dissect: split verity_dissect_and_mount helper out for reuse

src/core/namespace.c

@@ -962,75 +962,13 @@ static int mount_run(const MountEntry *m) {
 }
 
 static int mount_images(const MountEntry *m) {
-        _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
-        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
-        _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
-        _cleanup_(verity_settings_done) VeritySettings verity = VERITY_SETTINGS_DEFAULT;
-        DissectImageFlags dissect_image_flags;
         int r;
 
         assert(m);
 
-        r = verity_settings_load(&verity, mount_entry_source(m), NULL, NULL);
+        r = verity_dissect_and_mount(mount_entry_source(m), mount_entry_path(m), m->image_options);
         if (r < 0)
-                return log_debug_errno(r, "Failed to load root hash: %m");
-
-        dissect_image_flags =
-                (m->read_only ? DISSECT_IMAGE_READ_ONLY : 0) |
-                (verity.data_path ? DISSECT_IMAGE_NO_PARTITION_TABLE : 0);
-
-        r = loop_device_make_by_path(
-                        mount_entry_source(m),
-                        m->read_only ? O_RDONLY : -1 /* < 0 means writable if possible, read-only as fallback */,
-                        verity.data_path ? 0 : LO_FLAGS_PARTSCAN,
-                        &loop_device);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to create loop device for image: %m");
-
-        r = dissect_image(
-                        loop_device->fd,
-                        &verity,
-                        m->image_options,
-                        dissect_image_flags,
-                        &dissected_image);
-        /* No partition table? Might be a single-filesystem image, try again */
-        if (!verity.data_path && r == -ENOPKG)
-                 r = dissect_image(
-                                 loop_device->fd,
-                                 &verity,
-                                 m->image_options,
-                                 dissect_image_flags|DISSECT_IMAGE_NO_PARTITION_TABLE,
-                                 &dissected_image);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to dissect image: %m");
-
-        r = dissected_image_decrypt(
-                        dissected_image,
-                        NULL,
-                        &verity,
-                        dissect_image_flags,
-                        &decrypted_image);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to decrypt dissected image: %m");
-
-        r = mkdir_p_label(mount_entry_path(m), 0755);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to create destination directory %s: %m", mount_entry_path(m));
-        r = umount_recursive(mount_entry_path(m), 0);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to umount under destination directory %s: %m", mount_entry_path(m));
-
-        r = dissected_image_mount(dissected_image, mount_entry_path(m), UID_INVALID, dissect_image_flags);
-        if (r < 0)
-                return log_debug_errno(r, "Failed to mount image: %m");
-
-        if (decrypted_image) {
-                r = decrypted_image_relinquish(decrypted_image);
-                if (r < 0)
-                        return log_debug_errno(r, "Failed to relinquish decrypted image: %m");
-        }
-
-        loop_device_relinquish(loop_device);
+                return log_debug_errno(r, "Failed to mount image %s on %s: %m", mount_entry_source(m), mount_entry_path(m));
 
         return 1;
 }

src/shared/dissect-image.c

@@ -2554,4 +2554,77 @@ static const char *const partition_designator_table[] = {
         [PARTITION_VAR] = "var",
 };
 
+int verity_dissect_and_mount(const char *src, const char *dest, const MountOptions *options) {
+        _cleanup_(loop_device_unrefp) LoopDevice *loop_device = NULL;
+        _cleanup_(decrypted_image_unrefp) DecryptedImage *decrypted_image = NULL;
+        _cleanup_(dissected_image_unrefp) DissectedImage *dissected_image = NULL;
+        _cleanup_(verity_settings_done) VeritySettings verity = VERITY_SETTINGS_DEFAULT;
+        DissectImageFlags dissect_image_flags;
+        int r;
+
+        assert(src);
+        assert(dest);
+
+        r = verity_settings_load(&verity, src, NULL, NULL);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to load root hash: %m");
+
+        dissect_image_flags = verity.data_path ? DISSECT_IMAGE_NO_PARTITION_TABLE : 0;
+
+        r = loop_device_make_by_path(
+                        src,
+                        -1,
+                        verity.data_path ? 0 : LO_FLAGS_PARTSCAN,
+                        &loop_device);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to create loop device for image: %m");
+
+        r = dissect_image(
+                        loop_device->fd,
+                        &verity,
+                        options,
+                        dissect_image_flags,
+                        &dissected_image);
+        /* No partition table? Might be a single-filesystem image, try again */
+        if (!verity.data_path && r == -ENOPKG)
+                 r = dissect_image(
+                                loop_device->fd,
+                                &verity,
+                                options,
+                                dissect_image_flags|DISSECT_IMAGE_NO_PARTITION_TABLE,
+                                &dissected_image);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to dissect image: %m");
+
+        r = dissected_image_decrypt(
+                        dissected_image,
+                        NULL,
+                        &verity,
+                        dissect_image_flags,
+                        &decrypted_image);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to decrypt dissected image: %m");
+
+        r = mkdir_p_label(dest, 0755);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to create destination directory %s: %m", dest);
+        r = umount_recursive(dest, 0);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to umount under destination directory %s: %m", dest);
+
+        r = dissected_image_mount(dissected_image, dest, UID_INVALID, dissect_image_flags);
+        if (r < 0)
+                return log_debug_errno(r, "Failed to mount image: %m");
+
+        if (decrypted_image) {
+                r = decrypted_image_relinquish(decrypted_image);
+                if (r < 0)
+                        return log_debug_errno(r, "Failed to relinquish decrypted image: %m");
+        }
+
+        loop_device_relinquish(loop_device);
+
+        return 0;
+}
+
 DEFINE_STRING_TABLE_LOOKUP(partition_designator, PartitionDesignator);

src/shared/dissect-image.h

@@ -161,3 +161,5 @@ bool dissected_image_can_do_verity(const DissectedImage *image, PartitionDesigna
 bool dissected_image_has_verity(const DissectedImage *image, PartitionDesignator d);
 
 int mount_image_privately_interactively(const char *path, DissectImageFlags flags, char **ret_directory, LoopDevice **ret_loop_device, DecryptedImage **ret_decrypted_image);
+
+int verity_dissect_and_mount(const char *src, const char *dest, const MountOptions *options);