ref: 62b4c820ffb7561ca397d46a2b895d8c98726ec7
author: kvik <kvik@a-b.xyz>
date: Mon Apr 22 17:12:51 EDT 2019
let there be unions
--- /dev/null
+++ b/mkfile
@@ -1,0 +1,7 @@
+</$objtype/mkfile
+
+TARG=unionfs
+OFILES=$TARG.$O
+BIN=$home/bin/$objtype
+
+</sys/src/cmd/mkone
--- /dev/null
+++ b/unionfs.c
@@ -1,0 +1,716 @@
+#include <u.h>
+#include <libc.h>
+#include <fcall.h>
+#include <thread.h>
+#include <9p.h>
+
+typedef struct Union Union;
+typedef struct Fil Fil;
+typedef struct Flist Flist;
+typedef struct Fstate Fstate;
+typedef struct Qidmap Qidmap;
+
+struct Union {+ char *root;
+ int create;
+ Union *prev, *next;
+};
+
+enum {+ Nqidbits = 5,
+ Nqidmap = 1 << Nqidbits,
+};
+
+struct Qidmap {+ Ref;
+ ushort type;
+ uint dev;
+ uvlong path;
+ uvlong qpath;
+ Qidmap *next;
+};
+
+struct Fil {+ Ref;
+ Dir;
+ Qidmap *qmap;
+ char *path; /* real path */
+ char *fspath; /* internal path */
+};
+
+struct Flist {+ Fil *file;
+ Flist *next;
+};
+
+struct Fstate {+ int fd;
+ Fil *file;
+ Flist *dir, *idx;
+};
+
+Union u0 = {.next = &u0, .prev = &u0};+Union *unionlist = &u0;
+uvlong qidnext;
+Qidmap *qidmap[Nqidmap];
+
+void
+LOG(char *fmt, ...)
+{+ static int fd = -1;
+ va_list args;
+
+ if(fd < 0 && (fd = open("/mnt/log/log", OWRITE)) < 0){+ fprint(2, "failed to open log pipe\n");
+ return;
+ }
+ va_start(args, fmt);
+ vfprint(fd, fmt, args);
+ va_end(args);
+}
+
+void*
+emalloc(ulong sz)
+{+ void *v;
+
+ if((v = malloc(sz)) == nil)
+ sysfatal("emalloc: %r");+ memset(v, 0, sz);
+
+ setmalloctag(v, getcallerpc(&sz));
+ return v;
+}
+
+char*
+estrdup(char *s)
+{+ char *p;
+
+ if((p = strdup(s)) == nil)
+ sysfatal("estrdup: %r");+ setmalloctag(p, getcallerpc(&s));
+ return p;
+}
+
+char*
+esmprint(char *fmt, ...)
+{+ char *s;
+ va_list arg;
+
+ va_start(arg, fmt);
+ s = vsmprint(fmt, arg);
+ va_end(arg);
+ if(s == nil)
+ sysfatal("esmprint: %r");+ return s;
+}
+
+Ref*
+copyref(Ref *r)
+{+ incref(r);
+ return r;
+}
+
+int
+qidhash(uvlong path)
+{+ int h, n;
+
+ h = 0;
+ for(n = 0; n < 64; n += Nqidbits){+ h ^= path;
+ path >>= Nqidbits;
+ }
+ return h & (Nqidmap-1);
+}
+
+Qidmap*
+qidlookup(Dir *d)
+{+ int h;
+ Qidmap *q;
+
+ h = qidhash(d->qid.path);
+ for(q = qidmap[h]; q != nil; q = q->next)
+ if(q->type == d->type && q->dev == d->dev && q->path == d->qid.path)
+ return q;
+ return nil;
+}
+
+int
+qidexists(uvlong path)
+{+ int h;
+ Qidmap *q;
+
+ for(h = 0; h < Nqidmap; h++)
+ for(q = qidmap[h]; q != nil; q = q->next)
+ if(q->qpath == path)
+ return 1;
+ return 0;
+}
+
+Qidmap*
+qidnew(Dir *d)
+{+ int h;
+ uvlong path;
+ Qidmap *q;
+
+ q = qidlookup(d);
+ if(q != nil)
+ return (Qidmap*)copyref(q);
+ path = d->qid.path;
+ while(qidexists(path)){+ path &= (1LL<<48)-1;
