[PATCH 1/2] teach convert_to_git a "dry run" mode

From: Jeff King <peff@peff.net>
Date: Feb 24, 2012, 09:41 UTC
Message-ID: <20120224094151.GA11846@sigill.intra.peff.net>
In-Reply-To: <20120224093924.GA11680@sigill.intra.peff.net>

Some callers may want to know whether convert_to_git will do any conversion without actually feeding file data to it (e.g., if you are using the decision to decide how to acquire the data that might be converted). Rather than replicate convert_to_git's logic in a separate function, this patch lets callers pass a NULL buffer. The function runs through its usual logic, except that it does not do any actual conversion; the return value, instead of specifying whether conversion happened, indicates whether conversion might occur.

Note the use of the word "might" above. We cannot know for sure whether conversion will occur without seeing the buffer itself (because CRLF conversion may decide the file is binary and do nothing). However, "might" is close enough for callers which are trying to find out whether filters are in used; they can be conservative and assume that the filters will be used in such a case.

Signed-off-by: Jeff King <peff@peff.net>
---
 convert.c |   18 ++++++++++++++----
 1 file changed, 14 insertions(+), 4 deletions(-)

diff --git a/convert.c b/convert.c
index 12868ed..33aa72f 100644
--- a/convert.c
+++ b/convert.c
@@ -195,9 +195,13 @@ static int crlf_to_git(const char *path, const char *src, size_t len,
 	char *dst;
 
 	if (crlf_action == CRLF_BINARY ||
-	    (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE) || !len)
+	    (crlf_action == CRLF_GUESS && auto_crlf == AUTO_CRLF_FALSE) ||
+	    (src && !len))
 		return 0;
 
+	if (!src)
+		return 1;
+
 	gather_stats(src, len, &stats);
 
 	if (crlf_action == CRLF_AUTO || crlf_action == CRLF_GUESS) {
@@ -391,6 +395,9 @@ static int apply_filter(const char *path, const char *src, size_t len,
 	if (!cmd)
 		return 0;
 
+	if (!src)
+		return 1;
+
 	memset(&async, 0, sizeof(async));
 	async.proc = filter_buffer;
 	async.data = &params;
@@ -522,9 +529,12 @@ static int ident_to_git(const char *path, const char *src, size_t len,
 {
 	char *dst, *dollar;
 
-	if (!ident || !count_ident(src, len))
+	if (!ident || (src && !count_ident(src, len)))
 		return 0;
 
+	if (!src)
+		return 1;
+
 	/* only grow if not in place */
 	if (strbuf_avail(buf) + buf->len < len)
 		strbuf_grow(buf, len - buf->len);
@@ -754,13 +764,13 @@ int convert_to_git(const char *path, const char *src, size_t len,
 		filter = ca.drv->clean;
 
 	ret |= apply_filter(path, src, len, dst, filter);
-	if (ret) {
+	if (ret && src) {
 		src = dst->buf;
 		len = dst->len;
 	}
 	ca.crlf_action = input_crlf_action(ca.crlf_action, ca.eol_attr);
 	ret |= crlf_to_git(path, src, len, dst, ca.crlf_action, checksafe);
-	if (ret) {
+	if (ret && src) {
 		src = dst->buf;
 		len = dst->len;
 	}

-- 
1.7.9.9.g04d94