[PR,guile/17247] Block SIGCHLD while initializing Guile

diff --git a/gdb/ChangeLog b/gdb/ChangeLog
index ad5ef6f..9d3f392 100644
--- a/gdb/ChangeLog
+++ b/gdb/ChangeLog
@@ -1,5 +1,22 @@ 
 2014-09-08  Doug Evans  <xdje42@gmail.com>
 
+	PR 17247
+	* guile.c: #include <signal.h>.
+	(_initialize_guile): Block SIGCHLD while initializing Guile.
+
+	Replaces the following, which is reverted.
+
+	2014-07-26  Doug Evans  <xdje42@gmail.com>
+
+	PR 17185
+	* configure.ac: Add check for header gc/gc.h.
+	Add check for function setenv.
+	* configure: Regenerate.
+	* config.in: Regenerate.
+	* guile/guile.c (_initialize_guile): Add workaround for libgc 7.4.0.
+
+2014-09-08  Doug Evans  <xdje42@gmail.com>
+
 	* guile/scm-cmd.c (gdbscm_parse_command_name): Replace magic number
 	with named constant.  Fix style of pointer comparison.
 	* python/py-cmd.c (gdbpy_parse_command_name): Ditto.
diff --git a/gdb/config.in b/gdb/config.in
index b853412..f1593bd 100644
--- a/gdb/config.in
+++ b/gdb/config.in
@@ -141,9 +141,6 @@ 
 /* Define if <sys/procfs.h> has fpregset_t. */
 #undef HAVE_FPREGSET_T
 
-/* Define to 1 if you have the <gc/gc.h> header file. */
-#undef HAVE_GC_GC_H
-
 /* Define to 1 if you have the `getgid' function. */
 #undef HAVE_GETGID
 
@@ -348,9 +345,6 @@ 
 /* Define to 1 if you have the `scm_new_smob' function. */
 #undef HAVE_SCM_NEW_SMOB
 
-/* Define to 1 if you have the `setenv' function. */
-#undef HAVE_SETENV
-
 /* Define to 1 if you have the `setlocale' function. */
 #undef HAVE_SETLOCALE
 
diff --git a/gdb/configure b/gdb/configure
index bf141f1..350ec0c 100755
--- a/gdb/configure
+++ b/gdb/configure
@@ -9276,32 +9276,6 @@  else
 fi
 
 
-# PR 17185, see if we can get the libgc version to see if we need
-# to apply the workaround.
-for ac_header in gc/gc.h
-do :
-  ac_fn_c_check_header_mongrel "$LINENO" "gc/gc.h" "ac_cv_header_gc_gc_h" "$ac_includes_default"
-if test "x$ac_cv_header_gc_gc_h" = x""yes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_GC_GC_H 1
-_ACEOF
-
-fi
-
-done
-
-for ac_func in setenv
-do :
-  ac_fn_c_check_func "$LINENO" "setenv" "ac_cv_func_setenv"
-if test "x$ac_cv_func_setenv" = x""yes; then :
-  cat >>confdefs.h <<_ACEOF
-#define HAVE_SETENV 1
-_ACEOF
-
-fi
-done
-
-
 # --------------------- #
 # Check for libmcheck.  #
 # --------------------- #
diff --git a/gdb/configure.ac b/gdb/configure.ac
index 26c8ecf..ab7b1c2 100644
--- a/gdb/configure.ac
+++ b/gdb/configure.ac
@@ -1233,11 +1233,6 @@  AC_SUBST(GUILE_CPPFLAGS)
 AC_SUBST(GUILE_LIBS)
 AM_CONDITIONAL(HAVE_GUILE, test "${have_libguile}" != no)
 
