Fish embeds store file names in UCS-4/UTF-32 literal strings

Meiyo Peng wrote on 27 Jan 2018 10:11

Fish shell has wrong path variables

Recipients:(address . bug-guix@gnu.org)

Message-ID:87inbnpsx9.fsf@gmail.com

Hi,

I am using GuixSD 0.14. After upgrading fish shell to latest version(v2.7.1) and

running `guix gc`, fish shell does not work well.

#+BEGIN_EXAMPLE

meiyo@guix ~$ fish

fish:

echo $_ " "; __fish_pwd

in command substitution

called on standard input

fish:

__fish_pwd

in command substitution

called on standard input

in command substitution

called on standard input

fish:

echo $_ " "; __fish_pwd

in command substitution

called on standard input

#+END_EXAMPLE

__fish_pwd is a fish function. It's defined in

`share/fish/functions/__fish_pwd.fish`. The error message shows that fish

cannot load __fish_pwd's function definition from disk. After doing some

research, I found out that the error was caused by wrong environment variables.

Fish shell is installed in:

#+BEGIN_EXAMPLE

/gnu/store/ajbbi9cgj9j0my7v5habp0lcysaf2a51-fish-2.7.1/

#+END_EXAMPLE

But the environment variable $fish_function_path does not exist. And these

environment variables point to non-existent paths:

#+BEGIN_EXAMPLE

__fish_bin_dir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/bin

__fish_datadir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/share/fish

#+END_EXAMPLE

Setting $fish_function_path to the correct path reduces the error message.

#+BEGIN_EXAMPLE

set fish_function_path /gnu/store/ajbbi9cgj9j0my7v5habp0lcysaf2a51-fish-2.7.1/share/fish/functions

#+END_EXAMPLE

`share/fish/config.fish` states $__fish_datadir is set by fish.cpp,

and $fish_function_path is derived from $__fish_datadir.

#+BEGIN_SRC fish

# __fish_datadir, __fish_sysconfdir, __fish_help_dir, __fish_bin_dir

# are expected to have been set up by read_init from fish.cpp

# Set up function and completion paths. Make sure that the fish

# default functions/completions are included in the respective path.

if not set -q fish_function_path

set fish_function_path $configdir/fish/functions $__fish_sysconfdir/functions $__extra_functionsdir $__fish_datadir/functions

end

if not contains -- $__fish_datadir/functions $fish_function_path

set fish_function_path $fish_function_path $__fish_datadir/functions

end

#+END_SRC

In conclusion, I think some path related variables are not set correctly when

fish is compiled from source code and that caused the bug I met. But since I'm

not good at C++ programming, I will not dive deeper.

I hope that the information provided above is helpful.

Meiyo Peng

ng0 wrote on 27 Jan 2018 11:36

Recipients:(address . 30265@debbugs.gnu.org)

Message-ID:87shar8u6d.fsf@abyayala.i-did-not-set--mail-host-address--so-tickle-me

Hi Meiyo,

thanks for your report. Indeed, Fish has some problems in Guix.

On Sat, 27 Jan 2018, Meiyo Peng <meiyo.peng@gmail.com> wrote:

Toggle quote (5 lines)

> Hi,

> I am using GuixSD 0.14. After upgrading fish shell to latest version(v2.7.1) and

> running `guix gc`, fish shell does not work well.

Can you explain a bit more about your setup? I assume you use

fish as you user shell and not just as a shell you switch into

from a Bash enabled user, correct?

