dfs: refine code

decrease indentation to make cleaner code
fix mkfs bug when there is no mkfs implementation

components/dfs/src/dfs_fs.c

@@ -103,25 +103,21 @@ struct dfs_filesystem *dfs_filesystem_lookup(const char *path)
     /* lookup it in the filesystem table */
     for (index = 0; index < DFS_FILESYSTEMS_MAX; index++)
     {
-        if (filesystem_table[index].path == RT_NULL)
+        if ((filesystem_table[index].path == RT_NULL)
+            || (filesystem_table[index].ops == RT_NULL))
             continue;
-        else
-        {
-            fspath = strlen(filesystem_table[index].path);
-            if (fspath < prefixlen)
-                continue;
-        }
 
-        if ((filesystem_table[index].ops != RT_NULL) &&
-            (strncmp(filesystem_table[index].path, path, fspath) == 0))
-        {
-            /* check next path separator */
-            if (fspath > 1 && (strlen(path) > fspath) && (path[fspath] != '/'))
-                continue;
+        fspath = strlen(filesystem_table[index].path);
+        if ((fspath < prefixlen)
+            || (strncmp(filesystem_table[index].path, path, fspath) != 0))
+            continue;
 
-            fs = &filesystem_table[index];
-            prefixlen = fspath;
-        }
+        /* check next path separator */
+        if (fspath > 1 && (strlen(path) > fspath) && (path[fspath] != '/'))
+            continue;
+
+        fs = &filesystem_table[index];
+        prefixlen = fspath;
     }
 
     dfs_unlock();
@@ -147,64 +143,42 @@ rt_err_t dfs_filesystem_get_partition(struct dfs_partition *part,
 
     rt_uint8_t *dpt;
     rt_uint8_t type;
-    rt_err_t result;
 
     RT_ASSERT(part != RT_NULL);
     RT_ASSERT(buf != RT_NULL);
 
-    result = RT_EOK;
-
     dpt = buf + DPT_ADDRESS + pindex * DPT_ITEM_SIZE;
 
+    /* check if it is a valid partition table */
     if ((*dpt != 0x80) && (*dpt != 0x00))
-    {
-        /* which is not a partition table */
-        result = -RT_ERROR;
-
-        return result;
-    }
+        return -RT_ERROR;
 
     /* get partition type */
     type = *(dpt+4);
-
-    if (type != 0)
-    {
-        /* set partition type */
-        part->type = type;
-
-        /* get partition offset and size */
-        part->offset = *(dpt+8) | *(dpt+9)<<8 | *(dpt+10)<<16 | *(dpt+11)<<24;
-        part->size = *(dpt+12) | *(dpt+13)<<8 | *(dpt+14)<<16 | *(dpt+15)<<24;
-
-        rt_kprintf("found part[%d], begin: %d, size: ",
-                   pindex, part->offset*512);
-        if ((part->size>>11) > 0) /* MB */
-        {
-            unsigned int part_size;
-            part_size = part->size >> 11;/* MB */
-            if ((part_size>>10) > 0) /* GB */
-            {
-                /* GB */
-                rt_kprintf("%d.%d%s",part_size>>10,part_size&0x3FF,"GB\r\n");
-            }
-            else
-            {
-                /* MB */
-                rt_kprintf("%d.%d%s",part_size,(part->size>>1)&0x3FF,"MB\r\n");
-            }
-        }
-        else
-        {
-            /* KB */
-            rt_kprintf("%d%s",part->size>>1,"KB\r\n");
-        }
-    }
+    if (type == 0)
+        return -RT_ERROR;
+
+    /* set partition information
+     *    size is the number of 512-Byte */
+    part->type = type;
+    part->offset = *(dpt+8) | *(dpt+9)<<8 | *(dpt+10)<<16 | *(dpt+11)<<24;
+    part->size = *(dpt+12) | *(dpt+13)<<8 | *(dpt+14)<<16 | *(dpt+15)<<24;
+
+    rt_kprintf("found part[%d], begin: %d, size: ",
+               pindex, part->offset*512);
+    if ((part->size>>11) == 0)
+        rt_kprintf("%d%s",part->size>>1,"KB\n");     /* KB */
     else
     {
-        result = -RT_ERROR;
+        unsigned int part_size;
+        part_size = part->size >> 11;                /* MB */
+        if ((part_size>>10) == 0)
+            rt_kprintf("%d.%d%s",part_size,(part->size>>1)&0x3FF,"MB\n");
+        else
+            rt_kprintf("%d.%d%s",part_size>>10,part_size&0x3FF,"GB\n");
     }
 
-    return result;
+    return RT_EOK;
 }
 
 /**
@@ -231,21 +205,16 @@ int dfs_mount(const char   *device_name,
     int index, free_index;
 
     /* open specific device */
-    if (device_name != RT_NULL)
+    if (device_name == RT_NULL)
     {
-        dev_id = rt_device_find(device_name);
-        if (dev_id == RT_NULL)
-        {
-            /* no this device */
-            rt_set_errno(-DFS_STATUS_ENODEV);
-
-            return -1;
-        }
+        /* which is a non-device filesystem mount */
+        dev_id = NULL;
     }
-    else
+    else if ((dev_id = rt_device_find(device_name)) == RT_NULL)
     {
-        /* which is a non-device filesystem mount */
-        dev_id = RT_NULL;
+        /* no this device */
+        rt_set_errno(-DFS_STATUS_ENODEV);
+        return -1;
     }
 
