teach convert_to_git a "dry run" mode

Some callers may want to know whether convert_to_git will
actually do anything before performing the conversion
itself (e.g., to decide whether to stream or handle blobs
in-core). This patch lets callers specify the dry run mode
by passing a NULL destination buffer. The return value,
instead of indicating whether conversion happened, will
indicate whether conversion would occur.

For readability, we also include a wrapper function which
makes it more obvious we are not actually performing the
conversion.

Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/convert.c b/convert.c
index 12868ed7bda11648704ffe4e5d3415067764a6e2..65fa9d5eda94749559cd183437a5a108c6a174db 100644 (file)
--- a/convert.c
+++ b/convert.c
@@ -231,6 +231,13 @@ static int crlf_to_git(const char *path, const char *src, size_t len,
        if (!stats.cr)
                return 0;
 
+       /*
+        * At this point all of our source analysis is done, and we are sure we
+        * would convert. If we are in dry-run mode, we can give an answer.
+        */
+       if (!buf)
+               return 1;
+
        /* only grow if not in place */
        if (strbuf_avail(buf) + buf->len < len)
                strbuf_grow(buf, len - buf->len);
@@ -391,6 +398,9 @@ static int apply_filter(const char *path, const char *src, size_t len,
        if (!cmd)
                return 0;
 
+       if (!dst)
+               return 1;
+
        memset(&async, 0, sizeof(async));
        async.proc = filter_buffer;
        async.data = &params;
@@ -525,6 +535,9 @@ static int ident_to_git(const char *path, const char *src, size_t len,
        if (!ident || !count_ident(src, len))
                return 0;
 
+       if (!buf)
+               return 1;
+
        /* only grow if not in place */
        if (strbuf_avail(buf) + buf->len < len)
                strbuf_grow(buf, len - buf->len);
@@ -754,13 +767,13 @@ 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 && dst) {
                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 && dst) {
                src = dst->buf;
                len = dst->len;
        }

diff --git a/convert.h b/convert.h
index d799a165b4731f2a44a44eaceffc588d1e9fcfc3..ec5fd69430908915cf9c0de62a2021882fd2c658 100644 (file)
--- a/convert.h
+++ b/convert.h
@@ -40,6 +40,11 @@ extern int convert_to_working_tree(const char *path, const char *src,
                                   size_t len, struct strbuf *dst);
 extern int renormalize_buffer(const char *path, const char *src, size_t len,
                              struct strbuf *dst);
+static inline int would_convert_to_git(const char *path, const char *src,
+                                      size_t len, enum safe_crlf checksafe)
+{
+       return convert_to_git(path, src, len, NULL, checksafe);
+}
 
 /*****************************************************************
  *