Changes between Version 43 and Version 44 of file_system

Timestamp:

Feb 2, 2016, 11:45:42 PM (9 years ago)

Author:

alain

Comment:

--

file_system

@@ -29 +29 @@
 To support various block device peripheral, this FAT32 implementation defines a generic function to transparently access various physical block devices, using the driver specified in the ''hard_config.h'' file. Five drivers are presently supported ( IOC_BDV / IOC_HBA / IOC_SDC / IOC_SPI / IOC_RDK ).
 
-WARNING 1: A node name (file or directory) cannot be larger than 31 characters.
-
-WARNING 2: There is no rescue mechanism (at the moment) in case of heap overflow: The system crash with a nice error message on the kernel terminal if the heap defined in the mapping is too small... 
+'''WARNING 1''': A node name (file or directory) cannot be larger than 31 characters.
+
+'''WARNING 2''': There is no rescue mechanism (at the moment) in case of heap overflow: The system crash with a nice error message on the kernel terminal if the heap defined in the mapping is too small for the File-Caches... 
 
 == 2) Cache Structure & Write Policy ==
@@ -198 +198 @@
 == 5) Internal functions ==
 
-The following functions can be used to implement new system calls if required.
-
-=== __int '''_fat_ioc_access'''( unsigned int use_irq ,  unsigned int to_mem ,  unsigned int lba , unsigned int buf_vaddr , unsigned int count )__ ===
-This function transfers one or several blocks between the block device and a memory buffer by calling the relevant driver. The <use_irq>  boolean argument forces the descheduling mode if supported by the IOC driver.
-The <to_mem> boolean argument defines the transfer direction (from block device to memory if non zero). The 
-<lba> argument is the logical block address on the block device. The <buf_vaddr> argument is the memory buffer virtual address. The <count> argument is the number of blocks to be transferred.
-It returns 0 on success, or -1 on failure.
-
-=== __void '''_display_one_block'''( unsigned char* buf , char* string , unsigned int block_id )__ ===
-This debug function displays the content of a 512 bytes buffer <buf>, with an identifier defined by the <string> and <block_id> arguments.
+=== __void '''_display_cluster_list'''()__ ===
+This debug function displays the list of clusters allocated to one file or directory.
 
 === __void '''_display_fat_descriptor'''()__ ===
 This debug function displays the FAT descriptor content. 
 
-=== __unsigned int '''_get_fat_cache_buffer'''( unsigned int cluster_id , fat_cache_desc_t**  desc )__ ===
-This function returns in the <desc> argument a pointer on a buffer descriptor contained in the Fat_Cache. 
-The <cluster_id> argument is the buffer index in the FAT_Cache. 
-In case of miss, a 4 Kbytesbuffer and a buffer descriptor are allocated from the local heap, and the missing cluster is loaded in the Fat_Cache.
-It returns 0 on success. It returns 1 on error.=== __void '''_get_name_from_long'''( unsigned char* buffer , char* name )__ ===
+=== __void '''_get_name_from_long'''( unsigned char* buffer , char* name )__ ===
 This function extract a (partial) name from a LFN directory entry.
 
 === __void '''_get_name_from_short'''( unsigned char* buffer , char* name )__ ===
-This function extract a name from a NORMAL directory entry.
+This function extract a <name> from a NORMAL directory entry.
 
 === __unsigned int '''_get_levels_from_size'''( unsigned int size )__ ===
-This function returns the number of levels of a File-Cache from the size of the file.
+This function returns the number of levels of a File-Cache from the <size> of the file.
 
 === __unsigned int '''_get_name_from_path'''( char* pathname , char* name , unsigned int*  nb_read )__ ===
 This function analyses the <pathname> argument, from the character defined by the <nb_read> argument.
 It copies the found name in the <name> buffer (without '/'), and updates the <nb_read"> argument.
+
 It returns 0 on success. It returns 1 if one name length > NAME_MAX_SIZE characters.
 
