| 0,0 → 1,87 |
|---|
| /* This file contains the procedures that manipulate file descriptors. */ |
| |
| /* |
| * Methods: |
| * get_fd: look for free file descriptor and free filp slots |
| * get_filp: look up the filp entry for a given file descriptor |
| * find_filp: find a filp slot that points to a given inode |
| */ |
| |
| |
| #include "fs.h" |
| #include "file.h" |
| #include "fproc.h" |
| #include "inode.h" |
| |
| |
| int get_fd(int start, int *k, filp_t **fpt) |
| { |
| /* Look for a free file descriptor and a free filp slot. */ |
| |
| register filp_t *f; |
| register int i; |
| |
| *k = -1; /* we need a way to tell if file desc found */ |
| |
| /* Search the fproc fp_filp table for a free file descriptor. */ |
| for (i = start; i < OPEN_MAX; i++) { |
| if (fp->fp_filp[i] == NIL_FILP) { |
| /* A file descriptor has been located. */ |
| *k = i; |
| break; |
| } |
| } |
| |
| /* Check to see if a file descriptor has been found. */ |
| if (*k < 0) |
| return FS_EMFILE; /* this is why we initialized k to -1 */ |
| |
| /* Now that a file descriptor has been found, look for a free filp slot. */ |
| for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
| if (f->filp_count == 0) { |
| f->filp_mode = R_BIT; |
| f->filp_pos = 0L; |
| f->filp_flags = 0; |
| *fpt = f; |
| return OK; |
| } |
| } |
| |
| /* If control passes here, the filp table must be full. Report that back. */ |
| return FS_ENFILE; |
| } |
| |
| |
| filp_t *get_filp(int fild) |
| { |
| |
| /* See if 'fild' refers to a valid file descr. If so, return its filp ptr. */ |
| |
| err_code = FS_EBADF; |
| if (fild < 0 || fild >= OPEN_MAX ) |
| return NIL_FILP; |
| |
| return(fp->fp_filp[fild]); /* may also be NIL_FILP */ |
| } |
| |
| |
| filp_t *find_filp(register inode_t *rip) |
| { |
| |
| /* Find a filp slot that refers to the inode 'rip' in a way as described. |
| * Used for determining whether somebody is still interested in. |
| * Like 'get_fd' it performs its job by linear search through the filp table. |
| */ |
| |
| register filp_t *f; |
| |
| for (f = &filp[0]; f < &filp[NR_FILPS]; f++) { |
| if (f->filp_count != 0 && f->filp_ino == rip){ |
| return f; |
| } |
| } |
| |
| /* If control passes here, the filp wasn't there. Report that back. */ |
| return NIL_FILP; |
| } |
| |