Remove stdin mode: require explicit file arguments#88
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Without a base directory there is no boundary to enforce for path traversal checks, so any embed directive passed via stdin can read arbitrary files on the host. Additionally, stdin mode has little practical utility because local file paths embedded in a document have no anchor without a known base directory. This commit removes the stdin-reading path entirely. Calling embedmd with no file arguments now exits with an error instead of blocking on stdin. The `stdin` package-level variable and all associated branches in `embed` are deleted; `TestEmbedStreams` is replaced by `TestEmbedNoPaths` which verifies the new error behaviour. Follow-up to #84.
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Summary
embedmdwith no arguments now exits immediately witherror: no markdown files providedinstead of blocking on stdin.stdinpackage-level variable and all stdin-handling branches inembed.TestEmbedStreamswithTestEmbedNoPaths, which verifies the new error behaviour and the existing-w/-dconflict check.Motivation
The stdin path was never an intentional feature — it fell out of the "if no args, read stdin" idiom. It is a security liability: without a known base directory there is no boundary to enforce for path traversal checks, so an embed directive arriving via stdin can instruct embedmd to read arbitrary files on the host. The feature also has little practical utility, because file paths embedded in a document have no anchor without a base directory. Removing it eliminates the attack surface entirely.
Follow-up to #84.
Test plan
go test ./...passes with no changes to test coverage of non-stdin paths.TestEmbedNoPathsverifies thatembed(nil, false, false)returns"error: no markdown files provided".TestEmbedNoPathsalso verifies that-w -dtogether still returns"error: cannot use -w and -d simultaneously".