+ if(++qidnext >= 1<<16)
+ qidnext = 1;
+ path |= qidnext<<48;
+ }
+ q = emalloc(sizeof(*q));
+ q->type = d->type;
+ q->dev = d->dev;
+ q->path = d->qid.path;
+ q->qpath = path;
+ h = qidhash(q->path);
+ q->next = qidmap[h];
+ qidmap[h] = q;
+ return (Qidmap*)copyref(q);
+}
+
+void
+qidfree(Qidmap *q)
+{+ int h;
+ Qidmap *l;
+
+ if(q == nil)
+ return;
+ if(decref(q))
+ return;
+ h = qidhash(q->path);
+ if(qidmap[h] == q)
+ qidmap[h] = q->next;
+ else{+ for(l = qidmap[h]; l->next != q; l = l->next)
+ ;
+ l->next = q->next;
+ }
+ free(q);
+}
+
+void
+unionlink(Union *p, Union *n)
+{+ p = p->prev;
+ n->next = p->next;
+ n->prev = p;
+ p->next->prev = n;
+ p->next = n;
+}
+
+Fil*
+filenew(Dir *d)
+{+ Fil *f;
+
+ f = emalloc(sizeof(*f));
+ f->ref = 1;
+ f->qmap = qidnew(d);
+ f->Dir = *d;
+ f->qid.path = f->qmap->qpath;
+ f->name = estrdup(d->name);
+ f->uid = estrdup(d->uid);
+ f->gid = estrdup(d->gid);
+ f->muid = estrdup(d->muid);
+ return f;
+}
+
+void
+filefree(Fil *f)
+{+ if(f == nil)
+ return;
+ if(decref(f))
+ return;
+// qidfree(f->qmap);
+ free(f->name);
+ free(f->uid);
+ free(f->gid);
+ free(f->muid);
+ free(f->path);
+ free(f->fspath);
+ free(f);
+}
+
+void
+flistadd(Flist **list, Fil *f)
+{+ Flist *p;
+
+ p = emalloc(sizeof(*p));
+ p->file = f;
+ p->next = *list;
+ *list = p;
+}
+
+void
+flistfree(Flist *l)
+{+ Flist *lp;
+
+ for(lp = l; lp != nil; l = lp){+ lp = lp->next;
+ filefree(l->file);
+ free(l);
+ }
+}
+
+int
+flisthas(Flist *list, char *name)
+{+ for(; list != nil; list = list->next)
+ if(strcmp(list->file->name, name) == 0)
+ return 1;
+ return 0;
+}
+
+Fstate*
+fstatenew(Fil *f)
+{+ Fstate *st;
+
+ st = emalloc(sizeof(*st));
+ st->fd = -1;
+ st->file = (Fil*)copyref(f);
+ return st;
+}
+
+void
+fstatefree(Fstate *st)
+{+ if(st == nil)
+ return;
+ filefree(st->file);
+ flistfree(st->dir);
+ close(st->fd);
+ free(st);
+}
+
+void
+fsattach(Req *r)
+{+ Dir d;
+ Fil *root;
+ Fstate *st;
+
+ nulldir(&d);
+ d.qid = (Qid){0, 0, QTDIR};+ d.name = ".";
+ d.mode = 0777|DMDIR;
+ d.uid = r->fid->uid;
+ d.gid = r->fid->uid;
+ d.muid = r->fid->uid;
+ d.mtime = time(0);
+ d.atime = time(0);
+ d.length = 0;
+
+ root = filenew(&d);
+ root->fspath = estrdup(d.name);
+ root->path = estrdup(d.name);
+
+ st = fstatenew(root);
+ decref(root);
+
+ r->fid->aux = st;
+ r->fid->qid = root->qid;
+ r->ofcall.qid = root->qid;
+ respond(r, nil);
+}
+
+Fil*
+filewalk(Fil *p, char *name)
+{+ char *path;
+ char *s;
+ Dir *d;
+ Fil *f;
+ Union *u;
+
+ if(strcmp(name, "..") == 0){+ s = strrchr(p->fspath, '/');
+ if(s == nil)
+ return p;
+ *s = 0;
+ return filewalk(p, "");
+ }
+ for(u = unionlist->next; u != unionlist; u = u->next){+ path = esmprint("%s/%s/%s", u->root, p->fspath, name);+ d = dirstat(path);
