From bc571dfb016351c94670a03904b96c03204ffffa Mon Sep 17 00:00:00 2001
From: Simon Marchi <simon.marchi@efficios.com>
Date: Tue, 26 Feb 2019 15:06:01 -0500
Subject: [PATCH] hang_processes.sh: Obtain list of loaded dynamic objects
 using strings

While this is quite ugly, it has the advantage that we get the path to
the object files actually loaded by the application.  So if it loaded
some particular shared object due due to some LD_LIBRARY_PATH value or
because it dlopen'ed them, we will catch them.

Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
---
 scripts/lttng-tools/hang_processes.sh | 60 ++++++++++++++++-----------
 1 file changed, 35 insertions(+), 25 deletions(-)

diff --git a/scripts/lttng-tools/hang_processes.sh b/scripts/lttng-tools/hang_processes.sh
index 0967218..f0d2ccf 100755
--- a/scripts/lttng-tools/hang_processes.sh
+++ b/scripts/lttng-tools/hang_processes.sh
@@ -17,7 +17,6 @@
 
 PGREP=pgrep
 pids=""
-dependencies=""
 file_list=$(mktemp)
 ret=0
 
@@ -34,39 +33,50 @@ if [ -n "$lttng_processes" ]; then
 
     # Stop the processes to make sure everything is frozen
     kill -SIGSTOP $pids
-
-    # Get dependencies for coredump analysis
-    # Use /proc/$PID/exe and ldd to get all shared libs necessary
-    array=(${pids})
-    # Add the /proc/ prefix using parameter expansion
-    array=("${array[@]/#/\/proc\/}")
-    # Add the /exe suffix using parameter expansion
-    array=("${array[@]/%/\/exe}")
-    dependencies=$(ldd "${array[@]}" | grep -v "not found")
-    dependencies=$(awk '/=>/{print$(NF-1)}' <<< "$dependencies" | sort | uniq)
-
     kill -SIGABRT $pids
     kill -SIGCONT $pids
     ret=1
 fi
 
-core_files=$(find "/tmp" -name "core\.[0-9]*" -type f 2>/dev/null) || true
-if [ -n "$core_files" ]; then
-    echo "$core_files" >> "$file_list"
-    echo "$dependencies" >> "$file_list"
+# Add the file passed as $1 to the list of files to collect.
+#
+# If that file is a symlink, follow it and collect the target, recursively.
+
+function collect_recursive
+{
+    file_to_collect=$1
+
+    if [ -f "$file_to_collect" ]; then
+        echo "$file_to_collect" >> "$file_list"
+
+        if [ -L "$file_to_collect" ]; then
+            collect_recursive "$(readlink "$file_to_collect")"
+        fi
+    fi
+}
 
-    # Make sure the coredump is finished using fuser
-    for core in $core_files; do
-        while fuser "$core"; do
-            sleep 1
-        done
+# For each core file...
+while read -r core_file; do
+    # Make sure the coredump is finished using fuser.
+    while fuser "$core_file"; do
+        sleep 1
     done
 
-    mkdir -p "${WORKSPACE}/build"
-    tar cfzh "${WORKSPACE}/build/core.tar.gz" -T "$file_list"
-    rm -f "$core_files"
+    # Collect everything in the core file that looks like a reference to a
+    # shared lib.
+    strings "$core_file" | grep '^/.*\.so.*' | while read -r str; do
+        collect_recursive "$str"
+    done
+
+    rm -f "$core_file"
     ret=1
+done < <(find "/tmp" -maxdepth 1 -name "core\.[0-9]*" -type f 2>/dev/null)
+
+# If we recorded some files to collect, pack them up.
+if [ -s "$file_list" ]; then
+    mkdir -p "${WORKSPACE}/build"
+    tar cfzh "${WORKSPACE}/build/core.tar.gz" -T <(sort "$file_list" | uniq)
 fi
 
-rm -rf "$file_list"
+rm -f "$file_list"
 exit $ret
-- 
2.34.1