externalize ar parsing to arpy

3 files changed, 10 insertions, 98 deletions

diff --git a/README b/README
index 4572c8a..ed4e8cb 100644
--- a/README
+++ b/README
@@ -1,7 +1,7 @@
 Required packages
 -----------------
 
-    aptitude install python3 python3-debian python3-lzma python3-jinja2 python3-werkzeug sqlite3 python3-pil python3-yaml python3-concurrent.futures python3-pkg-resources
+    aptitude install python3 python3-arpy python3-debian python3-lzma python3-jinja2 python3-werkzeug sqlite3 python3-pil python3-yaml python3-concurrent.futures python3-pkg-resources
 
 Create a database
 -----------------
diff --git a/dedup/arreader.py b/dedup/arreader.py
deleted file mode 100644
index 8b14ff9..0000000
--- a/dedup/arreader.py
+++ /dev/null
@@ -1,79 +0,0 @@
-import struct
-
-class ArReader:
-    """Streaming AR file reader. After constructing an object, you usually
-    call read_magic once. Then you call read_entry in a loop and use the
-    ArReader object as file-like only providing read() to read the respective
-    file contents until you get EOFError from read_entry.
-    """
-    global_magic = b"!<arch>\n"
-    file_magic = b"`\n"
-
-    def __init__(self, fileobj):
-        """
-        @param fileobj: a file-like object providing nothing but read(length)
-        """
-        self.fileobj = fileobj
-        self.remaining = None
-        self.padding = 0
-
-    def read_magic(self):
-        """Consume the AR magic marker at the beginning of an AR file. You
-        must not call any other method before calling this method.
-        @raises ValueError: if the magic is not found
-        """
-        data = self.fileobj.read(len(self.global_magic))
-        if data != self.global_magic:
-            raise ValueError("ar global header not found")
-        self.remaining = 0
-
-    def read_entry(self):
-        """Read the next file header, return the filename and record the
-        length of the next file, so that the read method can be used to
-        exhaustively read the current file.
-        @rtype: bytes
-        @returns: the name of the next file
-        @raises ValueError: if the data format is wrong
-        @raises EOFError: when the end f the stream is reached
-        """
-        self.skip_current_entry()
-        if self.padding:
-            if self.fileobj.read(1) != b'\n':
-                raise ValueError("missing ar padding")
-            self.padding = 0
-        file_header = self.fileobj.read(60)
-        if not file_header:
-            raise EOFError("end of archive found")
-        parts = struct.unpack("16s 12s 6s 6s 8s 10s 2s", file_header)
-        parts = [p.rstrip(b"/ ") for p in parts]
-        if parts.pop() != self.file_magic:
-            raise ValueError("ar file header not found")
-        self.remaining = int(parts[5])
-        self.padding = self.remaining % 2
-        return parts[0] # name
-
-    def skip_current_entry(self):
-        """Skip the remainder of the current file. This method must not be
-        called before calling read_entry.
-        @raises ValueError: if the archive appears truncated
-        """
-        while self.remaining:
-            data = self.fileobj.read(min(4096, self.remaining))
-            if not data:
-                raise ValueError("archive truncated")
-            self.remaining -= len(data)
-
-    def read(self, length=None):
-        """
-        @type length: int or None
-        @param length: number of bytes to read from the current file
-        @rtype: bytes
-        @returns: length or fewer bytes from the current file
-        """
-        if length is None:
-            length = self.remaining
-        else:
-            length = min(self.remaining, length)
-        data = self.fileobj.read(length)
-        self.remaining -= len(data)
-        return data
diff --git a/dedup/debpkg.py b/dedup/debpkg.py
index 38086ec..0ecb123 100644
--- a/dedup/debpkg.py
+++ b/dedup/debpkg.py
@@ -1,8 +1,8 @@
 import tarfile
 
+import arpy
 from debian import deb822
 
-from dedup.arreader import ArReader
 from dedup.compression import decompress
 from dedup.hashing import hash_file
 
@@ -52,45 +52,36 @@ class DebExtractor:
         @param filelike: is a file-like object containing the contents of the
                          Debian packge and can be read once without seeks.
         """
-        af = ArReader(filelike)
-        af.read_magic()
-        while True:
-            try:
-                name = af.read_entry()
-            except EOFError:
-                break
-            else:
-                self.handle_ar_member(name, af)
+        af = arpy.Archive(fileobj=filelike)
+        for member in af:
+            self.handle_ar_member(member)
         self.handle_ar_end()
 
-    def handle_ar_member(self, name, filelike):
+    def handle_ar_member(self, arfiledata: arpy.ArchiveFileData) -> None:
         """Handle an ar archive member of the Debian package.
         If you replace this method, you must also replace handle_ar_end and
         none of the methods handle_debversion, handle_control_tar or
         handle_data_tar are called.
-        @type name: bytes
-        @param name: is the name of the member
-        @param filelike: is a file-like object containing the contents of the
-                         member and can be read once without seeks.
         """
+        name = arfiledata.header.name
         if self.arstate == "start":
             if name != b"debian-binary":
                 raise ValueError("debian-binary not found")
-            version = filelike.read()
+            version = arfiledata.read()
             self.handle_debversion(version)
             if not version.startswith(b"2."):
                 raise ValueError("debian version not recognized")
             self.arstate = "version"
         elif self.arstate == "version":
             if name.startswith(b"control.tar"):
-                filelike = decompress(filelike, name[11:].decode("ascii"))
+                filelike = decompress(arfiledata, name[11:].decode("ascii"))
                 self.handle_control_tar(opentar(filelike))
                 self.arstate = "control"
             elif not name.startswith(b"_"):
                 raise ValueError("unexpected ar member %r" % name)
         elif self.arstate == "control":
             if name.startswith(b"data.tar"):
-                filelike = decompress(filelike, name[8:].decode("ascii"))
+                filelike = decompress(arfiledata, name[8:].decode("ascii"))
                 self.handle_data_tar(opentar(filelike))
                 self.arstate = "data"
             elif not name.startswith(b"_"):