kc3-lang/libbsd/src/setproctitle_ctor.c
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Hash : c5b95902
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Date : 2013-07-11T12:25:54
Move setproctitle() automatic initialization to its own library The automatic initialization cannot be part of the main shared library, because there is no thread-safe way to change the environ global variable. This is not a problem if the initializaion happens just at program load time, but becomes one if the shared library is directly or indirectly dlopen()ed during the execution of the program, which could have either kept references to the old environ or could change it in some other thread. This has been observed for example on systems using Samba NSS modules. To avoid any other possible fallout, the constructor is split into a new static library that needs to be linked explicitly into programs using setproctitle(). As an additional safety measure the pkg-config linker flags will mark the program as not allowing to be dlopen()ed so that we avoid the problem described above. Reported-by: Jan Alexander Steffens (heftig) <jan.steffens@gmail.com> Fixes: https://bugs.freedesktop.org/show_bug.cgi?id=66679
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src/setproctitle_ctor.c
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/* * Copyright © 2013 Guillem Jover <guillem@hadrons.org> * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include <unistd.h> /* * The automatic initialization cannot be part of the main shared library, * because there is no thread-safe way to change the environ global * variable. This is not a problem if the initializaion happens just at * program load time, but becomes one if the shared library is directly or * indirectly dlopen()ed during the execution of the program, which could * have either kept references to the old environ or could change it in * some other thread. This has been observed for example on systems using * Samba NSS modules. * * To avoid any other possible fallout, the constructor is split into a * new static library that needs to be linked explicitly into programs * using setproctitle(). As an additional safety measure the pkg-config * linker flags will mark the program as not allowing to be dlopen()ed * so that we make sure to avoid the problem described above. */ /* * Force setproctitle_init() function into the .init_array section instead of * expecting either the compiler to place constructors there or the linker to * move them from .ctors to .init_array. */ void (*libbsd_init_func)(int argc, char *argv[], char *envp[]) __attribute__((section(".init_array"))) = setproctitle_init;