wrapper: move is_empty_file() and rename it as is_empty_or_missing_file()

is_empty_file() can help to refactor a lot of code. This will be very
helpful in porting "git bisect" to C.

Suggested-by: Torsten Bögershausen <[email protected]>
Mentored-by: Lars Schneider <[email protected]>
Mentored-by: Christian Couder <[email protected]>
Signed-off-by: Pranit Bauva <[email protected]>
Signed-off-by: Junio C Hamano <[email protected]>

Author: pranitbauva1997

builtin/am.c

@@ -34,22 +34,6 @@
 #include "packfile.h"
 #include "repository.h"
 
-/**
- * Returns 1 if the file is empty or does not exist, 0 otherwise.
- */
-static int is_empty_file(const char *filename)
-{
-	struct stat st;
-
-	if (stat(filename, &st) < 0) {
-		if (errno == ENOENT)
-			return 1;
-		die_errno(_("could not stat %s"), filename);
-	}
-
-	return !st.st_size;
-}
-
 /**
  * Returns the length of the first line of msg.
  */
@@ -1220,7 +1204,7 @@ static int parse_mail(struct am_state *state, const char *mail)
 		goto finish;
 	}
 
-	if (is_empty_file(am_path(state, "patch"))) {
+	if (is_empty_or_missing_file(am_path(state, "patch"))) {
 		printf_ln(_("Patch is empty."));
 		die_user_resolve(state);
 	}
@@ -1803,7 +1787,7 @@ static void am_run(struct am_state *state, int resume)
 		resume = 0;
 	}
 
-	if (!is_empty_file(am_path(state, "rewritten"))) {
+	if (!is_empty_or_missing_file(am_path(state, "rewritten"))) {
 		assert(state->rebasing);
 		copy_notes_for_rebase(state);
 		run_post_rewrite_hook(state);

cache.h

@@ -1788,4 +1788,7 @@ void safe_create_dir(const char *dir, int share);
  */
 extern int print_sha1_ellipsis(void);
 
+/* Return 1 if the file is empty or does not exists, 0 otherwise. */
+extern int is_empty_or_missing_file(const char *filename);
+
 #endif /* CACHE_H */

wrapper.c

@@ -690,3 +690,16 @@ int xgethostname(char *buf, size_t len)
 		buf[len - 1] = 0;
 	return ret;
 }
+
+int is_empty_or_missing_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		die_errno(_("could not stat %s"), filename);
+	}
+
+	return !st.st_size;
+}