--- /dev/null
+/*****************************************************************************
+ * mmap.c: memory-mapped file input
+ *****************************************************************************
+ * Copyright © 2007-2008 Rémi Denis-Courmont
+ * $Id$
+ *
+ * This program 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 of the License, or
+ * (at your option) any later version.
+ *
+ * This program 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., 51 Franklin Street, Fifth Floor, Boston MA 02110-1301, USA.
+ *****************************************************************************/
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+#include <vlc/vlc.h>
+#include <vlc_access.h>
+#include <vlc_input.h>
+#include <vlc_charset.h>
+#include <vlc_interface.h>
+
+#include <assert.h>
+
+#include <errno.h>
+#include <sys/types.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <sys/stat.h>
+#include <sys/mman.h>
+
+#define FILE_MMAP_TEXT N_("Use file memory mapping")
+#define FILE_MMAP_LONGTEXT N_( \
+ "Try to use memory mapping to read files and block devices." )
+
+static int Open (vlc_object_t *);
+static void Close (vlc_object_t *);
+
+vlc_module_begin();
+ set_shortname (_("MMap"));
+ set_description (_("Memory-mapped file input"));
+ set_category (CAT_INPUT);
+ set_subcategory (SUBCAT_INPUT_ACCESS);
+ set_capability ("access2", 52);
+ add_shortcut ("file");
+ set_callbacks (Open, Close);
+
+ add_bool ("file-mmap", VLC_TRUE, NULL,
+ FILE_MMAP_TEXT, FILE_MMAP_LONGTEXT, VLC_TRUE);
+vlc_module_end();
+
+static block_t *Block (access_t *);
+static int Seek (access_t *, int64_t);
+static int Control (access_t *, int, va_list);
+
+struct access_sys_t
+{
+ size_t page_size;
+ size_t mtu;
+ int fd;
+};
+
+#define MMAP_SIZE (1 << 20)
+
+static int Open (vlc_object_t *p_this)
+{
+ access_t *p_access = (access_t *)p_this;
+ access_sys_t *p_sys;
+ const char *path = p_access->psz_path;
+ int fd;
+
+ if (!var_CreateGetBool (p_this, "file-mmap"))
+ return VLC_EGENERIC; /* disabled */
+
+ STANDARD_BLOCK_ACCESS_INIT;
+
+ if (!strcmp (p_access->psz_path, "-"))
+ fd = dup (0);
+ else
+ {
+ msg_Dbg (p_access, "opening file %s", path);
+ fd = utf8_open (path, O_RDONLY | O_NOCTTY, 0666);
+ }
+
+ if (fd == -1)
+ {
+ msg_Warn (p_access, "cannot open %s: %m", path);
+ goto error;
+ }
+
+ /* mmap() is only safe for regular and block special files.
+ * For other types, it may be some idiosyncrasic interface (e.g. packet
+ * sockets are a good example), if it works at all. */
+ struct stat st;
+
+ if (fstat (fd, &st))
+ {
+ msg_Err (p_access, "cannot stat %s: %m", path);
+ goto error;
+ }
+
+ if (!S_ISREG (st.st_mode) && !S_ISBLK (st.st_mode))
+ {
+ msg_Dbg (p_access, "skipping non regular file %s", path);
+ goto error;
+ }
+
+ /* Autodetect mmap() support */
+ if (st.st_size > 0)
+ {
+ void *addr = mmap (NULL, 1, PROT_READ|PROT_WRITE, MAP_PRIVATE, fd, 0);
+ if (addr != MAP_FAILED)
+ munmap (addr, 1);
+ else
+ goto error;
+ }
+
+ p_sys->page_size = sysconf (_SC_PAGE_SIZE);
+ p_sys->mtu = MMAP_SIZE;
+ if (p_sys->mtu < p_sys->page_size)
+ p_sys->mtu = p_sys->page_size;
+ p_sys->fd = fd;
+
+ p_access->info.i_size = st.st_size;
+
+ return VLC_SUCCESS;
+
+error:
+ if (fd != -1)
+ close (fd);
+ free (p_sys);
+ return VLC_EGENERIC;
+}
+
+
+static void Close (vlc_object_t * p_this)
+{
+ access_t *p_access = (access_t *)p_this;
+ access_sys_t *p_sys = p_access->p_sys;
+
+ close (p_sys->fd); /* don't care about error when only reading */
+ free (p_sys);
+}
+
+static block_t *Block (access_t *p_access)
+{
+ access_sys_t *p_sys = p_access->p_sys;
+#ifndef NDEBUG
+ int64_t dbgpos = lseek (p_sys->fd, 0, SEEK_CUR);
+ if (dbgpos != p_access->info.i_pos)
+ msg_Err (p_access, "position: 0x%08llx instead of 0x%08llx",
