From: Zooko O'Whielacronx <zooko@zooko.com>
Date: Sat, 3 Jan 2009 21:02:45 +0000 (-0700)
Subject: immutable: fix think-o in previous patch which caused all reads to return "", and... 
X-Git-Url: https://git.rkrishnan.org/vdrive/index.php?a=commitdiff_plain;h=38f293a9135fe99af5aa7ad4b3309fa8a5177925;p=tahoe-lafs%2Ftahoe-lafs.git

immutable: fix think-o in previous patch which caused all reads to return "", and also optimize by not opening the file when the answer is going to be ""
---

diff --git a/src/allmydata/storage.py b/src/allmydata/storage.py
index 1bed937d..74eeaa84 100644
--- a/src/allmydata/storage.py
+++ b/src/allmydata/storage.py
@@ -138,12 +138,12 @@ class ShareFile:
         # reads beyond the end of the data are truncated. Reads that start beyond the end of the
         # data return an empty string.
         # I wonder why Python doesn't do the following computation for me?
-        f = open(self.home, 'rb')
         seekpos = self._data_offset+offset
         fsize = os.path.getsize(self.home)
-        actuallength = min(0, length, fsize-seekpos)
+        actuallength = max(0, min(length, fsize-seekpos))
         if actuallength == 0:
             return ""
+        f = open(self.home, 'rb')
         f.seek(seekpos)
         return f.read(actuallength)