[PATCH] changelog: fix decoding of extra data (issue3156)

[Lars Boehnke]

# HG changeset patch
# User lboehnke <lboehnke at symmetricom.com>
# Date 1324058856 25200
# Node ID 56a4a7dd2adc50e4db9486b5b90c4b1a5fb06ccd
# Parent  c7b0bedbb07ac3752243db046f54c9a4bbc3273d
changelog: fix decoding of extra data (issue3156)

The 'string_escape' codec is not compatible with the custom
encoding used in _string_escape.  This adds a custom decoder that
is compatible.

diff -r c7b0bedbb07a -r 56a4a7dd2adc mercurial/changelog.py
--- a/mercurial/changelog.py	Thu Dec 15 16:50:21 2011 -0600
+++ b/mercurial/changelog.py	Fri Dec 16 11:07:36 2011 -0700
@@ -23,11 +23,43 @@
     text = text.replace('\\', '\\\\').replace('\n', '\\n').replace('\r', '\\r')
     return text.replace('\0', '\\0')
 
+def _string_unescape(text):
+    result = ""
+    char = None
+    inescape = False
+    for x in text:
+        if inescape is False and x == '\\':
+            inescape = True
+            continue
+
+        if inescape:
+            if x == '\\':
+                char = '\\'
+            elif x == 'n':
+                char = '\n'
+            elif x == 'r':
+                char = '\r'
+            elif x == '0':
+                char = '\x00'
+            else:
+                raise error.RevlogError(_("bad escaped character: '%s'")%x)
+            inescape = False
+        else:
+            char = x
+
+        result += char
+
+    # defensive - make sure we did not end in an escape sequence
+    if inescape:
+        raise error.RevlogError(_("ended in escape sequence"))
+    return result
+
+
 def decodeextra(text):
     extra = {}
     for l in text.split('\0'):
         if l:
-            k, v = l.decode('string_escape').split(':', 1)
+            k, v = _string_unescape(l).split(':', 1)
             extra[k] = v
     return extra