FSEntry_File (changes)

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Operations on whole files

Various calls are made by FileSwitch through these entry points to perform operations on whole files. Actions are specified by R0 as follows:

FSEntry_File 0 / ImageEntry_File 0

Save file

Use

Request the filing system saves data from a buffer held in memory to a file. FileSwitch has already validated the buffer and ensured that the leafname is not wildcarded. If the file currently exists and is not locked, the old file is first discarded. The new file should have the same access attributes as the one it is replacing, or some default access if the file doesn’t already exist.

Return an error such as “File locked” if the specified file could not be saved.

FileSwitch immediately copies the leafname returned in R6, so it need not have a long
lifetime – hold it in a small static buffer, for example.

FSEntry_File 1 / ImageEntry_File 1

Write catalogue information

Use

Request the filing system update the catalogue information for an object. If the object is a directory either write the information (FileCore-based filing systems do) or return an error.

Does not return an error if the object does not exist.

FSEntry_File 2

Write load address

Use

Sets the load address for a file. If the object is a directory either write the information
(FileCore-based filing systems do) or return an error.

Does not return an error if the object does not exist.

FSEntry_File 3

Write execution address

Use

Sets the execution address for a file. If the object is a directory either write the
information (FileCore-based filing systems do) or return an error

Does not return an error if the object does not exist.

FSEntry_File 4

Write attributes

Use

Sets the attributes of an object.

Does not return an error if the object does not exist.

FSEntry_File 5 / ImageEntry_File 5

Read catalogue information

Use

Returns the catalogue information for an object.

Return an error if:

• the pathname specifies a drive that is unknown
• the pathname specifies a media name that is unknown and not made available after
  any UpCall
• the special field specifies an unknown server or subsystem

Returns type 0 if:

• the place specified by the pathname exists, but the leafname does not match any
  object there
• the place specified by the pathname does not exist

FSEntry_File 6 / ImageEntry_File 6

Delete object

Use

Deletes an object. FileSwitch will already have ensured that the leafname is not wildcarded. No data need be transferred to the file.

Returns an error if the object is locked against deletion, but not if the object does not exist. The results refer to the object that was deleted.

FSEntry_File 7 / ImageEntry_File 7

Create file

Use

Creates a file with a given name. R4 and R5 are used only to calculate the length of the file to be created. If the file currently exists and is not locked, the old file is first discarded. The new file should have the same access attributes as the one it is replacing, or some default access if the file doesn’t already exist.

Returns an error if the file could not be created

FSEntry_File 8 / ImageEntry_File 8

Create directory

Use

Create a directory. If the directory already exists then the filing system can:

• return without any modification to the existing directory
• attempt to rename the directory – it must not return an error if this fails.

If directories don’t support load and execute addresses (which will only be of the directory type/datestamp form) then no error should be returned.

FileSwitch will already have ensured that the leafname is not wildcarded.

Should return an error if the directory could not be created.

FSEntry_File 9 / ImageEntry_File 9

Read catalogue information (no length)

Use

Read the catalogue information for an object, save for the object length.

Does not return an error if the object does not exist.

Bit 26 of your Filing System Information Word must have been set when the filing system was initialised. Otherwise FileSwitch calls FSEntry_File 5 and the length returned in R4 is ignored.

FSEntry_File 10 / ImageEntry_File 10

Read block size

Use

Read the natural block size for a file (see FSEntry_Open and ImageEntry_Open)

FSEntry_File 255

Load file

Use

Load a file into memory.

FileSwitch will already have called FSEntry_File 5 and validated the client’s load request. If FSEntry_File 5 returned with object type 0 then the user will have been returned the “File ‘xyz’ not found” error; type 2 will have returned the “‘xyz’ is a directory” error; types 1 with corresponding load actions will have had them executed (which may recurse back down to load again), those with no read access will have returned ‘Access violation’, and those being partially or wholly loaded into invalid memory will have returned ‘No writeable memory at this address’.

Therefore unless the filing system is accessing data stored on a multi-user server such as NetFS/FileStore, the object will still be the one whose info was read earlier.

The filename pointed to by R6 on exit should be the non-wildcarded ‘leaf’ name of the file. That is, if the filename given on entry was “$.!b*”, and the file accessed was the “!Boot” file, R6 should point to the string “!Boot”.

See also

• FS Information Block
• Filing System Information Word