vfs: correctly handle reading small files.

After the recent change to let vfs seek around in files, we broke support
for files that were only one chunk.  Fix it up, then add some unit tests to
detect such mistakes in the future.

Also, 'bup ftp' now returns nonzero if it catches any exceptions during
execution, making it more suitable for use in scripts... such as the unit
tests :)

Signed-off-by: Avery Pennarun <apenwarr@gmail.com>

cmd/ftp-cmd.py

@@ -125,6 +125,7 @@ def completer(text, state):
 
 top = vfs.RefList(None)
 pwd = top
+rv = 0
 
 if extra:
     lines = extra
@@ -156,6 +157,7 @@ def completer(text, state):
                 write_to_file(pwd.resolve(parm).open(), sys.stdout)
         elif cmd == 'get':
             if len(words) not in [2,3]:
+                rv = 1
                 raise Exception('Usage: get <filename> [localname]')
             rname = words[1]
             (dir,base) = os.path.split(rname)
@@ -175,13 +177,18 @@ def completer(text, state):
                             write_to_file(inf, outf)
                             outf.close()
                         except Exception, e:
+                            rv = 1
                             log('  error: %s\n' % e)
         elif cmd == 'help' or cmd == '?':
             log('Commands: ls cd pwd cat get mget help quit\n')
         elif cmd == 'quit' or cmd == 'exit' or cmd == 'bye':
             break
         else:
+            rv = 1
             raise Exception('no such command %r' % cmd)
     except Exception, e:
+        rv = 1
         log('error: %s\n' % e)
         #raise
+
+sys.exit(rv)

lib/bup/vfs.py

@@ -88,7 +88,7 @@ def __init__(self, hash, isdir, startofs):
             self.blob = None
         else:
             self.it = None
-            self.blob = cp().get(hash.encode('hex'))
+            self.blob = ''.join(cp().join(hash.encode('hex')))[startofs:]
 
     def next(self, size):
         out = ''

t/test.sh

@@ -26,8 +26,10 @@ WVFAIL [ -e $D.fake ]
 WVFAIL bup index --check -u $D.fake
 WVPASS bup index --check -u $D
 WVPASSEQ "$(bup index --check -p $D)" "$D/"
-touch $D/a $D/b $D/f
+touch $D/a
+bup random 128k >$D/b
 mkdir $D/d $D/d/e
+bup random 512 >$D/f
 WVPASSEQ "$(bup index -s $D/)" "A $D/"
 WVPASSEQ "$(bup index -s $D/b)" ""
 WVPASSEQ "$(bup index --check -us $D/b)" "A $D/b"
@@ -161,6 +163,14 @@ WVSTART "save/git-fsck"
     WVPASS [ "$n" -eq 0 ]
 ) || exit 1
 
+WVSTART "ftp"
+WVPASS bup ftp "cat /master/latest/$TOP/$D/b" >$D/b.new
+WVPASS bup ftp "cat /master/latest/$TOP/$D/f" >$D/f.new
+WVPASS bup ftp "cat /master/latest/$TOP/$D/a" >$D/a.new
+WVPASSEQ "$(sha1sum <$D/b)" "$(sha1sum <$D/b.new)"
+WVPASSEQ "$(sha1sum <$D/f)" "$(sha1sum <$D/f.new)"
+WVPASSEQ "$(sha1sum <$D/a)" "$(sha1sum <$D/a.new)"
+
 WVSTART "fsck"
 WVPASS bup fsck
 WVPASS bup fsck --quick