What causes "Couldn't write bindings!" in run-llama/liteparse?

Free disk space in the target/ filesystem or point CARGO_TARGET_DIR at a location with room, then rebuild.

Couldn't write bindings!

Error message

Couldn't write bindings!

What it means

The pdfium-sys build script panics because bindgen succeeded in generating the bindings but `write_to_file()` failed to write them to `$OUT_DIR/bindings.rs`. This is an I/O failure writing the generated bindings file, raised as a build-time panic that aborts compilation of the crate.

Solutions

Free disk space in the target/ filesystem or point CARGO_TARGET_DIR at a location with room, then rebuild.
Check permissions on the OUT_DIR / target directory and ensure the build user can write there (e.g. chown the target dir or rebuild outside the read-only mount).
Clear the stale/corrupted target dir (`cargo clean`) and rebuild.
Exclude the target directory from antivirus/monitoring that may lock or remove freshly written files.

Example fix

// before: OUT_DIR unwritable due to disk/permission issue
# df -h $CARGO_TARGET_DIR   # check space
# cargo clean
// after: use a writable target dir
# CARGO_TARGET_DIR=/tmp/cargo-target cargo build -p pdfium-sys

Defensive patterns

Strategy: validation

Validate before calling

# shell — ensure writable target dir with space before building
test -w "$CARGO_TARGET_DIR" || export CARGO_TARGET_DIR=/tmp/cargo-target
df --output=avail -h "$CARGO_TARGET_DIR" | awk 'NR==2 && $1+0 < 1048576 {print "low disk"; exit 1}'

Prevention

Monitor disk space on CI runners; cargo clean stale targets regularly
Keep CARGO_TARGET_DIR on a writable, non-read-only filesystem
Exclude target/ from antivirus and container volume mounts with sync/locking quirks
Run builds as a user with write access to the target directory

When it happens

Trigger: Building pdfium-sys with the `bindgen` feature while the OUT_DIR path is unwritable or missing: full disk, restrictive permissions, another process/antivirus locking the file, OUT_DIR removed mid-build, or an invalid/oversized target directory path.

Common situations: CI runners with read-only or quota-exhausted target directories; Docker containers running the build as a non-root user without write access to CARGO_TARGET_DIR; disk-full during large builds; security software deleting generated files.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

AI-assisted analysis of run-llama/liteparse@22d2dd8cd7 (2026-09-08). Data as JSON: /api/errors/102d35e4f970a975. Report an issue: GitHub.

Appendix: source

Thrown at crates/pdfium-sys/build.rs:290

            .allowlist_function("FORM_.*")
            .allowlist_function("FPDFText_.*")
            .allowlist_function("FPDFPage.*")
            .allowlist_function("FPDFLink_.*")
            .allowlist_function("FPDFFont_.*")
            .allowlist_type("FPDF.*")
            .allowlist_type("FS_.*")
            .allowlist_var("FPDF.*")
            .allowlist_var("FLAT.*")
            .derive_debug(true)
            .derive_default(true)
            .layout_tests(false)
            .parse_callbacks(Box::new(bindgen::CargoCallbacks::new()))
            .generate()
            .expect("Unable to generate bindings");

        bindings
            .write_to_file(&out_file)
            .expect("Couldn't write bindings!");
    }

    #[cfg(not(feature = "bindgen"))]
    {
        let _ = include_dir;
        let pregenerated = Path::new(env!("CARGO_MANIFEST_DIR")).join("bindings.rs");
        fs::copy(&pregenerated, &out_file).unwrap_or_else(|e| {
            panic!(
                "Failed to copy pre-generated bindings from {}: {e}",
                pregenerated.display()
            )
        });
    }
}

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