Comtrol eCos - Manual (Page 435)

Chapter 29. Writing a New Filesystem
To create a new filesystem it is necessary to define the fstab entry and the file IO operations. The easiest way to
do this is to copy an existing filesystem: either the test filesystem in the FILEIO package, or the RAM or ROM
filesystem packages.
To make this clearer, the following is a brief tour of the FILEIO relevant parts of the RAM filesystem.
First, it is necessary to provide forward definitions of the functions that constitute the filesystem interface:
//==========================================================================
// Forward definitions
// Filesystem operations
static int ramfs_mount ( cyg_fstab_entry *fste, cyg_mtab_entry *mte );
static int ramfs_umount ( cyg_mtab_entry *mte );
static int ramfs_open ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
int mode, cyg_file *fte );
static int ramfs_unlink ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );
static int ramfs_mkdir ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );
static int ramfs_rmdir ( cyg_mtab_entry *mte, cyg_dir dir, const char *name );
static int ramfs_rename ( cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,
cyg_dir dir2, const char *name2 );
static int ramfs_link ( cyg_mtab_entry *mte, cyg_dir dir1, const char *name1,
cyg_dir dir2, const char *name2, int type );
static int ramfs_opendir ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
cyg_file *fte );
static int ramfs_chdir ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
cyg_dir *dir_out );
static int ramfs_stat ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
struct stat *buf);
static int ramfs_getinfo ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
int key, void *buf, int len );
static int ramfs_setinfo ( cyg_mtab_entry *mte, cyg_dir dir, const char *name,
int key, void *buf, int len );
// File operations
static int ramfs_fo_read (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);
static int ramfs_fo_write (struct CYG_FILE_TAG *fp, struct CYG_UIO_TAG *uio);
static int ramfs_fo_lseek (struct CYG_FILE_TAG *fp, off_t *pos, int whence );
static int ramfs_fo_ioctl (struct CYG_FILE_TAG *fp, CYG_ADDRWORD com,
CYG_ADDRWORD data);
static int ramfs_fo_fsync (struct CYG_FILE_TAG *fp, int mode );
static int ramfs_fo_close (struct CYG_FILE_TAG *fp);
static int ramfs_fo_fstat (struct CYG_FILE_TAG *fp, struct stat *buf );
static int ramfs_fo_getinfo (struct CYG_FILE_TAG *fp, int key, void *buf, int len );
static int ramfs_fo_setinfo (struct CYG_FILE_TAG *fp, int key, void *buf, int len );
// Directory operations
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