Add a simple script for mapping linker dependencies

This only supports FreeBSD currently.

The graphviz portion is split from the linker dependency enumeration
portion because the host where the linker dependencies are enumerated
may not have easy access to graphviz and its associated libraries.

tools/graph-linker-dependencies/MANIFEST.in

@@ -0,0 +1 @@
+include graph_linker_dependencies/templates/*.pyt

tools/graph-linker-dependencies/setup.py

@@ -0,0 +1,32 @@
+#!/usr/bin/env python3
+
+import platform
+import sys
+from setuptools import find_packages
+from setuptools import setup
+
+
+osname = platform.system().lower()
+if osname not in "freebsd":
+    sys.exit("This package only works on FreeBSD.")
+
+GLD = "graph_linker_dependencies"
+
+setup(
+    name="graph_linker_dependencies",
+    version="0.1",
+    description="Tool for graphing FreeBSD linker dependencies.",
+    author="Enji Cooper",
+    author_email="[email protected]",
+    url="https://github.com/ngie-eign/scratch",
+    include_package_data=True,
+    packages=find_packages(where="src"),
+    package_data={f"{GLD}": ["templates/*.pyt"]},
+    package_dir={"": "src"},
+    entry_points={
+        "console_scripts": [
+            f"create_link_dependency_graph={GLD}.create_link_dependency_graph:main"
+        ]
+    },
+    requirements=["jinja2"],
+)

tools/graph-linker-dependencies/src/graph_linker_dependencies/__init__.py

@@ -0,0 +1,2 @@
+import pkg_resources
+pkg_resources.declare_namespace(__name__)

tools/graph-linker-dependencies/src/graph_linker_dependencies/create_link_dependency_graph.py

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+#!/usr/bin/env python
+
+import argparse
+import collections
+import os
+import pathlib
+
+# import pprint
+import pkg_resources
+import re
+import subprocess
+
+from jinja2 import Environment
+from jinja2 import FileSystemLoader
+from jinja2 import Template
+from jinja2 import select_autoescape
+
+
+LIBDEPS_CACHE = collections.defaultdict(list)
+LDCONFIG_HINT_RE = re.compile(r".+\s+=>\s+(.+)")
+NEEDED_SHLIB_RE = re.compile(r".+NEEDED\s+Shared library: \[(.+)\]")
+
+
+def build_library_path_cache():
+    ldconfig_hints_map = {}
+
+    all_ldconfig_hints = subprocess.check_output(["ldconfig", "-r"], text=True)
+    for ldconfig_hint in all_ldconfig_hints.splitlines(False):
+        matches = LDCONFIG_HINT_RE.match(ldconfig_hint)
+        if matches is None:
+            continue
+
+        so_full = so_split = matches.group(1)
+        ldconfig_hints_map[so_full] = so_full
+
+        while True:
+            so_short = os.path.basename(so_split)
+            ldconfig_hints_map[so_short] = ldconfig_hints_map[so_split] = so_full
+            so_split, ext = os.path.splitext(so_split)
+            if ext == ".so":
+                break
+
+    return ldconfig_hints_map
+
+
+def find_library_dependencies(library_, ldconfig_hints_map, libdep_cache):
+    if library_ in libdep_cache:
+        return
+
+    lib_path = ldconfig_hints_map[library_]
+
+    readelf_lines = subprocess.check_output(["readelf", "-d", lib_path], text=True)
+    for readelf_line in readelf_lines.splitlines(False):
+        matches = NEEDED_SHLIB_RE.match(readelf_line)
+        if matches is None:
+            continue
+        libdep = matches.group(1)
+        libdep_cache[library_].append(libdep)
+        find_library_dependencies(libdep, ldconfig_hints_map, libdep_cache)
+
+
+def main(argv=None):
+    parser = argparse.ArgumentParser()
+    parser.add_argument("library")
+    parser.add_argument("--graph-generator-file")
+    parser.add_argument("--graph-output-file")
+    args = parser.parse_args(args=argv)
+
+    libdep_cache = collections.defaultdict(list)
+
+    ldconfig_hints_map = build_library_path_cache()
+
+    library_full_path = str(pathlib.Path(args.library).resolve())
+    assert (
+        library_full_path in ldconfig_hints_map
+    ), f"{library_full_path} not found in ldconfig cache"
+
+    find_library_dependencies(library_full_path, ldconfig_hints_map, libdep_cache)
+
+    env = Environment(
+        loader=FileSystemLoader(
+            pkg_resources.resource_filename(
+                "graph_linker_dependencies",
+                "templates",
+            )
+        ),
+        autoescape=select_autoescape(),
+    )
+    template = env.get_template("libdep_template.pyt")
+
+    library_name = pathlib.Path(args.library).stem
+    graph_py_filename = (
+        args.graph_generator_file or f"graph_{library_name}_dependencies.py"
+    )
+    graph_output_file = (
+        args.graph_output_file or f"{library_name}_dependencies_graph.png"
+    )
+    with open(graph_py_filename, "w") as filep:
+        filep.write(
+            template.render(
+                libdep_cache=libdep_cache, output_file=args.graph_output_file
+            )
+        )
+    print(f"Please run {graph_py_filename} on host where python-graphviz is installed.")
+
+
+if __name__ == "__main__":
+    main()

tools/graph-linker-dependencies/src/graph_linker_dependencies/templates/__init__.py

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+import pkg_resources
+pkg_resources.declare_namespace(__name__)

tools/graph-linker-dependencies/src/graph_linker_dependencies/templates/libdep_template.pyt

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+#!/usr/bin/env python
+
+try:
+    import graphviz
+except ImportError:
+    warnings.warn("This script requires python-graphviz")
+    raise
+
+dot = graphviz.Digraph("libdependencies-graph", comment="Library Dependencies Graph")
+
+{% for library, dependencies in libdep_cache.items() %}dot.node("{{library}}")
+{% for dependency in dependencies %}dot.edge("{{library}}", "{{dependency}}")
+{% endfor %}{% endfor %}
+dot.render(format="png", outfile="{{output_file}}")