build failures on docs.rs

[ckaran]

You're getting build failures on docs.rs for eframe (and maybe others?) Here is a link to the log file:

https://docs.rs/crate/eframe/0.8.0/builds/338677

I didn't see anything else that jumped out at me, but I'm not as familiar with the project as I wish I was.

[emilk]

Thanks for noticing! It seems egui_glium docs have been broken from the very start. Here is 0.1.0 from august 2020: https://docs.rs/crate/egui_glium/0.1.3/builds/279591

The build error is rather cryptic. I'll put it down as yet another reason to switch from glium (#93)

[follower]

[ TL;DR: Try upgrading xcb version to 0.9.0. ]

Summary

I also encountered this issue with the eframe docs.

Underlying cause seems to be the v0.8.2 version of xcb doesn't write its build files into the required directory.

The v0.9.0 release appears to include a fix.

Background

From a brief investigation[1] I noticed:

xcb related aspects

• There is a more recent version of the xcb crate (the crate that seems to be cause of the issue). (0.9.0 vs 0.8.2)

  • v0.9.0: https://crates.io/crates/xcb/0.9.0

  • A commit in v0.9.0 that seems it may fix issue: "code is generated in OUT_DIR"

  • (Maybe also: "do not gen __pycache__ ")

docs.rs related aspects

• The docs.rs help (linked in the orange build failure notice on the crate page) has a section "Write attempt on read-only directories" that mentions:

  Most of the sandbox is a read-only file system, including the source directory of your crate and its dependencies. If your build.rs generates files that are relevant for documentation, consider writing to the cargo output directory, passed in the environment variable OUT_DIR.

• The same page also mentions in https://docs.rs/about/builds#detecting-docsrs:

  To recognize Docs.rs from build.rs files, you can test for the environment variable DOCS_RS, [...]
  This approach can be helpful if you need dependencies for building the library, but not for building the documentation.

Potential solutions

So, it seems two options for solving/working around could be:

1. Bump version of xcb required to latest.
2. Detect when building docs only and/or on DOC_RS and skip the build step/dependency (assuming it's not required for doc generation.)

---

[1] Key sections of the logs are:

• https://docs.rs/crate/eframe/0.8.0/builds/338677:

  • Note: The underlying error appears to be this Python error OSError: [Errno 30] Read-only file system: '/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/src/ffi/selinux.rs' (which--somewhat confusingly--refers to a .rs file that is presumably the name of the .rs file being generated--not the file that is the origin of the error).

  • However, when that error is being handled by the Python exception handler another error (Error in sys.excepthook:) occurs due to KeyError: 'getpwuid(): uid not found: 1001'.

  • The line number given in the traceback as line 114, in writeout, with code snippet with open(path, 'w') as f: corresponds to changes made in the commit in v0.9.0 I mentioned above.

[INFO] [stderr] error: failed to run custom build command for `xcb v0.8.2`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/target/debug/build/xcb-4495dea23494d888/build-script-build` (exit code: 101)
[INFO] [stderr]   --- stderr
[INFO] [stderr]   error occured in handler:  ('request: ', ('xcb', 'SELinux', 'GetClientContext'))
[INFO] [stderr]   Traceback (most recent call last):
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 2448, in <module>
[INFO] [stderr]       module.generate()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/xcbgen/state.py", line 108, in generate
[INFO] [stderr]       self.close()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 296, in rs_close
[INFO] [stderr]       _f.writeout(os.path.join(module.rs_srcdir, "ffi", "%s.rs" % _module_name(_ns.ext_name)))
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 114, in writeout
[INFO] [stderr]       with open(path, 'w') as f:
[INFO] [stderr]   OSError: [Errno 30] Read-only file system: '/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/src/ffi/selinux.rs'
[INFO] [stderr]   Error in sys.excepthook:
[INFO] [stderr]   Traceback (most recent call last):
[INFO] [stderr]     File "/usr/lib/python3/dist-packages/apport_python_hook.py", line 119, in apport_excepthook
[INFO] [stderr]       pr.add_user_info()
[INFO] [stderr]     File "/usr/lib/python3/dist-packages/apport/report.py", line 424, in add_user_info
[INFO] [stderr]       user = pwd.getpwuid(os.getuid())[0]
[INFO] [stderr]   KeyError: 'getpwuid(): uid not found: 1001'
[INFO] [stderr] 
[INFO] [stderr]   Original exception was:
[INFO] [stderr]   Traceback (most recent call last):
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 2448, in <module>
[INFO] [stderr]       module.generate()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/xcbgen/state.py", line 108, in generate
[INFO] [stderr]       self.close()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 296, in rs_close
[INFO] [stderr]       _f.writeout(os.path.join(module.rs_srcdir, "ffi", "%s.rs" % _module_name(_ns.ext_name)))
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 114, in writeout
[INFO] [stderr]       with open(path, 'w') as f:
[INFO] [stderr]   OSError: [Errno 30] Read-only file system: '/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/src/ffi/selinux.rs'
[INFO] [stderr]   thread 'main' panicked at 'processing of /opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/xml/xselinux.xml returned non-zero (1)', /opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/build.rs:75:17
[INFO] [stderr]   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