     /* find out specific filesystem */
@@ -264,17 +233,22 @@ int dfs_mount(const char   *device_name,
     if (index == DFS_FILESYSTEM_TYPES_MAX)
     {
         rt_set_errno(-DFS_STATUS_ENODEV);
-
         return -1;
     }
+
+    /* check if there is mount implementation */
     ops = filesystem_operation_table[index];
+    if ((ops == NULL) || (ops->mount == NULL))
+    {
+        rt_set_errno(-DFS_STATUS_ENOSYS);
+        return -1;
+    }
 
     /* make full path for special file */
     fullpath = dfs_normalize_path(RT_NULL, path);
     if (fullpath == RT_NULL) /* not an abstract path */
     {
         rt_set_errno(-DFS_STATUS_ENOTDIR);
-
         return -1;
     }
 
@@ -293,8 +267,8 @@ int dfs_mount(const char   *device_name,
         dfs_file_close(&fd);
     }
 
-    free_index = DFS_FILESYSTEMS_MAX;
     /* check whether the file system mounted or not */
+    free_index = DFS_FILESYSTEMS_MAX;
     dfs_lock();
     for (index = 0; index < DFS_FILESYSTEMS_MAX; index ++)
     {
@@ -304,6 +278,7 @@ int dfs_mount(const char   *device_name,
             if (free_index == DFS_FILESYSTEMS_MAX)
                 free_index = index;
         }
+        /* check if the PATH is mounted */
         else if (strcmp(filesystem_table[index].path, path) == 0)
         {
             rt_set_errno(-DFS_STATUS_EINVAL);
@@ -330,23 +305,8 @@ int dfs_mount(const char   *device_name,
     if (dev_id != RT_NULL)
         rt_device_open(fs->dev_id, RT_DEVICE_OFLAG_RDWR);
 
-    /* there is no mount implementation */
-    if (ops->mount == RT_NULL)
-    {
-        if (dev_id != RT_NULL)
-            rt_device_close(dev_id);
-        dfs_lock();
-        /* clear filesystem table entry */
-        rt_memset(fs, 0, sizeof(struct dfs_filesystem));
-        dfs_unlock();
-
-        rt_free(fullpath);
-        rt_set_errno(-DFS_STATUS_ENOSYS);
-
-        return -1;
-    }
     /* call mount of this filesystem */
-    else if (ops->mount(fs, rwflag, data) < 0)
+    if (ops->mount(fs, rwflag, data) < 0)
     {
         /* close device */
         if (dev_id != RT_NULL)
@@ -356,19 +316,14 @@ int dfs_mount(const char   *device_name,
         dfs_lock();
         /* clear filesystem table entry */
         rt_memset(fs, 0, sizeof(struct dfs_filesystem));
-        dfs_unlock();
-
-        rt_free(fullpath);
-
-        return -1;
+        goto err1;
     }
 
     return 0;
 
 err1:
     dfs_unlock();
-    if (fullpath != RT_NULL)
-        rt_free(fullpath);
+    rt_free(fullpath);
 
     return -1;
 }
@@ -437,12 +392,10 @@ err1:
 int dfs_mkfs(const char *fs_name, const char *device_name)
 {
     int index;
-    rt_device_t dev_id;
+    rt_device_t dev_id = RT_NULL;
 
     /* check device name, and it should not be NULL */
-    if (device_name == RT_NULL)
-        dev_id = RT_NULL;
-    else
+    if (device_name != RT_NULL)
         dev_id = rt_device_find(device_name);
 
     if (dev_id == RT_NULL)
@@ -458,19 +411,23 @@ int dfs_mkfs(const char *fs_name, const char *device_name)
     {
         if (filesystem_operation_table[index] != RT_NULL &&
             strcmp(filesystem_operation_table[index]->name, fs_name) == 0)
-        {
-            /* find file system operation */
-            const struct dfs_filesystem_operation *ops = filesystem_operation_table[index];
-            dfs_unlock();
-
-            if (ops->mkfs != RT_NULL)
-                return ops->mkfs(dev_id);
-
             break;
-        }
     }
     dfs_unlock();
 
+    if (index < DFS_FILESYSTEM_TYPES_MAX)
+    {
+        /* find file system operation */
+        const struct dfs_filesystem_operation *ops = filesystem_operation_table[index];
+        if (ops->mkfs == RT_NULL)
+        {
+            rt_set_errno(-DFS_STATUS_ENOSYS);
+            return -1;
+        }
+
+        return ops->mkfs(dev_id);
+    }
+
     rt_kprintf("Can not find the file system which named as %s.\n", fs_name);
     return -1;
 }
@@ -512,7 +469,7 @@ int dfs_mount_table(void)
 				mount_table[index].rwflag,
 				mount_table[index].data) != 0)
 		{
-			rt_kprintf("mount fs[%s] on %s failed.\n", mount_table[index].filesystemtype, 
+			rt_kprintf("mount fs[%s] on %s failed.\n", mount_table[index].filesystemtype,
 				mount_table[index].path);
 			return -RT_ERROR;
 		}
@@ -538,11 +495,7 @@ int df(const char *path)
     long long cap;
     struct statfs buffer;
 
-    if (path == RT_NULL)
-        result = dfs_statfs("/", &buffer);
-    else
-        result = dfs_statfs(path, &buffer);
-
+    result = dfs_statfs(path ? path : RT_NULL, &buffer);
     if (result != 0)
     {
         rt_kprintf("dfs_statfs failed.\n");