to src/linux, as it's not directly related to the pthreads API. __clone is called by pthread_create, which does not report errors via errno. Though not strictly necessary, it's nice to avoid clobbering errno here.