sd-device: add sd_device_new_from_syspath

Also add device_set_syspath, which does all sanity checking, unlike in libudev
where it only does some.

1 files changed, 113 insertions, 2 deletions

diff --git a/src/libsystemd/sd-device/sd-device.c b/src/libsystemd/sd-device/sd-device.c
index 715eae469..eca378fe3 100644
--- a/src/libsystemd/sd-device/sd-device.c
+++ b/src/libsystemd/sd-device/sd-device.c
@@ -18,13 +18,25 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include <ctype.h>
+
+#include "util.h"
 #include "refcnt.h"
+#include "path-util.h"
+#include "strxcpyx.h"
 
 #include "sd-device.h"
 
+#include "device-util.h"
+
 struct sd_device {
         RefCount n_ref;
-}
+
+        char *syspath;
+        const char *devpath;
+        char *sysname;
+        const char *sysnum;
+};
 
 static int device_new(sd_device **ret) {
         _cleanup_device_unref_ sd_device *device = NULL;
@@ -51,8 +63,107 @@ _public_ sd_device *sd_device_ref(sd_device *device) {
 }
 
 _public_ sd_device *sd_device_unref(sd_device *device) {
-        if (device && REFCNT_DEC(device->n_ref) <= 0)
+        if (device && REFCNT_DEC(device->n_ref) <= 0) {
+                free(device->syspath);
+                free(device->sysname);
                 free(device);
+        }
 
         return NULL;
 }
+
+static int device_set_syspath(sd_device *device, const char *_syspath) {
+        _cleanup_free_ char *syspath = NULL, *sysname = NULL;
+        const char *devpath, *sysnum;
+        const char *pos;
+        size_t len = 0;
+        int r;
+
+        assert(device);
+        assert(_syspath);
+
+        /* must be a subdirectory of /sys */
+        if (!path_startswith(_syspath, "/sys/"))
+                return -EINVAL;
+
+        r = readlink_and_canonicalize(_syspath, &syspath);
+        if (r < 0)
+                return r;
+
+        devpath = syspath + strlen("/sys");
+
+        if (path_startswith(devpath,  "/devices/")) {
+                char *path;
+
+                /* all 'devices' require an 'uevent' file */
+                path = strappenda(syspath, "/uevent");
+                r = access(path, F_OK);
+                if (r < 0)
+                        return -errno;
+        } else
+                /* everything else just just needs to be a directory */
+                if (!is_dir(syspath, false))
+                        return -EINVAL;
+
+        pos = strrchr(syspath, '/');
+        if (!pos)
+                return -EINVAL;
+        pos ++;
+
+        /* devpath is not a root directory */
+        if (*pos == '\0' || pos <= devpath)
+                return -EINVAL;
+
+        sysname = strdup(pos);
+        if (!sysname)
+                return -ENOMEM;
+
+        /* some devices have '!' in their name, change that to '/' */
+        while (sysname[len] != '\0') {
+                if (sysname[len] == '!')
+                        sysname[len] = '/';
+
+                len ++;
+        }
+
+        /* trailing number */
+        while (len > 0 && isdigit(sysname[--len]))
+                sysnum = &sysname[len];
+
+        if (len == 0)
+                sysnum = NULL;
+
+        free(device->syspath);
+        device->syspath = syspath;
+        syspath = NULL;
+
+        free(device->sysname);
+        device->sysname = sysname;
+        sysname = NULL;
+
+        device->devpath = devpath;
+        device->sysnum = sysnum;
+
+        return 0;
+}
+
+_public_ int sd_device_new_from_syspath(sd_device **ret, const char *syspath) {
+        _cleanup_device_unref_ sd_device *device = NULL;
+        int r;
+
+        assert_return(ret, -EINVAL);
+        assert_return(syspath, -EINVAL);
+
+        r = device_new(&device);
+        if (r < 0)
+                return r;
+
+        r = device_set_syspath(device, syspath);
+        if (r < 0)
+                return r;
+
+        *ret = device;
+        device = NULL;
+
+        return 0;
+}