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Current File : //usr/share/emscripten/tools/gen_struct_info.py
# -*- encoding: utf8 -*-
'''
This tool extracts information about structs and defines from the C headers.
You can pass either the raw header files or JSON files to this script.
The JSON input format is as follows:
[
{
'file': 'some/header.h',
'structs': {
'struct_name': [
'field1',
'field2',
'field3',
{
'field4': [
'nested1',
'nested2',
{
'nested3': [
'deep_nested1',
...
]
}
...
]
},
'field5'
],
'other_struct': [
'field1',
'field2',
...
]
},
'defines': [
'DEFINE_1',
'DEFINE_2',
['f', 'FLOAT_DEFINE'],
'DEFINE_3',
...
]
},
{
'file': 'some/other/header.h',
...
}
]
Please note that the 'f' for 'FLOAT_DEFINE' is just the format passed to printf(), you can put anything printf() understands.
If you call this script with the flag "-f" and pass a header file, it will create an automated boilerplate for you.
The JSON output format is based on the return value of Runtime.generateStructInfo().
{
'structs': {
'struct_name': {
'__size__': <the struct's size>,
'field1': <field1's offset>,
'field2': <field2's offset>,
'field3': <field3's offset>,
'field4': {
'__size__': <field4's size>,
'nested1': <nested1's offset>,
...
},
...
}
},
'defines': {
'DEFINE_1': <DEFINE_1's value>,
...
}
}
'''
import sys, os, re, json, argparse, tempfile, subprocess
import shared
QUIET = (__name__ != '__main__')
def show(msg):
global QUIET
if not QUIET:
sys.stderr.write(msg + '\n')
# Try to load pycparser.
try:
import pycparser
except ImportError:
# The import failed, warn the user.
show('WARN: pycparser isn\'t available. I won\'t be able to parse C files, only .json files.')
def parse_header(path, cpp_opts):
# Tell the user how to get pycparser, if he or she tries to parse a C file.
sys.stderr.write('ERR: I need pycparser to process C files. \n')
sys.stderr.write(' Use "pip install pycparser" to install or download it from "https://github.com/eliben/pycparser".\n')
sys.exit(1)
else:
# We successfully imported pycparser, the script will be completely functional.
class DelayedRef(object):
def __init__(self, dest):
self.dest = dest
def __str__(self):
return self.dest
# For a list of node types and their fields, look here: https://github.com/eliben/pycparser/blob/master/pycparser/_c_ast.cfg
class FieldVisitor(pycparser.c_ast.NodeVisitor):
def __init__(self):
self._name = None
self.structs = {}
self.named_structs = {}
def visit_Struct(self, node):
if node.decls == None:
self.named_structs[self._name] = DelayedRef(node.name)
return
fields = []
for decl in node.decls:
if decl.name == None:
# Well, this field doesn't have a name.
continue
if decl.type != None and isinstance(decl.type, pycparser.c_ast.PtrDecl):
# This field is a pointer, there's no point in looking for nested structs.
fields.append(decl.name)
else:
# Look for nested structs.
subwalk = FieldVisitor()
subwalk.visit(decl)
if subwalk.named_structs:
# Store the nested fields.
fields.append(subwalk.named_structs)
else:
# Just store the field name.
fields.append(decl.name)
if node.name != None:
self.structs[node.name] = fields
self.named_structs[self._name] = fields
def visit_Union(self, node):
self.visit_Struct(node)
def visit_TypeDecl(self, node):
# Remember the name of this typedef, so we can access it later in visit_Struct().
old_name = self._name
self._name = node.declname
self.generic_visit(node)
self._name = old_name
# The first parameter is a structure, the second is a path (a list containing all the keys, needed to reach the destination).
# The last parameter is an item to look for. This function will try to follow the path into the given object and then look there for this key.
# As long as the nested object doesn't have the given key, it will descent into the next higher object till it finds the given key.
#
# Example:
#
# res = look_through({
# 'la1': {
# 'lb1': {
# 'lc1': 99,
# 'lc2': { 'ld1': 11 }
# 'lc2': 200
# },
# 'nice': 100
# },
# 'nice': 300
# }, ['la1', 'lb1', 'lc2'], 'nice')
#
# print(res) # Prints 100 .
#
# In this case the function looked inside obj['la1']['lb1']['lc2']['nice'], then obj['la1']['lb1']['nice'] and found the value
# in obj['la1']['nice']. As soon as it finds a value it returns it and stops looking.
def look_through(obj, path, name):
cur_level = obj
path = path[:]
for i, p in enumerate(path):
cur_level = cur_level[p]
path[i] = cur_level
path = [ obj ] + path
while len(path) > 0:
if name in path[-1]:
return path[-1][name]
else:
path.pop()
return None
# Use the above function to resolve all DelayedRef() inside a list or dict recursively.
def resolve_delayed(item, root=None, path=[]):
if root == None:
root = item
if isinstance(item, DelayedRef):
if item.dest in path:
show('WARN: Circular reference found! Field "' + path[-1] + '" references "' + item.dest + '"! (Path = ' + '/'.join([str(part) for part in path]) + ')')
return { '__ref__': item.dest }
else:
return look_through(root, path[:-1], item.dest)
elif isinstance(item, dict):
for name, val in item.items():
item[name] = resolve_delayed(val, root, path + [ name ])
elif isinstance(item, list):
for i, val in enumerate(item):
item[i] = resolve_delayed(val, root, path + [ i ])
return item
def parse_header(path, cpp_opts):
show('Parsing header "' + path + '"...')
