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Eric Coissac
8c7017a99d
- Update obioptions.Version from "Release 4.4.29" to "/v/ Release v5" - Update version.txt from 4.29 → .30 (automated by Makefile)
25 lines
1.4 KiB
Markdown
25 lines
1.4 KiB
Markdown
# `TarFileReader` — Semantic Description
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The function `TarFileReader`, defined in the Go package `obiutils`, provides a targeted extraction capability for files within a TAR archive.
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- **Input**:
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- `file`: A generic reader (`*Reader`) implementing the standard Go `io.Reader` interface — typically wrapping an archive file or stream.
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- `path`: A string specifying the *exact* path (relative to archive root) of the desired file inside the TAR.
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- **Core Logic**:
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- Instantiates a `tar.Reader` from the provided input stream.
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- Iterates sequentially over TAR entries using `Next()`.
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- Compares each entry’s header name (`header.Name`) with the requested `path`.
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- **Output**:
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- On match: Returns a pointer to the *current* `tar.Reader`, positioned at the start of the requested file’s content (ready for subsequent reads).
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- On failure: Returns `nil` and a formatted error `"file not found: <path>"`.
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- **Semantics**:
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- Enables *lazy*, on-demand access to a specific file inside a TAR archive — without decompressing the entire structure.
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- Assumes exact path matching (no globbing, wildcards, or directory traversal).
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- Does *not* handle symbolic links, hardlinks, or nested archives — only plain file entries.
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- **Use Case**:
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Ideal for lightweight tools that need to inspect or extract a single known file from large TAR archives (e.g., config files, manifests), minimizing memory and I/O overhead.
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