From: Stefan Beller <sbeller@google.com>
To: Brandon Williams <bmwill@google.com>
Cc: "git@vger.kernel.org" <git@vger.kernel.org>,
Jeff King <peff@peff.net>, Jacob Keller <jacob.keller@gmail.com>
Subject: Re: [PATCH] real_path: make real_path thread-safe
Date: Mon, 5 Dec 2016 11:57:32 -0800 [thread overview]
Message-ID: <CAGZ79kauPdE1uiFSvBALkNiwXbnV6d6xhwLdWNQwRir_8rTG6Q@mail.gmail.com> (raw)
In-Reply-To: <1480964316-99305-2-git-send-email-bmwill@google.com>
On Mon, Dec 5, 2016 at 10:58 AM, Brandon Williams <bmwill@google.com> wrote:
> The current implementation of real_path uses chdir() in order to resolve
> symlinks. Unfortunately this isn't thread-safe as chdir() affects a
> process as a whole and not just an individual thread. Instead perform
> the symlink resolution by hand so that the calls to chdir() can be
> removed, making real_path reentrant.
>
> Signed-off-by: Brandon Williams <bmwill@google.com>
Thanks for working on this, some comments below:
>
> +/* removes the last path component from 'path' except if 'path' is root */
> +static void strip_last_component(struct strbuf *path)
> +{
> + if (path->len > 1) {
> + char *last_slash = find_last_dir_sep(path->buf);
What happens when there is no dir_sep?
> +/* gets the next component in 'remaining' and places it in 'next' */
> +static void get_next_component(struct strbuf *next, struct strbuf *remaining)
> +{
It's more than just getting it, it also chops it off of 'remaining' ?
> + strbuf_reset(&resolved);
> +
> + if (is_absolute_path(path)) {
> + /* absolute path; start with only root as being resolved */
> + strbuf_addch(&resolved, '/');
> + strbuf_addstr(&remaining, path + 1);
This is where we would wait for input of Windows savy people.
> + } else {
> + /* relative path; can use CWD as the initial resolved path */
> + if (strbuf_getcwd(&resolved)) {
> + if (die_on_error)
> + die_errno("Could not get current working directory");
I am looking at xgetcwd, which words it slightly differently.
if (strbuf_getcwd(&sb))
die_errno(_("unable to get current working directory"));
Not sure if aligning them would be a good idea?
Going by "git grep die_errno" as well as our Coding guidelines,
we don't want to see capitalized error messages.
> +
> + if (next.len == 0) {
> + continue; /* empty component */
which means we resolve over path//with//double//slashes just fine,
as well as /./ parts. :)
> }
>
> - if (sb.len) {
> - if (!cwd.len && strbuf_getcwd(&cwd)) {
> + /* append the next component and resolve resultant path */
"resultant" indicates you have a math background. :)
But I had to look it up, I guess it is fine that way,
though "resulting" may cause less mental friction
for non native speakers.
> + if (!(errno == ENOENT && !remaining.len)) {
> if (die_on_error)
> - die_errno("Could not get current working directory");
> + die_errno("Invalid path '%s'",
> + resolved.buf);
> else
> goto error_out;
> }
> + } else if (S_ISLNK(st.st_mode)) {
As far as I can tell, we could keep the symlink strbuf
at a smaller scope here? (I was surprised how many strbufs
are declared at the beginning of the function)
> + //strbuf_release(&resolved);
This is why the cover letter toned down expectations ?
(no // as comment, maybe remove that line?)
Thanks,
Stefan
next prev parent reply other threads:[~2016-12-05 19:57 UTC|newest]
Thread overview: 83+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-12-05 18:58 [PATCH] making real_path thread-safe Brandon Williams
2016-12-05 18:58 ` [PATCH] real_path: make " Brandon Williams
2016-12-05 19:57 ` Stefan Beller [this message]
2016-12-05 20:12 ` Brandon Williams
2016-12-05 20:38 ` Stefan Beller
2016-12-05 20:14 ` Stefan Beller
2016-12-05 20:16 ` Brandon Williams
2016-12-08 9:41 ` Duy Nguyen
2016-12-08 17:50 ` Brandon Williams
2016-12-06 23:44 ` Junio C Hamano
2016-12-07 0:10 ` Brandon Williams
2016-12-07 1:12 ` Ramsay Jones
2016-12-07 20:14 ` Torsten Bögershausen
2016-12-07 20:32 ` Junio C Hamano
2016-12-07 22:13 ` Brandon Williams
