- Add a new ioctl for getting the provider name of a geom provider.

- Add a routine for looking up a device and checking if it is a valid geom
  provider given a partial or full path to its device node.

Reviewed by:	phk
Approved by:	pjd (mentor)

lib/libgeom/geom_util.c

@@ -42,29 +42,22 @@ __FBSDID("$FreeBSD$");
 
 #include <libgeom.h>
 
+static char	*g_device_path_open(const char *, int *, int);
+
 /*
  * Open the given provider and at least check if this is a block device.
  */
 int
 g_open(const char *name, int dowrite)
 {
-	char path[MAXPATHLEN];
+	char *path;
 	int fd;
 
-	if (name[0] == '/')
-		strlcpy(path, name, sizeof(path));
-	else
-		snprintf(path, sizeof(path), "%s%s", _PATH_DEV, name);
-
-	fd = open(path, dowrite ? O_RDWR : O_RDONLY);
+	path = g_device_path_open(name, &fd, dowrite);
+	if (path != NULL)
+		free(path);
 	if (fd == -1)
 		return (-1);
-	/* Let try to get sectorsize, which will prove it is a GEOM provider. */
-	if (g_sectorsize(fd) == -1) {
-		close(fd);
-		errno = EFTYPE;
-		return (-1);
-	}
 	return (fd);
 }
 
@@ -120,6 +113,19 @@ g_sectorsize(int fd)
 	return ((ssize_t)sectorsize);
 }
 
+/*
+ * Return the correct provider name.
+ */
+char *
+g_providername(int fd)
+{
+	char name[MAXPATHLEN];
+
+	if (g_ioctl_arg(fd, DIOCGPROVIDERNAME, name) == -1)
+		return (NULL);
+	return (strdup(name));
+}
+
 /*
  * Call BIO_FLUSH for the given provider.
  */
@@ -234,3 +240,77 @@ end:
 	}
 	return (fd);
 }
+
+/*
+ * Return the device path device given a partial or full path to its node.
+ * A pointer can be provided, which will be set to an opened file descriptor of
+ * not NULL.
+ */
+static char *
+g_device_path_open(const char *devpath, int *fdp, int dowrite)
+{
+	char *path;
+	int fd;
+
+	/* Make sure that we can fail. */
+	if (fdp != NULL)
+		*fdp = -1;
+	/* Use the device node if we're able to open it. */
+	do {
+		fd = open(devpath, dowrite ? O_RDWR : O_RDONLY);
+		if (fd == -1)
+			break;
+		/*
+		 * Let try to get sectorsize, which will prove it is a GEOM
+		 * provider. 
+		 */
+		if (g_sectorsize(fd) == -1) {
+			close(fd);
+			errno = EFTYPE;
+			return (NULL);
+		}
+		if ((path = strdup(devpath)) == NULL) {
+			close(fd);
+			return (NULL);
+		}
+		if (fdp != NULL)
+			*fdp = fd;
+		else
+			close(fd);
+		return (path);
+	} while (0);
+
+	/* If we're not given an absolute path, assume /dev/ prefix. */
+	if (*devpath != '/') {
+		asprintf(&path, "%s%s", _PATH_DEV, devpath);
+		if (path == NULL)
+			return (NULL);
+		fd = open(path, dowrite ? O_RDWR : O_RDONLY);
+		if (fd == -1) {
+			free(path);
+			return (NULL);
+		}
+		/*
+		 * Let try to get sectorsize, which will prove it is a GEOM
+		 * provider.
+		 */
+		if (g_sectorsize(fd) == -1) {
+			free(path);
+			close(fd);
+			errno = EFTYPE;
+			return (NULL);
+		}
+		if (fdp != NULL)
+			*fdp = fd;
+		else
+			close(fd);
+		return (path);
+	}
+	return (NULL);
+}
+
+char *
+g_device_path(const char *devpath)
+{
+	return (g_device_path_open(devpath, NULL, 0));
+}

lib/libgeom/libgeom.h

@@ -154,6 +154,8 @@ int g_delete(int, off_t, off_t);
 int g_get_ident(int, char *, size_t);
 int g_get_name(const char *, char *, size_t);
 int g_open_by_ident(const char *, int, char *, size_t);
+char *g_device_path(const char *);
+char *g_providername(int);
 
 __END_DECLS
 

sys/geom/geom_dev.c

@@ -244,6 +244,7 @@ g_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread
 {
 	struct g_geom *gp;
 	struct g_consumer *cp;
+	struct g_provider *pp;
 	struct g_kerneldump kd;
 	off_t offset, length, chunk;
 	int i, error;
@@ -251,6 +252,7 @@ g_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread
 
 	gp = dev->si_drv1;
 	cp = dev->si_drv2;
+	pp = cp->provider;
 
 	error = 0;
 	KASSERT(cp->acr || cp->acw,
@@ -329,6 +331,11 @@ g_dev_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int fflag, struct thread
 	case DIOCGIDENT:
 		error = g_io_getattr("GEOM::ident", cp, &i, data);
 		break;
+	case DIOCGPROVIDERNAME:
+		if (pp == NULL)
+			return (ENOENT);
+		strlcpy(data, pp->name, i);
+		break;
 
 	default:
 		if (cp->provider->geom->ioctl != NULL) {

sys/sys/disk.h

@@ -98,4 +98,10 @@ void disk_err(struct bio *bp, const char *what, int blkdone, int nl);
 	 * - ident is optional and applications can't relay on its presence.
 	 */
 
+#define DIOCGPROVIDERNAME _IOR('d', 138, char[MAXPATHLEN])
+	/*-
+	 * Store the provider name, given a device path, in a buffer. The buffer
+	 * must be at least MAXPATHLEN bytes long.
+	 */
+
 #endif /* _SYS_DISK_H_ */