Use pc_from_ucontext.m4 from Google Performance Tools

This M4 module lets us learn the right way (out of at least 18
possibilities) to extract the current PC for stack-trace-fixup-in-signal
purposes.  The Google Performance Tools license is 3-clause BSD.

3 files changed, 166 insertions, 0 deletions

diff --git a/LICENSE b/LICENSE
index 4ed3bd8da..8a6fccaf4 100644
--- a/LICENSE
+++ b/LICENSE
@@ -135,6 +135,39 @@ 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
 DATABASE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 ===============================================================================
+m4/pc_from_ucontext.m4 is available under the following license.  Note that
+it is *not* built into the Tor license.
+
+Copyright (c) 2005, Google Inc.
+All rights reserved.
+
+Redistribution and use in source and binary forms, with or without
+modification, are permitted provided that the following conditions are
+met:
+
+    * Redistributions of source code must retain the above copyright
+notice, this list of conditions and the following disclaimer.
+    * 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.
+    * Neither the name of Google Inc. nor the names of its
+contributors may be used to endorse or promote products derived from
+this software without specific prior written permission.
+
+THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+"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 COPYRIGHT
+OWNER OR CONTRIBUTORS 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.
+
+===============================================================================
 If you got Tor as a static binary with OpenSSL included, then you should know:
  "This product includes software developed by the OpenSSL Project
  for use in the OpenSSL Toolkit (http://www.openssl.org/)"
diff --git a/configure.ac b/configure.ac
index 8e247db32..06e9e3b37 100644
--- a/configure.ac
+++ b/configure.ac
@@ -937,6 +937,8 @@ AC_CHECK_SIZEOF(pid_t)
 
 AC_CHECK_TYPES([uint, u_char, ssize_t])
 
