fix: pass Typst source across the FFI boundary with an explicit length - #34
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evolvedlight merged 1 commit intoAug 31, 2026
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The source was handed to the native library as a NUL-terminated C string, so a document containing a NUL byte was cut off at the first one. Nothing reported an error: the truncated document compiled cleanly and the caller got back a result that silently omitted everything after the NUL. Pass the source as a (pointer, length) pair instead. A null pointer keeps its meaning of "no in-memory source", which stays distinct from a zero length, meaning an empty document. Related to evolvedlight#27.
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Follows on from #33, which moved the diagnostics onto
(pointer, length)but left the inbound source as a C string.create_compilerreadinput_sourcewithCStr::from_ptr, so a document containing a NUL byte was cut off at the first one. Nothing reported an error: the truncated document compiled cleanly and the caller got back a result that silently omitted everything after the NUL.Marshal.StringToCoTaskMemUTF8writes the full bytes, interior NUL included, so the loss happened entirely on the native side.The source now crosses as a
(pointer, length)pair. A null pointer still means "no in-memory source", which stays distinct from a zero length meaning an empty document.fixedover an empty array yields null, so the managed side routes an empty source through a one-byte placeholder to keep those two apart.Paths,
sys_inputsand the format strings stay C strings on purpose. A path cannot contain a NUL on either Windows or POSIX, and JSON carries a NUL as a six-character escape rather than the byte itself, so that transport never sees it. Encoding the difference between "a path" and "arbitrary user text" in the signature seemed worth keeping.Tests
source_after_a_nul_byte_is_still_compiledputs a syntax error after the NUL and asserts it is reported. With the truncation restored it fails with "invalid document compiled without an error", which is the bug.SourceAfterNullByteIsNotTruncatedasserts a heading after the NUL is present in the rendered PDF.