• https://docs.rs/crate/egui_glium/0.1.3/builds/279591:

  • For some reason the second error in the exception doesn't occur here (maybe different infrastructure setup):

[INFO] [stderr] error: failed to run custom build command for `xcb v0.8.2`
[INFO] [stderr] 
[INFO] [stderr] Caused by:
[INFO] [stderr]   process didn't exit successfully: `/opt/rustwide/target/debug/build/xcb-e7147420ca72501a/build-script-build` (exit code: 101)
[INFO] [stderr]   --- stderr
[INFO] [stderr]   error occured in handler:  ('request: ', ('xcb', 'SELinux', 'GetClientContext'))
[INFO] [stderr]   Traceback (most recent call last):
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 2448, in <module>
[INFO] [stderr]       module.generate()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/xcbgen/state.py", line 108, in generate
[INFO] [stderr]       self.close()
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 296, in rs_close
[INFO] [stderr]       _f.writeout(os.path.join(module.rs_srcdir, "ffi", "%s.rs" % _module_name(_ns.ext_name)))
[INFO] [stderr]     File "/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/rs_client.py", line 114, in writeout
[INFO] [stderr]       with open(path, 'w') as f:
[INFO] [stderr]   OSError: [Errno 30] Read-only file system: '/opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/src/ffi/selinux.rs'
[INFO] [stderr]   thread 'main' panicked at 'processing of /opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/xml/xselinux.xml returned non-zero (1)', /opt/rustwide/cargo-home/registry/src/github.aaakk.us.kg-1ecc6299db9ec823/xcb-0.8.2/build.rs:75:17
[INFO] [stderr]   note: run with `RUST_BACKTRACE=1` environment variable to display a backtrace

[follower]

However, in terms of reasons to switch, I did notice that it appears there are some other, security related concerns with xcb (but it may still be a dependency of alternatives, also):

• https://github.com/rtbo/rust-xcb/issues/96

[follower]

TL;DR: Workaround is probably to override rust-clipboard dependency on x11-clipboard to version 0.5.1.

Details

cargo tree reveals:

│   ├── egui_glium v0.8.0
│   │   ├── clipboard v0.5.0
│   │   │   └── x11-clipboard v0.3.3
│   │   │       └── xcb v0.8.2
│   │   │           ├── libc v0.2.80
│   │   │           └── log v0.4.11
│   │   │               └── cfg-if v0.1.10
│   │   │           [build-dependencies]
│   │   │           └── libc v0.2.80
│   │   ├── egui v0.8.0 (*)

Which lead to discovering:

• "Update x11-clipboard dependency to use xcb [0.9.0] 0.5.1, fixes docs.rs builds #76"

  Which is an unmerged PR from a year ago bumping rust-clipboard's x11-clipboard dependency version to 0.5.1 which depends on xcb 0.9.0 which is seemingly fixed.

[MatchaChoco010]

For your information, copypasta is a fork in the rust-clipboard crate that is maintained.
You can find it at https://github.com/alacritty/copypasta
My egui integration changed to use copypasta from rust-clipboard and my docs.rs now builds correctly.

[follower]

Nice, thanks for mentioning copypasta[0]!

Can confirm the version bump is here:

• https://github.com/alacritty/copypasta/blob/f4125b09c30bee525327660e27411b76ddbe0718/Cargo.toml#L28

The README mentions also adding support for Wayland clipboard so not sure if that would cause any unexpected issues elsewhere.

Good to know that the docs now at least build for you.

---

[0] I had just noticed the copypasta dependency name earlier today while looking at some crates but hadn't actually looked to find out what the crate did! So it's amusing that it turned out to be a fix for this unrelated issue. :)