Initial Upload
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iDunnoDev
283
mkfs.c
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283
mkfs.c
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#include <stdio.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include <string.h>
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#include <fcntl.h>
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#include <assert.h>
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#define stat xv6_stat // avoid clash with host struct stat
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#include "types.h"
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#include "fs.h"
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#include "stat.h"
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#include "param.h"
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#ifndef static_assert
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#define static_assert(a, b) do { switch (0) case 0: \
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case (a): \
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; } while (0)
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#endif
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#define NINODES 200
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// Disk layout:
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// [ boot block | sb block | log | inode blocks | free bit map | data blocks ]
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int nbitmap = FSSIZE / (BSIZE * 8) + 1;
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int ninodeblocks = NINODES / IPB + 1;
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int nlog = LOGSIZE;
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int nmeta; // Number of meta blocks (boot, sb, nlog, inode, bitmap)
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int nblocks; // Number of data blocks
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int fsfd;
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struct superblock sb;
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char zeroes[BSIZE];
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uint freeinode = 1;
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uint freeblock;
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void balloc(int);
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void wsect(uint, void*);
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void winode(uint, struct dinode*);
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void rinode(uint inum, struct dinode *ip);
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void rsect(uint sec, void *buf);
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uint ialloc(ushort type);
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void iappend(uint inum, void *p, int n);
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// convert to intel byte order
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ushort xshort(ushort x) {
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ushort y;
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uchar *a = (uchar*)&y;
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a[0] = x;
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a[1] = x >> 8;
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return y;
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}
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uint xint(uint x) {
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uint y;
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uchar *a = (uchar*)&y;
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a[0] = x;
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a[1] = x >> 8;
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a[2] = x >> 16;
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a[3] = x >> 24;
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return y;
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}
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int main(int argc, char *argv[]) {
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int i, cc, fd;
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uint rootino, inum, off;
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struct dirent de;
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char buf[BSIZE];
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struct dinode din;
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static_assert(sizeof(int) == 4, "Integers must be 4 bytes!");
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if (argc < 2) {
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fprintf(stderr, "Usage: mkfs fs.img files...\n");
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exit(1);
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}
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assert((BSIZE % sizeof(struct dinode)) == 0);
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assert((BSIZE % sizeof(struct dirent)) == 0);
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fsfd = open(argv[1], O_RDWR | O_CREAT | O_TRUNC, 0666);
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if (fsfd < 0) {
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perror(argv[1]);
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exit(1);
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}
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// 1 fs block = 1 disk sector
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nmeta = 2 + nlog + ninodeblocks + nbitmap;
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nblocks = FSSIZE - nmeta;
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sb.size = xint(FSSIZE);
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sb.nblocks = xint(nblocks);
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sb.ninodes = xint(NINODES);
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sb.nlog = xint(nlog);
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sb.logstart = xint(2);
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sb.inodestart = xint(2 + nlog);
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sb.bmapstart = xint(2 + nlog + ninodeblocks);
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printf("nmeta %d (boot, super, log blocks %u inode blocks %u, bitmap blocks %u) blocks %d total %d\n",
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nmeta, nlog, ninodeblocks, nbitmap, nblocks, FSSIZE);
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freeblock = nmeta; // the first free block that we can allocate
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for (i = 0; i < FSSIZE; i++) {
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wsect(i, zeroes);
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}
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memset(buf, 0, sizeof(buf));
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memmove(buf, &sb, sizeof(sb));
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wsect(1, buf);
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rootino = ialloc(T_DIR);
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assert(rootino == ROOTINO);
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bzero(&de, sizeof(de));
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de.inum = xshort(rootino);
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strcpy(de.name, ".");
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iappend(rootino, &de, sizeof(de));
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bzero(&de, sizeof(de));
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de.inum = xshort(rootino);
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strcpy(de.name, "..");
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iappend(rootino, &de, sizeof(de));
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for (i = 2; i < argc; i++) {
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assert(index(argv[i], '/') == 0);
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if ((fd = open(argv[i], 0)) < 0) {
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perror(argv[i]);
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exit(1);
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}
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// Skip leading _ in name when writing to file system.
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// The binaries are named _rm, _cat, etc. to keep the
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// build operating system from trying to execute them
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// in place of system binaries like rm and cat.