2016-12-08 7:55 ` Torsten Bögershausen
2016-12-08 18:41 ` Johannes Sixt
2016-12-08 19:02 ` Brandon Williams
2016-12-07 20:43 ` Johannes Sixt
2016-12-07 22:29 ` Brandon Williams
2016-12-08 11:32 ` Johannes Sixt
2016-12-08 16:54 ` Junio C Hamano
2016-12-08 23:58 ` [PATCH v2 0/4] road to reentrant real_path Brandon Williams
2016-12-08 23:58 ` [PATCH v2 1/4] real_path: resolve symlinks by hand Brandon Williams
2016-12-09 1:49 ` Jacob Keller
2016-12-09 14:33 ` Johannes Sixt
2016-12-09 20:04 ` Brandon Williams
2016-12-08 23:58 ` [PATCH v2 2/4] real_path: convert real_path_internal to strbuf_realpath Brandon Williams
2016-12-08 23:58 ` [PATCH v2 3/4] real_path: create real_pathdup Brandon Williams
2016-12-09 14:35 ` Johannes Sixt
2016-12-08 23:58 ` [PATCH v2 4/4] real_path: have callers use real_pathdup and strbuf_realpath Brandon Williams
2016-12-09 12:33 ` [PATCH v2 0/4] road to reentrant real_path Duy Nguyen
2016-12-09 19:42 ` Brandon Williams
2016-12-10 11:02 ` Duy Nguyen
2016-12-12 18:16 ` [PATCH v3 " Brandon Williams
2016-12-12 18:16 ` [PATCH v3 1/4] real_path: resolve symlinks by hand Brandon Williams
2016-12-12 22:19 ` Junio C Hamano
2016-12-12 22:50 ` Brandon Williams
2016-12-12 23:32 ` Junio C Hamano
2016-12-12 18:16 ` [PATCH v3 2/4] real_path: convert real_path_internal to strbuf_realpath Brandon Williams
2016-12-12 22:20 ` Junio C Hamano
2016-12-12 18:16 ` [PATCH v3 3/4] real_path: create real_pathdup Brandon Williams
2016-12-12 22:25 ` Junio C Hamano
2016-12-12 18:16 ` [PATCH v3 4/4] real_path: have callers use real_pathdup and strbuf_realpath Brandon Williams
2016-12-12 22:26 ` Junio C Hamano
2016-12-12 23:47 ` Junio C Hamano
2016-12-12 23:58 ` Stefan Beller
2016-12-13 1:15 ` Brandon Williams
2016-12-13 6:39 ` Junio C Hamano
2016-12-21 21:51 ` [PATCH bw/realpath-wo-chdir] real_path: canonicalize directory separators in root parts Johannes Sixt
2016-12-21 22:33 ` Brandon Williams
2016-12-22 6:07 ` Johannes Sixt
2016-12-22 17:33 ` Brandon Williams
2016-12-22 18:54 ` Johannes Sixt
2016-12-22 19:33 ` Junio C Hamano
2017-01-03 19:09 ` [PATCH v4 0/5] road to reentrant real_path Brandon Williams
2017-01-03 19:09 ` [PATCH v4 1/5] real_path: resolve symlinks by hand Brandon Williams
2017-01-03 19:09 ` [PATCH v4 2/5] real_path: convert real_path_internal to strbuf_realpath Brandon Williams
2017-01-03 19:09 ` [PATCH v4 3/5] real_path: create real_pathdup Brandon Williams
2017-01-03 19:09 ` [PATCH v4 4/5] real_path: have callers use real_pathdup and strbuf_realpath Brandon Williams
2017-01-04 1:07 ` Jacob Keller
2017-01-04 18:14 ` Brandon Williams
2017-01-03 19:09 ` [PATCH v4 5/5] real_path: canonicalize directory separators in root parts Brandon Williams
2017-01-04 0:48 ` [PATCH v4 0/5] road to reentrant real_path Jeff King
2017-01-04 6:56 ` Torsten Bögershausen
2017-01-04 7:01 ` Jeff King
2017-01-04 18:13 ` Brandon Williams
2017-01-04 18:22 ` Stefan Beller
2017-01-04 21:46 ` Jacob Keller
2017-01-04 21:55 ` Brandon Williams
2017-01-04 22:01 ` [PATCH v5 " Brandon Williams
2017-01-04 22:01 ` [PATCH v5 1/5] real_path: resolve symlinks by hand Brandon Williams
2017-01-04 22:01 ` [PATCH v5 2/5] real_path: convert real_path_internal to strbuf_realpath Brandon Williams
2017-01-04 22:01 ` [PATCH v5 3/5] real_path: create real_pathdup Brandon Williams
2017-01-04 22:01 ` [PATCH v5 4/5] real_path: have callers use real_pathdup and strbuf_realpath Brandon Williams
2017-01-04 22:01 ` [PATCH v5 5/5] real_path: canonicalize directory separators in root parts Brandon Williams
2017-01-08 3:09 ` [PATCH v5 0/5] road to reentrant real_path Junio C Hamano
2017-01-09 18:04 ` Brandon Williams
2017-01-09 18:18 ` Junio C Hamano
2017-01-09 18:24 ` Brandon Williams
2017-01-09 19:26 ` Junio C Hamano
2017-01-09 18:50 ` [PATCH 1/2] real_path: prevent redefinition of MAXSYMLINKS Brandon Williams
2017-01-09 18:50 ` [PATCH 2/2] real_path: set errno when max number of symlinks is exceeded Brandon Williams
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