diff options
Diffstat (limited to 'os/boot/pc/kfsboot.c')
| -rw-r--r-- | os/boot/pc/kfsboot.c | 256 |
1 files changed, 256 insertions, 0 deletions
diff --git a/os/boot/pc/kfsboot.c b/os/boot/pc/kfsboot.c new file mode 100644 index 00000000..a99d226d --- /dev/null +++ b/os/boot/pc/kfsboot.c @@ -0,0 +1,256 @@ +#include "u.h" +#include "lib.h" +#include "mem.h" +#include "dat.h" +#include "fns.h" +#include "fs.h" + +typedef struct Tag Tag; + +/* + * tags on block + */ +enum +{ + Tnone = 0, + Tsuper, /* the super block */ + Tdir, /* directory contents */ + Tind1, /* points to blocks */ + Tind2, /* points to Tind1 */ + Tfile, /* file contents */ + Tfree, /* in free list */ + Tbuck, /* cache fs bucket */ + Tvirgo, /* fake worm virgin bits */ + Tcache, /* cw cache things */ + MAXTAG +}; + +#define QPDIR 0x80000000L +#define QPNONE 0 +#define QPROOT 1 +#define QPSUPER 2 + +/* DONT TOUCH, this is the disk structure */ +struct Tag +{ + short pad; + short tag; + long path; +}; + +static int thisblock = -1; +static Fs *thisfs; +static uchar *block; + +/* + * we end up reading 2x or 3x the number of blocks we need to read. + * this is okay because we need to read so few. if it wasn't okay, we could + * have getblock return a pointer to a block, and keep a cache of the last + * three read blocks. that would get us down to the minimum. + * but this is fine. + */ +static int +getblock(Fs *fs, ulong n) +{ + if(!block) + block = malloc(16384); + + if(thisblock == n && thisfs == fs) + return 0; + thisblock = -1; + if(fs->diskseek(fs, (vlong)n*fs->kfs.RBUFSIZE) < 0) + return -1; + if(fs->diskread(fs, block, fs->kfs.RBUFSIZE) != fs->kfs.RBUFSIZE) + return -1; + thisblock = n; + thisfs = fs; + + return 1; +} + +static int +checktag(Fs *fs, uchar *block, int tag, long qpath) +{ + Tag *t; + + t = (Tag*)(block+fs->kfs.BUFSIZE); + if(t->tag != tag) + return -1; + if(qpath != QPNONE && (qpath&~QPDIR) != t->path) + return -1; + return 1; +} + +static int +getblocktag(Fs *fs, ulong n, int tag, long qpath) +{ + if(getblock(fs, n) < 0 || checktag(fs, block, tag, qpath) < 0) + return -1; + return 1; +} + +static int +readinfo(Fs *fs) +{ + fs->kfs.RBUFSIZE = 512; + if(getblock(fs, 0) < 0) + return -1; + + if(memcmp(block+256, "kfs wren device\n", 16) != 0) + return -1; + + fs->kfs.RBUFSIZE = atoi((char*)block+256+16); + if(!fs->kfs.RBUFSIZE || (fs->kfs.RBUFSIZE&(fs->kfs.RBUFSIZE-1))) + return -1; + + fs->kfs.BUFSIZE = fs->kfs.RBUFSIZE - sizeof(Tag); + fs->kfs.DIRPERBUF = fs->kfs.BUFSIZE / sizeof(Dentry); + fs->kfs.INDPERBUF = fs->kfs.BUFSIZE / sizeof(long); + fs->kfs.INDPERBUF2 = fs->kfs.INDPERBUF * fs->kfs.INDPERBUF; + + return 1; +} + +static int +readroot(Fs *fs, Dentry *d) +{ + Dentry *d2; + + if(getblocktag(fs, 2, Tdir, QPROOT) < 0) + return -1; + d2 = (Dentry*)block; + if(strcmp(d2->name, "/") != 0) + return -1; + *d = *(Dentry*)block; + return 1; +} + +static long +indfetch(Fs *fs, long addr, long off, int tag, long path) +{ + if(getblocktag(fs, addr, tag, path) < 0) + return -1; + return ((long*)block)[off]; +} + +static long +rel2abs(Fs *fs, Dentry *d, long a) +{ + long addr; + + if(a < NDBLOCK) + return d->dblock[a]; + a -= NDBLOCK; + if(a < fs->kfs.INDPERBUF){ + if(d->iblock == 0) + return 0; + addr = indfetch(fs, d->iblock, a, Tind1, d->qid.path); + if(addr == 0) + print("rel2abs indfetch 0 %s %ld\n", d->name, a); + return addr; + } + a -= fs->kfs.INDPERBUF; + if(a < fs->kfs.INDPERBUF2){ + if(d->diblock == 0) + return 0; + addr = indfetch(fs, d->diblock, a/fs->kfs.INDPERBUF, Tind2, d->qid.path); + if(addr == 0){ + print("rel2abs indfetch 0 %s %ld\n", d->name, a/fs->kfs.INDPERBUF); + return 0; + } + addr = indfetch(fs, addr, a%fs->kfs.INDPERBUF, Tind1, d->qid.path); + return addr; + } + print("rel2abs trip ind %s %ld\n", d->name, a); + return -1; +} + +static int +readdentry(Fs *fs, Dentry *d, int n, Dentry *e) +{ + long addr, m; + + m = n/fs->kfs.DIRPERBUF; + if((addr = rel2abs(fs, d, m)) <= 0) + return addr; + if(getblocktag(fs, addr, Tdir, d->qid.path) < 0) + return -1; + *e = *(Dentry*)(block+(n%fs->kfs.DIRPERBUF)*sizeof(Dentry)); + return 1; +} + +static int +getdatablock(Fs *fs, Dentry *d, long a) +{ + long addr; + + if((addr = rel2abs(fs, d, a)) == 0) + return -1; + return getblocktag(fs, addr, Tfile, QPNONE); +} + +static int +walk(Fs *fs, Dentry *d, char *name, Dentry *e) +{ + int i, n; + Dentry x; + + for(i=0;; i++){ + if((n=readdentry(fs, d, i, &x)) <= 0) + return n; + if(strcmp(x.name, name) == 0){ + *e = x; + return 1; + } + } +} + +static long +kfsread(File *f, void *va, long len) +{ + uchar *a; + long tot, off, o, n; + Fs *fs; + + a = va; + fs = f->fs; + off = f->kfs.off; + tot = 0; + while(tot < len){ + if(getdatablock(fs, &f->kfs, off/fs->kfs.BUFSIZE) < 0) + return -1; + o = off%fs->kfs.BUFSIZE; + n = fs->kfs.BUFSIZE - o; + if(n > len-tot) + n = len-tot; + memmove(a+tot, block+o, n); + off += n; + tot += n; + } + f->kfs.off = off; + return tot; +} + +static int +kfswalk(File *f, char *name) +{ + int n; + + n = walk(f->fs, &f->kfs, name, &f->kfs); + if(n < 0) + return -1; + f->kfs.off = 0; + return 1; +} + +int +kfsinit(Fs *fs) +{ + if(readinfo(fs) < 0 || readroot(fs, &fs->root.kfs) < 0) + return -1; + + fs->root.fs = fs; + fs->read = kfsread; + fs->walk = kfswalk; + return 0; +} |