Re: [PATCH v7 1/1] sideband: highlight keywords in remote sideband output

Han-Wen Nienhuys [off-list ref] writes:

+/*
+ * Optionally highlight one keyword in remote output if it appears at the start
+ * of the line. This should be called for a single line only, which is
+ * passed as the first N characters of the SRC array.
+ */
+static void maybe_colorize_sideband(struct strbuf *dest, const char *src, int n)
+{
+	int i;
+
+	if (!want_color_stderr(use_sideband_colors())) {
+		strbuf_add(dest, src, n);
+		return;
+	}
+
+	while (isspace(*src)) {
+		strbuf_addch(dest, *src);
+		src++;
+		n--;
+	}

This loop can run out of bytes in src in search of non-space before
n gets to zero or negative, and when that happens ...

+	for (i = 0; i < ARRAY_SIZE(keywords); i++) {
+		struct keyword_entry *p = keywords + i;
+		int len = strlen(p->keyword);
+		/*
+		 * Match case insensitively, so we colorize output from existing
+		 * servers regardless of the case that they use for their
+		 * messages. We only highlight the word precisely, so
+		 * "successful" stays uncolored.
+		 */
+		if (!strncasecmp(p->keyword, src, len) && !isalnum(src[len])) {

... these access src[] beyond the end of what the caller intended to
show us, and also ...

+			strbuf_addstr(dest, p->color);
+			strbuf_add(dest, src, len);
+			strbuf_addstr(dest, GIT_COLOR_RESET);
+			n -= len;
+			src += len;
+			break;
+		}
+	}
+
+	strbuf_add(dest, src, n);

... this will now try to add 0 or negative number of bytes.

+
+}
+

Perhaps this will help (not really tested).  The second hunk is an
unrelated style clean-up.


 sideband.c | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/sideband.c b/sideband.c
index 1c6bb0e25b..d99a559a44 100644
--- a/sideband.c
+++ b/sideband.c

@@ -75,11 +75,13 @@ static void maybe_colorize_sideband(struct strbuf *dest, const char *src, int n)
 		return;
 	}
 
-	while (isspace(*src)) {
+	while (isspace(*src) && n) {
 		strbuf_addch(dest, *src);
 		src++;
 		n--;
 	}
+	if (!n)
+		return;
 
 	for (i = 0; i < ARRAY_SIZE(keywords); i++) {
 		struct keyword_entry *p = keywords + i;

@@ -101,7 +103,6 @@ static void maybe_colorize_sideband(struct strbuf *dest, const char *src, int n)
 	}
 
 	strbuf_add(dest, src, n);
-
 }