ref: dc725301592117ad0e70a0ab21926dcf5302ed31
dir: /sys/src/cmd/git/ref.c/
#include <u.h>
#include <libc.h>
#include <ctype.h>
#include "git.h"
typedef struct Eval Eval;
typedef struct Lcaq Lcaq;
struct Lcaq {
Objq;
Hash *head;
Hash *tail;
int nhead;
int ntail;
Object *best;
int dist;
};
enum {
Blank,
Keep,
Drop,
};
struct Eval {
char *str;
char *p;
Object **stk;
int nstk;
int stksz;
};
static char *colors[] = {
[Keep] "keep",
[Drop] "drop",
[Blank] "blank",
};
static Object zcommit = {
.type=GCommit
};
void
eatspace(Eval *ev)
{
while(isspace(ev->p[0]))
ev->p++;
}
void
push(Eval *ev, Object *o)
{
if(ev->nstk == ev->stksz){
ev->stksz = 2*ev->stksz + 1;
ev->stk = erealloc(ev->stk, ev->stksz*sizeof(Object*));
}
ev->stk[ev->nstk++] = o;
}
Object*
pop(Eval *ev)
{
if(ev->nstk == 0)
sysfatal("stack underflow");
return ev->stk[--ev->nstk];
}
Object*
peek(Eval *ev)
{
if(ev->nstk == 0)
sysfatal("stack underflow");
return ev->stk[ev->nstk - 1];
}
int
isword(char e)
{
return isalnum(e) || e == '/' || e == '-' || e == '_' || e == '.';
}
int
word(Eval *ev, char *b, int nb)
{
char *p, *e;
int n;
p = ev->p;
for(e = p; isword(*e) && strncmp(e, "..", 2) != 0; e++)
/* nothing */;
/* 1 for nul terminator */
n = e - p + 1;
if(n >= nb)
n = nb;
snprint(b, n, "%s", p);
ev->p = e;
return n > 0;
}
int
take(Eval *ev, char *m)
{
int l;
l = strlen(m);
if(strncmp(ev->p, m, l) != 0)
return 0;
ev->p += l;
return 1;
}
static int
pickbest(Lcaq *q, Qelt *e, int color)
{
int i, best, exact;
best = 0;
exact = 0;
if(color == Blank || e->color == color)
return 0;
if(e->dist < q->dist){
dprint(1, "found best (dist %d < %d): %H\n", e->dist, q->dist, e->o->hash);
best = 1;
}
for(i = 0; i < q->nhead; i++)
if(hasheq(&q->head[i], &e->o->hash)){
dprint(1, "found best (exact head): %H\n", e->o->hash);
best = 1;
exact = 1;
}
for(i = 0; i < q->ntail; i++)
if(hasheq(&q->tail[i], &e->o->hash)){
dprint(1, "found best (exact tail): %H\n", e->o->hash);
best = 1;
exact = 1;
}
if(best){
q->best = e->o;
q->dist = e->dist;
}
return exact;
}
static int
repaint(Lcaq *lcaq, Objset *keep, Objset *drop, Object *o, int dist, int ancestor)
{
Lcaq objq;
Qelt e;
Object *p;
int i;
qinit(&objq);
if((o = readobject(o->hash)) == nil)
return -1;
qput(&objq, o, Drop, dist);
while(qpop(&objq, &e)){
o = e.o;
if(oshas(drop, o->hash))
continue;
if(ancestor && pickbest(lcaq, &e, Keep))
goto out;
if(!oshas(keep, o->hash)){
dprint(2, "repaint: blank => drop %H\n", o->hash);
osadd(drop, o);
continue;
}
for(i = 0; i < o->commit->nparent; i++){
if(oshas(drop, o->commit->parent[i]))
continue;
if((p = readobject(o->commit->parent[i])) == nil)
goto out;
if(p->type != GCommit){
fprint(2, "hash %H not commit\n", p->hash);
unref(p);
}
qput(&objq, p, Drop, e.dist+1);
}
unref(e.o);
}
out:
qclear(&objq);
return 0;
}
static int
paint(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres, int ancestor)
{
Qelt e;
Lcaq objq;
Objset keep, drop;
Object *o, *c;
int i, ncolor;
osinit(&keep);
osinit(&drop);
memset(&objq, 0, sizeof(objq));
qinit(&objq);
objq.head = head;
objq.nhead = nhead;
objq.tail = tail;
objq.ntail = ntail;
objq.dist = 1<<30;
for(i = 0; i < nhead; i++){
if((o = readobject(head[i])) == nil){
fprint(2, "warning: %H does not point at commit\n", o->hash);
werrstr("read head %H: %r", head[i]);
return -1;
}
if(o->type != GCommit){
fprint(2, "warning: %H does not point at commit\n", o->hash);
unref(o);
continue;
}
dprint(1, "init: keep %H\n", o->hash);
qput(&objq, o, Keep, 0);
unref(o);
}
for(i = 0; i < ntail; i++){
if((o = readobject(tail[i])) == nil){
werrstr("read tail %H: %r", tail[i]);
return -1;