Toggle quote (82 lines)> #+BEGIN_EXAMPLE
>   meiyo@guix ~$ fish
>   fish:
>   echo $_ " "; __fish_pwd
>                ^
>   in command substitution
>           called on standard input
>
>   fish:
>   __fish_pwd
>   ^
>   in command substitution
>           called on standard input
>
>   in command substitution
>           called on standard input
>
>   fish:
>   echo $_ " "; __fish_pwd
>                ^
>   in command substitution
>           called on standard input
> #+END_EXAMPLE
>
>
> __fish_pwd is a fish function. It's defined in
> `share/fish/functions/__fish_pwd.fish`.  The error message shows that fish
> cannot load __fish_pwd's function definition from disk. After doing some
> research, I found out that the error was caused by wrong environment variables.
>
> Fish shell is installed in:
>
> #+BEGIN_EXAMPLE
>   /gnu/store/ajbbi9cgj9j0my7v5habp0lcysaf2a51-fish-2.7.1/
> #+END_EXAMPLE
>
>
> But the environment variable $fish_function_path does not exist. And these
> environment variables point to non-existent paths:
>
> #+BEGIN_EXAMPLE
>   __fish_bin_dir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/bin
>   __fish_datadir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/share/fish
> #+END_EXAMPLE
>
>
> Setting $fish_function_path to the correct path reduces the error message.
>
> #+BEGIN_EXAMPLE
>   set fish_function_path /gnu/store/ajbbi9cgj9j0my7v5habp0lcysaf2a51-fish-2.7.1/share/fish/functions
> #+END_EXAMPLE
>
>
> `share/fish/config.fish` states $__fish_datadir is set by fish.cpp,
> and $fish_function_path is derived from $__fish_datadir.
>
> #+BEGIN_SRC fish
>   # __fish_datadir, __fish_sysconfdir, __fish_help_dir, __fish_bin_dir
>   # are expected to have been set up by read_init from fish.cpp
>
>
>   # Set up function and completion paths. Make sure that the fish
>   # default functions/completions are included in the respective path.
>
>   if not set -q fish_function_path
>       set fish_function_path $configdir/fish/functions $__fish_sysconfdir/functions $__extra_functionsdir $__fish_datadir/functions
>   end
>
>   if not contains -- $__fish_datadir/functions $fish_function_path
>       set fish_function_path $fish_function_path $__fish_datadir/functions
>   end
> #+END_SRC
>
> In conclusion, I think some path related variables are not set correctly when
> fish is compiled from source code and that caused the bug I met. But since I'm
> not good at C++ programming, I will not dive deeper.
>
> I hope that the information provided above is helpful.
>
>
> Meiyo Peng

It's more or less known, I assume this is related to bug#27206

https://debbugs.gnu.org/cgi/bugreport.cgi?bug=27206

Which to my knowledge and sources I've read doesn't require C
knowledge but more knowledge of how Fish interacts on
system/vendor level and some testing with the resources I've
provided in the other thread/bug.
-- 
ng0 :: https://ea.n0.is
A88C8ADD129828D7EAC02E52E22F9BBFEE348588 :: https://ea.n0.is/keys/

Ricardo Wurmus wrote on 27 Jan 2018 13:19

Recipients:(name . Meiyo Peng)(address . meiyo.peng@gmail.com)(address . 30265@debbugs.gnu.org)

Message-ID:87inbntryj.fsf@elephly.net

Hi Meiyo,

thanks for the report.

Toggle quote (2 lines)

> I am using GuixSD 0.14. After upgrading fish shell to latest version(v2.7.1) and

> running `guix gc`, fish shell does not work well.

[…]

Toggle quote (12 lines)> Fish shell is installed in:
> #+BEGIN_EXAMPLE
>   /gnu/store/ajbbi9cgj9j0my7v5habp0lcysaf2a51-fish-2.7.1/
> #+END_EXAMPLE
>
> But the environment variable $fish_function_path does not exist. And these
> environment variables point to non-existent paths:
> #+BEGIN_EXAMPLE
>   __fish_bin_dir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/bin
>   __fish_datadir /gnu/store/4jkxcz8kpy621ycmqn3rvs0fv6c98h6p-fish-2.7.1/share/fish
> #+END_EXAMPLE

Where are these environment variables defined?

Toggle quote (4 lines)

> In conclusion, I think some path related variables are not set

> correctly when fish is compiled from source code and that caused the

> bug I met.

Some other packages record exact store references in cache files in the

user’s home directory. As packages get upgraded and removed after

garbage collection, these references become invalid.

The question is whether these old store references are kept in files

outside of the store (and thus are not directly under our control), or

if the packages that Guix builds include incorrect references. I guess

that it’s the former.

As is the case for these other programmes that record paths in cache

files, we would need to patch fish to record only the stable names of

links to those files (e.g. ~/.guix-profile/foo/bar) rather than the

actual file names in the store, which may disappear upon “guix gc”.

Ricardo

GPG: BCA6 89B6 3655 3801 C3C6 2150 197A 5888 235F ACAC

https://elephly.net

Meiyo Peng wrote on 27 Jan 2018 14:45

Recipients:(name . Ricardo Wurmus)(address . rekado@elephly.net)(address . 30265@debbugs.gnu.org)

Message-ID:87wp03h0us.fsf@gmail.com

Ricardo Wurmus <rekado@elephly.net> writes:

Toggle quote (1 lines)

> Where are these environment variables defined?