-# PR 17185, see if we can get the libgc version to see if we need
-# to apply the workaround.
-AC_CHECK_HEADERS(gc/gc.h)
-AC_CHECK_FUNCS([setenv])
-
 # --------------------- #
 # Check for libmcheck.  #
 # --------------------- #
diff --git a/gdb/guile/guile.c b/gdb/guile/guile.c
index 575bb6c..97da042 100644
--- a/gdb/guile/guile.c
+++ b/gdb/guile/guile.c
@@ -34,10 +34,8 @@ 
 #ifdef HAVE_GUILE
 #include "guile.h"
 #include "guile-internal.h"
-#ifdef HAVE_GC_GC_H
-#include <gc/gc.h> /* PR 17185 */
-#endif
 #endif
+#include <signal.h>
 
 /* The Guile version we're using.
    We *could* use the macros in libguile/version.h but that would preclude
@@ -833,39 +831,46 @@  extern initialize_file_ftype _initialize_guile;
 void
 _initialize_guile (void)
 {
-  char *msg;
-
   install_gdb_commands ();
 
 #if HAVE_GUILE
-  /* The Python support puts the C side in module "_gdb", leaving the Python
-     side to define module "gdb" which imports "_gdb".  There is evidently no
-     similar convention in Guile so we skip this.  */
-
-  /* PR 17185 There are problems with using libgc 7.4.0.
-     Copy over the workaround Guile uses (Guile is working around a different
-     problem, but the workaround is the same).  */
-#if (GC_VERSION_MAJOR == 7 && GC_VERSION_MINOR == 4 && GC_VERSION_MICRO == 0)
-  /* The bug is only known to appear with pthreads.  We assume any system
-     using pthreads also uses setenv (and not putenv).  That is why we don't
-     have a similar call to putenv here.  */
-#if defined (HAVE_SETENV)
-  setenv ("GC_MARKERS", "1", 1);
+  {
+#ifdef HAVE_SIGPROCMASK
+    sigset_t sigchld_mask, prev_mask;
 #endif
+
+    /* The Python support puts the C side in module "_gdb", leaving the Python
+       side to define module "gdb" which imports "_gdb".  There is evidently no
+       similar convention in Guile so we skip this.  */
+
+#ifdef HAVE_SIGPROCMASK
+    /* Before we initialize Guile, block SIGCHLD.
+       This is done so that all threads created during Guile initialization
+       have SIGCHLD blocked.  PR 17247.
+       Really libgc and Guile should do this, but we need to work with
+       libgc 7.4.x.  */
+    sigemptyset (&sigchld_mask);
+    sigaddset (&sigchld_mask, SIGCHLD);
+    sigprocmask (SIG_BLOCK, &sigchld_mask, &prev_mask);
+#endif
+
+    /* scm_with_guile is the most portable way to initialize Guile.
+       Plus we need to initialize the Guile support while in Guile mode
+       (e.g., called from within a call to scm_with_guile).  */
+    scm_with_guile (call_initialize_gdb_module, NULL);
+
+#ifdef HAVE_SIGPROCMASK
+    sigprocmask (SIG_SETMASK, &prev_mask, NULL);
 #endif
 
-  /* scm_with_guile is the most portable way to initialize Guile.
-     Plus we need to initialize the Guile support while in Guile mode
-     (e.g., called from within a call to scm_with_guile).  */
-  scm_with_guile (call_initialize_gdb_module, NULL);
-
-  /* Set Guile's backtrace to match the "set guile print-stack" default.
-     [N.B. The two settings are still separate.]
-     But only do this after we've initialized Guile, it's nice to see a
-     backtrace if there's an error during initialization.
-     OTOH, if the error is that gdb/init.scm wasn't found because gdb is being
-     run from the build tree, the backtrace is more noise than signal.
-     Sigh.  */
-  gdbscm_set_backtrace (0);
+    /* Set Guile's backtrace to match the "set guile print-stack" default.
+       [N.B. The two settings are still separate.]
+       But only do this after we've initialized Guile, it's nice to see a
+       backtrace if there's an error during initialization.
+       OTOH, if the error is that gdb/init.scm wasn't found because gdb is
+       being run from the build tree, the backtrace is more noise than signal.
+       Sigh.  */
+    gdbscm_set_backtrace (0);
+  }
 #endif
 }