+ p_access->info.i_pos, dbgpos);
+#endif
+
+ if ((uint64_t)p_access->info.i_pos >= (uint64_t)p_access->info.i_size)
+ {
+ /* End of file - check if file size changed... */
+ struct stat st;
+
+ if ((fstat (p_sys->fd, &st) == 0)
+ && (st.st_size != p_access->info.i_size))
+ {
+ p_access->info.i_size = st.st_size;
+ p_access->info.i_update |= INPUT_UPDATE_SIZE;
+ }
+
+ /* Really at end of file then */
+ if ((uint64_t)p_access->info.i_pos >= (uint64_t)p_access->info.i_size)
+ {
+ p_access->info.b_eof = VLC_TRUE;
+ msg_Dbg (p_access, "at end of memory mapped file");
+ return NULL;
+ }
+ }
+
+ const uintptr_t page_mask = p_sys->page_size - 1;
+ /* Start the mapping on a page boundary: */
+ off_t outer_offset = p_access->info.i_pos & ~page_mask;
+ /* Skip useless bytes at the beginning of the first page: */
+ size_t inner_offset = p_access->info.i_pos & page_mask;
+ /* Map no more bytes than remain: */
+ size_t length = p_sys->mtu;
+ if (outer_offset + length > p_access->info.i_size)
+ length = p_access->info.i_size - outer_offset;
+
+ assert (outer_offset <= p_access->info.i_pos); /* and */
+ assert (p_access->info.i_pos < p_access->info.i_size); /* imply */
+ assert (outer_offset < p_access->info.i_size); /* imply */
+ assert (length > 0);
+
+ /* NOTE: We use PROT_WRITE and MAP_PRIVATE so that the block can be
+ * modified down the chain, without messing up with the underlying
+ * original file. This does NOT need open write permission. */
+ void *addr = mmap (NULL, length, PROT_READ|PROT_WRITE, MAP_PRIVATE,
+ p_sys->fd, outer_offset);
+ if (addr == MAP_FAILED)
+ {
+ msg_Err (p_access, "memory mapping failed (%m)");
+ intf_UserFatal (p_access, VLC_FALSE, _("File reading failed"),
+ _("VLC could not read the file."));
+ msleep (INPUT_ERROR_SLEEP);
+ return NULL;
+ }
+
+ block_t *block = block_mmap_Alloc (addr, length);
+ if (block == NULL)
+ return NULL;
+
+ block->p_buffer += inner_offset;
+ block->i_buffer -= inner_offset;
+
+#ifndef NDEBUG
+ msg_Dbg (p_access, "mapped 0x%lx bytes at %p from offset 0x%lx",
+ (unsigned long)length, addr, (unsigned long)outer_offset);
+
+ /* Compare normal I/O with memory mapping */
+ char *buf = malloc (block->i_buffer);
+ ssize_t i_read = read (p_sys->fd, buf, block->i_buffer);
+
+ if (i_read != (ssize_t)block->i_buffer)
+ msg_Err (p_access, "read %u instead of %u bytes", (unsigned)i_read,
+ (unsigned)block->i_buffer);
+ if (memcmp (buf, block->p_buffer, block->i_buffer))
+ msg_Err (p_access, "inconsistent data buffer");
+ free (buf);
+#endif
+
+ p_access->info.i_pos = outer_offset + length;
+ return block;
+}
+
+
+static int Seek (access_t *p_access, int64_t i_pos)
+{
+ p_access->info.i_pos = i_pos;
+ p_access->info.b_eof = VLC_FALSE;
+ return VLC_SUCCESS;
+}
+
+
+static int Control (access_t *p_access, int query, va_list args)
+{
+ access_sys_t *p_sys = p_access->p_sys;
+
+ switch (query)
+ {
+ case ACCESS_CAN_SEEK:
+ case ACCESS_CAN_FASTSEEK:
+ case ACCESS_CAN_PAUSE:
+ case ACCESS_CAN_CONTROL_PACE:
+ *((vlc_bool_t *)va_arg (args, vlc_bool_t *)) = VLC_TRUE;
+ return VLC_SUCCESS;
+
+ case ACCESS_GET_MTU:
+ *((int *)va_arg (args, int *)) = p_sys->mtu;
+ return VLC_SUCCESS;
+
+ case ACCESS_GET_PTS_DELAY:
+ *((int64_t *)va_arg (args, int64_t *)) = DEFAULT_PTS_DELAY;
+ return VLC_SUCCESS;
+
+ case ACCESS_GET_TITLE_INFO:
+ case ACCESS_GET_META:
+ break;
+
+ case ACCESS_SET_PAUSE_STATE:
+ return VLC_SUCCESS;
+
+ case ACCESS_SET_TITLE:
+ case ACCESS_SET_SEEKPOINT:
+ case ACCESS_SET_PRIVATE_ID_STATE:
+ case ACCESS_SET_PRIVATE_ID_CA:
+ case ACCESS_GET_PRIVATE_ID_STATE:
+ case ACCESS_GET_CONTENT_TYPE:
+ break;
+
+ default:
+ msg_Warn (p_access, "unimplemented query %d in control", query);
+ }
+
+ return VLC_EGENERIC;
+}
projects / vlc / commitdiff