loader: support for permanent dlopen()
Asterisk assumes that dlopen() will always run the constructor of a shared library and every dlclose() will run its destructor. But dlopen() may be permanent, meaning the constructor will only be run once, as is the case with musl libc. With a permanent dlopen() the Asterisk module loader does not work correctly, because it's expectations regarding when the constructors and destructors are run are not met. In fact a segmentation fault will occur when the first module is "re-opened" that has AST_MODFLAG_GLOBAL_SYMBOLS set (the dlopen() does not call the constructor, resource_being_loaded is not set to NULL, then strlen is called with NULL instead of a string, see issue ASTERISK-28319). This commit adds code to the loader that will manually run the constructors/destructors of the (non-builtin) modules where needed. To achieve this a new ao2 container (linked list) is started and filled with objects that contain the names of the modules and the pointers to their respective info structs. This behavior can be activated when configuring Asterisk (--enable-permanent-dlopen). By default this is disabled, of course. ASTERISK-28319 #close Signed-off-by: Sebastian Kemper <sebastian_ml@gmx.net> Change-Id: I86693a0ecf25d5ba81c73773a03df4abc3426875
This commit is contained in:
Sebastian Kemper
Corey Farrell
parent
4f0b8c3ed3
commit
8ec4de7501
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@ -702,6 +702,7 @@ PBX_DYNAMIC_LIST
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POW_LIB
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PBX_WORKING_FORK
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LIBOBJS
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PERMANENT_DLOPEN
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DISABLE_XMLDOC
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CONFIG_LIBXML2
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JANSSON_LIBS
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@ -1337,7 +1338,6 @@ infodir
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docdir
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oldincludedir
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includedir
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runstatedir
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localstatedir
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sharedstatedir
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sysconfdir
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@ -1446,6 +1446,7 @@ with_vpb
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with_x11
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with_z
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enable_xmldoc
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enable_permanent_dlopen
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enable_largefile
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enable_internal_poll
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enable_asteriskssl
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@ -1525,7 +1526,6 @@ datadir='${datarootdir}'
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sysconfdir='${prefix}/etc'
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sharedstatedir='${prefix}/com'
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localstatedir='${prefix}/var'
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runstatedir='${localstatedir}/run'
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includedir='${prefix}/include'
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oldincludedir='/usr/include'
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docdir='${datarootdir}/doc/${PACKAGE_TARNAME}'
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@ -1778,15 +1778,6 @@ do
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| -silent | --silent | --silen | --sile | --sil)
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silent=yes ;;
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-runstatedir | --runstatedir | --runstatedi | --runstated \
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| --runstate | --runstat | --runsta | --runst | --runs \
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| --run | --ru | --r)
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ac_prev=runstatedir ;;
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-runstatedir=* | --runstatedir=* | --runstatedi=* | --runstated=* \
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| --runstate=* | --runstat=* | --runsta=* | --runst=* | --runs=* \
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| --run=* | --ru=* | --r=*)
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runstatedir=$ac_optarg ;;
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-sbindir | --sbindir | --sbindi | --sbind | --sbin | --sbi | --sb)
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ac_prev=sbindir ;;
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-sbindir=* | --sbindir=* | --sbindi=* | --sbind=* | --sbin=* \
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@ -1924,7 +1915,7 @@ fi
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for ac_var in exec_prefix prefix bindir sbindir libexecdir datarootdir \
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datadir sysconfdir sharedstatedir localstatedir includedir \
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oldincludedir docdir infodir htmldir dvidir pdfdir psdir \
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libdir localedir mandir runstatedir
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libdir localedir mandir
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do
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eval ac_val=\$$ac_var
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# Remove trailing slashes.
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@ -2077,7 +2068,6 @@ Fine tuning of the installation directories:
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--sysconfdir=DIR read-only single-machine data [PREFIX/etc]
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--sharedstatedir=DIR modifiable architecture-independent data [PREFIX/com]
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--localstatedir=DIR modifiable single-machine data [PREFIX/var]
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--runstatedir=DIR modifiable per-process data [LOCALSTATEDIR/run]
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--libdir=DIR object code libraries [EPREFIX/lib]
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--includedir=DIR C header files [PREFIX/include]
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--oldincludedir=DIR C header files for non-gcc [/usr/include]
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@ -2116,6 +2106,9 @@ Optional Features:
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--enable-dev-mode Turn on developer mode
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--enable-coverage Turn on code coverage tracking (for gcov)
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--disable-xmldoc Explicitly disable XML documentation
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--enable-permanent-dlopen
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Enable when your libc has a permanent dlopen like
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musl
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--disable-largefile omit support for large files
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--enable-internal-poll Use Asterisk's poll implementation
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--disable-asteriskssl Disable Asterisk's SSL wrapper library
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@ -14814,6 +14807,25 @@ fi
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fi
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# Check whether --enable-permanent-dlopen was given.
