[PATCH] Make sq_expand() available as sq_quote().

A useful shell safety helper sq_expand() was hidden as a static
function in diff.c.  Extract it out and make it available as
sq_quote().

Signed-off-by: Junio C Hamano <junkio@cox.net>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 41 insertions, 0 deletions

diff --git a/quote.c b/quote.c
new file mode 100644
index 0000000..5e6fda3
--- /dev/null
+++ b/quote.c
@@ -0,0 +1,41 @@
+#include "cache.h"
+#include "quote.h"
+
+/* Help to copy the thing properly quoted for the shell safety.
+ * any single quote is replaced with '\'', and the caller is
+ * expected to enclose the result within a single quote pair.
+ *
+ * E.g.
+ *  original     sq_quote     result
+ *  name     ==> name      ==> 'name'
+ *  a b      ==> a b       ==> 'a b'
+ *  a'b      ==> a'\''b    ==> 'a'\''b'
+ */
+char *sq_quote(const char *src)
+{
+	static char *buf = NULL;
+	int cnt, c;
+	const char *cp;
+	char *bp;
+
+	/* count bytes needed to store the quoted string. */
+	for (cnt = 3, cp = src; *cp; cnt++, cp++)
+		if (*cp == '\'')
+			cnt += 3;
+
+	buf = xmalloc(cnt);
+	bp = buf;
+	*bp++ = '\'';
+	while ((c = *src++)) {
+		if (c != '\'')
+			*bp++ = c;
+		else {
+			bp = strcpy(bp, "'\\''");
+			bp += 4;
+		}
+	}
+	*bp++ = '\'';
+	*bp = 0;
+	return buf;
+}
+