Use libbacktrace to generate better leak callstacks.

git-svn-id: https://www.unprompted.com/svn/projects/tildefriends/trunk@3986 ed5197a5-7fde-0310-b194-c3ffbd925b24

deps/libbacktrace/allocfail.sh

@@ -0,0 +1,104 @@
+#!/bin/sh
+
+# allocfail.sh -- Test for libbacktrace library.
+# Copyright (C) 2018-2021 Free Software Foundation, Inc.
+
+# 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 BY THE AUTHOR ``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.
+
+set -e
+
+if [ ! -f ./allocfail ]; then
+    # Hard failure.
+    exit 99
+fi
+
+allocs=$(./allocfail 2>&1)
+if [ "$allocs" = "" ]; then
+    # Hard failure.
+    exit 99
+fi
+
+# This generates the following output:
+# ...
+# $ allocfail.sh
+# allocs: 80495
+# Status changed to 0 at 1
+# Status changed to 1 at 3
+# Status changed to 0 at 11
+# Status changed to 1 at 12
+# Status changed to 0 at 845
+# ...
+#
+# We have status 0 for an allocation failure at:
+# - 1 because backtrace_create_state handles failure robustly
+# - 2 because the fail switches backtrace_full to !can_alloc mode.
+# - 11 because failure of elf_open_debugfile_by_buildid does not generate an
+#   error callback beyond the one for the allocation failure itself.
+
+echo "allocs: $allocs"
+
+step=1
+i=1
+passes=0
+prev_status=-1
+while [ $i -le $allocs ]; do
+    if ./allocfail $i >/dev/null 2>&1; status=$?; then
+	true
+    fi
+    if [ $status -gt 1 ]; then
+	echo "Unallowed fail found: $i"
+	# Failure.
+	exit 1
+    fi
+
+    # The test-case would run too long if we would excercise all allocs.
+    # So, run with step 1 initially, and increase the step once we have 10
+    # subsequent passes, and drop back to step 1 once we encounter another
+    # failure.  This takes ~2.6 seconds on an i7-6600U CPU @ 2.60GHz.
+    if [ $status -eq 0 ]; then
+	passes=$(($passes + 1))
+	if [ $passes -ge 10 ]; then
+	    step=$((step * 10))
+	    passes=0
+	fi
+    elif [ $status -eq 1 ]; then
+	passes=0
+	step=1
+    fi
+
+    if [ $status -ne $prev_status ]; then
+	echo "Status changed to $status at $i"
+    fi
+    prev_status=$status
+
+    i=$(($i + $step))
+done
+
+# Success.
+exit 0