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if (argv[i][0] == '_') {
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++argv[i];
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}
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inum = ialloc(T_FILE);
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bzero(&de, sizeof(de));
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de.inum = xshort(inum);
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strncpy(de.name, argv[i], DIRSIZ);
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iappend(rootino, &de, sizeof(de));
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while ((cc = read(fd, buf, sizeof(buf))) > 0) {
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iappend(inum, buf, cc);
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}
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close(fd);
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}
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// fix size of root inode dir
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rinode(rootino, &din);
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off = xint(din.size);
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off = ((off / BSIZE) + 1) * BSIZE;
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din.size = xint(off);
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winode(rootino, &din);
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balloc(freeblock);
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exit(0);
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}
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void wsect(uint sec, void *buf) {
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if (lseek(fsfd, sec * BSIZE, 0) != sec * BSIZE) {
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perror("lseek");
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exit(1);
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}
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if (write(fsfd, buf, BSIZE) != BSIZE) {
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perror("write");
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exit(1);
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}
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}
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void winode(uint inum, struct dinode *ip) {
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char buf[BSIZE];
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uint bn;
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struct dinode *dip;
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bn = IBLOCK(inum, sb);
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rsect(bn, buf);
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dip = ((struct dinode*)buf) + (inum % IPB);
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*dip = *ip;
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wsect(bn, buf);
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}
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void rinode(uint inum, struct dinode *ip) {
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char buf[BSIZE];
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uint bn;
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struct dinode *dip;
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bn = IBLOCK(inum, sb);
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rsect(bn, buf);
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dip = ((struct dinode*)buf) + (inum % IPB);
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*ip = *dip;
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}
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void rsect(uint sec, void *buf) {
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if (lseek(fsfd, sec * BSIZE, 0) != sec * BSIZE) {
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perror("lseek");
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exit(1);
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}
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if (read(fsfd, buf, BSIZE) != BSIZE) {
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perror("read");
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exit(1);
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}
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}
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uint ialloc(ushort type) {
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uint inum = freeinode++;
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struct dinode din;
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bzero(&din, sizeof(din));
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din.type = xshort(type);
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din.nlink = xshort(1);
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din.size = xint(0);
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winode(inum, &din);
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return inum;
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}
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void balloc(int used) {
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uchar buf[BSIZE];
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int i;
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printf("balloc: first %d blocks have been allocated\n", used);
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assert(used < BSIZE * 8);
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bzero(buf, BSIZE);
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for (i = 0; i < used; i++) {
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buf[i / 8] = buf[i / 8] | (0x1 << (i % 8));
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}
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printf("balloc: write bitmap block at sector %d\n", sb.bmapstart);
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wsect(sb.bmapstart, buf);
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}
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#define min(a, b) ((a) < (b) ? (a) : (b))
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void iappend(uint inum, void *xp, int n) {
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char *p = (char*)xp;
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uint fbn, off, n1;
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struct dinode din;
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char buf[BSIZE];
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uint indirect[NINDIRECT];
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uint x;
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rinode(inum, &din);
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off = xint(din.size);
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// printf("append inum %d at off %d sz %d\n", inum, off, n);
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while (n > 0) {
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fbn = off / BSIZE;
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assert(fbn < MAXFILE);
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if (fbn < NDIRECT) {
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if (xint(din.addrs[fbn]) == 0) {
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din.addrs[fbn] = xint(freeblock++);
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}
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x = xint(din.addrs[fbn]);
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}
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else {
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if (xint(din.addrs[NDIRECT]) == 0) {
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din.addrs[NDIRECT] = xint(freeblock++);
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}
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rsect(xint(din.addrs[NDIRECT]), (char*)indirect);
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if (indirect[fbn - NDIRECT] == 0) {
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indirect[fbn - NDIRECT] = xint(freeblock++);
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wsect(xint(din.addrs[NDIRECT]), (char*)indirect);
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}
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x = xint(indirect[fbn - NDIRECT]);
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}
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n1 = min(n, (fbn + 1) * BSIZE - off);
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rsect(x, buf);
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bcopy(p, buf + off - (fbn * BSIZE), n1);
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wsect(x, buf);
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n -= n1;
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off += n1;
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p += n1;
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}
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din.size = xint(off);
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winode(inum, &din);
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}
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