src/lib/libc/stdlib/system.c, branch release/14.4.0

libc: Purge unneeded cdefs.h

2023-11-27T04:20:09Z

These sys/cdefs.h are not needed. Purge them. They are mostly left-over from the $FreeBSD$ removal. A few in libc are still required for macros that cdefs.h defines. Keep those. Sponsored by: Netflix Differential Revision: https://reviews.freebsd.org/D42385 (cherry picked from commit 559a218c9b257775fb249b67945fe4a05b7a6b9f)

Remove $FreeBSD$: one-line .c pattern

2023-08-16T17:54:42Z

Remove /^[\s*]*__FBSDID$"\$FreeBSD\$"$;?\s*\n/

General further adoption of SPDX licensing ID tags.

2017-11-20T19:49:47Z

Mainly focus on files that use BSD 3-Clause license. The Software Package Data Exchange (SPDX) group provides a specification to make it easier for automated tools to detect and summarize well known opensource licenses. We are gradually adopting the specification, noting that the tags are considered only advisory and do not, in any way, superceed or replace the license texts. Special thanks to Wind River for providing access to "The Duke of Highlander" tool: an older (2014) run over FreeBSD tree was useful as a starting point.

Switch libc from using _sig{procmask,action,suspend} symbols, which

2015-08-29T14:25:01Z

are aliases for the syscall stubs and are plt-interposed, to the libc-private aliases of internally interposed sigprocmask() etc. Since e.g. _sigaction is not interposed by libthr, calling signal() removes thr_sighandler() from the handler slot etc. The result was breaking signal semantic and rtld locking. The added __libc_sigprocmask and other symbols are hidden, they are not exported and cannot be called through PLT. The setjmp/longjmp functions for x86 were changed to use direct calls, and since PIC_PROLOGUE only needed for functional PLT indirection on i386, it is removed as well. The PowerPC bug of calling the syscall directly in the setjmp/longjmp implementation is kept as is. Reported by: Pete French Tested by: Michiel Boland Reviewed by: jilles (previous version) Sponsored by: The FreeBSD Foundation MFC after: 1 week

Fix known issues which blow up the process after dlopen("libthr.so")

2015-01-03T18:38:46Z

(or loading a dso linked to libthr.so into process which was not linked against threading library). - Remove libthr interposers of the libc functions, including __error(). Instead, functions calls are indirected through the interposing table, similar to how pthread stubs in libc are already done. Libc by default points either to syscall trampolines or to existing libc implementations. On libthr load, libthr rewrites the pointers to the cancellable implementations already in libthr. The interposition table is separate from pthreads stubs indirection table to not pull pthreads stubs into static binaries. - Postpone the malloc(3) internal mutexes initialization until libthr is loaded. This avoids recursion between calloc(3) and static pthread_mutex_t initialization. - Reinstall signal handlers with wrapper on libthr load. The _rtld_is_dlopened(3) is used to avoid useless calls to sigaction(2) when libthr is statically referenced from the main binary. In the process, fix openat(2), swapcontext(2) and setcontext(2) interposing. The libc symbols were exported at different versions than libthr interposers. Export both libc and libthr versions from libc now, with default set to the higher version from libthr. Remove unused and disconnected swapcontext(3) userspace implementation from libc/gen. No objections from: deischen Tested by: pho, antoine (exp-run) (previous versions) Sponsored by: The FreeBSD Foundation MFC after: 1 week

system(): Restore behaviour for SIGINT and SIGQUIT.

2013-09-01T19:59:54Z

As mentioned in r16117 and the book "Advanced Programming in the Unix Environment" by W. Richard Stevens, we should ignore SIGINT and SIGQUIT before forking, since it is not guaranteed that the parent process starts running soon enough. To avoid calling sigaction() in the vforked child, instead block SIGINT and SIGQUIT before vfork() and keep the sigaction() to ignore after vfork(). The FreeBSD kernel discards ignored signals, even if they are blocked; therefore, it is not necessary to unblock SIGINT and SIGQUIT earlier.

vfork(2) was listed as deprecated in 1994 (r1573) and was the false

2013-08-13T20:38:55Z

reports of its impending demise were removed in 2009 (r199257). However, in 1996 (r16117) system(3) was switched from vfork(2) to fork(2) based partly on this. Switch back to vfork(2). This has a dramatic effect in cases of extreme mmap use - such as excessive abuse (500+) of shared libraries. popen(3) has used vfork(2) for a while. vfork(2) isn't going anywhere.

Renumber clauses to reduce diffs to other versions

2013-06-13T00:19:30Z

NetBSD, OpenBSD, and Android's Bionic number the clauses 1 through 3, so follow suit to make comparison easier.

Fix many "function declaration isn't a prototype" warnings in libc.

2009-12-05T19:31:38Z

I've only fixed code that seems to be written by `us'. There are still many warnings like this present in resolv/, rpc/, stdtime/ and yp/.

Per Regents of the University of Calfornia letter, remove advertising

2007-01-09T00:28:16Z

clause. # If I've done so improperly on a file, please let me know.