dd: don't silently swallow truncate failures#12340
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The wrapper around set_len() was suppressing every error from the truncate step because set_len() on `/dev/null` returns EINVAL. That also hid real failures like ENOSPC (disk full) and EROFS (read-only filesystem), so dd would exit 0 while leaving stale tail bytes in the output file. Backup scripts trusting dd's exit code would then think a copy succeeded when it didn't. Only swallow InvalidInput (the kind ftruncate returns on non-regular files); everything else propagates up to the caller and dd exits non-zero. Verified that `of=/dev/null` still works. Closes uutils#9745. Signed-off-by: Charlie Tonneslan <cst0520@gmail.com>
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Closes #9745.
Output::truncatewas suppressing every error fromset_len()by calling.ok(), which the comment justified by pointing atof=/dev/null(whereftruncatereturns EINVAL). That also hid real failures like ENOSPC and EROFS, so dd would exit 0 while leaving stale tail bytes in the output file.Narrow the swallow to InvalidInput (which is what
set_lenreturns on non-regular files) and propagate everything else.of=/dev/nullstill works, real I/O errors now surface.