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-rw-r--r--libgamma_linux_drm_site_initialise.c42
1 files changed, 42 insertions, 0 deletions
diff --git a/libgamma_linux_drm_site_initialise.c b/libgamma_linux_drm_site_initialise.c
new file mode 100644
index 0000000..81f6e12
--- /dev/null
+++ b/libgamma_linux_drm_site_initialise.c
@@ -0,0 +1,42 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Initialise an allocated site state
+ *
+ * @param this The site state to initialise
+ * @param site The site identifier, unless it is `NULL` it must a
+ * `free`:able. Once the state is destroyed the library
+ * will attempt to free it. There you should not free
+ * it yourself, and it must not be a string constant
+ * or allocate on the stack. Note however that it will
+ * not be free:d if this function fails.
+ * @return Zero on success, otherwise (negative) the value of an
+ * error identifier provided by this library
+ */
+int
+libgamma_linux_drm_site_initialise(libgamma_site_state_t *restrict this, char *restrict site)
+{
+ char pathname[PATH_MAX];
+ struct stat _attr;
+
+ if (site)
+ return LIBGAMMA_NO_SUCH_SITE;
+
+ /* Count the number of available graphics cards by
+ `stat`:ing their existence in an API filesystem */
+ this->partitions_available = 0;
+ for (;;) {
+ /* Construct pathname of graphics card device */
+ snprintf(pathname, sizeof(pathname) / sizeof(char),
+ DRM_DEV_NAME, DRM_DIR_NAME, (int)(this->partitions_available));
+ /* `stat` the graphics card's existence */
+ if (stat(pathname, &_attr))
+ break;
+ /* Move on to next graphics card */
+ if (this->partitions_available++ > INT_MAX)
+ return LIBGAMMA_IMPOSSIBLE_AMOUNT;
+ }
+ return 0;
+}