}
if(o->type != GCommit){
fprint(2, "warning: %H does not point at commit\n", o->hash);
unref(o);
continue;
}
dprint(1, "init: drop %H\n", o->hash);
qput(&objq, o, Drop, 0);
unref(o);
}
dprint(1, "finding twixt commits\n");
while(qpop(&objq, &e)){
if(oshas(&drop, e.o->hash))
ncolor = Drop;
else if(oshas(&keep, e.o->hash))
ncolor = Keep;
else
ncolor = Blank;
if(ancestor && pickbest(&objq, &e, ncolor))
goto exactlca;
if(ncolor == Keep && e.color == Keep || ncolor == Drop)
continue;
if(ncolor == Keep && e.color == Drop){
if(repaint(&objq, &keep, &drop, e.o, e.dist, ancestor) == -1)
goto error;
}else if (ncolor == Blank) {
if(e.color == Keep)
osadd(&keep, e.o);
else
osadd(&drop, e.o);
o = readobject(e.o->hash);
for(i = 0; i < o->commit->nparent; i++){
if((c = readobject(e.o->commit->parent[i])) == nil)
goto error;
if(c->type != GCommit){
fprint(2, "warning: %H does not point at commit\n", c->hash);
unref(c);
continue;
}
dprint(2, "\tenqueue: %s %H\n", colors[e.color], c->hash);
qput(&objq, c, e.color, e.dist+1);
unref(c);
}
unref(o);
}
}
exactlca:
if(ancestor){
dprint(1, "found ancestor\n");
if(objq.best == nil){
*nres = 0;
*res = nil;
}else{
*nres = 1;
*res = eamalloc(1, sizeof(Object*));
(*res)[0] = objq.best;
}
}else{
dprint(1, "found twixt\n");
*res = eamalloc(keep.nobj, sizeof(Object*));
*nres = 0;
for(i = 0; i < keep.sz; i++){
if(keep.obj[i] != nil && !oshas(&drop, keep.obj[i]->hash)){
(*res)[*nres] = keep.obj[i];
(*nres)++;
}
}
}
osclear(&keep);
osclear(&drop);
return 0;
error:
dprint(1, "twixt error: %r\n");
free(objq.heap);
return -1;
}
int
findtwixt(Hash *head, int nhead, Hash *tail, int ntail, Object ***res, int *nres)
{
return paint(head, nhead, tail, ntail, res, nres, 0);
}
Object*
ancestor(Object *a, Object *b)
{
Object **o, *r;
int n;
if(paint(&a->hash, 1, &b->hash, 1, &o, &n, 1) == -1 || n == 0)
return nil;
r = ref(o[0]);
free(o);
return r;
}
int
lca(Eval *ev)
{
Object *a, *b, **o;
int n;
if(ev->nstk < 2){
werrstr("ancestor needs 2 objects");
return -1;
}
n = 0;
b = pop(ev);
a = pop(ev);
paint(&a->hash, 1, &b->hash, 1, &o, &n, 1);
if(n == 0)
return -1;
push(ev, *o);
free(o);
return 0;
}
static int
parent(Eval *ev)
{
Object *o, *p;
o = pop(ev);
/* Special case: first commit has no parent. */
if(o->commit->nparent == 0)
p = emptydir();
else if ((p = readobject(o->commit->parent[0])) == nil){
werrstr("no parent for %H", o->hash);
return -1;
}
push(ev, p);
return 0;
}
static int
unwind(Eval *ev, Object **obj, int *idx, int nobj, Object **p, Objset *set, int keep)
{
int i;
for(i = nobj; i >= 0; i--){
idx[i]++;
if(keep && !oshas(set, obj[i]->hash)){
push(ev, obj[i]);
osadd(set, obj[i]);
}else{
osadd(set, obj[i]);
}
if(idx[i] < obj[i]->commit->nparent){
*p = obj[i];
return i;
}
unref(obj[i]);
}
return -1;
}
static int
range(Eval *ev)
{
Object *a, *b, *p, *q, **all;
int nall, *idx;
Objset keep, skip;
b = pop(ev);
a = pop(ev);
if(hasheq(&b->hash, &Zhash))
b = &zcommit;
if(hasheq(&a->hash, &Zhash))
a = &zcommit;
if(a->type != GCommit || b->type != GCommit){
werrstr("non-commit object in range");
return -1;
}
p = b;
all = nil;
idx = nil;
nall = 0;
osinit(&keep);
osinit(&skip);
osadd(&keep, a);
while(1){
all = earealloc(all, (nall + 1), sizeof(Object*));
idx = earealloc(idx, (nall + 1), sizeof(int));
all[nall] = p;
idx[nall] = 0;
if(p == a || p->commit->nparent == 0 && a == &zcommit){
if((nall = unwind(ev, all, idx, nall, &p, &keep, 1)) == -1)
break;
}else if(p->commit->nparent == 0){
if((nall = unwind(ev, all, idx, nall, &p, &skip, 0)) == -1)
break;
}else if(oshas(&keep, p->hash)){
if((nall = unwind(ev, all, idx, nall, &p, &keep, 1)) == -1)