 === __unsigned int '''_get_last_name'''( char* pathname , char* name )__ ===
-This function scan the "pathname" argument, and copies in the <name> buffer the last name in <pathname>.
+This function scan the <pathname> argument, and copies in the <name> buffer the last name in the <pathname>.
+
 It returns 0 on success.It returns 1 if one name length > NAME_MAX_SIZE characters.
 
 === __unsigned int '''_get_fat_entry'''( unsigned int  cluster , unsigned int* value )__ ===
-This function accesses the Fat-Cache and returns in the <value> argument the content of the FAT slot identified by the <cluster> argument. It loads the missing cluster from block device in the Fat-Cache in case of miss. It returns 0 on success. It returns 1 on error.
+This function accesses the Fat-Cache and returns in the <value> argument the content of the FAT slot identified by the <cluster> argument. It loads the missing cluster from block device in the Fat-Cache in case of miss. 
+
+It returns 0 on success. It returns 1 on error.
 
 === __unsigned int '''_set_fat_entry'''( unsigned int  cluster , unsigned int  value )__ ===
 This function writes a new <value> in the Fat-Cache, in the slot identified by the <cluster> argument.  
 It loads the missing cluster from block device in the Fat-Cache in case of miss.
+
 It returns 0 on success, It returns 1 on error.
 
 === __void '''_add_inode_in_tree'''( fat_inode_t*  child , fat_inode_t*  parent )__ ===
-This function introduces the inode identified by the <child> argument as a new child for the <parent> inode in the Inode-Tree.
-All checking are supposed to be done by the caller. Nor the File-Cache, neither the block device are modified.
+This function introduces the inode identified by the <child> argument as a new child for the <parent> inode in the Inode-Tree. All checking are supposed to be done by the caller. Nor the File-Cache, neither the block device are modified.
 
 === __void '''_remove_inode_from_tree'''( fat_inode_t* inode )__ ===
@@ -251 +243 @@
 === __unsigned int '''_update_device_from_cache'''( unsigned int levels , fat_cache_node_t* root , char* string )__ ===
 This recursive function scan one File-Cache (or the Fat-Cache) from root to leaves, to writes all dirty clusters to block device, and reset the dirty bits. The cache is identified by the <root> an <levels> arguments.
-The <string> argument is only used for debug.  It returns 0 on success. It returns 1 on error.
+The <string> argument is only used for debug.  
+
+It returns 0 on success. It returns 1 on error.
 
 === __unsigned int '''_update_fs_info()'''__ ===
 This function accesses directly the FS_INFO block on the block device, to update the "first_free_cluster" and "free_clusters_number" values, using only the Fat-Descriptor single block buffer.
+
 It return 0 on success. It return 1 on error.
 
@@ -265 +260 @@
 
 === __unsigned int '''_get_nb_entries'''( fat_inode_t* inode , unsigned int* nb_entries )__ ===
-This function returns in the <nb_entries> argument the number of entries  contained in a directory identified by the <inode> pointer. It returns 0 on success. It returns 1 on error. 
+This function returns in the <nb_entries> argument the number of entries  contained in a directory identified by the <inode> pointer. 
+
+It returns 0 on success. It returns 1 on error. 
 
 === __unsigned int '''_get_child_from_parent'''( fat_inode_t* parent , char* name , fat_inode_t**  inode )__ === 
-This function search in the directory identified by the <parent> inode pointer a child (file or directory) identified by its <name>.
-It returns in the <inode> argument the searched child inode pointer.
+This function search in the directory identified by the <parent> inode pointer a child (file or directory) identified by its <name>. It returns in the <inode> argument the searched child inode pointer.
 If the searched name is not found in the Inode-Tree, the function accesses the File-cache associated to the parent directory.
 If the child exists on block device, the Inode-Tree is updated, and a success code is returned.
 If the file/dir does not exist on block device, a error code is returned.
+
 It returns 0 if inode found. It returns 1 if inode not found. It returns 2 in case of error in cache access.
 