According to `share/fish/config.fish`, they are defined in fish.cpp.

#+BEGIN_SRC fish

# __fish_datadir, __fish_sysconfdir, __fish_help_dir, __fish_bin_dir

# are expected to have been set up by read_init from fish.cpp

#+END_SRC

You can get fish shell's environment variables using fish's `set` command.

A single `set` without argument will print all environment variables.

Toggle quote (10 lines)> The question is whether these old store references are kept in files
> outside of the store (and thus are not directly under our control), or
> if the packages that Guix builds include incorrect references.  I guess
> that it’s the former.
>
> As is the case for these other programmes that record paths in cache
> files, we would need to patch fish to record only the stable names of
> links to those files (e.g. ~/.guix-profile/foo/bar) rather than the
> actual file names in the store, which may disappear upon “guix gc”.
>

Maybe you are right. Guix is still new to me, so I do not know details

about guix's mechanism.

Meiyo Peng

Meiyo Peng wrote on 27 Jan 2018 15:13

Recipients:(address . 30265@debbugs.gnu.org)(address . 30265@debbugs.gnu.org)

Message-ID:87lggjgzk3.fsf@gmail.com

ng0 wrote:

Toggle quote (4 lines)

> Can you explain a bit more about your setup? I assume you use

> fish as you user shell and not just as a shell you switch into

> from a Bash enabled user, correct?

My GuixSD is a fresh setup. I did no customization to fish and did not
set fish as login shell.

The bug I reported is reproducible. I tried it in a virtual machine
several times.
1. Install GuixSD 0.14 with fish
2. guix pull
3. Upgrade all packages
4. guix gc
5. Start a fish shell, and the bug I reported occur

Ludovic Courtès wrote on 27 Jan 2018 17:25

Recipients:(address . 30265@debbugs.gnu.org)

Message-ID:87bmhf1d7k.fsf@gnu.org

Hi ng0 and Meiyo,

ng0@n0.is skribis:

Toggle quote (10 lines)> On Sat, 27 Jan 2018, Meiyo Peng <meiyo.peng@gmail.com> wrote:
>> Hi,
>>
>> I am using GuixSD 0.14. After upgrading fish shell to latest version(v2.7.1) and
>> running `guix gc`, fish shell does not work well.
>
> Can you explain a bit more about your setup? I assume you use
> fish as you user shell and not just as a shell you switch into
> from a Bash enabled user, correct?

Note that the current ‘guix’ package, 0.14.0-7.33988f9, includes Fish

completion support, which was not the case before:

Toggle snippet (8 lines)

$ ls -R $(guix build guix)/share/fish

/gnu/store/apji9j8cwf9xpd5jk5mk8s6r1a391yvq-guix-0.14.0-7.33988f9/share/fish:

vendor_completions.d

/gnu/store/apji9j8cwf9xpd5jk5mk8s6r1a391yvq-guix-0.14.0-7.33988f9/share/fish/vendor_completions.d:

guix.fish

Could it be the reason why you’re having problems now that you didn’t

experience earlier?

Any ideas, ng0?

Thanks,

Ludo’.

ng0 wrote on 27 Jan 2018 19:19

Recipients:(address . 30265@debbugs.gnu.org)

Message-ID:878tcjjham.fsf@abyayala.i-did-not-set--mail-host-address--so-tickle-me

On Sat, 27 Jan 2018, ludo@gnu.org (Ludovic Courtès) wrote:

Toggle quote (38 lines)> Hi ng0 and Meiyo,
>
> ng0@n0.is skribis:
>
>> On Sat, 27 Jan 2018, Meiyo Peng <meiyo.peng@gmail.com> wrote:
>>> Hi,
>>>
>>> I am using GuixSD 0.14. After upgrading fish shell to latest version(v2.7.1) and
>>> running `guix gc`, fish shell does not work well.
>>
>> Can you explain a bit more about your setup? I assume you use
>> fish as you user shell and not just as a shell you switch into
>> from a Bash enabled user, correct?
>
> Note that the current ‘guix’ package, 0.14.0-7.33988f9, includes Fish
> completion support, which was not the case before:
>
> --8<---------------cut here---------------start------------->8---
> $ ls -R $(guix build guix)/share/fish
> /gnu/store/apji9j8cwf9xpd5jk5mk8s6r1a391yvq-guix-0.14.0-7.33988f9/share/fish:
> vendor_completions.d
>
> /gnu/store/apji9j8cwf9xpd5jk5mk8s6r1a391yvq-guix-0.14.0-7.33988f9/share/fish/vendor_completions.d:
> guix.fish
> --8<---------------cut here---------------end--------------->8---
>
> Could it be the reason why you’re having problems now that you didn’t
> experience earlier?
>
> Any ideas, ng0?
>
> Thanks,
> Ludo’.
>
>
>
>