+ if(d != nil){+ f = filenew(d);
+ free(d);
+ f->fspath = cleanname(esmprint("%s/%s", p->fspath, name));+ f->path = cleanname(path);
+ return f;
+ }
+ free(path);
+ }
+ return nil;
+}
+
+char*
+walk1(Fid *fid, char *name, void *)
+{+ Fil *p, *f;
+ Fstate *st;
+
+ st = fid->aux;
+ p = st->file;
+ f = filewalk(p, name);
+ if(f == nil)
+ return "no file";
+ st->file = f;
+ filefree(p);
+
+ fid->qid = f->qid;
+ return nil;
+}
+
+char*
+clone(Fid *old, Fid *new, void*)
+{+ Fstate *fs;
+
+ fs = old->aux;
+ new->aux = fstatenew(fs->file);
+ return nil;
+}
+
+void
+destroyfid(Fid *fid)
+{+ fstatefree((Fstate*)fid->aux);
+}
+
+void
+fswalk(Req *r)
+{+ walkandclone(r, walk1, clone, nil);
+}
+
+Flist*
+filereaddir(Fil *p)
+{+ int fd;
+ long i, n;
+ Dir *dir, *d;
+ char *path;
+ Union *u;
+ Fil *f;
+ Flist *list;
+
+ list = nil;
+ for(u = unionlist->next; u != unionlist; u = u->next){+ path = esmprint("%s/%s", u->root, p->fspath);+ d = dirstat(path);
+ if(d == nil){+ free(path);
+ continue;
+ }
+ free(d);
+ fd = open(path, OREAD);
+ if(fd < 0){+ free(path);
+ continue;
+ }
+ free(path);
+ n = dirreadall(fd, &dir);
+ close(fd);
+ if(n < 0)
+ continue;
+ for(i = 0; i < n; i++){+ if(flisthas(list, dir[i].name))
+ continue;
+ f = filenew(&dir[i]);
+ flistadd(&list, f);
+ }
+ free(dir);
+ }
+ return list;
+}
+
+void
+fsopen(Req *r)
+{+ Fcall *i;
+ Fstate *st;
+ Fil *f;
+
+ i = &r->ifcall;
+ st = r->fid->aux;
+ f = st->file;
+ if(f->mode&DMDIR){+ st->dir = filereaddir(f);
+ st->idx = st->dir;
+ }else{+ st->fd = open(f->path, i->mode);
+ if(st->fd < 0){+ responderror(r);
+ return;
+ }
+ }
+ respond(r, nil);
+}
+
+void
+fscreate(Req *r)
+{+ char *path, *npath;
+ Dir *d;
+ Fcall *i, *o;
+ Union *u;
+ Fstate *st;
+ Fil *f, *nf;
+
+ i = &r->ifcall;
+ o = &r->ofcall;
+ st = r->fid->aux;
+ f = st->file;
+
+ for(u = unionlist->next; u != unionlist; u = u->next)
+ if(u->create == 1)
+ break;
+ assert(u != unionlist);
+ path = cleanname(esmprint("%s/%s", u->root, f->fspath));+ d = dirstat(path);
+ if(d != nil)
+ goto work;
+ for(u = unionlist->next; u != unionlist; u = u->next){+ if(u->create == 1)
+ continue;
+ free(path);
+ path = cleanname(esmprint("%s/%s", u->root, f->fspath));+ d = dirstat(path);
+ if(d != nil){+ free(d);
+ goto work;
+ }
+ }
+ sysfatal("something's fucked");+
+work:
+ npath = cleanname(esmprint("%s/%s", path, i->name));+ free(path);
+ st = emalloc(sizeof(*st));
+ st->fd = create(npath, i->mode, i->perm);
+ if(st->fd < 0){+ responderror(r);
+ return;
+ }
+ d = dirfstat(st->fd);
+ if(d == nil){+ fstatefree(st);
+ responderror(r);
+ return;
+ }
+ nf = filenew(d);
+ free(d);
+ nf->path = npath;
+ nf->fspath = estrdup(f->fspath);
+ st->file = nf;
+