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if test "${enable_permanent_dlopen+set}" = set; then :
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enableval=$enable_permanent_dlopen; case "${enableval}" in
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y|ye|yes) PERMANENT_DLOPEN=yes ;;
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n|no) PERMANENT_DLOPEN=no ;;
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*) as_fn_error $? "bad value ${enableval} for --enable-permanent-dlopen" "$LINENO" 5 ;;
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esac
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else
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PERMANENT_DLOPEN=no
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fi
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if test "${PERMANENT_DLOPEN}" == "yes"; then
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$as_echo "#define HAVE_PERMANENT_DLOPEN 1" >>confdefs.h
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fi
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# some embedded systems omit internationalization (locale) support
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@ -14880,7 +14892,7 @@ else
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We can't simply define LARGE_OFF_T to be 9223372036854775807,
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since some C++ compilers masquerading as C compilers
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incorrectly reject 9223372036854775807. */
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#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
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#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
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int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
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&& LARGE_OFF_T % 2147483647 == 1)
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? 1 : -1];
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@ -14926,7 +14938,7 @@ else
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We can't simply define LARGE_OFF_T to be 9223372036854775807,
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since some C++ compilers masquerading as C compilers
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incorrectly reject 9223372036854775807. */
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#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
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#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
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int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
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&& LARGE_OFF_T % 2147483647 == 1)
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? 1 : -1];
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@ -14950,7 +14962,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
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We can't simply define LARGE_OFF_T to be 9223372036854775807,
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since some C++ compilers masquerading as C compilers
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incorrectly reject 9223372036854775807. */
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#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
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#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
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int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
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&& LARGE_OFF_T % 2147483647 == 1)
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? 1 : -1];
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@ -14995,7 +15007,7 @@ else
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We can't simply define LARGE_OFF_T to be 9223372036854775807,
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since some C++ compilers masquerading as C compilers
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incorrectly reject 9223372036854775807. */
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#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
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#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
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int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
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&& LARGE_OFF_T % 2147483647 == 1)
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? 1 : -1];
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@ -15019,7 +15031,7 @@ rm -f core conftest.err conftest.$ac_objext conftest.$ac_ext
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We can't simply define LARGE_OFF_T to be 9223372036854775807,
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since some C++ compilers masquerading as C compilers
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incorrectly reject 9223372036854775807. */
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#define LARGE_OFF_T ((((off_t) 1 << 31) << 31) - 1 + (((off_t) 1 << 31) << 31))
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#define LARGE_OFF_T (((off_t) 1 << 62) - 1 + ((off_t) 1 << 62))
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int off_t_is_large[(LARGE_OFF_T % 2147483629 == 721
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&& LARGE_OFF_T % 2147483647 == 1)
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? 1 : -1];
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@ -16319,8 +16331,6 @@ main ()
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if (*(data + i) != *(data3 + i))
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return 14;
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close (fd);
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free (data);
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free (data3);
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return 0;
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}
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_ACEOF
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14
configure.ac
14
configure.ac
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@ -727,6 +727,20 @@ if test "${DISABLE_XMLDOC}" != "yes"; then
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fi
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AC_ARG_ENABLE([permanent-dlopen],
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[AS_HELP_STRING([--enable-permanent-dlopen],
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[Enable when your libc has a permanent dlopen like musl])],
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[case "${enableval}" in
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y|ye|yes) PERMANENT_DLOPEN=yes ;;
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n|no) PERMANENT_DLOPEN=no ;;
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*) AC_MSG_ERROR(bad value ${enableval} for --enable-permanent-dlopen) ;;
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esac], [PERMANENT_DLOPEN=no])
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AC_SUBST([PERMANENT_DLOPEN])
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if test "${PERMANENT_DLOPEN}" == "yes"; then
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AC_DEFINE([HAVE_PERMANENT_DLOPEN], 1, [Define to support libc with permanent dlopen.])
