ref: 4410517b44fd2610abe0dcd1349bb3e6b3c5ddb8
dir: /sys/src/cmd/ramfs.c/
#include <u.h> #include <libc.h> #include <auth.h> #include <fcall.h> #include <thread.h> #include <9p.h> #include <pool.h> char Ebadoff[] = "bad file offset or count"; char Eexist[] = "file already exists"; char Enomem[] = "no memory"; char Eperm[] = "permission denied"; char Enotowner[] = "not owner"; char Elocked[] = "file locked"; enum { Tdat = 0xbabababa, Tind = 0xdadadada, ESIZE = 64*1024, }; #define MAXFSIZE ((0x7fffffffll/sizeof(Ram*))*ESIZE) typedef struct Ram Ram; struct Ram { int type; int size; Ram **link; Ram *ent[]; }; int private; void* ramalloc(ulong size) { void *v; v = sbrk(size); if(v == (void*)-1) return nil; return v; } void rammoved(void*, void *to) { Ram **link, **elink, *x = to; *x->link = x; if(x->type != Tind) return; link = x->ent; for(elink = link + (x->size / sizeof(Ram*)); link < elink; link++) if((x = *link) != nil) x->link = link; } void ramnolock(Pool*) { } Pool rampool = { .name= "ram", .maxsize= 800*1024*1024, .minarena= 4*1024, .quantum= 32, .alloc= ramalloc, .move= rammoved, .lock= ramnolock, .unlock= ramnolock, .flags= 0, }; void accessfile(File *f, int a) { f->atime = time(0); if(a & AWRITE){ f->mtime = f->atime; f->qid.vers++; } } void fsread(Req *r) { int o, n, i, count; vlong top, off; File *f; Ram *x; char *p; f = r->fid->file; off = r->ifcall.offset; count = r->ifcall.count; if(count == 0 || off >= f->length || f->aux == nil){ r->ofcall.count = 0; respond(r, nil); return; } top = off + count; if(top > MAXFSIZE){ respond(r, Ebadoff); return; } if(top > f->length){ top = f->length; count = top - off; } p = (char*)r->ofcall.data; while(count > 0){ i = off / ESIZE; o = off % ESIZE; x = (Ram*)f->aux; if(i < (x->size / sizeof(Ram*))) x = x->ent[i]; else x = nil; if(x != nil && o < x->size){ n = x->size - o; if(n > count) n = count; memmove(p, (char*)&x[1] + o, n); } else { n = ESIZE - o; if(n > count) n = count; memset(p, 0, n); } p += n; off += n; count -= n; } accessfile(f, AREAD); r->ofcall.count = p - (char*)r->ofcall.data; respond(r, nil); } void fswrite(Req *r) { int o, n, i, count; Ram *x, **link; vlong top, off; File *f; char *p; f = r->fid->file; off = r->ifcall.offset; count = r->ifcall.count; if(f->mode & DMAPPEND) off = f->length; if(count == 0){ r->ofcall.count = 0; respond(r, nil); return; } top = off + count; if(top > MAXFSIZE){ respond(r, Ebadoff); return; } n = ((top + ESIZE-1)/ESIZE) * sizeof(Ram*); x = (Ram*)f->aux; if(x == nil || x->size < n){ x = poolrealloc(&rampool, x, sizeof(Ram) + n); if(x == nil){ respond(r, Enomem); return; } link = (Ram**)&f->aux; if(*link == nil){ memset(x, 0, sizeof(Ram)); x->type = Tind; x->link = link; *link = x; } else if(x != *link) rammoved(*link, x); memset((char*)&x[1] + x->size, 0, n - x->size); x->size = n; } p = (char*)r->ifcall.data; while(count > 0){ i = off / ESIZE; o = off % ESIZE; n = ESIZE - o; if(n > count) n = count; x = ((Ram*)f->aux)->ent[i]; if(x == nil || x->size < o+n){ x = poolrealloc(&rampool, x, sizeof(Ram) + o+n); if(x == nil){ respond(r, Enomem); return; } link = &((Ram*)f->aux)->ent[i]; if(*link == nil){ memset(x, 0, sizeof(Ram)); x->type = Tdat; } if(o > x->size) memset((char*)&x[1] + x->size, 0, o - x->size); x->size = o + n; x->link = link; *link = x; } memmove((char*)&x[1] + o, p, n); p += n; off += n; count -= n; } if(top > f->length) f->length = top; accessfile(f, AWRITE); r->ofcall.count = p - (char*)r->ifcall.data; respond(r, nil); } void truncfile(File *f, vlong l) { int i, o, n; Ram *x; x = (Ram*)f->aux; if(x != nil){ n = x->size / sizeof(Ram*); i = l / ESIZE; if(i < n){ o = l % ESIZE; if(o != 0 && x->ent[i] != nil){ x->ent[i]->size = o * sizeof(Ram*); i++; } while(i < n){ if(x->ent[i] != nil){ poolfree(&rampool, x->ent[i]); x->ent[i] = nil; } i++; } } if(l == 0){ poolfree(&rampool, (Ram*)f->aux); f->aux = nil; } } f->length = l; } void