+#define cttyvp(p) ((p)->p_flag & P_CONTROLT ? (p)->p_session->s_ttyvp : NULL)
+
+#define FDL_WANT 0x01
+#define FDL_LOCKED 0x02
+static int fdcache_lock;
+
+dev_t devctty;
+
+#if (FD_STDIN != FD_STDOUT-1) || (FD_STDOUT != FD_STDERR-1)
+FD_STDIN, FD_STDOUT, FD_STDERR must be a sequence n, n+1, n+2
+#endif
+
+#define NFDCACHE 3
+#define FD_NHASH(ix) ((ix) & NFDCACHE)
+
+/*
+ * Cache head
+ */
+struct fdcache {
+ struct fdescnode *fc_forw;
+ struct fdescnode *fc_back;
+};
+
+static struct fdcache fdcache[NFDCACHE];
+
+/*
+ * Initialise cache headers
+ */
+fdesc_init()
+{
+ struct fdcache *fc;
+
+ devctty = makedev(nchrdev, 0);
+
+ for (fc = fdcache; fc < fdcache + NFDCACHE; fc++)
+ fc->fc_forw = fc->fc_back = (struct fdescnode *) fc;
+}
+
+/*
+ * Compute hash list for given target vnode
+ */
+static struct fdcache *
+fdesc_hash(ix)
+ int ix;
+{
+
+ return (&fdcache[FD_NHASH(ix)]);
+}
+
+int
+fdesc_allocvp(ftype, ix, mp, vpp)
+ fdntype ftype;
+ int ix;
+ struct mount *mp;
+ struct vnode **vpp;
+{
+ struct fdcache *fc;
+ struct fdescnode *fd;
+ int error = 0;
+
+loop:
+ fc = fdesc_hash(ix);
+ for (fd = fc->fc_forw; fd != (struct fdescnode *) fc; fd = fd->fd_forw) {
+ if (fd->fd_ix == ix && fd->fd_vnode->v_mount == mp) {
+ if (vget(fd->fd_vnode, 0))
+ goto loop;
+ *vpp = fd->fd_vnode;
+ return (error);
+ }
+ }
+
+ /*
+ * otherwise lock the array while we call getnewvnode
+ * since that can block.
+ */
+ if (fdcache_lock & FDL_LOCKED) {
+ fdcache_lock |= FDL_WANT;
+ sleep((caddr_t) &fdcache_lock, PINOD);
+ goto loop;
+ }
+ fdcache_lock |= FDL_LOCKED;
+
+ error = getnewvnode(VT_FDESC, mp, fdesc_vnodeop_p, vpp);
+ if (error)
+ goto out;
+ MALLOC(fd, void *, sizeof(struct fdescnode), M_TEMP, M_WAITOK);
+ (*vpp)->v_data = fd;
+ fd->fd_vnode = *vpp;
+ fd->fd_type = ftype;
+ fd->fd_fd = -1;
+ fd->fd_link = 0;
+ fd->fd_ix = ix;
+ fc = fdesc_hash(ix);
+ insque(fd, fc);
+
+out:;
+ fdcache_lock &= ~FDL_LOCKED;
+
+ if (fdcache_lock & FDL_WANT) {
+ fdcache_lock &= ~FDL_WANT;
+ wakeup((caddr_t) &fdcache_lock);
+ }
+
+ return (error);
+}
+
projects / unix-history / blobdiff