First version.

.gitignore

@@ -158,3 +158,6 @@ cython_debug/
 #  and can be added to the global gitignore or merged into this file.  For a more nuclear
 #  option (not recommended) you can uncomment the following to ignore the entire idea folder.
 #.idea/
+
+out.dot
+out.svg

Makefile

@@ -0,0 +1,7 @@
+TGT=`which glxgears`
+
+all:
+	./sotrace.py $(TGT) out.dot
+	dot -Tsvg -o out.svg out.dot
+	-display out.svg
+

README.md

@@ -1,2 +1,34 @@
 # sotrace
 Traces the shared-object dependencies of a binary, and graphs them.
+
+## Usage
+
+```
+./sotrace.py /path/to/foo out.dot
+dot -Tout.svg out.dot
+eog out.svg
+```
+
+![example output](images/out-glxgears.svg "glxgears dependencies")
+
+## Rationale
+
+Dynamically linked binaries pull in a large amount of dependencies.
+It is often hard to get a good idea of what gets pulled in, recursively.
+
+This tool will create a graphic that clearly shows the dependencies.
+
+It is also a useful tool to identify software bloat.
+
+## Limitations
+
+Currently, it will only find dependencies that are dynamically linked.
+
+This means it will miss:
+ * statically linked dependencies.
+ * plugins (.so files that are loaded at run-time, not load-time.)
+
+## Author
+
+Bram Stolk [email protected]
+

sotrace.py

@@ -0,0 +1,81 @@
+#!/bin/env python3
+#
+# sotrace.py
+#
+# shared object trace
+#
+# Usage:
+#    sotrace.py /path/to/binary out.dot
+#    dot -Tout.svg out.dot
+#
+# (c)2024 Bram Stolk
+
+
+import os	# For popen
+import sys	# For argv
+
+
+# Given a target library name, see what this library directly depends on.
+def dep_list(tgt) :
+	cmd = "readelf -d " + tgt + " | grep NEEDED"
+	f = os.popen(cmd, 'r')
+	lines = f.readlines()
+	f.close()
+	vals = [ x.split(": ")[1].strip() for x in lines ]
+	deps = [ x[1:-1] for x in vals ]
+	return deps
+
+
+# Given a set of dependency names, check to what path the are resolved using ldd
+def dep_to_lib(tgt, deps) :
+	cmd = "ldd " + tgt
+	f = os.popen(cmd, 'r')
+	lines = f.readlines()
+	f.close()
+	mapping = {}
+	for line in lines:
+		if "=>" in line:
+			parts = line.strip().split(" => ")
+			nam = parts[0].strip()
+			if nam in deps :
+				mapping[nam] = parts[1].split(" (")[0]
+	return mapping
+
+
+# Walk the dependencies of the target, and write the graph to file.
+def traverse_so(tgt, nam, f, depth, visited, linked) :
+	deps = dep_list(tgt)
+	lib_map = dep_to_lib(tgt, deps)
+
+	for val in lib_map.keys() :
+		if nam != val and (nam,val) not in linked:
+			linked.append( (nam,val) )
+			f.write('"' + nam + '" -> "' + val + '"\n')
+
+	for dep in deps:
+		if dep in lib_map:
+			m = lib_map[dep]
+			if not m in visited:
+				visited.append(m)
+				dnam = os.path.basename(dep)
+				traverse_so(m, dnam, f, depth+1, visited, linked)
+
+# Main entry point
+if __name__ == '__main__' :
+
+	if len(sys.argv) != 3 :
+		print("Usage:", sys.argv[0], "libfoo.so graph.dot")
+		sys.exit(1)
+
+	tgt = sys.argv[1]
+	out = sys.argv[2]
+	nam = os.path.basename(tgt)
+
+	f = open(out, "w")
+	f.write("digraph G {\n")
+	f.write("  rankdir = LR;\n")
+	traverse_so(tgt, nam, f, 0, [], [])
+	f.write("}\n");
+	f.close()
+
+