No, I'm pretty sure this has nothing to do with adding fish
support to Guix.
-- 
ng0 :: https://ea.n0.is
A88C8ADD129828D7EAC02E52E22F9BBFEE348588 :: https://ea.n0.is/keys/

Pierre Neidhardt wrote on 19 Sep 2018 11:09

Recipients:(address . 30265@debbugs.gnu.org)

Message-ID:87pnx9yhsx.fsf@ambrevar.xyz

I haven't investigated too deep into this, but I've figured out a few

things.

First of all, to reproduce the issue:

- Install fish.

- Run `guix build --check fish`, it should output something like

#+BEGIN_SRC sh

> guix build --check fish

Building /gnu/store/g9ra27952ay2a7j3mn7yp13b7m18kl1b-fish-2.7.1.drv - x86_64-linux

grafting '/gnu/store/vgrav12zra9zky21ahm4x1qg8g4v58fj-fish-2.7.1' -> '/gnu/store/avk637800w1n7z1z0hnzx80r0fpd6729-fish-2.7.1'...

/gnu/store/avk637800w1n7z1z0hnzx80r0fpd6729-fish-2.7.1

#+END_SRC

- The graft source is a dead GC item:

#+BEGIN_SRC sh

> guix gc --list-dead | grep vgrav12zra9zky21ahm4x1qg8g4v58fj

/gnu/store/vgrav12zra9zky21ahm4x1qg8g4v58fj-fish-2.7.1

#+END_SRC

Collect it:

#+BEGIN_SRC sh

guix gc --delete /gnu/store/vgrav12zra9zky21ahm4x1qg8g4v58fj-fish-2.7.1

#+END_SRC

- Start fish:

#+BEGIN_SRC sh

> fish

fish:

echo $_ " "; __fish_pwd

in command substitution

called on standard input

...

#+END_SRC

I think Ricardo got a hunch of what's happening, except that it's not

about cache files in the user home's directory. Instead, Fish seems to

record the path to the graft source. A grep in the fish folder does not

seem to reveal anything, nor does `strings

/gnu/store/...-fish.../bin/fish`.

Could this be a grafting issue? Like what was recently mentioned about

Racket?

Otherwise, as Meiyo pointed out, the solution might lie in patching

fish.cpp if grafting is not responsible for this.

Pierre Neidhardt

https://ambrevar.xyz/

Ludovic Courtès wrote on 19 Sep 2018 22:39

Recipients:(name . Pierre Neidhardt)(address . mail@ambrevar.xyz)

Message-ID:87o9ctdxxk.fsf@gnu.org

Hi Pierre,

Pierre Neidhardt <mail@ambrevar.xyz> skribis:

Toggle quote (9 lines)

> I think Ricardo got a hunch of what's happening, except that it's not

> about cache files in the user home's directory. Instead, Fish seems to

> record the path to the graft source. A grep in the fish folder does not

> seem to reveal anything, nor does `strings

> /gnu/store/...-fish.../bin/fish`.

> Could this be a grafting issue? Like what was recently mentioned about

> Racket?

It may well be a reference that doesn’t get properly grafted. We can

see it when running the grafted fish under ‘strace’.

The culprit is this bit from fish.cpp:

// Fall back to what got compiled in.

debug(2, L"Using compiled in paths:");

paths.data = L"" DATADIR "/fish";

paths.sysconf = L"" SYSCONFDIR "/fish";

paths.doc = L"" DOCDIR;

paths.bin = L"" BINDIR;

The “L” here means these are “wide string” literals, and indeed, the

“Using…” string above looks like this in the ELF file:

001140d0: 5500 0000 7300 0000 6900 0000 6e00 0000 U...s...i...n...

001140e0: 6700 0000 2000 0000 6300 0000 6f00 0000 g... ...c...o...

001140f0: 6d00 0000 7000 0000 6900 0000 6c00 0000 m...p...i...l...

00114100: 6500 0000 6400 0000 2000 0000 6900 0000 e...d... ...i...

