Fix reading of /etc/paths on OS X #4852

akalin · 2018-03-24T20:45:46Z

(and /etc/paths.d/*)

Do so by emulating the behavior of /usr/libexec/path_helper for login shells,
matching the behavior in /etc/profile.

Also add a path_helper command to reproduce the behavior of
/usr/libexec/path_helper for fish.

This also handles setting MANPATH if necessary.

Fixes issue #4336

TODOs:

Changes to fish usage are reflected in user documentation/manpages.
Tests have been added for regressions fixed
User-visible changes noted in CHANGELOG.md

akalin · 2018-03-24T20:46:09Z

This is the follow-up promised in #4337 (comment) .

akalin · 2018-03-24T20:47:46Z

share/functions/path_helper.fish

+# see __fish_construct_path in config.fish and
+# https://opensource.apple.com/source/shell_cmds/shell_cmds-203/path_helper/path_helper.c.auto.html .
+
+function __quote -d "single-quote arguments, escaping characters as necessary"


I couldn't find a built-in way to quote a string. Thought string escape would do it, but it does something different.

string escape will do what you want - escape a string so that it'll pass through source unharmed. It just doesn't always use single-quotes. Instead it falls back to using \\ for more complicated things.

However, I'm not quite sure why this path_helper function exists at all - you're not using it anywhere as far as I can see, and since it would run in the fish process, there's no need to output the set statements - instead, you could just directly run them. Which would also remove the need for quoting.

It's just a driver for debugging the path_helper logic without having to start shells and examine environment variables. I can remove it if needed.

Yes, please! This looks like something to invoke, and it really shouldn't be.

Done! Please take another look.

akalin · 2018-03-24T20:51:41Z

share/functions/path_helper.fish

+
+function __quote -d "single-quote arguments, escaping characters as necessary"
+    for x in $argv
+        set -l quoted (string replace -a -r '([\\\\\'])' '\\\\\\\\$1' $x)


Not exactly sure why I need to triple-escape the \ in \\\\\\\\$1; need to escape once because it's in a single-quoted string, another because it's a replacement string for a regexp, but I can't think of a reason for a third escape.

akalin · 2018-03-24T20:56:57Z

Pinging original main reviewer @krader1961.

akalin · 2018-03-24T21:00:30Z

~~Hmm, not sure why invocation/login-interactive.invoke is failing. Seems to fail on master for me, so might be unrelated.~~ Never mind, should be fixed now.

zanchey · 2018-03-24T23:45:28Z

@ridiculousfish is probably the best reviewer here.

ridiculousfish · 2018-03-25T02:43:57Z

Thanks for doing this!

Can you please catch me up on the rationale? /usr/libexec/path_helper is meant to be consumed by shells, not exported by them, so I don't understand why we would want to implement it in fish?

akalin · 2018-03-25T06:42:30Z

Sure thing! My previous PR #4337 took the approach of parsing path_helper's output. However, that turned out to be more complicated and brittle, for a few reasons:

path_helper prints out lines meant to be evaluated in csh or sh. So fish would have to parse those lines, which is more complicated than just reading the same files that path_helper does. Someone did suggest just eval'ing the csh output, but that's just scary.
path_helper tries to escape its output, but does so half-heartedly (in particular, it doesn't handle spaces). So we'd have to unescape that output, which makes it more complicated than just parsing the files.
By implementing the logic in fish, we avoid a fork.

If you compare this PR to #4337 , this one does seem simpler to understand. The danger of our behavior diverging from path_helper is minimal, since path_helper has barely changed since it was first implemented.

However, if you prefer the other approach, I could always resurrect #4337 .

faho · 2018-03-26T15:11:58Z

share/config.fish

+    end
+
+    for x in $result
+        echo $x


Note: This entire for-loop could also be replaced with set -xg $argv[1] $result - then the outer set becomes unnecessary.

Thanks, done!

faho · 2018-03-26T15:13:46Z

This looks quite nice to me.

Unfortunately, I can't really test it, so I'll leave that up to @ridiculousfish!

ridiculousfish · 2018-03-26T20:19:32Z

@akalin thanks for the explanation. I'm on board with emulating path_helper, but I don't understand the reason behind the second change, the "add a path_helper command to reproduce the behavior of
/usr/libexec/path_helper for fish". Who will call this function?

Implement it just for PATH.

akalin · 2018-03-28T06:17:10Z

@ridiculousfish Per @faho's suggestion, I removed the path_helper function; I had it around only for debugging. Please take another look!

ridiculousfish · 2018-03-28T06:49:34Z

Looks good. Squash-merged as adbaddf. Thanks!!

zanchey · 2018-03-30T14:03:03Z

Note that this changes the behaviour from running for all shells to running for login shells only. This matches the behaviour for other shells but breaks sessions run using iTerm2's "run command" option, for example.

akalin · 2018-03-30T18:46:09Z

@zanchey how do people using other shells solve the problem? Perhaps we could expose a function for people to call (that does what this PR does for a login shell) if they want that behavior?

ridiculousfish · 2018-03-31T19:04:32Z

Nice spotting @zanchey, I switched it back to running for all shells in c0f832a.

akalin · 2018-04-01T03:34:16Z

Hi, just to be clear, I made it login-shell-only to match the behavior of sh/bash (since the call to path_helper is in /etc/profile). So it's intended that fish deviate from that and read the paths for every shell?

ridiculousfish · 2018-04-01T19:11:22Z

Nothing is really intended. I reverted that because it looked like an undocumented behavior change, and zanchey observed that it broke a use case ("Run Command" in iTerm2).

Nobody has made a case for what the right behavior should be, so it's better to not break any users who might be depending on the existing behavior.

akalin commented Mar 24, 2018

View reviewed changes

faho reviewed Mar 26, 2018

View reviewed changes

faho added this to the fish-3.0 milestone Mar 26, 2018

faho added the enhancement label Mar 26, 2018

akalin added 17 commits March 27, 2018 23:08

Set PATH on OS X according to /etc/profile

5fb4efd

Don't clobber $PATH if $__fish_tmp_path is empty

b2914f7

Match behavior of path_helper

6bedd00

Add -- back in

e4bd145

Call /usr/libexec/path_helper

7e53ee1

Use command -sq instead

52644c7

Make parsing of path_helper output more robust

b7a627d

Fix diff

814beea

Add examples

4139ad7

Add path_helper function

04ee0d3

Implement it just for PATH.

Handle MANPATH

05b74e6

Change variable name

f296637

Fix comment

b8c6665

Plug into config.fish

5746f7e

Fix MANPATH check

b3d6cab

Remove path_helper function

c02076c

Address comments

2b5f33c

ridiculousfish closed this Mar 28, 2018

faho mentioned this pull request Apr 10, 2018

fish incorrectly sets a default $PATH on macOS #4336

Closed

faho mentioned this pull request Jan 3, 2019

Unexpected $PATH contents when using fish as the vim shell #5464

Closed

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Fix reading of /etc/paths on OS X #4852

Fix reading of /etc/paths on OS X #4852

akalin commented Mar 24, 2018

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faho Mar 25, 2018

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ridiculousfish commented Mar 31, 2018

akalin commented Apr 1, 2018

ridiculousfish commented Apr 1, 2018

Fix reading of /etc/paths on OS X #4852

Fix reading of /etc/paths on OS X #4852

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akalin commented Mar 24, 2018

TODOs:

akalin commented Mar 24, 2018

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