/* Remote file contents caching Copyright (C) 1997, 1999 Free Software Foundation, Inc. Written by Miles Bader This file is part of the GNU Hurd. The GNU Hurd is free software; you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation; either version 2, or (at your option) any later version. The GNU Hurd is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program; if not, write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111, USA. */ #include #include #include #include "ccache.h" #define READ_CHUNK_SIZE (8*1024) #define ALLOC_CHUNK_SIZE (64*1024) /* Read LEN bytes at OFFS in the file referred to by CC into DATA, or return an error. */ error_t ccache_read (struct ccache *cc, off_t offs, size_t len, void *data) { error_t err = 0; size_t max = offs + len; mutex_lock (&cc->lock); if (max > cc->size) max = cc->size; while (cc->max < max && !err) { if (cc->fetching_active) /* Some thread is fetching data, so just let it do its thing, but get a wakeup call when it's done. */ { if (hurd_condition_wait (&cc->wakeup, &cc->lock)) err = EINTR; } else { int re_connected = 0; struct netnode *nn = cc->node->nn; cc->fetching_active = 1; while (cc->max < max && !err) { mutex_unlock (&cc->lock); if (! cc->conn) /* We need to setup a connection to fetch data over. */ { err = ftpfs_get_ftp_conn (nn->fs, &cc->conn); if (! err) { err = ftp_conn_start_retrieve (cc->conn, nn->rmt_path, &cc->data_conn); if (err == ENOENT) err = ESTALE; if (err) { ftpfs_release_ftp_conn (nn->fs, cc->conn); cc->conn = 0; } else cc->data_conn_pos = 0; } re_connected = 1; } if (! err) /* Try and read some data over the connection. */ { size_t new_end = cc->max + READ_CHUNK_SIZE; if (new_end > cc->size) new_end = cc->size; if (new_end > cc->alloced) /* Make some room in memory for the new part of the image. */ { size_t alloc_end = cc->alloced + ALLOC_CHUNK_SIZE; if (alloc_end < new_end) alloc_end = new_end; else if (alloc_end > cc->size) alloc_end = cc->size; if (cc->alloced == 0) { vm_address_t addr = 0; err = vm_allocate (mach_task_self (), &addr, alloc_end, 1); if (! err) cc->image = (char *)addr; } else { vm_address_t addr = (vm_address_t)cc->image + cc->alloced; err = vm_allocate (mach_task_self (), &addr, alloc_end - cc->alloced, 0); if (err == EKERN_NO_SPACE) /* Gack. We've goota move the whole splooge. */ { addr = 0; err = vm_allocate (mach_task_self (), &addr, alloc_end, 1); if (! err) /* That worked; copy what's already-fetched. */ { bcopy (cc->image, (void *)addr, cc->max); munmap (cc->image, cc->alloced); cc->image = (char *)addr; } } } if (! err) cc->alloced = alloc_end; } if (! err) { ssize_t rd = read (cc->data_conn, cc->image + cc->data_conn_pos, new_end - cc->data_conn_pos); if (rd < 0) err = errno; else if (rd == 0) /* EOF. This either means the file changed size, or our data-connection got closed; we just try to open the connection a second time, and then if that fails, assume the size changed. */ { if (re_connected) err = EIO; /* Something's fucked */ else /* Try opening the connection again. */ { close (cc->data_conn); ftp_conn_finish_transfer (cc->conn); ftpfs_release_ftp_conn (nn->fs, cc->conn); cc->conn = 0; } } else { cc->data_conn_pos += rd; if (cc->data_conn_pos > cc->max) cc->max = cc->data_conn_pos; } } if (!err && ports_self_interrupted ()) err = EINTR; } mutex_lock (&cc->lock); if (cc->max < max && !err) /* If anyone's waiting for data, let them look (if we're done fetching, this gets delayed until below). */ condition_broadcast (&cc->wakeup); } if (!err && cc->conn && cc->max == cc->size) /* We're finished reading all data, close the data connection. */ { close (cc->data_conn); ftp_conn_finish_transfer (cc->conn); ftpfs_release_ftp_conn (nn->fs, cc->conn); cc->conn = 0; } /* We're done, error or no. */ cc->fetching_active = 0; /* Let others know something's going on. */ condition_broadcast (&cc->wakeup); } } if (! err) bcopy (cc->image + offs, data, max - offs); mutex_unlock (&cc->lock); return err; } /* Discard any cached contents in CC. */ error_t ccache_invalidate (struct ccache *cc) { error_t err = 0; mutex_lock (&cc->lock); while (cc->fetching_active && !err) /* Some thread is fetching data, so just let it do its thing, but get a wakeup call when it's done. */ { if (hurd_condition_wait (&cc->wakeup, &cc->lock)) err = EINTR; } if (! err) { if (cc->alloced > 0) { munmap (cc->image, cc->alloced); cc->image = 0; cc->alloced = 0; cc->max = 0; } if (cc->conn) { close (cc->data_conn); ftp_conn_finish_transfer (cc->conn); ftpfs_release_ftp_conn (cc->node->nn->fs, cc->conn); cc->conn = 0; } } mutex_unlock (&cc->lock); return err; } /* Return a ccache object for NODE in CC. */ error_t ccache_create (struct node *node, struct ccache **cc) { struct ccache *new = malloc (sizeof (struct ccache)); if (! new) return ENOMEM; new->node = node; new->image = 0; new->size = node->nn_stat.st_size; new->max = 0; new->alloced = 0; mutex_init (&new->lock); condition_init (&new->wakeup); new->fetching_active = 0; new->conn = 0; new->data_conn = -1; *cc = new; return 0; } /* Free all resources used by CC. */ void ccache_free (struct ccache *cc) { if (cc->alloced > 0) munmap (cc->image, cc->alloced); if (cc->data_conn >= 0) close (cc->data_conn); if (cc->conn) { ftp_conn_finish_transfer (cc->conn); ftpfs_release_ftp_conn (cc->node->nn->fs, cc->conn); } free (cc); }