src/lib/libc/stdlib/realpath.c, branch release/13.1.0

vfs: add realpathat syscall

2020-02-20T16:58:19Z

realpath(3) is used a lot e.g., by clang and is a major source of getcwd and fstatat calls. This can be done more efficiently in the kernel. This works by performing a regular lookup while saving the name and found parent directory. If the terminal vnode is a directory we can resolve it using usual means. Otherwise we can use the name saved by lookup and resolve the parent. See the review for sample syscall counts. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D23574

Fix -Wsign-compare warnings in realpath.c

2019-06-26T15:43:20Z

This is needed in order to build realpath.c as part of rtld.

libc: further adoption of SPDX licensing ID tags.

2017-11-25T17:12:48Z

Mainly focus on files that use BSD 2-Clause license, however the tool I was using mis-identified many licenses so this was mostly a manual - error prone - task. 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.

Style.

2017-05-15T17:54:36Z

Sponsored by: The FreeBSD Foundation MFC after: 2 weeks

Simplify cleanup on failure in realpath(3).

2017-05-15T17:34:17Z

If realpath() allocated memory for result and failed, the memory is freed in each place where return is performed. More, the function needs to track the allocation status, to not free user-supplied buffer. Consolidate the memory handling in the wrapper, freeing the buffer if the actual worker failed. Reviewed by: emaste (previous version) Sponsored by: The FreeBSD Foundation MFC after: 2 weeks Differential revision: https://reviews.freebsd.org/D10670

Fix several buffer overflows in realpath(3).

2017-05-15T17:14:53Z

- The statement "left_len -= s - left;" does not take the slash into account if one was found. This results in the invariant "left[left_len] == '\0'" being violated (and possible buffer overflows). The patch replaces the variable "s" with a size_t "next_token_len" for more clarity. - "slen" from readlink(2) can be 0 when encountering empty symlinks. Then, further down, "symlink[slen - 1]" underflows the buffer. When slen == 0, realpath(3) should probably return ENOENT (http://austingroupbugs.net/view.php?id=825, https://lwn.net/Articles/551224/). Some other minor issues: - The condition "resolved_len >= PATH_MAX" cannot be true. - Similarly, "s - left >= sizeof(next_token)" cannot be true, as long as "sizeof(next_token) >= sizeof(left)". - Return ENAMETOOLONG when a resolved symlink from readlink(2) is too long for the symlink buffer (instead of just truncating it). - "resolved_len > 1" below the call to readlink(2) is always true as "strlcat(resolved, next_token, PATH_MAX);" always results in a string of length > 1. Also, "resolved[resolved_len - 1] = '\0';" is not needed; there can never be a trailing slash here. - The truncation check for "strlcat(symlink, left, sizeof(symlink));" should be against "sizeof(symlink)" (the third argument to strlcat) instead of "sizeof(left)". Submitted by: Jan Kokemц╪ller PR: 219154 MFC after: 2 weeks

realpath(): Properly fail "." or ".." components after non-directories.

2014-04-13T19:48:28Z

If realpath() is called on pathnames like "/dev/null/." or "/dev/null/..", it should fail with [ENOTDIR]. Pathnames like "/dev/null/" already failed as they should. Also, put the check for non-directories after lstatting the previous component instead of when the empty component (consecutive or trailing slashes) is detected, saving an lstat() call and some lines of code. PR: kern/82980 MFC after: 2 weeks

- Correct mispellings of the word occurrence

2013-04-17T11:40:10Z

Submitted by: Christoph Mallon (via private mail)

Avoid mapping ENOENT to ENOTDIR for non-existent path components.

2012-09-12T17:05:39Z

The ENOTDIR mapping was introduced in r235266 for kern/128933 based on an interpretation of the somewhat ambiguous language in the POSIX realpath specification. The interpretation is inconsistent with Solaris and Linux, a regression from 9.0, and does not appear to be permitted by the description of ENOTDIR: 20 ENOTDIR Not a directory. A component of the specified pathname existed, but it was not a directory, when a directory was expected. PR: standards/171577 MFC after: 3 days

1) Although unpublished version of standard

2012-06-05T16:16:33Z

http://austingroupbugs.net/view.php?id=385#c713 (Resolved state) recommend this way for the current standard (called "earlier" in the text) "However, earlier versions of this standard did not require this, and the same example had to be written as: // buf was obtained by malloc(buflen) ret = write(fd, buf, buflen); if (ret < 0) { int save = errno; free(buf); errno = save; return ret; } " from feedback I have for previous commit it seems that many people prefer to avoid mass code change needed for current standard compliance and prefer to track unpublished standard instead, which requires now that free() itself must save errno, not its usage code. So, I back out "save errno across free()" part of previous commit, and will fill PR for changing free() isntead. 2) Remove now unused serrno. MFC after: 1 week