Add python script to compile easily

.gitignore

@@ -30,3 +30,5 @@
 *.exe
 *.out
 *.app
+
+dwarf-assembly

Makefile

@@ -0,0 +1,5 @@
+all: dwarf-assembly
+
+dwarf-assembly:
+	$(MAKE) -C src/ $@
+	ln -s src/$@ ./$@

generate_eh_elf.py

@@ -0,0 +1,141 @@
+#!/usr/bin/env python3
+
+"""
+Generates the `.eh_frame` equivalent in C code of the given ELF file, and
+all the shared objects it depends upon.
+"""
+
+
+import os
+import sys
+import subprocess
+import re
+import tempfile
+import argparse
+
+
+DWARF_ASSEMBLY_BIN = os.path.join(
+    os.path.dirname(os.path.abspath(sys.argv[0])),
+    'dwarf-assembly')
+CXX_BIN = (
+    'g++' if 'CXX' not in os.environ
+    else os.environ['CXX'])
+
+
+def elf_so_deps(path):
+    ''' Get the list of shared objects dependencies of the given ELF object.
+    This is obtained by running `ldd`. '''
+
+    deps_list = []
+
+    try:
+        ldd_output = subprocess.check_output(['/usr/bin/ldd', path],
+                                             encoding='utf8')
+        ldd_re = re.compile(r'^.* => (.*) \(0x[0-9a-fA-F]*\)$')
+
+        ldd_lines = ldd_output.strip().split('\n')
+        for line in ldd_lines:
+            line = line.strip()
+            match = ldd_re.match(line)
+            if match is None:
+                continue  # Just ignore that line — it might be eg. linux-vdso
+            deps_list.append(match.group(1))
+
+        return deps_list
+
+    except subprocess.CalledProcessError as e:
+        raise Exception(
+            ("Cannot get dependencies for {}: ldd terminated with exit code "
+             "{}.").format(path, e.returncode))
+
+
+def gen_dw_asm_c(obj_path, out_path):
+    ''' Generate the C code produced by dwarf-assembly from `obj_path`, saving
+    it as `out_path` '''
+
+    try:
+        with open(out_path, 'w') as out_handle:
+            dw_asm_output = subprocess.check_output(
+                [DWARF_ASSEMBLY_BIN, obj_path],
+                encoding='utf8')  # TODO enhance error handling
+            out_handle.write(dw_asm_output)
+    except subprocess.CalledProcessError as e:
+        raise Exception(
+            ("Cannot generate C code from object file {} using {}: process "
+             "terminated with exit code {}.").format(
+                 obj_path,
+                 DWARF_ASSEMBLY_BIN,
+                 e.returncode))
+
+
+def gen_eh_elf(obj_path, out_dir=None):
+    ''' Generate the eh_elf corresponding to `obj_path`, saving it as
+    `out_dir/$(basename obj_path).eh_elf.so` (or in the current working
+    directory if out_dir is None) '''
+
+    if out_dir is None:
+        out_dir = '.'
+
+    print("> {}...".format(os.path.basename(obj_path)))
+
+    out_base_name = os.path.basename(obj_path) + '.eh_elf'
+
+    with tempfile.TemporaryDirectory() as compile_dir:
+        # Generate the C source file
+        print("\tGenerating C…")
+        c_path = os.path.join(compile_dir, (out_base_name + '.c'))
+        gen_dw_asm_c(obj_path, c_path)
+
+        # Compile it into a .o
+        print("\tCompiling into .o…")
+        o_path = os.path.join(compile_dir, (out_base_name + '.o'))
+        if subprocess.call([CXX_BIN, '-o', o_path, '-c', c_path,
+                            '-O3', '-fPIC']) != 0:
+            raise Exception("Failed to compile to a .o file")
+
+        # Compile it into a .so
+        print("\tCompiling into .so…")
+        so_path = os.path.join(out_dir, (out_base_name + '.so'))
+        if subprocess.call([CXX_BIN, '-o', so_path, '-shared', o_path]) != 0:
+            raise Exception("Failed to compile to a .so file")
+
+
+def gen_all_eh_elf(obj_path, out_dir=None):
+    ''' Call `gen_eh_elf` on obj_path and all its dependencies '''
+    if out_dir is None:
+        out_dir = '.'
+
+    deps = elf_so_deps(obj_path)
+    deps.append(obj_path)
+    for dep in deps:
+        gen_eh_elf(dep, out_dir)
+
+
+def process_args():
+    ''' Process `sys.argv` arguments '''
+    parser = argparse.ArgumentParser(
+        description="Compile ELFs into their related eh_elfs",
+    )
+
+    parser.add_argument('--deps', action='store_const',
+                        const=gen_all_eh_elf, default=gen_eh_elf,
+                        dest='gen_func',
+                        help=("Also generate eh_elfs for the shared objects "
+                              "this object depends on"))
+    parser.add_argument('-o', '--output', metavar="path",
+                        help=("Save the generated objects at the given path "
+                              "instead of the current working directory"))
+    parser.add_argument('object', nargs='+',
+                        help="The ELF object(s) to process")
+    return parser.parse_args()
+
+
+def main():
+    args = process_args()
+
+    for obj in args.object:
+        args.gen_func(obj, args.output)
+
+
+if __name__ == "__main__":
+    main()