src/lib/libc/gen/exec.c, branch releng/12.4

MFC r361995-r361996, r361999, r362111: posix_spawnp fixes

2020-06-17T16:22:08Z

r361995: execvp: fix up the ENOEXEC fallback If execve fails with ENOEXEC, execvp is expected to rebuild the command with /bin/sh instead and try again. The previous version did this, but overlooked two details: argv[0] can conceivably be NULL, in which case memp would never get terminated. We must allocate no less than three * sizeof(char *) so we can properly terminate at all times. For the non-NULL argv standard case, we count all the non-NULL elements and actually skip the first argument, so we end up capturing the NULL terminator in our bcopy(). The second detail is that the spec is actually worded such that we should have been preserving argv[0] as passed to execvp: "[...] executed command shall be as if the process invoked the sh utility using execl() as follows: execl(, arg0, file, arg1, ..., (char *)0); where is an unspecified pathname for the sh utility, file is the process image file, and for execvp(), where arg0, arg1, and so on correspond to the values passed to execvp() in argv[0], argv[1], and so on." So we make this change at this time as well, while we're already touching it. We decidedly can't preserve a NULL argv[0] as this would be incredibly, incredibly fragile, so we retain our legacy behavior of using "sh" for argv[] in this specific instance. Some light tests are added to try and detect some components of handling the ENOEXEC fallback; posix_spawnp_enoexec_fallback_null_argv0 is likely not 100% reliable, but it at least won't raise false-alarms and it did result in useful failures with pre-change libc on my machine. This is a secondary change in D25038. r361996: execvPe: obviate the need for potentially large stack allocations Some environments in which execvPe may be called have a limited amount of stack available. Currently, it avoidably allocates a segment on the stack large enough to hold PATH so that it may be mutated and use strsep() for easy parsing. This logic is now rewritten to just operate on the immutable string passed in and do the necessary math to extract individual paths, since it will be copying out those segments to another buffer anyways and piecing them together with the name for a full path. Additional size is also needed for the stack in posix_spawnp(), because it may need to push all of argv to the stack and rebuild the command with sh in front of it. We'll make sure it's properly aligned for the new thread, but future work should likely make rfork_thread a little easier to use by ensuring proper alignment. Some trivial cleanup has been done with a couple of error writes, moving strings into char arrays for use with the less fragile sizeof(). r361999: Add missing shell script from r361995 r362111: posix_spawn: fix for some custom allocator setups libc cannot assume that aligned_alloc and free come from jemalloc, or that any application providing its own malloc and free is actually providing aligned_alloc. Switch back to malloc and just make sure we're passing a properly aligned stack into rfork_thread, as an application perhaps can't reasonably replace just malloc or just free without headaches. This unbreaks ksh93 after r361996, which provides malloc/free but no aligned_alloc.

Clean up the vcs ID strings in libc's gen/ directory.

2018-07-03T17:31:45Z

- Move CSRG IDs into __SCCSID(). - When a file has been copied, consistently use 'From: ' for strings referencing the version of the source file copied from in the license block comment. - Some of the 'From:' tags were using $FreeBSD$ that was being expanded on each checkout. Fix those to hardcode the FreeBSD tag from the file that was copied at the time of the copy. - When multiple strings are present list them in "chronological" order, so CSRG (__SCCSID) before FreeBSD (__FBSDID). If a file came from OtherBSD and contains a CSRG ID from the OtherBSD file, use the order CSRG -> OtherBSD -> FreeBSD. Reviewed by: imp Differential Revision: https://reviews.freebsd.org/D15831

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.

Renumber copyright clause 4

2017-02-28T23:42:47Z

Renumber cluase 4 to 3, per what everybody else did when BSD granted them permission to remove clause 3. My insistance on keeping the same numbering for legal reasons is too pedantic, so give up on that point. Submitted by: Jan Schaumann Pull Request: https://github.com/freebsd/freebsd/pull/96

libc: do not include where was already included

2016-04-18T21:05:15Z

According to style(9): > normally, include OR , but not both. ( already includes when LOCORE is not defined).

Use ANSI C prototypes. Eliminates -Wold-style-definition warnings.

2015-09-20T20:23:16Z

Replace index() and rindex() calls with strchr() and strrchr().

2012-01-03T18:51:58Z

The index() and rindex() functions were marked LEGACY in the 2001 revision of POSIX and were subsequently removed from the 2008 revision. The strchr() and strrchr() functions are part of the C standard. This makes the source code a lot more consistent, as most of these C files also call into other str*() routines. In fact, about a dozen already perform strchr() calls.

Remove warnings from exec.c.

2009-12-05T18:55:16Z

The entries in the argv array are not const themselves, but sometimes we want to fill in const values. Just make the array const and use __DECONST() to make it const for the execve()-call itself. Also convert the only K&R prototype to ANSI.

Properly use the envp argument in execvPe().

2009-11-27T13:05:14Z

execvPe() is called by _execvpe(), which we added to implement posix_spawnp(). We just took execvP() and added the envp argument. Unfortunately we forgot to change the implementation to use envp over environ. This fixes the following piece of code: | char * const arg[2] = { "env", NULL }; | char * const env[2] = { "FOO=BAR", NULL }; | posix_spawnp(NULL, "/usr/bin/env", NULL, NULL, arg, env); MFC after: 2 weeks

Turn execvpe() into an internal libc routine.

2008-06-23T05:22:06Z

Adding exevpe() has caused some ports to break. Even though execvpe() is a useful routine, it does not conform to any standards. This patch is a little bit different from the patch sent to the mailing list. I forgot to remove execvpe from the Symbol.map (which does not seem to miscompile libc, though). Reviewed by: davidxu Approved by: philip