@@ -278 +275 @@
 For a file (or a directory) identified by the <pathname> argument, this function returns in the <inode> argument the inode pointer associated to the searched file (or directory), with code (0).
 If the searched file (or directory) is not found, but the parent directory is found, it returns in the <inode> argument the pointer on the parent inode, with code (1).  Code (2) and code (3) are error codes. Both the Inode-Tree and the involved Cache-Files are updated from the block device in case of miss on one inode during the search. Neither the Fat-Cache, nor the block device are updated.
+
 It returns 0 if searched inode found  It returns 1 if searched inode not found but parent directory found. It returns 2 if searched inode not found and parent directory not found. It returns 3 if one name too long
 
 === __unsigned int '''_is_ancestor'''( fat_inode_t* a , fat_inode_t* b )__ ===
 This function checks if inode <a> is an ancestor of inode <b>.
-It returns 0 on failure. It returns 1 otherwise.
-
-=== __unsigned int '''_check_name_length'''( char* name , unsigned int* length , unsigned int* nb_lfn )__ ===
-This function computes the length and the number of LFN entries required to store a node name, and return the values in the <length> and <nb_lfn> arguments.
+
+It returns 1 if it is true.
+
+=== __unsigned int '''_get_sfn_name'''( char* name , unsigned int* length , unsigned int* nb_lfn, char* sfn , unsigned char* checksum )__ ===
+This function returns  in the <length> and <nb_lfn> arguments the name length and the number of LFN entries required to store the <name> string. It returns in the <sfn> argument a legal SFN name extracted from the <name> string (upper case and 8-3 format). It returns in the <checksum> argument the SFN checksum.
  * Short name (less than 13 characters) require 1 LFN entry.
  * Medium names (from 14 to 26 characters require 2 LFN entries.
  * Large names (up to 31 characters) require 3 LFN entries. 
-It returns 0 on success. It returns 1 if length larger than 31 characters.
-
-=== __unsigned int '''_update_dir_entry'''( fat_inode_t*  inode )__ ===
-For a node identified by the <inode> argument, this function updates the "size" and "cluster" values in the parent directory entry File-Cache.
-It set the dirty bit in the modified buffer of the parent directory File-Cache.
+
+It returns 0 on success. It returns 1 if the name length is larger than 31 characters.
+
+=== __void '''_update_dir_entry'''( fat_inode_t*  inode )__ ===
+For a node identified by the <inode> argument, this function updates the "size" and "cluster" values in the parent directory entry File-Cache. It set the dirty bit in the modified buffer of the parent directory File-Cache.
 
 === __unsigned int '''_add_dir_entry'''( fat_inode_t* child , fat_inode_t* parent )__ ===
-The following function add new <child> entry in the Cache-File of the <parent> directory. It accesses the File_Cache associated to the parent directory, 
-and scan the clusters allocated to this directory to find the NO_MORE entry, that will be the first modified entry in the directory.
-Regarding the name storage, it uses LFN entries for all names, but computes a legal (upper case / 8.3) SFN name that will be stored in the NORMAL entry.
+This function add a new <child> entry in the Cache-File of the <parent> directory. It accesses the File_Cache associated to the parent directory, and scan the clusters allocated to this directory to find the NO_MORE entry, that will be the first modified entry in the directory.
+Regarding the name storage, it uses LFN entries for all names, but computes a legal (upper case / 8-3) SFN name that will be stored in the NORMAL entry.
 It writes 1, 2, or 3 LFN entries (depending on the child name actual length), writes one NORMAL entry, and writes the new NO_MORE entry.
 It updates the dentry field in the child inode. It set the dirty bit for all modified File-Cache buffers.
 The block device is not modified by this function.
+
+It returns 0 on success. It returns 1 in case of error.
 
 === __unsigned int '''_remove_dir_entry'''( fat_inode_t*  inode )__ ===
@@ -309 +309 @@
 The block device is not modified by this function.
 
+It returns 0 on success. It returns 1 in case of error.
+
 === __void '''_add_special_directories'''( fat_inode_t* child , fat_inode_t* parent )__ ===
 This function adds the special entries "." and ".." in the File-Cache of the directory identified by the <child> argument.