misc

Signed-off-by: Mattias Andrée <maandree@kth.se>

1 files changed, 151 insertions, 0 deletions

diff --git a/libgamma_linux_drm_partition_initialise.c b/libgamma_linux_drm_partition_initialise.c
new file mode 100644
index 0000000..02cfffc
--- /dev/null
+++ b/libgamma_linux_drm_partition_initialise.c
@@ -0,0 +1,151 @@
+/* See LICENSE file for copyright and license details. */
+#include "common.h"
+
+
+/**
+ * Figure out why `open` failed for a graphics card
+ * 
+ * @param   pathname  The pathname of the error card
+ * @return            The error code to report
+ */
+static int
+figure_out_card_open_error(const char *pathname)
+{
+	char buf[1024]; /* My output of `sysconf(_SC_GETGR_R_SIZE_MAX)`. */
+	gid_t supplemental_groups[NGROUPS_MAX];
+	struct group *group, _grp;
+	struct stat attr;
+	int i, n;
+
+
+	/* Check which the device exists */
+	if (errno == ENXIO || errno == ENODEV)
+		return LIBGAMMA_NO_SUCH_PARTITION;
+
+
+	/* If we did not get access permission, figure out why */
+
+	if (errno != EACCES) {
+		/* If we could not figure out what went
+		 * wrong, just return the error we got */
+		return LIBGAMMA_ERRNO_SET;
+	}
+
+#define __test(R, W) ((attr.st_mode & ((R) | (W))) == ((R) | (W)))
+
+	/* Get permission requirement for the file */
+	if (stat(pathname, &attr))
+		return errno == EACCES ? LIBGAMMA_NO_SUCH_PARTITION : LIBGAMMA_ERRNO_SET;
+
+	/* Test owner's, group's and others' permissions */
+	if ((attr.st_uid == geteuid() && __test(S_IRUSR, S_IWUSR)) ||
+	    (attr.st_gid == getegid() && __test(S_IRGRP, S_IWGRP)) || __test(S_IROTH, S_IWOTH))
+		return LIBGAMMA_DEVICE_ACCESS_FAILED;
+
+	/* The group should be "video", but perhaps
+	   it is "root" to restrict users */
+	if (!attr.st_gid /* root group */ || __test(S_IRGRP, S_IWGRP))
+		return LIBGAMMA_DEVICE_RESTRICTED;
+
+
+	/* Get the user's supplemental group membership list */
+	n = getgroups(NGROUPS_MAX, supplemental_groups);
+	if (n < 0)
+		return LIBGAMMA_ERRNO_SET;
+
+	/* Test whether any of the supplemental
+	   group should be satisfactory */
+	for (i = 0; i < n; i++)
+		if (supplemental_groups[i] == attr.st_gid)
+			break;
+
+	/* If one of the supplemental groups should be satisfactory,
+	   then we do not know anything more than that access failed */
+	if (i != n)
+		return LIBGAMMA_DEVICE_ACCESS_FAILED;
+
+	/* Otherwise, try to get the name of the group that is
+	   required and report the missing group membership */ 
+	errno = getgrgid_r(attr.st_gid, &_grp, buf, sizeof(buf) / sizeof(char), &group);
+	if (errno == ERANGE) {
+		/* The lenght of the group's name is absurdly long, degrade to thread-unsafe. */
+		errno = 0;
+		group = getgrgid(attr.st_gid);
+	} else if (errno) {
+		return LIBGAMMA_ERRNO_SET;
+	}
+
+	libgamma_group_gid_set(attr.st_gid);
+	libgamma_group_name_set(group ? group->gr_name : NULL);
+	return LIBGAMMA_DEVICE_REQUIRE_GROUP;
+#undef __test
+}
+
+
+/**
+ * Initialise an allocated partition state
+ * 
+ * @param   this       The partition state to initialise
+ * @param   site       The site state for the site that the partition belongs to
+ * @param   partition  The the index of the partition within the site
+ * @return             Zero on success, otherwise (negative) the value of an
+ *                     error identifier provided by this library
+ */
+int
+libgamma_linux_drm_partition_initialise(libgamma_partition_state_t *restrict this,
+                                        libgamma_site_state_t *restrict site, size_t partition)
+{
+	int rc = 0;
+	libgamma_drm_card_data_t *restrict data;
+	char pathname[PATH_MAX];
+
+	(void) site;
+
+	/* Check for partition index overflow */
+	if (partition > INT_MAX)
+		return LIBGAMMA_NO_SUCH_PARTITION;
+
+	/* Allocate and initialise graphics card data */
+	this->data = NULL;
+	data = malloc(sizeof(libgamma_drm_card_data_t));
+	if (!data)
+		return LIBGAMMA_ERRNO_SET;
+	data->fd = -1;
+	data->res = NULL;
+	data->encoders = NULL;
+	data->connectors = NULL;
+  
+	/* Get the pathname for the graphics card */
+	snprintf(pathname, sizeof(pathname) / sizeof(char), DRM_DEV_NAME, DRM_DIR_NAME, (int)partition);
+
+	/* Acquire access to the graphics card */
+	data->fd = open(pathname, O_RDWR | O_CLOEXEC);
+	if (data->fd < 0) {
+		rc = figure_out_card_open_error(pathname);
+		goto fail_data;
+	}
+
+	/* Acquire mode resources */
+	data->res = drmModeGetResources(data->fd);
+	if (!data->res) {
+		rc = LIBGAMMA_ACQUIRING_MODE_RESOURCES_FAILED;
+		goto fail_fd;
+	}
+
+	/* Get the number of CRTC:s that are available in the partition */
+	if (data->res->count_crtcs < 0) {
+		rc = LIBGAMMA_NEGATIVE_CRTC_COUNT;
+		goto fail_res;
+	}
+	this->crtcs_available = (size_t)data->res->count_crtcs;
+	this->data = data;
+	return 0;
+
+fail_res:
+	drmModeFreeResources(data->res);
+fail_fd:
+	close(data->fd);
+fail_data:
+	free(data);
+	return rc;
+}