diff options
Diffstat (limited to 'mkfs')
| -rw-r--r-- | mkfs/mkfs.c | 305 |
1 files changed, 305 insertions, 0 deletions
diff --git a/mkfs/mkfs.c b/mkfs/mkfs.c new file mode 100644 index 0000000..246a4e2 --- /dev/null +++ b/mkfs/mkfs.c @@ -0,0 +1,305 @@ +#include <stdio.h> +#include <unistd.h> +#include <stdlib.h> +#include <string.h> +#include <fcntl.h> +#include <assert.h> + +#define stat xv6_stat // avoid clash with host struct stat +#include "kernel/types.h" +#include "kernel/fs.h" +#include "kernel/stat.h" +#include "kernel/param.h" + +#ifndef static_assert +#define static_assert(a, b) do { switch (0) case 0: case (a): ; } while (0) +#endif + +#define NINODES 200 + +// Disk layout: +// [ boot block | sb block | log | inode blocks | free bit map | data blocks ] + +int nbitmap = FSSIZE/(BSIZE*8) + 1; +int ninodeblocks = NINODES / IPB + 1; +int nlog = LOGSIZE; +int nmeta; // Number of meta blocks (boot, sb, nlog, inode, bitmap) +int nblocks; // Number of data blocks + +int fsfd; +struct superblock sb; +char zeroes[BSIZE]; +uint freeinode = 1; +uint freeblock; + + +void balloc(int); +void wsect(uint, void*); +void winode(uint, struct dinode*); +void rinode(uint inum, struct dinode *ip); +void rsect(uint sec, void *buf); +uint ialloc(ushort type); +void iappend(uint inum, void *p, int n); + +// convert to intel byte order +ushort +xshort(ushort x) +{ + ushort y; + uchar *a = (uchar*)&y; + a[0] = x; + a[1] = x >> 8; + return y; +} + +uint +xint(uint x) +{ + uint y; + uchar *a = (uchar*)&y; + a[0] = x; + a[1] = x >> 8; + a[2] = x >> 16; + a[3] = x >> 24; + return y; +} + +int +main(int argc, char *argv[]) +{ + int i, cc, fd; + uint rootino, inum, off; + struct dirent de; + char buf[BSIZE]; + struct dinode din; + + + static_assert(sizeof(int) == 4, "Integers must be 4 bytes!"); + + if(argc < 2){ + fprintf(stderr, "Usage: mkfs fs.img files...\n"); + exit(1); + } + + assert((BSIZE % sizeof(struct dinode)) == 0); + assert((BSIZE % sizeof(struct dirent)) == 0); + + fsfd = open(argv[1], O_RDWR|O_CREAT|O_TRUNC, 0666); + if(fsfd < 0){ + perror(argv[1]); + exit(1); + } + + // 1 fs block = 1 disk sector + nmeta = 2 + nlog + ninodeblocks + nbitmap; + nblocks = FSSIZE - nmeta; + + sb.magic = FSMAGIC; + sb.size = xint(FSSIZE); + sb.nblocks = xint(nblocks); + sb.ninodes = xint(NINODES); + sb.nlog = xint(nlog); + sb.logstart = xint(2); + sb.inodestart = xint(2+nlog); + sb.bmapstart = xint(2+nlog+ninodeblocks); + + printf("nmeta %d (boot, super, log blocks %u inode blocks %u, bitmap blocks %u) blocks %d total %d\n", + nmeta, nlog, ninodeblocks, nbitmap, nblocks, FSSIZE); + + freeblock = nmeta; // the first free block that we can allocate + + for(i = 0; i < FSSIZE; i++) + wsect(i, zeroes); + + memset(buf, 0, sizeof(buf)); + memmove(buf, &sb, sizeof(sb)); + wsect(1, buf); + + rootino = ialloc(T_DIR); + assert(rootino == ROOTINO); + + bzero(&de, sizeof(de)); + de.inum = xshort(rootino); + strcpy(de.name, "."); + iappend(rootino, &de, sizeof(de)); + + bzero(&de, sizeof(de)); + de.inum = xshort(rootino); + strcpy(de.name, ".."); + iappend(rootino, &de, sizeof(de)); + + for(i = 2; i < argc; i++){ + // get rid of "user/" + char *shortname; + if(strncmp(argv[i], "user/", 5) == 0) + shortname = argv[i] + 5; + else + shortname = argv[i]; + + assert(index(shortname, '/') == 0); + + if((fd = open(argv[i], 0)) < 0){ + perror(argv[i]); + exit(1); + } + + // Skip leading _ in name when writing to file system. + // The binaries are named _rm, _cat, etc. to keep the + // build operating system from trying to execute them + // in place of system binaries like rm and cat. + if(shortname[0] == '_') + shortname += 1; + + inum = ialloc(T_FILE); + + bzero(&de, sizeof(de)); + de.inum = xshort(inum); + strncpy(de.name, shortname, DIRSIZ); + iappend(rootino, &de, sizeof(de)); + + while((cc = read(fd, buf, sizeof(buf))) > 0) + iappend(inum, buf, cc); + + close(fd); + } + + // fix size of root inode dir + rinode(rootino, &din); + off = xint(din.size); + off = ((off/BSIZE) + 1) * BSIZE; + din.size = xint(off); + winode(rootino, &din); + + balloc(freeblock); + + exit(0); +} + +void +wsect(uint sec, void *buf) +{ + if(lseek(fsfd, sec * BSIZE, 0) != sec * BSIZE){ + perror("lseek"); + exit(1); + } + if(write(fsfd, buf, BSIZE) != BSIZE){ + perror("write"); + exit(1); + } +} + +void +winode(uint inum, struct dinode *ip) +{ + char buf[BSIZE]; + uint bn; + struct dinode *dip; + + bn = IBLOCK(inum, sb); + rsect(bn, buf); + dip = ((struct dinode*)buf) + (inum % IPB); + *dip = *ip; + wsect(bn, buf); +} + +void +rinode(uint inum, struct dinode *ip) +{ + char buf[BSIZE]; + uint bn; + struct dinode *dip; + + bn = IBLOCK(inum, sb); + rsect(bn, buf); + dip = ((struct dinode*)buf) + (inum % IPB); + *ip = *dip; +} + +void +rsect(uint sec, void *buf) +{ + if(lseek(fsfd, sec * BSIZE, 0) != sec * BSIZE){ + perror("lseek"); + exit(1); + } + if(read(fsfd, buf, BSIZE) != BSIZE){ + perror("read"); + exit(1); + } +} + +uint +ialloc(ushort type) +{ + uint inum = freeinode++; + struct dinode din; + + bzero(&din, sizeof(din)); + din.type = xshort(type); + din.nlink = xshort(1); + din.size = xint(0); + winode(inum, &din); + return inum; +} + +void +balloc(int used) +{ + uchar buf[BSIZE]; + int i; + + printf("balloc: first %d blocks have been allocated\n", used); + assert(used < BSIZE*8); + bzero(buf, BSIZE); + for(i = 0; i < used; i++){ + buf[i/8] = buf[i/8] | (0x1 << (i%8)); + } + printf("balloc: write bitmap block at sector %d\n", sb.bmapstart); + wsect(sb.bmapstart, buf); +} + +#define min(a, b) ((a) < (b) ? (a) : (b)) + +void +iappend(uint inum, void *xp, int n) +{ + char *p = (char*)xp; + uint fbn, off, n1; + struct dinode din; + char buf[BSIZE]; + uint indirect[NINDIRECT]; + uint x; + + rinode(inum, &din); + off = xint(din.size); + // printf("append inum %d at off %d sz %d\n", inum, off, n); + while(n > 0){ + fbn = off / BSIZE; + assert(fbn < MAXFILE); + if(fbn < NDIRECT){ + if(xint(din.addrs[fbn]) == 0){ + din.addrs[fbn] = xint(freeblock++); + } + x = xint(din.addrs[fbn]); + } else { + if(xint(din.addrs[NDIRECT]) == 0){ + din.addrs[NDIRECT] = xint(freeblock++); + } + rsect(xint(din.addrs[NDIRECT]), (char*)indirect); + if(indirect[fbn - NDIRECT] == 0){ + indirect[fbn - NDIRECT] = xint(freeblock++); + wsect(xint(din.addrs[NDIRECT]), (char*)indirect); + } + x = xint(indirect[fbn-NDIRECT]); + } + n1 = min(n, (fbn + 1) * BSIZE - off); + rsect(x, buf); + bcopy(p, buf + off - (fbn * BSIZE), n1); + wsect(x, buf); + n -= n1; + off += n1; + p += n1; + } + din.size = xint(off); + winode(inum, &din); +} |