build-support: add strings-replace tool
#22323
Conversation
This is similar to `nuke-refs`, only not /nix/store specific. When
attempting to make minimal closures, sometimes various build tools end
up with hardcoded references to items in /nix/store. `nuke-refs` is
nice if these references are dead references. But sometimes, you want
to move these files to another derivation and swap these new locations
into the binary file.
An example of this problem is Haskell Cabal, which has a feature called
"data-files". For example, a popular Haskell monitoring library called
`ekg` uses this feature to compile in references to web assets like HTML
and Javascript files.
We can have Cabal/GHC statically compile binaries to reduce the size of
the transitive closure dramatically. But this doesn't help with strings
compiled into the data-section of a binary.
So this commit introduces a tool called "strings-replace" that allow for
a simple substitution of strings as as discovered by
strings -t d "$target" | grep e "$pattern"
Because this is a substitution of a null-terminated string into a
binary, there's a fail-safe to make sure the substituted string is not
longer than the original string.
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Note that there already is a |
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@edolstra it's great to know that's there. I have a repository where I'm testing this out. Let me try to use |
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Hey, I just updated my example-nix project to use |
This commit introduces a tool called "strings-replace" that allow for a simple substitution of strings as as discovered by
Because this is a substitution of a null-terminated string into a binary, there's a fail-safe to make sure the substituted string is not longer than the original string.
This is my first commit to nixpkgs, and I read through all the contributors documentation. Hopefully I didn't miss anything, but I'm happy to make changes as recommended.
Motivation for this change
This is similar to
nuke-refs, only not /nix/store specific. When attempting to make minimal closures, sometimes various build tools end up with hardcoded references to items in /nix/store.nuke-refsis nice if these references are dead references. But sometimes, you want to move these files to another derivation and swap these new locations into the binary file.An example of this problem is Haskell Cabal, which has a feature called "data-files". For example, a popular Haskell monitoring library called
ekguses this feature to compile in references to web assets like HTML and Javascript files.We can have Cabal/GHC statically compile binaries to reduce the size of the transitive closure dramatically. But this doesn't help with strings compiled into the data-section of a binary.
This problem has been discussed in Gabriella439/haskell-nix#12 and #4504.
Even if Cabal/GHC were fixed such that this weren't needed for
ekg, I think this might be a useful tool to have available. It's a sharp knife, though, so care must be exercised when using it.Things done
(nix.useSandbox on NixOS,
or option
build-use-sandboxinnix.confon non-NixOS)
nix-shell -p nox --run "nox-review wip"./result/bin/)