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fi
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# some embedded systems omit internationalization (locale) support
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AC_CHECK_HEADERS([xlocale.h])
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@ -603,6 +603,9 @@
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/* Define to 1 if your system defines the file flag O_SYMLINK in fcntl.h */
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#undef HAVE_O_SYMLINK
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/* Define to support libc with permanent dlopen. */
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#undef HAVE_PERMANENT_DLOPEN
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/* Define to indicate the PostgreSQL library */
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#undef HAVE_PGSQL
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147
main/loader.c
147
main/loader.c
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@ -153,6 +153,117 @@ static unsigned int loader_ready;
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static struct ast_vector_string startup_errors;
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static struct ast_str *startup_error_builder;
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#if defined(HAVE_PERMANENT_DLOPEN)
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#define FIRST_DLOPEN 999
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struct ao2_container *info_list = NULL;
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struct info_list_obj {
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const struct ast_module_info *info;
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int dlopened;
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char name[0];
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};
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static struct info_list_obj *info_list_obj_alloc(const char *name,
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const struct ast_module_info *info)
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{
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struct info_list_obj *new_entry;
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new_entry = ao2_alloc(sizeof(*new_entry) + strlen(name) + 1, NULL);
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if (!new_entry) {
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return NULL;
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}
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strcpy(new_entry->name, name); /* SAFE */
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new_entry->info = info;
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new_entry->dlopened = FIRST_DLOPEN;
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return new_entry;
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}
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AO2_STRING_FIELD_CMP_FN(info_list_obj, name)
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static char *get_name_from_resource(const char *resource)
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{
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int len;
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const char *last_three;
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char *mod_name;
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if (!resource) {
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return NULL;
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}
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len = strlen(resource);
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if (len > 3) {
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last_three = &resource[len-3];
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if (!strcasecmp(last_three, ".so")) {
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mod_name = ast_calloc(1, len - 2);
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if (mod_name) {
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ast_copy_string(mod_name, resource, len - 2);
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return mod_name;
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} else {
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/* Unable to allocate memory. */
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return NULL;
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}
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}
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}
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/* Resource is the name - happens when manually unloading a module. */
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mod_name = ast_calloc(1, len + 1);
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if (mod_name) {
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ast_copy_string(mod_name, resource, len + 1);
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return mod_name;
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}
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/* Unable to allocate memory. */
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return NULL;
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}
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static void manual_mod_reg(const void *lib, const char *resource)
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{
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struct info_list_obj *obj_tmp;
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char *mod_name;
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if (lib) {
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mod_name = get_name_from_resource(resource);
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if (mod_name) {
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obj_tmp = ao2_find(info_list, mod_name, OBJ_SEARCH_KEY);
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if (obj_tmp) {
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if (obj_tmp->dlopened == FIRST_DLOPEN) {
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obj_tmp->dlopened = 1;
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} else {
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ast_module_register(obj_tmp->info);
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}
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ao2_ref(obj_tmp, -1);
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}
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ast_free(mod_name);
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}
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}
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}
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static void manual_mod_unreg(const char *resource)
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{
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struct info_list_obj *obj_tmp;
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char *mod_name;
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/* When Asterisk shuts down the destructor is called automatically. */
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if (ast_shutdown_final()) {
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return;
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}
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mod_name = get_name_from_resource(resource);
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if (mod_name) {
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obj_tmp = ao2_find(info_list, mod_name, OBJ_SEARCH_KEY);
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if (obj_tmp) {
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ast_module_unregister(obj_tmp->info);
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ao2_ref(obj_tmp, -1);
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}
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ast_free(mod_name);
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}
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}
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#endif
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static __attribute__((format(printf, 1, 2))) void module_load_error(const char *fmt, ...)
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{
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char *copy = NULL;
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@ -597,6 +708,23 @@ void ast_module_register(const struct ast_module_info *info)
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/* give the module a copy of its own handle, for later use in registrations and the like */
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*((struct ast_module **) &(info->self)) = mod;
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#if defined(HAVE_PERMANENT_DLOPEN)
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if (mod->flags.builtin != 1) {
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struct info_list_obj *obj_tmp = ao2_find(info_list, info->name,
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OBJ_SEARCH_KEY);
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if (!obj_tmp) {
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obj_tmp = info_list_obj_alloc(info->name, info);
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if (obj_tmp) {
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ao2_link(info_list, obj_tmp);
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ao2_ref(obj_tmp, -1);
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}
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} else {
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ao2_ref(obj_tmp, -1);
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}
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}
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#endif
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}
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static int module_post_register(struct ast_module *mod)
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@ -843,6 +971,10 @@ static void logged_dlclose(const char *name, void *lib)
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error = dlerror();
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ast_log(AST_LOG_ERROR, "Failure in dlclose for module '%s': %s\n",
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S_OR(name, "unknown"), S_OR(error, "Unknown error"));
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#if defined(HAVE_PERMANENT_DLOPEN)
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} else {
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manual_mod_unreg(name);
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#endif
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}
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}
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@ -949,6 +1081,9 @@ static struct ast_module *load_dlopen(const char *resource_in, const char *so_ex
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resource_being_loaded = mod;
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mod->lib = dlopen(filename, flags);
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#if defined(HAVE_PERMANENT_DLOPEN)
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manual_mod_reg(mod->lib, mod->resource);
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#endif
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if (resource_being_loaded) {
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struct ast_str *list;
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int c = 0;
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@ -968,6 +1103,9 @@ static struct ast_module *load_dlopen(const char *resource_in, const char *so_ex
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resource_being_loaded = mod;
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mod->lib = dlopen(filename, RTLD_LAZY | RTLD_LOCAL);
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#if defined(HAVE_PERMANENT_DLOPEN)
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manual_mod_reg(mod->lib, mod->resource);
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#endif
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if (resource_being_loaded) {
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resource_being_loaded = NULL;
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@ -2206,6 +2344,15 @@ int load_modules(void)
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ast_verb(1, "Asterisk Dynamic Loader Starting:\n");
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#if defined(HAVE_PERMANENT_DLOPEN)
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info_list = ao2_container_alloc_list(AO2_ALLOC_OPT_LOCK_NOLOCK, 0, NULL,
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info_list_obj_cmp_fn); /* must not be cleaned at shutdown */
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if (!info_list) {
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fprintf(stderr, "Module info list allocation failure.\n");
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return 1;
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}
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#endif
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AST_LIST_HEAD_INIT_NOLOCK(&load_order);
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AST_DLLIST_LOCK(&module_list);
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