Initial sketch of snapshot support code, based on code from marijn.

1 files changed, 95 insertions, 0 deletions

diff --git a/src/etc/get-snapshot.py b/src/etc/get-snapshot.py
new file mode 100755
index 00000000..d9547b2f
--- /dev/null
+++ b/src/etc/get-snapshot.py
@@ -0,0 +1,95 @@
+#!/usr/bin/env python
+
+import os, tarfile, hashlib, re, shutil
+from snapshot import *
+
+def snap_filename_hash_part(snap):
+  match = re.match(r".*([a-fA-F\d]{40}).tar.bz2$", snap)
+  if not match:
+    raise Exception("unable to find hash in filename: " + snap)
+  return match.group(1)
+
+def get_snapshot_and_check_hash(snap):
+
+  hsh = snap_filename_hash_part(snap)
+
+  h = hashlib.sha1()
+  url = download_url_base + "/" + snap
+  print "downloading " + url
+  u = urllib2.urlopen(url)
+  print "checking hash on download"
+  data = u.read()
+  h.update(data)
+  if h.hexdigest() != hsh:
+    raise Exception("hash check failed on " + snap)
+
+  print "hash ok"
+  with open(os.path.join(download_dir_base, snap), "w+b") as f:
+    f.write(data)
+  return True
+
+def unpack_snapshot(snap):
+  dl_path = os.path.join(download_dir_base, snap)
+  print "opening snapshot " + dl_path
+  tar = tarfile.open(dl_path)
+  kernel = get_kernel()
+  for name in snapshot_files[kernel]:
+    p = os.path.join("rust-stage0", name)
+    fp = os.path.join("stage0", name)
+    print "extracting " + fp
+    tar.extract(p, download_unpack_base)
+    tp = os.path.join(download_unpack_base, p)
+    shutil.move(tp, fp)
+  tar.close()
+  shutil.rmtree(download_unpack_base)
+
+def determine_last_snapshot_for_platform():
+  lines = open(snapshotfile).readlines();
+
+  platform = get_platform()
+
+  found = False
+  hsh = None
+  date = None
+  rev = None
+
+  for ln in range(len(lines) - 1, -1, -1):
+    parsed = parse_line(ln, lines[ln])
+    if (not parsed): continue
+
+    if parsed["type"] == "file":
+      if parsed["platform"] == platform:
+        hsh = parsed["hash"]
+    elif parsed["type"] == "snapshot":
+      date = parsed["date"]
+      rev = parsed["rev"]
+      found = True
+      break
+    elif parsed["type"] == "transition" and not foundSnapshot:
+      raise Exception("working on a transition, not updating stage0")
+
+  if not found:
+    raise Exception("no snapshot entries in file")
+
+  if not hsh:
+    raise Exception("no snapshot file found for platform %s, rev %s" %
+                    (platform, rev))
+
+  return full_snapshot_name(date, rev, get_kernel(), get_cpu(), hsh)
+
+# Main
+
+snap = determine_last_snapshot_for_platform()
+print "determined most recent snapshot: " + snap
+dl = os.path.join(download_dir_base, snap)
+if (os.path.exists(dl)):
+  if (snap_filename_hash_part(snap) == hash_file(dl)):
+    print "found existing download with ok hash"
+  else:
+    print "bad hash on existing download, re-fetching"
+    get_snapshot_and_check_hash(snap)
+else:
+  print "no cached download, fetching"
+  get_snapshot_and_check_hash(snap)
+
+unpack_snapshot(snap)