argv-array: add detach function

The usual pattern for an argv array is to initialize it,
push in some strings, and then clear it when done. Very
occasionally, though, we must do other exotic things with
the memory, like freeing the list but keeping the strings.
Let's provide a detach function so that callers can make use
of our API to build up the array, and then take ownership of
it.

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

diff --git a/Documentation/technical/api-argv-array.txt b/Documentation/technical/api-argv-array.txt
index 8076172a08ce0dfc80e9656cd1ee7712c32c1d3e..cfc063018c996a61b333b38d7b387f40b21e7a00 100644 (file)
--- a/Documentation/technical/api-argv-array.txt
+++ b/Documentation/technical/api-argv-array.txt
@@ -56,3 +56,10 @@ Functions
 `argv_array_clear`::
        Free all memory associated with the array and return it to the
        initial, empty state.
+
+`argv_array_detach`::
+       Disconnect the `argv` member from the `argv_array` struct and
+       return it. The caller is responsible for freeing the memory used
+       by the array, and by the strings it references. After detaching,
+       the `argv_array` is in a reinitialized state and can be pushed
+       into again.

diff --git a/argv-array.c b/argv-array.c
index eaed47712b44ed1a5f9e5d35d356d0de4a5a4d54..5d370fa3366163f8c0c81ca0b6b1a64a7030c696 100644 (file)
--- a/argv-array.c
+++ b/argv-array.c
@@ -74,3 +74,14 @@ void argv_array_clear(struct argv_array *array)
        }
        argv_array_init(array);
 }
+
+const char **argv_array_detach(struct argv_array *array)
+{
+       if (array->argv == empty_argv)
+               return xcalloc(1, sizeof(const char *));
+       else {
+               const char **ret = array->argv;
+               argv_array_init(array);
+               return ret;
+       }
+}

diff --git a/argv-array.h b/argv-array.h
index a2fa0aa606a01d5277e87d2368d7d6876b699474..29056e49a1208b5506d0809c7311e4112dc1f7f3 100644 (file)
--- a/argv-array.h
+++ b/argv-array.h
@@ -20,5 +20,6 @@ void argv_array_pushl(struct argv_array *, ...);
 void argv_array_pushv(struct argv_array *, const char **);
 void argv_array_pop(struct argv_array *);
 void argv_array_clear(struct argv_array *);
+const char **argv_array_detach(struct argv_array *);
 
 #endif /* ARGV_ARRAY_H */