1999/0608/mpc/devsac.c (diff list | history)

mpc/devsac.c on 1999/0608
1999/0608		#include "u.h" #include "../port/lib.h" #include "mem.h" #include "dat.h" #include "fns.h" #include "io.h" /* * Rather than reading /adm/users, which is a lot of work for * a toy program, we assume all groups have the form * NNN:user:user: * meaning that each user is the leader of his own group. */ enum { OPERM = 0x3, /* mask of all permission types in open mode */ Nram = 512, }; typedef struct SacPath SacPath; typedef struct Sac Sac; typedef struct SacHeader SacHeader; typedef struct SacDir SacDir; enum { Magic = 0x5acf5, }; struct SacDir { char name[NAMELEN]; char uid[NAMELEN]; char gid[NAMELEN]; uchar qid[4]; uchar mode[4]; uchar atime[4]; uchar mtime[4]; uchar length[8]; uchar blocks[8]; }; struct SacHeader { uchar magic[4]; uchar length[8]; uchar blocksize[4]; uchar md5[16]; }; struct Sac { SacDir; SacPath *path; }; struct SacPath { Ref; SacPath *up; vlong blocks; int entry; }; enum { Pexec = 1, Pwrite = 2, Pread = 4, Pother = 1, Pgroup = 8, Powner = 64, }; uchar *data = SACMEM; int blocksize; Sac root; void sacstat(SacDir*, char*); void io(void); void usage(void); ulong getl(void *p); vlong getv(void *p); void init(char*); Sac *saccpy(Sac *s); Sac *saclookup(Sac *s, char *name); int sacdirread(Sac *s, char *p, long off, long cnt); void loadblock(void *buf, uchar *offset, int blocksize); void sacfree(Sac*); void devinit(void) { SacHeader *hdr; hdr = (SacHeader*)data; if(getl(hdr->magic) != Magic) { print("devsac: bad magic"); return; } blocksize = getl(hdr->blocksize); root.SacDir = *(SacDir*)(data + sizeof(SacHeader)); } static Chan* sacattach(char* spec) { Chan *c; int dev; dev = atoi(spec); if(dev != 0) error("bad specification"); // check if init found sac file system in memory if(blocksize == 0) error("devsac: bad magic"); c = devattach('C', spec); c->qid = (Qid){getl(root.qid), 0}; c->dev = dev; c->aux = saccpy(&root); return c; } Chan* sacclone(Chan *c, Chan *nc) { nc = devclone(c, nc); nc->aux = saccpy(c->aux); return nc; } int devwalk(Chan *c, char *name, Dirtab *tab, int ntab, Devgen *gen) { Sac *sac; isdir(c); sac = c->aux; if(strcmp(name, ".") == 0) return 1; sac = saclookup(sac, name); if(sac == nil) { strncpy(up->error, Enonexist, NAMELEN); return 0; } c->aux = sac; c->qid = (Qid){getl(sac->qid), 0}; op = c->path; c->path = ptenter(&syspt, op, name); decref(op); return 1; } char * ropen(Fid *f) { int mode, trunc; if(f->open) return Eisopen; if(f->busy == 0) return Enotexist; mode = rhdr.mode; if(f->qid.path & CHDIR){ if(mode != OREAD) return Eperm; thdr.qid = f->qid; return 0; } if(mode & ORCLOSE) return Erdonly; trunc = mode & OTRUNC; mode &= OPERM; if(mode==OWRITE || mode==ORDWR || trunc) return Erdonly; if(mode==OREAD) if(!perm(f, f->sac, Pread)) return Eperm; if(mode==OEXEC) if(!perm(f, f->sac, Pexec)) return Eperm; thdr.qid = f->qid; f->open = 1; return 0; } char * rcreate(Fid *f) { if(f->open) return Eisopen; if(f->busy == 0) return Enotexist; return Erdonly; } char* rread(Fid *f) { Sac *sac; char *buf, *buf2; long off; int n, cnt, i, j; uchar *blocks; vlong length; if(f->busy == 0) return Enotexist; sac = f->sac; thdr.count = 0; off = rhdr.offset; buf = thdr.data; cnt = rhdr.count; if(f->qid.path & CHDIR){ cnt = (rhdr.count/DIRLEN)*DIRLEN; if(off%DIRLEN) return "i/o error"; thdr.count = sacdirread(sac, buf, off, cnt); return 0; } length = getv(sac->length); if(off >= length) { rhdr.count = 0; return 0; } if(cnt > length-off) cnt = length-off; thdr.count = cnt; if(cnt == 0) return 0; blocks = data + getv(sac->blocks); buf2 = malloc(blocksize); while(cnt > 0) { i = off/blocksize; loadblock(buf2, blocks+i*8, blocksize); j = off-i*blocksize; n = blocksize-j; if(n > cnt) n = cnt; memmove(buf, buf2+j, n); cnt -= n; off += n; } free(buf2); return 0; } char* sacwrite(Fid *f) { if(f->busy == 0) return Enotexist; return Erdonly; } char * rclunk(Fid *f) { f->busy = 0; f->open = 0; free(f->user); sacfree(f->sac); return 0; } char * rremove(Fid *f) { f->busy = 0; f->open = 0; free(f->user); sacfree(f->sac); return Erdonly; } char * rstat(Fid *f) { if(f->busy == 0) return Enotexist; sacstat(f->sac, thdr.stat); return 0; } char * rwstat(Fid *f) { if(f->busy == 0) return Enotexist; return Erdonly; } Sac* saccpy(Sac *s) { Sac *ss; ss = malloc(sizeof(Sac)); *ss = *s; if(ss->path) incref(ss->path); return ss; } SacPath * sacpathalloc(SacPath *p, vlong blocks, int entry) { SacPath *pp = malloc(sizeof(SacPath)); pp->ref = 1; pp->blocks = blocks; pp->entry = entry; pp->up = p; return pp; } static void sacpathfree(SacPath *p) { if(p == nil) return; if(decref(p) > 0) return; sacpathfree(p->up); free(p); } void sacfree(Sac *s) { sacpathfree(s->path); free(s); } void sacstat(SacDir *s, char *buf) { Dir dir; memmove(dir.name, s->name, NAMELEN); dir.qid = (Qid){getl(s->qid), 0}; dir.mode = getl(s->mode); dir.length = getv(s->length); if(dir.mode &CHDIR) dir.length *= DIRLEN; strcpy(dir.uid, s->uid); strcpy(dir.gid, s->gid); dir.atime = getl(s->atime); dir.mtime = getl(s->mtime); convD2M(&dir, buf); } void loadblock(void *buf, uchar *offset, int blocksize) { vlong block, n; block = getv(offset); if(block < 0) { block = -block; n = getv(offset+8); if(n < 0) n = -n; n -= block; //fprint(2, "blocksize = %d, block = %lld n = %lld\n", blocksize, block, n); if(unsac(buf, data+block, blocksize, n)<0) panic("unsac failed!"); } else { memmove(buf, data+block, blocksize); } } Sac* sacparent(Sac *s) { uchar *blocks; SacDir *buf; int per, i; SacPath *p; p = s->path; if(p == nil || p->up == nil) { pathfree(p); *s = root; return s; } p = p->up; //fprint(2, "sacparent = %lld %d\n", p->blocks, p->entry); blocks = data + p->blocks; per = blocksize/sizeof(SacDir); i = p->entry/per; buf = malloc(per*sizeof(SacDir)); loadblock(buf, blocks + i*8, per*sizeof(SacDir)); s->SacDir = buf[p->entry-i*per]; //fprint(2, "sacparent = %s\n", s->name); free(buf); incref(p); pathfree(s->path); s->path = p; return s; } int sacdirread(Sac *s, char *p, long off, long cnt) { uchar *blocks; SacDir *buf; int iblock, per, i, j, ndir; blocks = data + getv(s->blocks); per = blocksize/sizeof(SacDir); ndir = getv(s->length); off /= DIRLEN; cnt /= DIRLEN; if(off >= ndir) return 0; if(cnt > ndir-off) cnt = ndir-off; iblock = -1; buf = malloc(per*sizeof(SacDir)); for(i=off; i<off+cnt; i++) { j = i/per; if(j != iblock) { loadblock(buf, blocks + j*8, per*sizeof(SacDir)); iblock = j; } j *= per; sacstat(buf+i-j, p); p += DIRLEN; } free(buf); return cnt*DIRLEN; } Sac* saclookup(Sac *s, char *name) { int ndir; int top, bot, i, j, k, per; uchar *blocks; SacDir *buf; int iblock; SacDir *sd; if(strcmp(name, "..") == 0) return sacparent(s); blocks = data + getv(s->blocks); per = blocksize/sizeof(SacDir); ndir = getv(s->length); buf = malloc(per*sizeof(SacDir)); iblock = -1; if(1) { // linear search for(i=0; i<ndir; i++) { j = i/per; if(j != iblock) { loadblock(buf, blocks + j*8, per*sizeof(SacDir)); iblock = j; } j *= per; sd = buf+i-j; k = strcmp(name, sd->name); if(k == 0) { //print("walk %s %lld %d\n", name, getv(s->blocks), i); s->path = sacpathalloc(s->path, getv(s->blocks), i); s->SacDir = *sd; free(buf); return s; } } free(buf); return 0; } // binary search top = ndir; bot = 0; while(bot != top){ if(bot>top) sysfatal("binary serach failed: %d %d\n", bot, top); i = (bot+top)>>1; j = i/per; if(j != iblock) { loadblock(buf, blocks + j*8, per*sizeof(SacDir)); iblock = j; } j *= per; sd = buf+i-j; k = strcmp(name, sd->name); if(k == 0) { s->path = sacpathalloc(s->path, getv(s->blocks), i); s->SacDir = *sd; free(buf); } if(k < 0) { top = i; sd = buf; if(strcmp(name, sd->name) < 0) top = j; } else { bot = i+1; if(ndir-j < per) i = ndir-j; else i = per; sd = buf+i-1; if(strcmp(name, sd->name) > 0) bot = j+i; } } return 0; } Fid * newfid(int fid) { Fid *f, *ff; ff = 0; for(f = fids; f; f = f->next) if(f->fid == fid) return f; else if(!ff && !f->busy) ff = f; if(ff){ ff->fid = fid; return ff; } f = malloc(sizeof *f); //fprint(2, "newfid\n"); memset(f, 0 , sizeof(Fid)); f->fid = fid; f->next = fids; fids = f; return f; } void io(void) { char *err; int n; for(;;){ /* * reading from a pipe or a network device * will give an error after a few eof reads * however, we cannot tell the difference * between a zero-length read and an interrupt * on the processes writing to us, * so we wait for the error */ n = read(mfd[0], mdata, sizeof mdata); if(n == 0) continue; if(n < 0) error("mount read"); if(convM2S(mdata, &rhdr, n) == 0) continue; if(debug) fprint(2, "sacfs:<-%F\n", &rhdr); thdr.data = mdata + MAXMSG; if(!fcalls[rhdr.type]) err = "bad fcall type"; else err = (*fcalls[rhdr.type])(newfid(rhdr.fid)); if(err){ thdr.type = Rerror; strncpy(thdr.ename, err, ERRLEN); }else{ thdr.type = rhdr.type + 1; thdr.fid = rhdr.fid; } thdr.tag = rhdr.tag; if(debug) fprint(2, "ramfs:->%F\n", &thdr);/**/ n = convS2M(&thdr, mdata); if(write(mfd[1], mdata, n) != n) error("mount write"); } } int perm(Fid *f, Sac *s, int p) { ulong perm = getl(s->mode); if((p*Pother) & perm) return 1; if(strcmp(f->user, s->gid)==0 && ((p*Pgroup) & perm)) return 1; if(strcmp(f->user, s->uid)==0 && ((p*Powner) & perm)) return 1; return 0; } ulong getl(void *p) { uchar *a = p; return (a[0]<<24) | (a[1]<<16) | (a[2]<<8) | a[3]; } vlong getv(void *p) { uchar *a = p; ulong l0, l1; vlong v; l0 = (a[0]<<24) | (a[1]<<16) | (a[2]<<8) | a[3]; a += 4; l1 = (a[0]<<24) | (a[1]<<16) | (a[2]<<8) | a[3]; v = l0; v <<= 32; v |= l1; return v; } Dev sacdevtab = { 'C', "sac", devreset, sacinit, sacattach, sacclone, sacwalk, sacstat, sacopen, devcreate, sacclose, sacread, devbread, sacwrite, devbwrite, devremove, devwstat, };