blockdev-util: add correct API for detecting if block device has partition scanning...

Instead of checking the loopback ioctls, let's check sysfs, so that we
catch all kinds of block devices, not just loopback block devices.

diff --git a/src/basic/blockdev-util.c b/src/basic/blockdev-util.c
index 5f8212685b7781522fec1e7bf82ee2246d0c068c..21ff3ba1b13c018ac283476216d308b12585b19b 100644 (file)
--- a/src/basic/blockdev-util.c
+++ b/src/basic/blockdev-util.c
@@ -214,3 +214,40 @@ int lock_whole_block_device(dev_t devt, int operation) {
 
         return TAKE_FD(lock_fd);
 }
+
+int blockdev_partscan_enabled(int fd) {
+        _cleanup_free_ char *p = NULL, *buf = NULL;
+        unsigned long long ull;
+        struct stat st;
+        int r;
+
+        /* Checks if partition scanning is correctly enabled on the block device */
+
+        if (fstat(fd, &st) < 0)
+                return -errno;
+
+        if (!S_ISBLK(st.st_mode))
+                return -ENOTBLK;
+
+        if (asprintf(&p, "/sys/dev/block/%u:%u/capability", major(st.st_rdev), minor(st.st_rdev)) < 0)
+                return -ENOMEM;
+
+        r = read_one_line_file(p, &buf);
+        if (r == -ENOENT) /* If the capability file doesn't exist then we are most likely looking at a
+                           * partition block device, not the whole block device. And that means we have no
+                           * partition scanning on for it (we do for its parent, but not for the partition
+                           * itself). */
+                return false;
+        if (r < 0)
+                return r;
+
+        r = safe_atollu_full(buf, 16, &ull);
+        if (r < 0)
+                return r;
+
+#ifndef GENHD_FL_NO_PART_SCAN
+#define GENHD_FL_NO_PART_SCAN (0x0200)
+#endif
+
+        return !FLAGS_SET(ull, GENHD_FL_NO_PART_SCAN);
+}

diff --git a/src/basic/blockdev-util.h b/src/basic/blockdev-util.h
index 1e7588f71cab9f1d840fc7ba7e392da15c0ef333..58a7050f53b2f1e0eb993b7b769e4c97edf5bd10 100644 (file)
--- a/src/basic/blockdev-util.h
+++ b/src/basic/blockdev-util.h
@@ -20,3 +20,5 @@ int get_block_device(const char *path, dev_t *dev);
 int get_block_device_harder(const char *path, dev_t *dev);
 
 int lock_whole_block_device(dev_t devt, int operation);
+
+int blockdev_partscan_enabled(int fd);