+AC_PC_FROM_UCONTEXT([/bin/true])
+
 dnl used to include sockaddr_storage, but everybody has that.
 AC_CHECK_TYPES([struct in6_addr, struct sockaddr_in6, sa_family_t], , ,
 [#ifdef HAVE_SYS_TYPES_H
diff --git a/m4/pc_from_ucontext.m4 b/m4/pc_from_ucontext.m4
new file mode 100644
index 000000000..6bedcbb2d
--- /dev/null
+++ b/m4/pc_from_ucontext.m4
@@ -0,0 +1,131 @@
+# This file is from Google Performance Tools, svn revision r226.
+#
+# The Google Performance Tools license is:
+########
+# Copyright (c) 2005, Google Inc.
+# All rights reserved.
+#
+# Redistribution and use in source and binary forms, with or without
+# modification, are permitted provided that the following conditions are
+# met:
+#
+#     * Redistributions of source code must retain the above copyright
+# notice, this list of conditions and the following disclaimer.
+#     * 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.
+#     * Neither the name of Google Inc. nor the names of its
+# contributors may be used to endorse or promote products derived from
+# this software without specific prior written permission.
+#
+# THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
+# "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 COPYRIGHT
+# OWNER OR CONTRIBUTORS 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.
+########
+# Original file follows below.
+
+# We want to access the "PC" (Program Counter) register from a struct
+# ucontext.  Every system has its own way of doing that.  We try all the
+# possibilities we know about.  Note REG_PC should come first (REG_RIP
+# is also defined on solaris, but does the wrong thing).
+
+# OpenBSD doesn't have ucontext.h, but we can get PC from ucontext_t
+# by using signal.h.
+
+# The first argument of AC_PC_FROM_UCONTEXT will be invoked when we
+# cannot find a way to obtain PC from ucontext.
+
+AC_DEFUN([AC_PC_FROM_UCONTEXT],
+  [AC_CHECK_HEADERS(ucontext.h)
+   # Redhat 7 has <sys/ucontext.h>, but it barfs if we #include it directly
+   # (this was fixed in later redhats).  <ucontext.h> works fine, so use that.
+   if grep "Red Hat Linux release 7" /etc/redhat-release >/dev/null 2>&1; then
+     AC_DEFINE(HAVE_SYS_UCONTEXT_H, 0, [<sys/ucontext.h> is broken on redhat 7])
+     ac_cv_header_sys_ucontext_h=no
+   else
+     AC_CHECK_HEADERS(sys/ucontext.h)       # ucontext on OS X 10.6 (at least)
+   fi
+   AC_CHECK_HEADERS(cygwin/signal.h)        # ucontext on cywgin
+   AC_MSG_CHECKING([how to access the program counter from a struct ucontext])
+   pc_fields="           uc_mcontext.gregs[[REG_PC]]"  # Solaris x86 (32 + 64 bit)
+   pc_fields="$pc_fields uc_mcontext.gregs[[REG_EIP]]" # Linux (i386)
+   pc_fields="$pc_fields uc_mcontext.gregs[[REG_RIP]]" # Linux (x86_64)
+   pc_fields="$pc_fields uc_mcontext.sc_ip"            # Linux (ia64)
+   pc_fields="$pc_fields uc_mcontext.uc_regs->gregs[[PT_NIP]]" # Linux (ppc)
+   pc_fields="$pc_fields uc_mcontext.gregs[[R15]]"     # Linux (arm old [untested])
+   pc_fields="$pc_fields uc_mcontext.arm_pc"           # Linux (arm arch 5)
+   pc_fields="$pc_fields uc_mcontext.gp_regs[[PT_NIP]]"  # Suse SLES 11 (ppc64)
+   pc_fields="$pc_fields uc_mcontext.mc_eip"           # FreeBSD (i386)
+   pc_fields="$pc_fields uc_mcontext.mc_rip"           # FreeBSD (x86_64 [untested])
+   pc_fields="$pc_fields uc_mcontext.__gregs[[_REG_EIP]]"  # NetBSD (i386)
+   pc_fields="$pc_fields uc_mcontext.__gregs[[_REG_RIP]]"  # NetBSD (x86_64)
+   pc_fields="$pc_fields uc_mcontext->ss.eip"          # OS X (i386, <=10.4)
+   pc_fields="$pc_fields uc_mcontext->__ss.__eip"      # OS X (i386, >=10.5)
+   pc_fields="$pc_fields uc_mcontext->ss.rip"          # OS X (x86_64)
+   pc_fields="$pc_fields uc_mcontext->__ss.__rip"      # OS X (>=10.5 [untested])
+   pc_fields="$pc_fields uc_mcontext->ss.srr0"         # OS X (ppc, ppc64 [untested])
+   pc_fields="$pc_fields uc_mcontext->__ss.__srr0"     # OS X (>=10.5 [untested])
+   pc_field_found=false
+   for pc_field in $pc_fields; do
+     if ! $pc_field_found; then
+       # Prefer sys/ucontext.h to ucontext.h, for OS X's sake.
+       if test "x$ac_cv_header_cygwin_signal_h" = xyes; then
+         AC_TRY_COMPILE([#define _GNU_SOURCE 1
+                         #include <cygwin/signal.h>],
+                        [ucontext_t u; return u.$pc_field == 0;],
+                        AC_DEFINE_UNQUOTED(PC_FROM_UCONTEXT, $pc_field,
+                                           How to access the PC from a struct ucontext)
+                        AC_MSG_RESULT([$pc_field])
+                        pc_field_found=true)
+       elif test "x$ac_cv_header_sys_ucontext_h" = xyes; then
+         AC_TRY_COMPILE([#define _GNU_SOURCE 1
+                         #include <sys/ucontext.h>],
+                        [ucontext_t u; return u.$pc_field == 0;],
+                        AC_DEFINE_UNQUOTED(PC_FROM_UCONTEXT, $pc_field,
+                                           How to access the PC from a struct ucontext)
+                        AC_MSG_RESULT([$pc_field])
+                        pc_field_found=true)
+       elif test "x$ac_cv_header_ucontext_h" = xyes; then
+         AC_TRY_COMPILE([#define _GNU_SOURCE 1
+                         #include <ucontext.h>],
+                        [ucontext_t u; return u.$pc_field == 0;],
+                        AC_DEFINE_UNQUOTED(PC_FROM_UCONTEXT, $pc_field,
+                                           How to access the PC from a struct ucontext)
+                        AC_MSG_RESULT([$pc_field])
+                        pc_field_found=true)
+       else     # hope some standard header gives it to us
+         AC_TRY_COMPILE([],
+                        [ucontext_t u; return u.$pc_field == 0;],
+                        AC_DEFINE_UNQUOTED(PC_FROM_UCONTEXT, $pc_field,
+                                           How to access the PC from a struct ucontext)
+                        AC_MSG_RESULT([$pc_field])
+                        pc_field_found=true)
+       fi
+     fi
+   done
+   if ! $pc_field_found; then
+     pc_fields="           sc_eip"  # OpenBSD (i386)
+     pc_fields="$pc_fields sc_rip"  # OpenBSD (x86_64)
+     for pc_field in $pc_fields; do
+       if ! $pc_field_found; then
+         AC_TRY_COMPILE([#include <signal.h>],
+                        [ucontext_t u; return u.$pc_field == 0;],
+                        AC_DEFINE_UNQUOTED(PC_FROM_UCONTEXT, $pc_field,
+                                           How to access the PC from a struct ucontext)
+                        AC_MSG_RESULT([$pc_field])
+                        pc_field_found=true)
+       fi
+     done
+   fi
+   if ! $pc_field_found; then
+     [$1]
+   fi])