[PATCH v4 1/2] packfile: rename `derive_filename()` to `derive_pack_filename()`

["Sun Chao via GitGitGadget" <gitgitgadget@gmail.com>]

From: Sun Chao <16657101987@163.com>

In order to allow some function get a new file name from `.pack` file
with a new suffix, move `derive_filename()` in `builtin/index-pack.c`
to `packfile.c` with a new name `derive_pack_filename(), and export
it from `packfile.h`.

Signed-off-by: Sun Chao <16657101987@163.com>
---
 builtin/index-pack.c | 19 +++----------------
 packfile.c           | 13 +++++++++++++
 packfile.h           |  7 +++++++
 3 files changed, 23 insertions(+), 16 deletions(-)

diff --git a/builtin/index-pack.c b/builtin/index-pack.c
index 8336466865c..3c83789ccef 100644
--- a/builtin/index-pack.c
+++ b/builtin/index-pack.c
@@ -1435,19 +1435,6 @@ static void fix_unresolved_deltas(struct hashfile *f)
 	free(sorted_by_pos);
 }
 
-static const char *derive_filename(const char *pack_name, const char *strip,
-				   const char *suffix, struct strbuf *buf)
-{
-	size_t len;
-	if (!strip_suffix(pack_name, strip, &len) || !len ||
-	    pack_name[len - 1] != '.')
-		die(_("packfile name '%s' does not end with '.%s'"),
-		    pack_name, strip);
-	strbuf_add(buf, pack_name, len);
-	strbuf_addstr(buf, suffix);
-	return buf->buf;
-}
-
 static void write_special_file(const char *suffix, const char *msg,
 			       const char *pack_name, const unsigned char *hash,
 			       const char **report)
@@ -1458,7 +1445,7 @@ static void write_special_file(const char *suffix, const char *msg,
 	int msg_len = strlen(msg);
 
 	if (pack_name)
-		filename = derive_filename(pack_name, "pack", suffix, &name_buf);
+		filename = derive_pack_filename(pack_name, "pack", suffix, &name_buf);
 	else
 		filename = odb_pack_name(&name_buf, hash, suffix);
 
@@ -1853,13 +1840,13 @@ int cmd_index_pack(int argc, const char **argv, const char *prefix)
 	if (from_stdin && hash_algo)
 		die(_("--object-format cannot be used with --stdin"));
 	if (!index_name && pack_name)
-		index_name = derive_filename(pack_name, "pack", "idx", &index_name_buf);
+		index_name = derive_pack_filename(pack_name, "pack", "idx", &index_name_buf);
 
 	opts.flags &= ~(WRITE_REV | WRITE_REV_VERIFY);
 	if (rev_index) {
 		opts.flags |= verify ? WRITE_REV_VERIFY : WRITE_REV;
 		if (index_name)
-			rev_index_name = derive_filename(index_name,
+			rev_index_name = derive_pack_filename(index_name,
 							 "idx", "rev",
 							 &rev_index_name_buf);
 	}
diff --git a/packfile.c b/packfile.c
index 9ef6d982928..315c3da259a 100644
--- a/packfile.c
+++ b/packfile.c
@@ -40,6 +40,19 @@ char *sha1_pack_index_name(const unsigned char *sha1)
 	return odb_pack_name(&buf, sha1, "idx");
 }
 
+const char *derive_pack_filename(const char *pack_name, const char *strip,
+				const char *suffix, struct strbuf *buf)
+{
+	size_t len;
+	if (!strip_suffix(pack_name, strip, &len) || !len ||
+	    pack_name[len - 1] != '.')
+		die(_("packfile name '%s' does not end with '.%s'"),
+		    pack_name, strip);
+	strbuf_add(buf, pack_name, len);
+	strbuf_addstr(buf, suffix);
+	return buf->buf;
+}
+
 static unsigned int pack_used_ctr;
 static unsigned int pack_mmap_calls;
 static unsigned int peak_pack_open_windows;
diff --git a/packfile.h b/packfile.h
index 3ae117a8aef..ff702b22e6a 100644
--- a/packfile.h
+++ b/packfile.h
@@ -31,6 +31,13 @@ char *sha1_pack_name(const unsigned char *sha1);
  */
 char *sha1_pack_index_name(const unsigned char *sha1);
 
+/*
+ * Return the corresponding filename with given suffix from "file_name"
+ * which must has "strip" suffix.
+ */
+const char *derive_pack_filename(const char *file_name, const char *strip,
+		const char *suffix, struct strbuf *buf);
+
 /*
  * Return the basename of the packfile, omitting any containing directory
  * (e.g., "pack-1234abcd[...].pack").
-- 
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