00114110: 6e00 0000 2000 0000 7000 0000 6100 0000 n... ...p...a...

00114120: 7400 0000 6800 0000 7300 0000 3a00 0000 t...h...s...:...

The DATADIR literal is similarly “hidden”, and thus the grafting code

doesn’t see it.

Possible fixes include:

1. Finding a way to make the run-time detection in

‘determine_config_directory_paths’ to always work without going to

the fallback case where it relies on string literals. This could

be done by attempting to read /proc/self/exe (on GNU/Linux) instead

of relying on argv0.

2. Using “regular” strings, or at least arranging to store DATADIR &

co. in regular “const char” arrays. Maybe something like:

static const char datadir[] = DATADIR;

…

paths.data = L"" + datadir + L"/fish";

It probably takes some more casts from char[] to std::string to

wcstring, but you get the idea. ;-)

Thoughts?

Ludo’.

Pierre Neidhardt wrote on 20 Sep 2018 18:09

Recipients:(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:87efdoxia5.fsf@ambrevar.xyz

Thanks for this deep investigation, Ludo!

I'm not so well versed in grafting, so let me ask a few questions:

- Why is fish grafted in the first place?

- Is the issue here that grafting does not support wide string literals?

Shouldn't we fix the Guix code to support wide strings as well?

Pierre Neidhardt

https://ambrevar.xyz/

Ricardo Wurmus wrote on 20 Sep 2018 19:00

Recipients:(name . Pierre Neidhardt)(address . mail@ambrevar.xyz)

Message-ID:877ejgumrn.fsf@elephly.net

Pierre Neidhardt <mail@ambrevar.xyz> writes:

Toggle quote (4 lines)

> I'm not so well versed in grafting, so let me ask a few questions:

> - Why is fish grafted in the first place?

Almost any package can be grafted.  A package will be grafted when any
of its inputs (direct or transitive) have been replaced.  The goal of
grafting is to build a replacement package *quickly* and then only
rewrite references to the replaced package in all dependent packages.

The advantage is that dependent packages do not need to be rebuilt; they
just need to be copied, scanned for references, and have their
references updated.  This is usually *much* faster than rebuilding
all dependent packages, which may be an important consideration in
distributing security fixes.

Toggle quote (3 lines)

> - Is the issue here that grafting does not support wide string literals?

> Shouldn't we fix the Guix code to support wide strings as well?

Grafting succeeds when we can find all references to items that should
be replaced – in plain text files but also in binaries.  Past problems
with grafting were triggered by compiler behaviour that chopped up these
reference strings, or by build systems that split these reference
strings.

A grafting problem is usually also a garbage collection problem, because
both depend on successful scanning for store references.

--
Ricardo

Pierre Neidhardt wrote on 20 Sep 2018 19:12

Recipients:(name . Ricardo Wurmus)(address . rekado@elephly.net)

Message-ID:87bm8sxfd4.fsf@ambrevar.xyz

Toggle quote (3 lines)

> A package will be grafted when any

> of its inputs (direct or transitive) have been replaced.

I understand why that would happen when _updating_ fish, but why does it happen
when (re-)building it from scratch, for instance when the graft source is gone
from the store?

-- 
Pierre Neidhardt
https://ambrevar.xyz/

Ludovic Courtès wrote on 21 Sep 2018 14:03

Recipients:(name . Pierre Neidhardt)(address . mail@ambrevar.xyz)

Message-ID:87d0t72h2g.fsf@gnu.org

Pierre Neidhardt <mail@ambrevar.xyz> skribis:

Toggle quote (7 lines)

>> A package will be grafted when any

>> of its inputs (direct or transitive) have been replaced.

> I understand why that would happen when _updating_ fish, but why does it happen

> when (re-)building it from scratch, for instance when the graft source is gone

> from the store?

