[PATCH RFC 09/22] storage: Add API to check accessibility of storage volumes

[Peter Krempa <pkrempa@xxxxxxxxxx>]

Add a storage driver API equivalent ot the access() function.
Implementations for the filesystem and gluster backends are provided.
---
 src/storage/storage_backend.h         |  5 +++++
 src/storage/storage_backend_fs.c      | 13 +++++++++++++
 src/storage/storage_backend_gluster.c | 11 +++++++++++
 src/storage/storage_driver.c          | 24 ++++++++++++++++++++++++
 src/storage/storage_driver.h          |  1 +
 5 files changed, 54 insertions(+)

diff --git a/src/storage/storage_backend.h b/src/storage/storage_backend.h
index 5d71cde..56643fb 100644
--- a/src/storage/storage_backend.h
+++ b/src/storage/storage_backend.h
@@ -198,6 +198,10 @@ typedef ssize_t
 typedef const char *
 (*virStorageFileBackendGetUniqueIdentifier)(virStorageSourcePtr src);

+typedef int
+(*virStorageFileBackendAccess)(virStorageSourcePtr src,
+                               int mode);
+
 virStorageFileBackendPtr virStorageFileBackendForType(int type, int protocol);


@@ -220,6 +224,7 @@ struct _virStorageFileBackend {
     virStorageFileBackendCreate storageFileCreate;
     virStorageFileBackendUnlink storageFileUnlink;
     virStorageFileBackendStat   storageFileStat;
+    virStorageFileBackendAccess storageFileAccess;
 };

 #endif /* __VIR_STORAGE_BACKEND_H__ */
diff --git a/src/storage/storage_backend_fs.c b/src/storage/storage_backend_fs.c
index 1f436fa..85264a7 100644
--- a/src/storage/storage_backend_fs.c
+++ b/src/storage/storage_backend_fs.c
@@ -1439,6 +1439,15 @@ virStorageFileBackendFileGetUniqueIdentifier(virStorageSourcePtr src)
 }


+static int
+virStorageFileBackendFileAccess(virStorageSourcePtr src,
+                                int mode)
+{
+    return virFileAccessibleAs(src->path, mode,
+                               src->drv->uid, src->drv->gid);
+}
+
+
 virStorageFileBackend virStorageFileBackendFile = {
     .type = VIR_STORAGE_TYPE_FILE,

@@ -1448,6 +1457,7 @@ virStorageFileBackend virStorageFileBackendFile = {
     .storageFileUnlink = virStorageFileBackendFileUnlink,
     .storageFileStat = virStorageFileBackendFileStat,
     .storageFileReadHeader = virStorageFileBackendFileReadHeader,
+    .storageFileAccess = virStorageFileBackendFileAccess,

     .storageFileGetUniqueIdentifier = virStorageFileBackendFileGetUniqueIdentifier,
 };
@@ -1461,6 +1471,7 @@ virStorageFileBackend virStorageFileBackendBlock = {

     .storageFileStat = virStorageFileBackendFileStat,
     .storageFileReadHeader = virStorageFileBackendFileReadHeader,
+    .storageFileAccess = virStorageFileBackendFileAccess,

     .storageFileGetUniqueIdentifier = virStorageFileBackendFileGetUniqueIdentifier,
 };
@@ -1472,6 +1483,8 @@ virStorageFileBackend virStorageFileBackendDir = {
     .backendInit = virStorageFileBackendFileInit,
     .backendDeinit = virStorageFileBackendFileDeinit,

+    .storageFileAccess = virStorageFileBackendFileAccess,
+
     .storageFileGetUniqueIdentifier = virStorageFileBackendFileGetUniqueIdentifier,
 };

diff --git a/src/storage/storage_backend_gluster.c b/src/storage/storage_backend_gluster.c
index badffae..1a844c9 100644
--- a/src/storage/storage_backend_gluster.c
+++ b/src/storage/storage_backend_gluster.c
@@ -703,6 +703,16 @@ virStorageFileBackendGlusterReadHeader(virStorageSourcePtr src,
 }


+static int
+virStorageFileBackendGlusterAccess(virStorageSourcePtr src,
+                                   int mode)
+{
+    virStorageFileBackendGlusterPrivPtr priv = src->drv->priv;
+
+    return glfs_access(priv->vol, src->path, mode);
+}
+
+
 virStorageFileBackend virStorageFileBackendGluster = {
     .type = VIR_STORAGE_TYPE_NETWORK,
     .protocol = VIR_STORAGE_NET_PROTOCOL_GLUSTER,
@@ -713,4 +723,5 @@ virStorageFileBackend virStorageFileBackendGluster = {
     .storageFileUnlink = virStorageFileBackendGlusterUnlink,
     .storageFileStat = virStorageFileBackendGlusterStat,
     .storageFileReadHeader = virStorageFileBackendGlusterReadHeader,
+    .storageFileAccess = virStorageFileBackendGlusterAccess,
 };
diff --git a/src/storage/storage_driver.c b/src/storage/storage_driver.c
index 2fb70f2..dd58400 100644
--- a/src/storage/storage_driver.c
+++ b/src/storage/storage_driver.c
@@ -2990,3 +2990,27 @@ virStorageFileGetUniqueIdentifier(virStorageSourcePtr src)

     return src->drv->backend->storageFileGetUniqueIdentifier(src);
 }
+
+
+/**
+ * virStorageFileAccess: Check accessability of a storage file
+ *
+ * @src: storage file to check access permissions
+ * @mode: accessibility check options (see man 2 access)
+ *
+ * Returns 0 on success, -1 on error and sets errno. No libvirt
+ * error is reported. Returns -2 if the operation isn't supported
+ * by libvirt storage backend.
+ */
+int
+virStorageFileAccess(virStorageSourcePtr src,
+                     int mode)
+{
+    if (!virStorageFileIsInitialized(src) ||
+        !src->drv->backend->storageFileAccess) {
+        errno = ENOSYS;
+        return -2;
+    }
+
+    return src->drv->backend->storageFileAccess(src, mode);
+}
diff --git a/src/storage/storage_driver.h b/src/storage/storage_driver.h
index 9280ef0..5452df2 100644
--- a/src/storage/storage_driver.h
+++ b/src/storage/storage_driver.h
@@ -42,6 +42,7 @@ ssize_t virStorageFileReadHeader(virStorageSourcePtr src,
                                  ssize_t max_len,
                                  char **buf);
 const char *virStorageFileGetUniqueIdentifier(virStorageSourcePtr src);
+int virStorageFileAccess(virStorageSourcePtr src, int mode);

 int storageRegister(void);

-- 
1.9.2

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