[PATCH] xdiff-interface.c: strip newline (and cr) from line before pattern matching

From: Brandon Casey <casey@nrlssc.navy.mil>
Date: Oct 1, 2008, 19:28 UTC
Message-ID: <o5dqpNECJusQHKCTvRWiIqN2ZJ7w-fyC-0vM99FajJIgLsOwP3RNug@cipher.nrlssc.navy.mil>
In-Reply-To: <mJtumbyBuR0sRaFjwb6O5_D_ps0fVfz6APTAAjYMixV0MvzP8nEZRw@cipher.nrlssc.navy.mil>

POSIX doth sayeth:

   "In the regular expression processing described in IEEE Std 1003.1-2001,
    the <newline> is regarded as an ordinary character and both a period and
    a non-matching list can match one. ... Those utilities (like grep) that
    do not allow <newline>s to match are responsible for eliminating any
    <newline> from strings before matching against the RE."

Thus far git has not been removing the trailing newline from strings matched against regular expression patterns. This has the effect that (quoting Jonathan del Strother) "... a line containing just 'FUNCNAME' (terminated by a newline) will be matched by the pattern '^(FUNCNAME.$)' but not '^(FUNCNAME$)'", and more simply not '^FUNCNAME$'.

Signed-off-by: Brandon Casey <casey@nrlssc.navy.mil>
---

This could be a little simpler if I knew what was guaranteed from xdiff. Such as whether the len elements of line were guaranteed to be newline terminated, or be greater than zero. But, the code in def_ff() in xemit.c is wrapped in 'if (len > 0)', so..

-brandon

 xdiff-interface.c |   12 +++++++++++-
 1 files changed, 11 insertions(+), 1 deletions(-)

diff --git a/xdiff-interface.c b/xdiff-interface.c
index 8bab82e..61f5dab 100644
--- a/xdiff-interface.c
+++ b/xdiff-interface.c
@@ -191,12 +191,22 @@ struct ff_regs {
 static long ff_regexp(const char *line, long len,
 		char *buffer, long buffer_size, void *priv)
 {
-	char *line_buffer = xstrndup(line, len); /* make NUL terminated */
+	char *line_buffer;
 	struct ff_regs *regs = priv;
 	regmatch_t pmatch[2];
 	int i;
 	int result = -1;
 
+	/* Exclude terminating newline (and cr) from matching */
+	if (len > 0 && line[len-1] == '\n') {
+		if (len > 1 && line[len-2] == '\r')
+			len -= 2;
+		else
+			len--;
+	}
+
+	line_buffer = xstrndup(line, len); /* make NUL terminated */
+
 	for (i = 0; i < regs->nr; i++) {
 		struct ff_reg *reg = regs->array + i;
 		if (!regexec(&reg->re, line_buffer, 2, pmatch, 0)) {

-- 
1.6.0.2.323.g7c850