code: plan9front

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git/fs: use a better heuristic for permissions.

Since we now store /dist/plan9front in git, the
initial assumption that the owner of the repo
is the person touching it is not always true.

This change gives us a better heuristic for the
file permissions we should have in the files we
copy around, basing it off of the permissions of
the .git directory.

--- a/sys/man/4/gitfs

+++ b/sys/man/4/gitfs

@@ -74,6 +74,15 @@

 .PP

 Trees are presented as directory listings, and blobs

 as files.

+The repository controls the user permissions.

+The group and world permissions are derived by masking

+the user permissions with the permissions of the

+.I .git

+directory.

+The user and group presented is the same as the user and

+group of the

+.I .git

+directory.

 .SH FILES

 .TP

@@ -100,11 +109,14 @@

 .SH BUGS

 Symlinks are only partially supported.

-Symlinks are treated as regular files when reading.

-Modifying symlinks is unsupported.

+They will be followed when reading, but a commit that

+modifies a symlink is an error.

 .PP

-There is no way to inspect the raw objects. This is

-a feature that would be useful for debugging.

+For efficiency, git/fs only loads repo permissions at startup

+

+.PP

+There is no way to inspect the raw objects.

+Inspecting raw objects would be useful for debugging.

--- a/sys/src/cmd/git/fs.c

+++ b/sys/src/cmd/git/fs.c

@@ -79,6 +79,7 @@

 char	gitdir[512];

 char	*username;

+char	*groupname;

 char	*mntpt = ".git/fs";

 char	**branches = nil;

 Cache	uqidcache[512];

@@ -164,7 +165,7 @@

 	d->mode = c->mode;

 	d->name = estrdup9p(name);

 	d->uid = estrdup9p(username);

-	d->gid = estrdup9p(username);

+	d->gid = estrdup9p(groupname);

 	d->muid = estrdup9p(username);

 	if(o->type == GBlob || o->type == GTag){

 		d->qid.type = 0;

@@ -188,7 +189,7 @@

 	d->qid.type = strcmp(qroot[i], "ctl") == 0 ? 0 : QTDIR;

 	d->qid.path = qpath(nil, i, i, Qroot);

 	d->uid = estrdup9p(username);

-	d->gid = estrdup9p(username);

+	d->gid = estrdup9p(groupname);

 	d->muid = estrdup9p(username);

 	d->mtime = c->mtime;

 	return 0;

@@ -210,7 +211,7 @@

 	d->qid.path = qpath(c, i, branchid(aux, aux->refpath), Qbranch | Internal);

 	d->mode = 0555 | DMDIR;

 	d->uid = estrdup9p(username);

-	d->gid = estrdup9p(username);

+	d->gid = estrdup9p(groupname);

 	d->muid = estrdup9p(username);

 	d->mtime = c->mtime;

 	d->atime = c->mtime;

@@ -251,11 +252,10 @@

 	d->qid.type = o->type == GTree ? QTDIR : 0;

 	d->qid.path = qpath(c, i, o->id, aux->qdir);

 	d->mode = m;

-	d->mode |= (o->type == GTree) ? 0755 : 0644;

 	d->atime = c->mtime;

 	d->mtime = c->mtime;

 	d->uid = estrdup9p(username);

-	d->gid = estrdup9p(username);

+	d->gid = estrdup9p(groupname);

 	d->muid = estrdup9p(username);

 	d->name = estrdup9p(e->tree->ent[i].name);

 	d->length = o->size;

@@ -271,7 +271,7 @@

 	c = crumb(p, 0);

 	o = c->obj;

 	d->uid = estrdup9p(username);

-	d->gid = estrdup9p(username);

+	d->gid = estrdup9p(groupname);

 	d->muid = estrdup9p(username);

 	d->mode = 0444;

 	d->atime = o->commit->ctime;

@@ -490,7 +490,7 @@

 	}else if(o->type == GCommit){

 		q->type = 0;

 		c->mtime = o->commit->mtime;

-		c->mode = 0444;

+		c->mode = 0644;

 		assert(qdir == Qcommit || qdir == Qobject || qdir == Qcommittree || qdir == Qhead);

 		if(strcmp(name, "msg") == 0)

 			q->path = qpath(p, 0, o->id, Qcommitmsg);

@@ -804,7 +804,7 @@

 	aux = r->fid->aux;

 	c = crumb(aux, 0);

 	r->d.uid = estrdup9p(username);

-	r->d.gid = estrdup9p(username);

+	r->d.gid = estrdup9p(groupname);

 	r->d.muid = estrdup9p(username);

 	r->d.qid = r->fid->qid;

 	r->d.mtime = c->mtime;

@@ -837,6 +837,8 @@

 void

 main(int argc, char **argv)

 {

+	Dir *d;

+

 	gitinit();

 	ARGBEGIN{

 	case 'd':

@@ -852,7 +854,12 @@

 	if(argc != 0)

 		usage();

-	username = getuser();

+	if((d = dirstat(".git")) == nil)

+		sysfatal("dirstat .git: %r");

+	username = strdup(d->uid);

+	groupname = strdup(d->gid);

+	free(d);

+

 	branches = emalloc(sizeof(char*));

 	branches[0] = nil;

 	postmountsrv(&gitsrv, nil, mntpt, MCREATE);

--- a/sys/src/cmd/git/pack.c

+++ b/sys/src/cmd/git/pack.c

@@ -70,6 +70,7 @@

 Packf	*packf;

 int	npackf;

 int	openpacks;

+int	gitdirmode = -1;

 static void

 clear(Object *o)

@@ -887,7 +888,7 @@

 static void

 parsetree(Object *o)

 {

-	int m, entsz, nent;

+	int m, a, entsz, nent;

 	Dirent *t, *ent;

 	char *p, *ep;

@@ -908,7 +909,15 @@

 		if(*p != ' ')

 			sysfatal("malformed tree %H: *p=(%d) %c\n", o->hash, *p, *p);

 		p++;

-		t->mode = m & 0777;	

+		/*

+		 * only the stored permissions for the user

+		 * are relevant; git fills group and world

+		 * bits with whatever -- so to serve with

+		 * useful permissions, replicate the mode

+		 * of the git repo dir.

+		 */

+		a = (m & 0777)>>6;

+		t->mode = ((a<<6)|(a<<3)|a) & gitdirmode;

 		t->ismod = 0;

 		t->islink = 0;

 		if(m == 0160000){

@@ -1048,7 +1057,14 @@

 readobject(Hash h)

 {

 	Object *o;

+	Dir *d;

+	if(gitdirmode == -1){

+		if((d = dirstat(".git")) == nil)

+			sysfatal("stat .git: %r");

+		gitdirmode = d->mode & 0777;

+		free(d);

+	}

 	if((o = readidxobject(nil, h, 0)) == nil)

 		return nil;

 	parseobject(o);