Help/Advice needed on diff bug in xutils.c

From: Thell Fowler <tbfowler4@gmail.com>
Date: Aug 4, 2009, 23:33 UTC
Message-ID: <1249428804.2774.52.camel@GWPortableVCS>

Hi all!  Please give me a sanity check before I go crazy...

There is a bug in git diff (ignoring whitespace) that does not take into account a trailing space at the end of a line at the end of a file when no new line follows.

Here is the example of the bug: mkdir test_ws_eof cd test_ws_eof git init echo -n "Test" > test.txt git add . git commit -m'test' git symbolic-ref HEAD refs/heads/with_space rm .git/index git clean -f echo -n "Test ">test.txt git add . git commit -m'test' # Ignoring all whitespace there shouldn't be a diff. git diff -w master -- test.txt # Ignoring space at eol there shouldn't be a diff git diff --ignore-space-at-eol master -- test.txt # Ignoring with -b might have a case for a diff showing. git diff -b master -- test.txt

In the xutils.c xdl_hash_record_with_whitespace function the trailing space prior to eof was being calculated into the hash, I fixed that with the change below, but there is still a difference being noted in xdl_recmatch because of the size difference.

Before I go changing something that shouldn't be changed could someone provide some input please?

Thanks for reading, Thell

diff --git a/xdiff/xutils.c b/xdiff/xutils.c
index 04ad468..623da92 100644
--- a/xdiff/xutils.c
+++ b/xdiff/xutils.c
@@ -243,17 +243,17 @@ static unsigned long
xdl_hash_record_with_whitespace(char
const **data,
                if (isspace(*ptr)) {
                        const char *ptr2 = ptr;
                        while (ptr + 1 < top && isspace(ptr[1])
-                                       && ptr[1] != '\n')
+                                       && ( ptr[1] != '\n' && ptr[1] !=
'\0' ) )
                                ptr++;
                        if (flags & XDF_IGNORE_WHITESPACE)
                                ; /* already handled */
                        else if (flags & XDF_IGNORE_WHITESPACE_CHANGE
-                                       && ptr[1] != '\n') {
+                                       && ( ptr[1] != '\n' && ptr[1] !=
'\0' ) ) {
                                ha += (ha << 5);
                                ha ^= (unsigned long) ' ';
                        }
                        else if (flags & XDF_IGNORE_WHITESPACE_AT_EOL
-                                       && ptr[1] != '\n') {
+                                       && ( ptr[1] != '\n' && ptr[1] !=
'\0' ) ) {
                                while (ptr2 != ptr + 1) {