Whether a package is grafted depends on its dependencies and the set of

applicable grafts. For instance, these are the grafts that can

potentially be applied to Fish as of commit

1df40d3dbff82c2990271b406b32633fe216d143:

Toggle snippet (7 lines)

scheme@(guile-user)> ,use(guix)

scheme@(guile-user)> ,use(gnu packages shells)

scheme@(guile-user)> (define s (open-connection))

scheme@(guile-user)> (package-grafts s fish)

$8 = (#<graft /gnu/store/f4d2v9y191zvj66c4rr65s8bix67wnma-libtiff-4.0.9 ==> /gnu/store/p2531jppdwwgn312bzwmm6q2cbmcdyc5-libtiff-4.0.9 2ff7840> #<graft /gnu/store/74iniafz6s76vbshzkq7zvx6nicd91y6-jbig2dec-0.14 ==> /gnu/store/vjailgb48w3jcf7brb2cgf61j9an3blm-jbig2dec-0.15 33b2630> #<graft /gnu/store/dysmb6hz7rr5rvcb05p23dazc5hz26qm-libgcrypt-1.8.2 ==> /gnu/store/hc5cak3fj0dijbm86kpz2asl7ld4gf8y-libgcrypt-1.8.3 32688d0> #<graft /gnu/store/r8ppi963s5xlf78lxd74y31263m1fxl2-libx11-1.6.5 ==> /gnu/store/bid7hvpnm8nq04vm4dszywxsw9g2kmf2-libx11-1.6.6 3268630> #<graft /gnu/store/4n6v2zp5mslq2784j878dmfzzj4vvmza-openssl-1.0.2o ==> /gnu/store/x8nacy2qpqlwi0gm7r6slcynv1cwmicb-openssl-1.0.2o 305de40> #<graft /gnu/store/jxa597l2zp6ydi345djxwabg5gp9h4di-ghostscript-9.23 ==> /gnu/store/fhbiaq9bnp4m79bd6wdfi9px41mwmdib-ghostscript-9.24 294aa80> #<graft /gnu/store/6zz27h4l21b8f2mifrk9sidvib9cns2i-perl-5.26.1 ==> /gnu/store/7ifc22sh86zblnzamqimgmv06idyx69v-perl-5.26.1 3a7be40> #<graft /gnu/store/wvd2bm9zqgy2v6yw8cp9id6hw4zlwa4i-curl-7.59.0 ==> /gnu/store/ia117b5q4pzcm81xj1hkv2qgg898v7x5-curl-7.61.1 20b2c90> #<graft /gnu/store/k177ng58xf43g5v22n60g0w75pqdv339-perl-5.26.1 ==> /gnu/store/v6c0fksl6q8bkshwb0rb74l9n4lyjfnn-perl-5.26.1 3518360>)

In practice only a subset of these grafts are applied because, for

instance, Fish doesn’t depend (directly or indirectly) on Ghostscript at

run time whereas it does depend on Perl:

Toggle snippet (4 lines)

$ guix gc -R $(guix build fish) | grep -E '(perl|ghostscript)'

/gnu/store/7ifc22sh86zblnzamqimgmv06idyx69v-perl-5.26.1

HTH!

Ludo’.

Ludovic Courtès wrote on 21 Sep 2018 14:05

Recipients:(name . Pierre Neidhardt)(address . mail@ambrevar.xyz)

Message-ID:877ejf2gyp.fsf@gnu.org

Pierre Neidhardt <mail@ambrevar.xyz> skribis:

Toggle quote (3 lines)

> - Is the issue here that grafting does not support wide string literals?

> Shouldn't we fix the Guix code to support wide strings as well?

I’m not too keen on doing that: the scanner in (guix build grafts) would

have to be quite different if it were to catch /gnu/store references

burried in wide strings. That’d be a real challenge.

The proposed changes (using Fish’ relocatability mechanism or ensuring

that the /gnu/store references are in char[] arrays) would be far

easier.

Let me know if you need clarifications regarding these.

Thanks,

Ludo’.

Pierre Neidhardt wrote on 21 Sep 2018 16:42

Recipients:(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:877ejeykro.fsf@ambrevar.xyz

Toggle quote (9 lines)

> In practice only a subset of these grafts are applied because, for

> instance, Fish doesn’t depend (directly or indirectly) on Ghostscript at

> run time whereas it does depend on Perl:

> --8<---------------cut here---------------start------------->8---

> $ guix gc -R $(guix build fish) | grep -E '(perl|ghostscript)'

> /gnu/store/7ifc22sh86zblnzamqimgmv06idyx69v-perl-5.26.1

> --8<---------------cut here---------------end--------------->8---

Thanks for pointing out this nuance, I wasn't aware of it.

But I still wonder: why is fish first built to

vgrav12zra9zky21ahm4x1qg8g4v58fj... and then immediately grafted to

avk637800w1n7z1z0hnzx80r0fpd6729... Why not building directly to

avk637800w1n7z1z0hnzx80r0fpd6729...?

