Rewrite the mmap input as a separate access

configure.ac

@@ -469,7 +469,7 @@ dnl Check for system libs needed
 need_libc=false
 
 dnl Check for usual libc functions
-AC_CHECK_FUNCS([gettimeofday strtod strtol strtof strtoll strtoull strsep isatty vasprintf asprintf swab sigrelse getpwuid memalign posix_memalign if_nametoindex atoll getenv putenv setenv gmtime_r ctime_r localtime_r lrintf daemon scandir fork bsearch lstat strlcpy strdup strndup strnlen atof lldiv mmap])
+AC_CHECK_FUNCS([gettimeofday strtod strtol strtof strtoll strtoull strsep isatty vasprintf asprintf swab sigrelse getpwuid memalign posix_memalign if_nametoindex atoll getenv putenv setenv gmtime_r ctime_r localtime_r lrintf daemon scandir fork bsearch lstat strlcpy strdup strndup strnlen atof lldiv])
 AC_CHECK_FUNCS(strcasecmp,,[AC_CHECK_FUNCS(stricmp)])
 AC_CHECK_FUNCS(strncasecmp,,[AC_CHECK_FUNCS(strnicmp)])
 AC_CHECK_FUNCS(strcasestr,,[AC_CHECK_FUNCS(stristr)])
@@ -477,6 +477,8 @@ AC_FUNC_ALLOCA
 
 AH_BOTTOM([#include <vlc_fixups.h>])
 
+AC_CHECK_FUNC(mmap, [VLC_ADD_PLUGINS([access_mmap])])
+
 AS_IF([test "${SYS}" = "linux"], [
   AC_CHECK_FUNCS(tee)
 ])

modules/access/Modules.am

@@ -4,6 +4,7 @@
 LIBTOOL=@LIBTOOL@ --tag=CC
 
 SOURCES_access_file = file.c
+SOURCES_access_mmap = mmap.c
 SOURCES_access_directory = directory.c
 SOURCES_access_dv = dv.c
 SOURCES_access_udp = udp.c

modules/access/mmap.c

+/*****************************************************************************
+ * 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;
+}