lzep4: decompress an LZ4 file (block or frame) to stdout

README.md

@@ -54,6 +54,7 @@ This repository hosts various small personal tools.
 - [`links2markdown`](links2markdown): fetch title of links in a text file and replace to build Markdown links
 - [`log-snippet`](log-snippet): parse compilation-log and show snippets of files with context
 - [`log-ts-diff`](log-ts-diff): parse log and replace timestamps with diff to previous timestamp
+- [`lzep4`](lzep4): decompress an LZ4 file (block or frame) to stdout
 - [`mediadims`](mediadims): get audio/video duration or video width/height of a file with [mediainfo](https://mediaarea.net/)
 - [`morse`](morse): text from/to Morse code converter, and optional beep player
 - [`morsehtml`](morsehtml): HTML page with its background flashing a Morse code message

lzep4/.editorconfig

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+[*.py{,.jinja}]
+indent_style = space
+indent_size = 4

lzep4/README.md

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+# lzep4
+
+Extract LZ4 files to stdout
+
+## Example
+
+```
+lzep4 --moz --block ~/.mozilla/firefox/my.profile/sessionstore.jsonlz4
+```

lzep4/lzep4.py

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+#!/usr/bin/env python3
+
+# /// script
+# dependencies = ["lz4"]
+# ///
+
+import argparse
+import locale
+import signal
+import sys
+
+import lz4.block
+import lz4.frame
+
+
+__version__ = "0.1.0"
+
+
+def do_block(args, in_fp, out_fp):
+    data = in_fp.read()
+    if args.moz:
+        data = data[8:]
+    data = lz4.block.decompress(data)
+    out_fp.write(data)
+
+
+def do_frame(args, in_fp, out_fp):
+    with lz4.frame.LZ4FrameDecompressor() as decompressor:
+        while True:
+            buf = in_fp.read(10240)
+            if not buf:
+                break
+            buf = decompressor.decompress(buf)
+            out_fp.buffer.write(buf)
+
+
+def main():
+    locale.setlocale(locale.LC_ALL, "")
+
+    signal.signal(signal.SIGINT, signal.SIG_DFL)
+    signal.signal(signal.SIGPIPE, signal.SIG_DFL)
+
+    parser = argparse.ArgumentParser()
+    parser.add_argument(
+        "--block", action="store_true",
+        help="Extract 'block' LZ4 instead of 'frame' LZ4",
+    )
+    parser.add_argument(
+        "--moz", action="store_true",
+        help="Extract Mozilla .jsonlz4 files",
+    )
+    parser.add_argument(
+        "file", type=argparse.FileType(mode="rb"), nargs="?",
+        default=sys.stdin.buffer,
+    )
+    parser.add_argument("--version", action="version", version=__version__)
+    args = parser.parse_args()
+
+    if args.file.isatty():
+        print(f"warning: {parser.prog} is reading stdin", file=sys.stderr)
+
+    proc_func = do_frame
+    if args.block:
+        proc_func = do_block
+
+    with args.file:
+        proc_func(args, args.file, sys.stdout.buffer)
+
+
+if __name__ == "__main__":
+    main()

lzep4/requirements.txt

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+lz4

lzep4/test.sh

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+#!/bin/sh -eu
+# SPDX-License-Identifier: WTFPL
+# shellcheck enable=
+
+cd "$(dirname "$0")"
+
+got=$(mktemp lzep4.XXXXXX)
+trap 'rm "$got"' EXIT
+
+
+init () {
+	./lzep4.py "$@" > "$got"
+}
+
+check () {
+	diff -u - "$got"
+}
+
+
+# basic test
+printf '\025\000\000\000\033A\001\000PAAAA\n' | init --block
+
+echo AAAAAAAAAAAAAAAAAAAA | check