95 lines
3.5 KiB
C
95 lines
3.5 KiB
C
//---
|
|
// gint:fs - Filesystem abstraction
|
|
//---
|
|
|
|
#ifndef GINT_FS
|
|
#define GINT_FS
|
|
|
|
#ifdef __cplusplus
|
|
extern "C" {
|
|
#endif
|
|
|
|
#include <sys/types.h>
|
|
#include <stddef.h>
|
|
|
|
/* Maximum number of file descriptors */
|
|
#define FS_FD_MAX 32
|
|
|
|
/* fs_descriptor_type_t: Overloaded file descriptor functions
|
|
|
|
This structure provides the base functions for every type of file
|
|
descriptor. The prototypes are standard, except that the first argument
|
|
(int fd) is replaced by (void *data) which points to the custom data
|
|
allocator for the descriptor.
|
|
|
|
pread() is normally implemented in terms of lseek() and read(), however on
|
|
Fugue file descriptors on the G-III series there is no way to determine the
|
|
current position so this method won't work, and pread() is instead provided
|
|
by a non-standard parameter of BFile_Read(). The overloaded entry supports
|
|
this alternative. */
|
|
typedef struct {
|
|
/* See <unistd.h> for a description of these functions */
|
|
ssize_t (*read)(void *data, void *buf, size_t size);
|
|
ssize_t (*pread)(void *data, void *buf, size_t size, off_t offset);
|
|
ssize_t (*write)(void *data, void const *buf, size_t size);
|
|
off_t (*lseek)(void *data, off_t offset, int whence);
|
|
int (*close)(void *data);
|
|
|
|
} fs_descriptor_type_t;
|
|
|
|
/* fs_descriptor_t: File descriptor information
|
|
This internal type describes the entries of the descriptor table. */
|
|
typedef struct {
|
|
/* Interface functions */
|
|
fs_descriptor_type_t const *type;
|
|
/* Custom data (can also be an integer cast to (void *)) */
|
|
void *data;
|
|
|
|
} fs_descriptor_t;
|
|
|
|
/* fs_get_descriptor(): Get a file descriptor's data
|
|
|
|
This function is used internally in order to implement read(), write(), and
|
|
other standard functions functions. It could be useful for other APIs that
|
|
want to present their resources as file descriptors but still implement
|
|
extra non-standard functions; this allows them to use the file descriptor as
|
|
input and still access the custom data.
|
|
|
|
Returns NULL if there is no file descriptor with this number, in which case
|
|
the caller probably needs to set errno = EBADF. */
|
|
fs_descriptor_t const *fs_get_descriptor(int fd);
|
|
|
|
/* fs_create_descriptor(): Create a new file descriptor
|
|
|
|
This function is used in open() and its variants to allocate new file
|
|
descriptors. The descriptor's data is created with a copy of the provided
|
|
structure, which must include a non-NULL type attribute.
|
|
|
|
This function always returns the smallest file descriptor that is unused by
|
|
the application and is not 0, 1 or 2; unless it runs out of file
|
|
descriptors, in which case it returns -1 and the caller might want to set
|
|
errno = ENFILE. */
|
|
int fs_create_descriptor(fs_descriptor_t const *data);
|
|
|
|
/* fs_free_descriptor(): Clsoe a file descriptor's slot
|
|
|
|
This function frees the specified file descriptor. It is automatically
|
|
called by close() after the descriptor type's close() function, so there is
|
|
normally no need to call this function directly. */
|
|
void fs_free_descriptor(int fd);
|
|
|
|
/* open_generic(): Open a file descriptor using custom file functions
|
|
|
|
Opens a new file descriptor of the specified type with the provided user
|
|
data. If reuse_fd < 0, a new file descriptor is allocated, otherwise the
|
|
exact file descriptor reuse_fd is used. (This is useful to reopen standard
|
|
streams.) In this case, the only possible return values are -1 and reuse_fd
|
|
itself. */
|
|
int open_generic(fs_descriptor_type_t *type, void *data, int reuse_fd);
|
|
|
|
#ifdef __cplusplus
|
|
}
|
|
#endif
|
|
|
|
#endif /* GINT_FS */
|