open Function

Open a file.

Include

None

Prototype

int open(const char *name, int access, int mode);

Arguments

`name`	name of the file to be opened
`access`	access method to open file
`mode`	type of access permitted

Return Value

If successful, the function returns a file handle: a small positive integer. This handle is then used on subsequent low-level file I/O operations. A return value of ‘-1’ indicates an error.

Remarks

The access flag is a union of one of the following access methods and zero or more access qualifiers:

0 – Open a file for reading.
1 – Open a file for writing.
2 – Open a file for both reading and writing.

The following access qualifiers must be supported:

0x0008 – Move file pointer to end-of-file before every write operation.
0x0100 – Create and open a new file for writing.
0x0200 – Open the file and truncate it to zero length.
0x4000 – Open the file in text (translated) mode.
0x8000 – Open the file in binary (untranslated) mode.

The mode parameter may be one of the following:

0x0100 – Reading only permitted.
0x0080 – Writing permitted (implies reading permitted).

This helper function is called by the Standard C Library functions fopen() and freopen().

Default Behavior

As distributed, the parameters are passed to the host file system through the simulator. The return value is the value returned by the host file system. If the host system returns a value of ‘-1’, the global variable errno is set to the value of the symbolic constant, EFOPEN, defined in <errno.h>.

File

open.c