break;
}else if(oshas(&skip, p->hash))
if((nall = unwind(ev, all, idx, nall, &p, &skip, 0)) == -1)
break;
if(p->commit->nparent == 0)
break;
if((q = readobject(p->commit->parent[idx[nall]])) == nil){
werrstr("bad commit %H", p->commit->parent[idx[nall]]);
goto error;
}
if(q->type != GCommit){
werrstr("not commit: %H", q->hash);
goto error;
}
p = q;
nall++;
}
free(all);
return 0;
error:
free(all);
return -1;
}
int
readref(Hash *h, char *ref)
{
static char *try[] = {"", "refs/", "refs/heads/", "refs/remotes/", "refs/tags/", nil};
char buf[256], s[256], **pfx;
int r, f, n;
/* TODO: support hash prefixes */
if((r = hparse(h, ref)) != -1)
return r;
if(strcmp(ref, "HEAD") == 0){
snprint(buf, sizeof(buf), ".git/HEAD");
if((f = open(buf, OREAD)) == -1)
return -1;
if((n = readn(f, s, sizeof(s) - 1))== -1)
return -1;
s[n] = 0;
strip(s);
r = hparse(h, s);
goto found;
}
for(pfx = try; *pfx; pfx++){
snprint(buf, sizeof(buf), ".git/%s%s", *pfx, ref);
if((f = open(buf, OREAD)) == -1)
continue;
if((n = readn(f, s, sizeof(s) - 1)) == -1)
continue;
s[n] = 0;
strip(s);
r = hparse(h, s);
close(f);
goto found;
}
return -1;
found:
if(r == -1 && strstr(s, "ref: ") == s)
r = readref(h, s + strlen("ref: "));
return r;
}
int
evalpostfix(Eval *ev)
{
char name[256];
Object *o;
Hash h;
eatspace(ev);
if(!word(ev, name, sizeof(name))){
werrstr("expected name in expression");
return -1;
}
if(readref(&h, name) == -1){
werrstr("invalid ref %s", name);
return -1;
}
if(hasheq(&h, &Zhash))
o = &zcommit;
else if((o = readobject(h)) == nil){
werrstr("invalid ref %s (hash %H)", name, h);
return -1;
}
push(ev, o);
while(1){
eatspace(ev);
switch(ev->p[0]){
case '^':
case '~':
ev->p++;
if(parent(ev) == -1)
return -1;
break;
case '@':
ev->p++;
if(lca(ev) == -1)
return -1;
break;
default:
goto done;
break;
}
}
done:
return 0;
}
int
evalexpr(Eval *ev, char *ref)
{
memset(ev, 0, sizeof(*ev));
ev->str = ref;
ev->p = ref;
while(1){
if(evalpostfix(ev) == -1)
return -1;
if(ev->p[0] == '\0')
return 0;
else if(take(ev, ":") || take(ev, "..")){
if(evalpostfix(ev) == -1)
return -1;
if(ev->p[0] != '\0'){
werrstr("junk at end of expression");
return -1;
}
return range(ev);
}
}
}
int
resolverefs(Hash **r, char *ref)
{
Eval ev;
Hash *h;
int i;
if(evalexpr(&ev, ref) == -1){
free(ev.stk);
return -1;
}
h = eamalloc(ev.nstk, sizeof(Hash));
for(i = 0; i < ev.nstk; i++)
h[i] = ev.stk[i]->hash;
*r = h;
free(ev.stk);
return ev.nstk;
}
int
resolveref(Hash *r, char *ref)
{
Eval ev;
if(evalexpr(&ev, ref) == -1){
free(ev.stk);
return -1;
}
if(ev.nstk != 1){
werrstr("ambiguous ref expr");
free(ev.stk);
return -1;
}
*r = ev.stk[0]->hash;
free(ev.stk);
return 0;
}
int
readrefdir(Hash **refs, char ***names, int *nrefs, char *dpath, char *dname)
{
Dir *d, *e, *dir;
char *path, *name, *sep;
int ndir;
if((ndir = slurpdir(dpath, &dir)) == -1)
return -1;
sep = (*dname == '\0') ? "" : "/";
e = dir + ndir;
for(d = dir; d != e; d++){
path = smprint("%s/%s", dpath, d->name);
name = smprint("%s%s%s", dname, sep, d->name);
if(d->mode & DMDIR) {
if(readrefdir(refs, names, nrefs, path, name) == -1)
goto noref;
}else{
*refs = erealloc(*refs, (*nrefs + 1)*sizeof(Hash));
*names = erealloc(*names, (*nrefs + 1)*sizeof(char*));
if(resolveref(&(*refs)[*nrefs], name) == -1)
goto noref;
(*names)[*nrefs] = name;
*nrefs += 1;
goto next;
}
noref: free(name);
next: free(path);
}
free(dir);
return 0;
}
int
listrefs(Hash **refs, char ***names)
{
int nrefs;
*refs = nil;
*names = nil;
nrefs = 0;
if(readrefdir(refs, names, &nrefs, ".git/refs", "") == -1){
free(*refs);
return -1;
}
return nrefs;
}