I might be misunderstanding the basics of grafting :p

Pierre Neidhardt

https://ambrevar.xyz/

Ricardo Wurmus wrote on 21 Sep 2018 16:46

Recipients:(name . Pierre Neidhardt)(address . mail@ambrevar.xyz)

Message-ID:87y3buucw2.fsf@elephly.net

Pierre Neidhardt <mail@ambrevar.xyz> writes:

Toggle quote (16 lines)>> In practice only a subset of these grafts are applied because, for
>> instance, Fish doesn’t depend (directly or indirectly) on Ghostscript at
>> run time whereas it does depend on Perl:
>>
>> --8<---------------cut here---------------start------------->8---
>> $ guix gc -R $(guix build fish) | grep -E '(perl|ghostscript)'
>> /gnu/store/7ifc22sh86zblnzamqimgmv06idyx69v-perl-5.26.1
>> --8<---------------cut here---------------end--------------->8---
>
> Thanks for pointing out this nuance, I wasn't aware of it.
>
> But I still wonder: why is fish first built to
> vgrav12zra9zky21ahm4x1qg8g4v58fj... and then immediately grafted to
> avk637800w1n7z1z0hnzx80r0fpd6729... Why not building directly to
> avk637800w1n7z1z0hnzx80r0fpd6729...?

Grafting is independent of building a package. These are separate

derivations. The first derivation is merely about building the package

— it is unaware of the need for grafting.

The second derivation only performs the graft. All it knows about is

that it takes “vgrav12zra9zky21ahm4x1qg8g4v58fj” as an input and should

produce “avk637800w1n7z1z0hnzx80r0fpd6729”.

Ricardo

Pierre Neidhardt wrote on 21 Sep 2018 17:11

Recipients:(name . Ricardo Wurmus)(address . rekado@elephly.net)

Message-ID:875zyyyjez.fsf@ambrevar.xyz

Makes sense, that explains it. Thanks!

Pierre Neidhardt

https://ambrevar.xyz/

Ludovic Courtès wrote on 26 Dec 2018 17:08

control message for bug #30265

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87pntoe0ek.fsf@gnu.org

retitle 30265 Fish embeds store file names in UCS-4/UTF-32 literal strings

Ludovic Courtès wrote on 26 Dec 2018 17:08

Recipients:(address . control@debbugs.gnu.org)

Message-ID:87o998e0eg.fsf@gnu.org

severity 30265 important

Meiyo Peng wrote on 2 Feb 2019 08:20

Re: bug#30265: Fish embeds store file names in UCS-4/UTF-32 literal strings

Recipients:(address . 30265@debbugs.gnu.org)

Message-ID:871s4q7j23.fsf@disroot.org

Hi,

`guix gc` does not break fish shell any more. I am not sure if this is

related to changes in fish shell v3.0.0.

If no one is interested in doing more investigation, maybe we should

close this bug.

Meiyo Peng

https://www.pengmeiyu.com/

Ludovic Courtès wrote on 4 Feb 2019 23:16

Recipients:(name . Meiyo Peng)(address . meiyo@disroot.org)(address . 30265@debbugs.gnu.org)

Message-ID:87va1znqrn.fsf@gnu.org

Hi Meiyo,

Meiyo Peng <meiyo@disroot.org> skribis:

Toggle quote (3 lines)

> `guix gc` does not break fish shell any more. I am not sure if this is

> related to changes in fish shell v3.0.0.

It’s not really ‘guix gc’ that’s problematic but rather grafting: those

UCS-4 strings do not get grafted, and eventually become “dangling

references.”

Could you check whether fish.cpp still looks like

https://issues.guix.info/issue/30265#8, with the ‘L’ prefix for

literal strings?

Thanks,

Ludo’.

John Soo wrote on 30 Mar 2020 08:29

Fish embeds store file names in UCS-4/UTF-32 literal strings

Recipients:(address . 30265@debbugs.gnu.org)(name . Ludovic Courtès)(address . ludo@gnu.org)

Message-ID:8B84EF65-4CCC-4CAF-A6E9-BF6F5566D11E@asu.edu

Hi Ludo,

I am willing to work on this. I use fish as my login shell and noticed some more funky behavior when I tried to use fish-foreign-env.

It looks like fish.cpp still uses widestrings. So the references to old store paths I think become stale, if I understand the rest of the conversation.

I will do some more research on fish semantics and see what might be done.

Thanks, as always,

John

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