Changes between Version 16 and Version 17 of file_system

Timestamp:

Jul 8, 2015, 5:29:42 PM (9 years ago)

Author:

alain

Comment:

--

file_system

@@ -69 +69 @@
 It returns 0 if success /  It returns -1 if failure.
 
-=== int '''_fat_open'''( unsigned int  use_irq , char* pathname ) ===
+=== int '''_fat_open'''( char* pathname , unsigned int flags ) ===
 This function implements the giet_fat_open() system call.
-The semantic is similar to the UNIX open() function, but the UNIX flags and access rights are not supported. 
-If the file does not exist in the specified directory, it is created, and both the Inode-Tree, the Fat-Cache and the FAT region
-on device true are updated..
+The semantic is similar to the UNIX open() function,  but only the O_CREATE
+and O_RDONLY flags are supported. The UNIX access rights are not supported. 
+If the file does not exist in the specified directory, it is created, and the Inode-Tree, 
+the Fat-Cache and the FAT region on device are updated.
 If the specified directory does not exist, an error is returned.
-In case of success, It allocates a private file descriptor to the calling task, and the reference count is updated.
- * '''use_irq''' : boolean (use descheduling mode if supported by the IOC driver)
+It allocates a file descriptor to the calling task, for the file identified 
+by "pathname". If several tasks try to open the same file, each task  
+obtains a private file descriptor and the reference count is updated. 
+A node name (file or directory) cannot be larger than 31 characters.
  * '''pathname''' : define both the specified directory and the file name.
-It returns the file descriptor index if success / It returns -1 if failure.
+ * '''flags''' :  O_CREATE and O_RDONLY can be ored.
+It returns the file descriptor index if success.
+It returns a negative value if error:
+ *   -1  :  "fat not initialised"
+ *   -2  :  "path to parent not found"
+ *   -3  :  "one name in path too long"
+ *   -4  :  "file not found"
+ *   -5  :  "Cannot update parent directory"
+ *   -6  :  "Cannot update DATA region"
+ *   -7  :  "Cannot update FAT region"
+ *   -8  :  "Cannot update FS_INFO sector"
+ *   -9  :  "file descriptor array full"
 
 === int '''_fat_close'''( unsigned int fd_id  ) ===
@@ -84 +98 @@
 The semantic is similar to the UNIX "close()" function.
 It decrements the inode reference count, and release the fd_id entry in the file descriptors array.
-If the reference count is zero, it writes all dirty clusters on block device, and releases the memory allocated to the file_cache.
+If the reference count is zero, it writes all dirty clusters on block device, and releases the memory allocated to the file_cache:
+The cache 64-Tree infrastructure (depending on file size) is kept, but all buffers and all buffer descriptors are released.
  * '''fd_id''' : file descriptor index 
-It returns 0 if success /  It returns -1 if failure.
+It returns 0 if success. It returns a negative value if error:
+ *  -1  : "FAT not initialised"
+ *  -2  : "Illegal file descriptor"
+ *  -3  : "Cannot update DATA region for closed file"
+ *  -4  : "Cannot release memory"
 
 === int '''_fat_file_info'''( unsigned int fd_id , unsigned int* size , unsigned int* offset ) ===
@@ -94 +113 @@
  * '''size''' : pointer on the size (return buffer)
  * '''offset''' : pointer on the offset (return buffer) 
-It returns 0 if success /  It returns -1 if failure. 
+It returns 0 if success. It returns a negative value if error:
+ *  -1  : "FAT not initialised"
+ *  -2  : "Illegal file descriptor"
+ *  -3  : "File not open"
 
 === int '''_fat_read'''( unsigned int fd_id , void* buffer , unsigned int count ) ===