Add streaming filter API

This introduces an API to plug custom filters to an input stream.

The caller gets get_stream_filter("path") to obtain an appropriate
filter for the path, and then uses it when opening an input stream
via open_istream().  After that, the caller can read from the stream
with read_istream(), and close it with close_istream(), just like an
unfiltered stream.

This only adds a "null" filter that is a pass-thru filter, but later
changes can add LF-to-CRLF and other filters, and the callers of the
streaming API do not have to change.

Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 10 insertions, 6 deletions

diff --git a/entry.c b/entry.c
index e2dc16c131..852fea1395 100644
--- a/entry.c
+++ b/entry.c
@@ -116,6 +116,7 @@ static int fstat_output(int fd, const struct checkout *state, struct stat *st)
 }
 
 static int streaming_write_entry(struct cache_entry *ce, char *path,
+				 struct stream_filter *filter,
 				 const struct checkout *state, int to_tempfile,
 				 int *fstat_done, struct stat *statbuf)
 {
@@ -126,7 +127,7 @@ static int streaming_write_entry(struct cache_entry *ce, char *path,
 	ssize_t kept = 0;
 	int fd = -1;
 
-	st = open_istream(ce->sha1, &type, &sz);
+	st = open_istream(ce->sha1, &type, &sz, filter);
 	if (!st)
 		return -1;
 	if (type != OBJ_BLOB)
@@ -186,11 +187,14 @@ static int write_entry(struct cache_entry *ce, char *path, const struct checkout
 	size_t wrote, newsize = 0;
 	struct stat st;
 
-	if ((ce_mode_s_ifmt == S_IFREG) &&
-	    can_bypass_conversion(path) &&
-	    !streaming_write_entry(ce, path, state, to_tempfile,
-				   &fstat_done, &st))
-		goto finish;
+	if (ce_mode_s_ifmt == S_IFREG) {
+		struct stream_filter *filter = get_stream_filter(path, ce->sha1);
+		if (filter &&
+		    !streaming_write_entry(ce, path, filter,
+					   state, to_tempfile,
+					   &fstat_done, &st))
+			goto finish;
+	}
 
 	switch (ce_mode_s_ifmt) {
 	case S_IFREG: