Re: [Qemu-devel] [PATCH v7 5/8] module: implement module loading function

["Daniel P. Berrange" <berrange@redhat.com>]

On Thu, Sep 12, 2013 at 03:04:56PM +0800, Fam Zheng wrote:
> Added three types of modules:
> 
>     typedef enum {
>         MODULE_LOAD_BLOCK = 0,
>         MODULE_LOAD_UI,
>         MODULE_LOAD_NET,
>         MODULE_LOAD_MAX,
>     } module_load_type;
> 
> and their loading function:
> 
>     void module_load(module_load_type).
> 
> which loads all ".so" files in a subdir under "${PREFIX}/qemu/", e.g.
> "/usr/lib/qemu/block". Modules of each type should be loaded before
> respective subsystem initialization code.
> 
> Requires gmodule-2.0 from glib.
> 
> Signed-off-by: Fam Zheng <famz@redhat.com>
> ---
>  block.c               |  1 +
>  configure             | 28 +++++++++++++++++---------
>  include/qemu/module.h |  9 +++++++++
>  scripts/create_config | 10 ++++++++++
>  util/module.c         | 55 +++++++++++++++++++++++++++++++++++++++++++++++++++
>  vl.c                  |  2 ++
>  6 files changed, 96 insertions(+), 9 deletions(-)
> 
> diff --git a/block.c b/block.c
> index 26639e8..16ceaaf 100644
> --- a/block.c
> +++ b/block.c
> @@ -4008,6 +4008,7 @@ BlockDriverAIOCB *bdrv_aio_discard(BlockDriverState *bs,
>  
>  void bdrv_init(void)
>  {
> +    module_load(MODULE_LOAD_BLOCK);
>      module_call_init(MODULE_INIT_BLOCK);
>  }
>  
> diff --git a/configure b/configure
> index 5bc7256..275b1a0 100755
> --- a/configure
> +++ b/configure
> @@ -199,6 +199,7 @@ datadir="\${prefix}/share"
>  qemu_docdir="\${prefix}/share/doc/qemu"
>  bindir="\${prefix}/bin"
>  libdir="\${prefix}/lib"
> +moddir="\${prefix}/lib/qemu"
>  libexecdir="\${prefix}/libexec"
>  includedir="\${prefix}/include"
>  sysconfdir="\${prefix}/etc"
> @@ -676,6 +677,8 @@ for opt do
>    ;;
>    --libdir=*) libdir="$optarg"
>    ;;
> +  --moddir=*) moddir="$optarg"
> +  ;;
>    --libexecdir=*) libexecdir="$optarg"
>    ;;
>    --includedir=*) includedir="$optarg"
> @@ -1052,6 +1055,7 @@ echo "  --datadir=PATH           install firmware in PATH$confsuffix"
>  echo "  --docdir=PATH            install documentation in PATH$confsuffix"
>  echo "  --bindir=PATH            install binaries in PATH"
>  echo "  --libdir=PATH            install libraries in PATH"
> +echo "  --moddir=PATH            install modules in PATH"
>  echo "  --sysconfdir=PATH        install config in PATH$confsuffix"
>  echo "  --localstatedir=PATH     install local state in PATH (set at runtime on win32)"
>  echo "  --with-confsuffix=SUFFIX suffix for QEMU data inside datadir and sysconfdir [$confsuffix]"
> @@ -2256,15 +2260,19 @@ if test "$mingw32" = yes; then
>  else
>      glib_req_ver=2.12
>  fi
> -if $pkg_config --atleast-version=$glib_req_ver gthread-2.0; then
> -    glib_cflags=`$pkg_config --cflags gthread-2.0`
> -    glib_libs=`$pkg_config --libs gthread-2.0`
> -    CFLAGS="$glib_cflags $CFLAGS"
> -    LIBS="$glib_libs $LIBS"
> -    libs_qga="$glib_libs $libs_qga"
> -else
> -    error_exit "glib-$glib_req_ver required to compile QEMU"
> -fi
> +
> +for i in gthread-2.0 gmodule-2.0; do
> +    if $pkg_config --atleast-version=$glib_req_ver $i; then
> +        glib_cflags=`$pkg_config --cflags $i`
> +        glib_libs=`$pkg_config --libs $i`
> +        CFLAGS="$glib_cflags $CFLAGS"
> +        LIBS="$glib_libs $LIBS"
> +        libs_qga="$glib_libs $libs_qga"
> +    else
> +        error_exit "glib-$glib_req_ver required to compile QEMU"
> +    fi
> +done
> +
>  
>  ##########################################
>  # pixman support probe
> @@ -3557,6 +3565,7 @@ echo "Install prefix    $prefix"
>  echo "BIOS directory    `eval echo $qemu_datadir`"
