[PATCH v7 1/4] lib/igt_sysfs: Add engine list helpers

[Jonathan Cavitt <jonathan.cavitt@intel.com>]

Create two new helper functions, igt_sysfs_get_engine_list and
igt_sysfs_free_engine_list, that create and destroy lists of open
engines, respectively.  The list created by igt_sysfs_get_engine_list
can be used to iterate over the set of engines in sysfs/engines and must
be freed by igt_sysfs_free_engine_list after use.

Signed-off-by: Jonathan Cavitt <jonathan.cavitt@intel.com>
---
 lib/igt_sysfs.c | 54 +++++++++++++++++++++++++++++++++++++++++++++++++
 lib/igt_sysfs.h |  3 +++
 2 files changed, 57 insertions(+)

diff --git a/lib/igt_sysfs.c b/lib/igt_sysfs.c
index 00d5822fd3..3d2dd364cf 100644
--- a/lib/igt_sysfs.c
+++ b/lib/igt_sysfs.c
@@ -1307,6 +1307,60 @@ static uint16_t xe_get_engine_class(char *name)
 	return class;
 }
 
+/**
+ * igt_sysfs_get_engine_list:
+ * @engines: fd of the directory engine
+ * @size: pointer to store the size of the returned char pointer
+ *
+ * Iterates over sysfs/engines and returns an array of
+ * opened engines.  The user will be in charge of closing
+ * the opened engines.
+ *
+ * The number of opened engines will be saved to size.
+ */
+int *igt_sysfs_get_engine_list(int engines, int *size)
+{
+	struct dirent *de;
+	DIR *dir;
+	int* ret = calloc(1, sizeof(int));
+
+	lseek(engines, 0, SEEK_SET);
+
+	dir = fdopendir(engines);
+	if (!dir)
+		close(engines);
+
+	*size = 0;
+	while ((de = readdir(dir))) {
+		if (*de->d_name == '.')
+			continue;
+		ret[*size] = openat(engines, de->d_name, O_RDONLY);
+		if (ret[*size] < 0) {
+			ret[*size] = 0;
+			continue;
+		}
+		*size += 1;
+		reallocarray(ret, *size + 1, sizeof(int));
+	}
+	return ret;
+}
+
+/**
+ * igt_sysfs_free_engine_list:
+ * @list: list of opened engines
+ * @size: number of engines in list
+ *
+ * Helper for cleaning up after igt_sysfs_get_engine_list.
+ * Closes all engines in list before freeing the list.
+ */
+void igt_sysfs_free_engine_list(int *list, int size)
+{
+	int i;
+	for (i = 0; i < size; i++)
+		close(list[i]);
+	free(list);
+}
+
 /**
  * igt_sysfs_engines:
  * @xe: fd of the device
diff --git a/lib/igt_sysfs.h b/lib/igt_sysfs.h
index 54a4087918..ba0a74755c 100644
--- a/lib/igt_sysfs.h
+++ b/lib/igt_sysfs.h
@@ -168,6 +168,9 @@ typedef struct igt_sysfs_rw_attr {
 
 void igt_sysfs_rw_attr_verify(igt_sysfs_rw_attr_t *rw);
 
+int *igt_sysfs_get_engine_list(int engines, int *size);
+void igt_sysfs_free_engine_list(int *list, int size);
+
 void igt_sysfs_engines(int xe, int engines, int gt, bool all, const char **property,
 		       void (*test)(int, int, const char **, uint16_t, int));
 
-- 
2.43.0