app/test: create files from resources

A resource can be written into the target filesystem by calling
resource_fwrite or resource_fwrite_file. Such file can be created
before a test is started and removed after the test finishes.

Signed-off-by: Jan Viktorin <viktorin@rehivetech.com>

app/test/resource.c

@@ -31,6 +31,7 @@
  *   OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
+#include <stdio.h>
 #include <string.h>
 #include <errno.h>
 #include <sys/queue.h>
@@ -60,6 +61,40 @@ const struct resource *resource_find(const char *name)
 	return NULL;
 }
 
+int resource_fwrite(const struct resource *r, FILE *f)
+{
+	const size_t goal = resource_size(r);
+	size_t total = 0;
+
+	while (total < goal) {
+		size_t wlen = fwrite(r->begin + total, 1, goal - total, f);
+		if (wlen == 0) {
+			perror(__func__);
+			return -1;
+		}
+
+		total += wlen;
+	}
+
+	return 0;
+}
+
+int resource_fwrite_file(const struct resource *r, const char *fname)
+{
+	FILE *f;
+	int ret;
+
+	f = fopen(fname, "w");
+	if (f == NULL) {
+		perror(__func__);
+		return -1;
+	}
+
+	ret = resource_fwrite(r, f);
+	fclose(f);
+	return ret;
+}
+
 void resource_register(struct resource *r)
 {
 	TAILQ_INSERT_TAIL(&resource_list, r, next);

app/test/resource.h

@@ -45,6 +45,7 @@
  */
 
 #include <sys/queue.h>
+#include <stdio.h>
 #include <stddef.h>
 
 #include <rte_eal.h>
@@ -74,6 +75,19 @@ size_t resource_size(const struct resource *r);
  */
 const struct resource *resource_find(const char *name);
 
+/**
+ * Write the raw data of the resource to the given file.
+ * @return 0 on success
+ */
+int resource_fwrite(const struct resource *r, FILE *f);
+
+/**
+ * Write the raw data of the resource to the given file given by name.
+ * The name is relative to the current working directory.
+ * @return 0 on success
+ */
+int resource_fwrite_file(const struct resource *r, const char *fname);
+
 /**
  * Register a resource in the global list of resources.
  * Not intended for direct use, please check the REGISTER_RESOURCE

app/test/test_resource.c

@@ -65,6 +65,7 @@ REGISTER_LINKED_RESOURCE(test_resource_c);
 static int test_resource_c(void)
 {
 	const struct resource *r;
+	FILE *f;
 
 	r = resource_find("test_resource_c");
 	TEST_ASSERT_NOT_NULL(r, "No test_resource_c found");
@@ -72,6 +73,15 @@ static int test_resource_c(void)
 			"Found resource %s, expected test_resource_c",
 			r->name);
 
+	TEST_ASSERT_SUCCESS(resource_fwrite_file(r, "test_resource.c"),
+			"Failed to to write file %s", r->name);
+
+	f = fopen("test_resource.c", "r");
+	TEST_ASSERT_NOT_NULL(f,
+			"Missing extracted file resource.c");
+	fclose(f);
+	remove("test_resource.c");
+
 	return 0;
 }