>  echo "binary directory  `eval echo $bindir`"
>  echo "library directory `eval echo $libdir`"
> +echo "module directory  `eval echo $moddir`"
>  echo "libexec directory `eval echo $libexecdir`"
>  echo "include directory `eval echo $includedir`"
>  echo "config directory  `eval echo $sysconfdir`"
> @@ -3680,6 +3689,7 @@ echo all: >> $config_host_mak
>  echo "prefix=$prefix" >> $config_host_mak
>  echo "bindir=$bindir" >> $config_host_mak
>  echo "libdir=$libdir" >> $config_host_mak
> +echo "moddir=$moddir" >> $config_host_mak
>  echo "libexecdir=$libexecdir" >> $config_host_mak
>  echo "includedir=$includedir" >> $config_host_mak
>  echo "mandir=$mandir" >> $config_host_mak
> diff --git a/include/qemu/module.h b/include/qemu/module.h
> index c4ccd57..f00bc25 100644
> --- a/include/qemu/module.h
> +++ b/include/qemu/module.h
> @@ -37,4 +37,13 @@ void register_module_init(void (*fn)(void), module_init_type type);
>  
>  void module_call_init(module_init_type type);
>  
> +typedef enum {
> +    MODULE_LOAD_BLOCK = 0,
> +    MODULE_LOAD_UI,
> +    MODULE_LOAD_NET,
> +    MODULE_LOAD_MAX,
> +} module_load_type;
> +
> +void module_load(module_load_type type);
> +
>  #endif
> diff --git a/scripts/create_config b/scripts/create_config
> index b1adbf5..50391c2 100755
> --- a/scripts/create_config
> +++ b/scripts/create_config
> @@ -26,6 +26,13 @@ case $line in
>      # save for the next definitions
>      prefix=${line#*=}
>      ;;
> + moddir=*)
> +    eval "moddir=\"${line#*=}\""
> +    echo "#define CONFIG_MODDIR \"$moddir\""
> +    ;;
> + CONFIG_MODULES=*)
> +    echo "#define CONFIG_MODULES \"${line#*=}\""
> +    ;;
>   CONFIG_AUDIO_DRIVERS=*)
>      drivers=${line#*=}
>      echo "#define CONFIG_AUDIO_DRIVERS \\"
> @@ -104,6 +111,9 @@ case $line in
>      value=${line#*=}
>      echo "#define $name $value"
>      ;;
> + DSOSUF=*)
> +    echo "#define HOST_DSOSUF \"${line#*=}\""
> +    ;;
>  esac
>  
>  done # read
> diff --git a/util/module.c b/util/module.c
> index 7acc33d..8dd3544 100644
> --- a/util/module.c
> +++ b/util/module.c
> @@ -13,6 +13,8 @@
>   * GNU GPL, version 2 or (at your option) any later version.
>   */
>  
> +#include <gmodule.h>
> +#include <dirent.h>
>  #include "qemu-common.h"
>  #include "qemu/queue.h"
>  #include "qemu/module.h"
> @@ -79,3 +81,56 @@ void module_call_init(module_init_type type)
>          e->init();
>      }
>  }
> +
> +void module_load(module_load_type type)
> +{
> +#ifdef CONFIG_MODULES
> +    const char *path;
> +    const char *dsosuf = HOST_DSOSUF;
> +    char *fname;
> +    int suf_len = strlen(dsosuf);
> +    DIR *dp;
> +    struct dirent *ep = NULL;
> +    GModule *g_module;
> +
> +    if (!g_module_supported()) {
> +        return;
> +    }
> +
> +    switch (type) {
> +    case MODULE_LOAD_BLOCK:
> +        path = CONFIG_MODDIR "/block/";
> +        break;
> +    case MODULE_LOAD_UI:
> +        path = CONFIG_MODDIR "/ui/";
> +        break;
> +    case MODULE_LOAD_NET:
> +        path = CONFIG_MODDIR "/net/";
> +        break;
> +    default:
> +        return;
> +    }
> +
> +    dp = opendir(path);
> +    if (!dp) {
> +        fprintf(stderr, "Failed to open dir %s\n", path);
> +        return;
> +    }
> +    for (ep = readdir(dp); ep; ep = readdir(dp)) {

Per previous posting, I believe you should not be blindly loading
all modules in the directory using readdir(). Should whitelist
load only individual module files that are part of QEMU, to add
a block against 3rd party out of tree modules.

In addition this still seems to lack any kind of symbol hash
addition, which should be a blocker for merging this series.


Daniel
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