[PATCH v2 3/6] wrapper: move is_empty_file() from builtin/am.c

[Pranit Bauva <pranit.bauva@gmail.com>]

is_empty_file() can help to refactor a lot of code. Also it is quite
helpful while converting shell scripts which use `test -s`. Since
is_empty_file() is now a "library" function, its inappropriate to die() so
instead error_errno() is used to convey the message to stderr while the
appropriate boolean value is returned.

Suggested-by: Torsten Bögershausen <tboegi@web.de>
Mentored-by: Lars Schneider <larsxschneider@gmail.com>
Mentored-by: Christian Couder <chriscool@tuxfamily.org>
Signed-off-by: Pranit Bauva <pranit.bauva@gmail.com>
---
 builtin/am.c | 16 ----------------
 cache.h      |  3 +++
 wrapper.c    | 13 +++++++++++++
 3 files changed, 16 insertions(+), 16 deletions(-)

diff --git a/builtin/am.c b/builtin/am.c
index 3dfe70b..84f21d0 100644
--- a/builtin/am.c
+++ b/builtin/am.c
@@ -30,22 +30,6 @@
 #include "mailinfo.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.
  */
 static int linelen(const char *msg)
diff --git a/cache.h b/cache.h
index 6049f86..8eaad70 100644
--- a/cache.h
+++ b/cache.h
@@ -1870,4 +1870,7 @@ void sleep_millisec(int millisec);
  */
 void safe_create_dir(const char *dir, int share);
 
+/* Return 1 if the file is empty or does not exists, 0 otherwise. */
+extern int is_empty_file(const char *filename);
+
 #endif /* CACHE_H */
diff --git a/wrapper.c b/wrapper.c
index 5dc4e15..36a3eeb 100644
--- a/wrapper.c
+++ b/wrapper.c
@@ -696,3 +696,16 @@ void sleep_millisec(int millisec)
 {
 	poll(NULL, 0, millisec);
 }
+
+int is_empty_file(const char *filename)
+{
+	struct stat st;
+
+	if (stat(filename, &st) < 0) {
+		if (errno == ENOENT)
+			return 1;
+		error_errno(_("could not stat %s"), filename);
+	}
+
+	return !st.st_size;
+}
-- 
2.9.0