Mercurial > hg > Members > innparusu > xv6-rpi
view src/file.c @ 6:2617849843ec
fedore virsh edit file
author | tobaru |
---|---|
date | Fri, 26 Jan 2018 16:42:49 +0900 |
parents | 83c23a36980d |
children | 36bd61f5c847 |
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// // File descriptors // #include "types.h" #include "defs.h" #include "param.h" #include "fs.h" #include "file.h" #include "spinlock.h" struct devsw devsw[NDEV]; struct { struct spinlock lock; struct file file[NFILE]; } ftable; void fileinit (void) { initlock(&ftable.lock, "ftable"); } // Allocate a file structure. struct file* filealloc (void) { struct file *f; acquire(&ftable.lock); for (f = ftable.file; f < ftable.file + NFILE; f++) { if (f->ref == 0) { f->ref = 1; release(&ftable.lock); return f; } } release(&ftable.lock); return 0; } // Increment ref count for file f. struct file* filedup (struct file *f) { acquire(&ftable.lock); if (f->ref < 1) { panic("filedup"); } f->ref++; release(&ftable.lock); return f; } // Close file f. (Decrement ref count, close when reaches 0.) void fileclose (struct file *f) { struct file ff; acquire(&ftable.lock); if (f->ref < 1) { panic("fileclose"); } if (--f->ref > 0) { release(&ftable.lock); return; } ff = *f; f->ref = 0; f->type = FD_NONE; release(&ftable.lock); if (ff.type == FD_PIPE) { pipeclose(ff.pipe, ff.writable); } else if (ff.type == FD_INODE) { begin_trans(); iput(ff.ip); commit_trans(); } } // Get metadata about file f. int filestat (struct file *f, struct stat *st) { if (f->type == FD_INODE) { ilock(f->ip); stati(f->ip, st); iunlock(f->ip); return 0; } return -1; } // Read from file f. int fileread (struct file *f, char *addr, int n) { int r; if (f->readable == 0) { return -1; } if (f->type == FD_PIPE) { return piperead(f->pipe, addr, n); } if (f->type == FD_INODE) { ilock(f->ip); if ((r = readi(f->ip, addr, f->off, n)) > 0) { f->off += r; } iunlock(f->ip); return r; } panic("fileread"); } //PAGEBREAK! // Write to file f. int filewrite (struct file *f, char *addr, int n) { int r; int i; int max; int n1; if (f->writable == 0) { return -1; } if (f->type == FD_PIPE) { return pipewrite(f->pipe, addr, n); } if (f->type == FD_INODE) { // write a few blocks at a time to avoid exceeding // the maximum log transaction size, including // i-node, indirect block, allocation blocks, // and 2 blocks of slop for non-aligned writes. // this really belongs lower down, since writei() // might be writing a device like the console. max = ((LOGSIZE - 1 - 1 - 2) / 2) * 512; i = 0; while (i < n) { n1 = n - i; if (n1 > max) { n1 = max; } begin_trans(); ilock(f->ip); if ((r = writei(f->ip, addr + i, f->off, n1)) > 0) { f->off += r; } iunlock(f->ip); commit_trans(); if (r < 0) { break; } if (r != n1) { panic("short filewrite"); } i += r; } return i == n ? n : -1; } panic("filewrite"); }