Bug 1809575 - Implement enough of a CPIO unpacker to handle pkg files. r=gsvelto

Instead of using an external tool.

Differential Revision: https://phabricator.services.mozilla.com/D166503

tools/crashreporter/system-symbols/mac/PackageSymbolDumper.py

@@ -45,6 +45,7 @@ import errno
 import logging
 import os
 import shutil
+import stat
 import subprocess
 import tempfile
 import traceback
@@ -177,17 +178,16 @@ def extract_payload(payload_path, output_path):
             return True
         elif header == b"pb":
             logging.info("Extracting pbzx payload")
-            from extract_pbzx import Pbzx
+            from macpkg import Pbzx, uncpio
+
+            for path, mode, content in uncpio(Pbzx(open(payload_path, "rb"))):
+                if not path or not stat.S_ISREG(mode):
+                    continue
+                out = os.path.join(output_path, path.decode())
+                os.makedirs(os.path.dirname(out), exist_ok=True)
+                with open(out, "wb") as fh:
+                    shutil.copyfileobj(content, fh)
 
-            # Feed the extracted PBZX into pax.
-            pax_proc = subprocess.Popen(
-                ["pax", "-r", "-k", "-s", ":^/::"],
-                stdin=subprocess.PIPE,
-                cwd=output_path,
-            )
-            shutil.copyfileobj(Pbzx(open(payload_path, "rb")), pax_proc.stdin)
-            pax_proc.stdin.close()
-            pax_proc.wait()
             return True
         else:
             # Unsupported format
@@ -196,7 +196,7 @@ def extract_payload(payload_path, output_path):
             )
             return False
 
-    except subprocess.CalledProcessError:
+    except Exception:
         return False
 
 

tools/crashreporter/system-symbols/mac/macpkg.py

@@ -51,3 +51,67 @@ class Pbzx(object):
                 # XXX: suboptimal if length is larger than the chunk size
                 result += self.read(None if length is None else length - len(result))
             return result
+
+
+class Take(object):
+    """
+    File object wrapper that allows to read at most a certain length.
+    """
+
+    def __init__(self, fileobj, limit):
+        self.fileobj = fileobj
+        self.limit = limit
+
+    def read(self, length=None):
+        if length is None:
+            length = self.limit
+        else:
+            length = min(length, self.limit)
+        result = self.fileobj.read(length)
+        self.limit -= len(result)
+        return result
+
+
+def uncpio(fileobj):
+    while True:
+        magic = fileobj.read(6)
+        # CPIO payloads in mac pkg files are using the portable ASCII format.
+        if magic != b"070707":
+            if magic.startswith(b"0707"):
+                raise Exception("Unsupported CPIO format")
+            raise Exception("Not a CPIO header")
+        header = fileobj.read(70)
+        (
+            dev,
+            ino,
+            mode,
+            uid,
+            gid,
+            nlink,
+            rdev,
+            mtime,
+            namesize,
+            filesize,
+        ) = struct.unpack(">6s6s6s6s6s6s6s11s6s11s", header)
+        mode = int(mode, 8)
+        nlink = int(nlink, 8)
+        namesize = int(namesize, 8)
+        filesize = int(filesize, 8)
+        name = fileobj.read(namesize)
+        if name[-1] != 0:
+            raise Exception("File name is not NUL terminated")
+        name = name[:-1]
+        if name == b"TRAILER!!!":
+            break
+
+        if b"/../" in name or name.startswith(b"../") or name == b"..":
+            raise Exception(".. is forbidden in file name")
+        if name.startswith(b"."):
+            name = name[1:]
+        if name.startswith(b"/"):
+            name = name[1:]
+        content = Take(fileobj, filesize)
+        yield name, mode, content
+        # Ensure the content is totally consumed
+        while content.read(4096):
+            pass