fswstat(Req *r) { File *f, *w; char *u; f = r->fid->file; u = r->fid->uid; /* * To change length, must have write permission on file. */ if(r->d.length != ~0 && r->d.length != f->length){ if(r->d.length > MAXFSIZE){ respond(r, Ebadoff); return; } if(!hasperm(f, u, AWRITE) || (f->mode & DMDIR) != 0) goto Perm; } /* * To change name, must have write permission in parent. */ if(r->d.name[0] != '\0' && strcmp(r->d.name, f->name) != 0){ if((w = f->parent) == nil) goto Perm; incref(w); if(!hasperm(w, u, AWRITE)){ closefile(w); goto Perm; } if((w = walkfile(w, r->d.name)) != nil){ closefile(w); respond(r, Eexist); return; } } /* * To change mode, must be owner or group leader. * Because of lack of users file, leader=>group itself. */ if(r->d.mode != ~0 && f->mode != r->d.mode){ if(strcmp(u, f->uid) != 0) if(strcmp(u, f->gid) != 0){ respond(r, Enotowner); return; } } /* * To change group, must be owner and member of new group, * or leader of current group and leader of new group. * Second case cannot happen, but we check anyway. */ while(r->d.gid[0] != '\0' && strcmp(f->gid, r->d.gid) != 0){ if(strcmp(u, f->uid) == 0) break; if(strcmp(u, f->gid) == 0) if(strcmp(u, r->d.gid) == 0) break; respond(r, Enotowner); return; } if(r->d.mode != ~0){ f->mode = r->d.mode; f->qid.type = f->mode >> 24; } if(r->d.name[0] != '\0'){ free(f->name); f->name = estrdup9p(r->d.name); } if(r->d.length != ~0 && r->d.length != f->length) truncfile(f, r->d.length); accessfile(f, AWRITE); if(r->d.mtime != ~0){ f->mtime = r->d.mtime; } respond(r, nil); return; Perm: respond(r, Eperm); } void fscreate(Req *r) { File *f; int p; f = r->fid->file; p = r->ifcall.perm; if((p & DMDIR) != 0) p = (p & ~0777) | ((p & f->mode) & 0777); else p = (p & ~0666) | ((p & f->mode) & 0666); if((f = createfile(f, r->ifcall.name, r->fid->uid, p, nil)) == nil){ responderror(r); return; } f->atime = f->mtime = time(0); f->aux = nil; r->fid->file = f; r->ofcall.qid = f->qid; respond(r, nil); } void fsopen(Req *r) { File *f; f = r->fid->file; if((f->mode & DMEXCL) != 0){ if(f->ref > 2 && (long)((ulong)time(0)-(ulong)f->atime) < 300){ respond(r, Elocked); return; } } if((f->mode & DMAPPEND) == 0 && (r->ifcall.mode & OTRUNC) != 0){ truncfile(f, 0); accessfile(f, AWRITE); } respond(r, nil); } void fsdestroyfid(Fid *fid) { File *f; f = fid->file; if(fid->omode != -1 && (fid->omode & ORCLOSE) != 0 && f != nil && f->parent != nil) removefile(f); } void fsdestroyfile(File *f) { truncfile(f, 0); } void fsstart(Srv *) { char buf[40]; int ctl; if(private){ snprint(buf, sizeof buf, "/proc/%d/ctl", getpid()); if((ctl = open(buf, OWRITE)) < 0) sysfatal("can't protect memory: %r"); fprint(ctl, "noswap\n"); fprint(ctl, "private\n"); close(ctl); } } Srv fs = { .open= fsopen, .read= fsread, .write= fswrite, .wstat= fswstat, .create= fscreate, .destroyfid= fsdestroyfid, .start= fsstart, }; void usage(void) { fprint(2, "usage: %s [-Dipsubac] [-m mountpoint] [-S srvname]\n", argv0); exits("usage"); } void main(int argc, char **argv) { char *srvname = nil; char *mtpt = "/tmp"; int mountflags; Qid q; fs.tree = alloctree(nil, nil, DMDIR|0777, fsdestroyfile); q = fs.tree->root->qid; mountflags = 0; ARGBEGIN{ case 'D': chatty9p++; break; case 's': srvname = "ramfs"; mtpt = nil; break; case 'S': srvname = EARGF(usage()); mtpt = nil; break; case 'm': mtpt = EARGF(usage()); break; case 'i': fs.nopipe = 1; srvname = nil; mtpt = nil; break; case 'p': private = 1; break; case 'u': rampool.maxsize = (uintptr)~0; break; case 'b': mountflags |= MBEFORE; break; case 'c': mountflags |= MCREATE; break; case 'a': mountflags |= MAFTER; break; default: usage(); }ARGEND; if(argc > 0) usage(); if(fs.nopipe){ fs.infd = 0; fs.outfd = 1; srv(&fs); exits(0); } if(srvname == nil && mtpt == nil) sysfatal("must specify -S, or -m option"); if(mountflags == 0) mountflags = MREPL | MCREATE; postmountsrv(&fs, srvname, mtpt, mountflags); exits(0); }