+ r->fid->aux = st;
+ r->fid->qid = f->qid;
+ o->qid = f->qid;
+ respond(r, nil);
+}
+
+void
+fsremove(Req *r)
+{+ Fstate *st;
+ Fil *f;
+
+ st = r->fid->aux;
+ f = st->file;
+ if(remove(f->path) < 0){+ responderror(r);
+ return;
+ }
+ respond(r, nil);
+}
+
+void
+dirfill(Dir *dir, Fil *f)
+{+ *dir = f->Dir;
+ dir->qid = f->qid;
+ dir->name = estrdup(f->name);
+ dir->uid = estrdup(f->uid);
+ dir->gid = estrdup(f->gid);
+ dir->muid = estrdup(f->muid);
+}
+
+int
+dirgen(int, Dir *dir, void *aux)
+{+ Fstate *fs;
+ Flist *l;
+
+ fs = aux;
+ l = fs->idx;
+ if(l == nil)
+ return -1;
+ dirfill(dir, l->file);
+ fs->idx = l->next;
+ return 0;
+}
+
+void
+fsread(Req *r)
+{+ long n;
+ Fcall *i, *o;
+ Fil *f;
+ Fstate *st;
+
+ i = &r->ifcall;
+ o = &r->ofcall;
+ st = r->fid->aux;
+ f = st->file;
+
+ if(f->mode&DMDIR){+ dirread9p(r, dirgen, st);
+ respond(r, nil);
+ return;
+ }
+ if((n = pread(st->fd, o->data, i->count, i->offset)) < 0){+ responderror(r);
+ return;
+ }
+ r->ofcall.count = n;
+ respond(r, nil);
+}
+
+void
+fswrite(Req *r)
+{+ Fcall *i, *o;
+ Fstate *fs;
+
+ i = &r->ifcall;
+ o = &r->ofcall;
+ fs = r->fid->aux;
+
+ if((o->count = pwrite(fs->fd, i->data, i->count, i->offset)) != i->count){+ responderror(r);
+ return;
+ }
+ respond(r, nil);
+}
+
+void
+fsstat(Req *r)
+{+ Fstate *st;
+
+ st = r->fid->aux;
+ dirfill(&r->d, st->file);
+ respond(r, nil);
+}
+
+void
+fswstat(Req *r)
+{+ Fstate *st;
+ Fil *f;
+
+ st = r->fid->aux;
+ f = st->file;
+ if(dirwstat(f->path, &r->d) < 0){+ responderror(r);
+ return;
+ }
+ respond(r, nil);
+}
+
+Srv fs = {+ .attach = fsattach,
+ .walk = fswalk,
+ .open = fsopen,
+ .create = fscreate,
+ .remove = fsremove,
+ .read = fsread,
+ .write = fswrite,
+ .stat = fsstat,
+ .wstat = fswstat,
+ .destroyfid = destroyfid,
+};
+
+void
+usage(void)
+{+ fprint(2, "%s [-D] [-m mtpt] [-s srv] [-c] path ...\n", argv0);
+ exits("usage");+}
+
+void
+main(int argc, char *argv[])
+{+ int c, i;
+ int mflag;
+ char *mtpt, *srv;
+ Union *u;
+
+ c = 0;
+ mflag = MREPL|MCREATE;
+ mtpt = "/n/un";
+ srv = nil;
+ ARGBEGIN{+ case 'a':
+ mflag = MAFTER;
+ break;
+ case 'b':
+ mflag = MBEFORE;
+ break;
+ case 'm':
+ mtpt = EARGF(usage());
+ break;
+ case 's':
+ srv = EARGF(usage());
+ break;
+ case 'D':
+ chatty9p++;
+ break;
+ case 'c':
+ c++;
+ break;
+ case 'C':
+ mflag |= MCACHE;
+ break;
+ default:
+ usage();
+ }ARGEND;
+ if(argc < 1)
+ usage();
+ for(i = 0; i < argc; i++){+ if(strncmp(argv[i], "-c", 2) == 0){+ c++;
+ continue;
+ }
+ u = emalloc(sizeof(*u));
+ u->create = c == 1 ? c : 0;
+ u->root = estrdup(cleanname(argv[i]));
+ unionlink(unionlist, u);
+ }
+ if(c == 0)
+ unionlist->next->create = 1;
+
+ postmountsrv(&fs, srv, mtpt, mflag);
+
+ exits(nil);
+}