Mercurial > hg > Members > mitsuki > xv6_rpi2_port
diff source/file.c @ 0:ed10291ff195
first commit
author | mir3636 |
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date | Sun, 06 Jan 2019 19:27:03 +0900 |
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--- /dev/null Thu Jan 01 00:00:00 1970 +0000 +++ b/source/file.c Sun Jan 06 19:27:03 2019 +0900 @@ -0,0 +1,162 @@ +// +// 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) +{ + memset(&ftable, 0, sizeof(ftable)); + 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); +//cprintf("inside fileread\n"); + if((r = readi(f->ip, addr, f->off, n)) > 0) + f->off += r; +//cprintf("inside fileread: after readi rv=%x\n", r); + iunlock(f->ip); + return r; + } + panic("fileread"); + return -1; +} + +//PAGEBREAK! +// Write to file f. +int +filewrite(struct file *f, char *addr, int n) +{ + int r; + + if(f->writable == 0) + return -1; +//cprintf("inside filewrite\n"); + 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. + int max = ((LOGSIZE-1-1-2) / 2) * 512; + int i = 0; + while(i < n){ + int 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"); + return -1; +} +