# Use clang -E as the preprocessor for pycparser.
ast = pycparser.parse_file(path, True, cpp_path=shared.CLANG_CC, cpp_args=['-E'] + cpp_opts)
# Walk the parsed AST and filter out all the declared structs and their fields.
walker = FieldVisitor()
walker.visit(ast)
walker.structs = resolve_delayed(walker.structs)
with open(path, 'r') as stream:
defines = re.findall(r'(?:^|\n)\s*#define\s+([A-Z|_|0-9]+)\s.*', stream.read())
return {
'file': path,
'defines': defines,
'structs': walker.structs
}
# The following three functions generate C code. The output of the compiled code will be
# parsed later on and then put back together into a dict structure by parse_c_output().
#
# Example:
# c_descent('test1', code)
# c_set('item', 'i%i', '111', code)
# c_set('item2', 'i%i', '9', code)
# c_set('item3', 's%s', '"Hello"', code)
# c_ascent(code)
# c_set('outer', 'f%f', '0.999', code)
#
# Will result in:
# {
# 'test1': {
# 'item': 111,
# 'item2': 9,
# 'item3': 'Hello',
# },
# 'outer': 0.999
# }
def c_set(name, type_, value, code):
code.append('printf("K' + name + '\\n");')
code.append('printf("V' + type_ + '\\n", ' + value + ');')
def c_descent(name, code):
code.append('printf("D' + name + '\\n");')
def c_ascent(code):
code.append('printf("A\\n");')
def parse_c_output(lines):
result = {}
cur_level = result
parent = []
key = None
for line in lines:
arg = line[1:].strip()
if line[0] == 'K':
# This is a key
key = arg
elif line[0] == 'V':
# A value
if arg[0] == 'i':
arg = int(arg[1:])
elif arg[0] == 'f':
arg = float(arg[1:])
elif arg[0] == 's':
arg = arg[1:]
cur_level[key] = arg
elif line[0] == 'D':
# Remember the current level as the last parent.
parent.append(cur_level)
# We descend one level.
cur_level[arg] = {}
cur_level = cur_level[arg]
elif line[0] == 'A':
# We return to the parent dict. (One level up.)
cur_level = parent.pop()
return result
def gen_inspect_code(path, struct, code):
if path[0][-1] == '#':
path[0] = path[0][:-1]
prefix = ''
else:
prefix = 'struct '
c_descent(path[-1], code)
if len(path) == 1:
c_set('__size__', 'i%u', 'sizeof (' + prefix + path[0] + ')', code)
else:
c_set('__size__', 'i%u', 'sizeof ((' + prefix + path[0] + ' *)0)->' + '.'.join(path[1:]), code)
#c_set('__offset__', 'i%u', 'offsetof(' + prefix + path[0] + ', ' + '.'.join(path[1:]) + ')', code)
for field in struct:
if isinstance(field, dict):
# We have to recurse to inspect the nested dict.
fname = field.keys()[0]
gen_inspect_code(path + [fname], field[fname], code)
else:
c_set(field, 'i%u', 'offsetof(' + prefix + path[0] + ', ' + '.'.join(path[1:] + [field]) + ')', code)
c_ascent(code)
def inspect_code(headers, cpp_opts, structs, defines):
show('Generating C code...')
code = ['#include <stdio.h>', '#include <stddef.h>']
# Include all the needed headers.
for path in headers:
code.append('#include "' + path + '"')
code.append('int main() {')
c_descent('structs', code)
for name, struct in structs.items():
gen_inspect_code([name], struct, code)
c_ascent(code)
c_descent('defines', code)
for name, type_ in defines.items():
# Add the necessary python type, if missing.
if '%' not in type_:
if type_[-1] in ('d', 'i', 'u'):
# integer
type_ = 'i%' + type_
elif type_[-1] in ('f', 'F', 'e', 'E', 'g', 'G'):
# float
type_ = 'f%' + type_
elif type_[-1] in ('x', 'X', 'a', 'A', 'c', 's'):
# hexadecimal or string
type_ = 's%' + type_
c_set(name, type_, name, code)
code.append('return 0;')
code.append('}')
# Write the source code to a temporary file.
src_file = tempfile.mkstemp('.c')
bin_file = tempfile.mkstemp('.ll')
os.write(src_file[0], '\n'.join(code))
# Close all unneeded FDs.
os.close(src_file[0])
os.close(bin_file[0])
# NOTE: We can't generate an executable in the next step because it won't run on the current system without changing the target.
# If we change the target, some type sizes will change resulting in wrong data. As a workaround, we will be generating bitcode and
# run that with the LLVM interpreter. That way we can use the default target and still run the code.
info = []
try:
# Compile the program.
show('Compiling generated code...')
subprocess.check_call([shared.CLANG_CC, '-emit-llvm', '-S'] + cpp_opts + ['-o', bin_file[1], src_file[1]])
# Run the compiled program.
show('Calling generated program...')
info = subprocess.check_output([shared.LLVM_INTERPRETER, bin_file[1]]).splitlines()
except subprocess.CalledProcessError:
if os.path.isfile(bin_file[1]):
sys.stderr.write('FAIL: Running the generated program failed!\n')
else:
sys.stderr.write('FAIL: Compilation failed!\n')
sys.exit(1)
finally:
# Remove all temporary files.
os.unlink(src_file[1])
if os.path.exists(bin_file[1]):
os.unlink(bin_file[1])
# Parse the output of the program into a dict.
return parse_c_output(info)
def parse_json(path, header_files, structs, defines):
with open(path, 'r') as stream:
# Remove comments before loading the JSON.
data = json.loads(re.sub(r'//.*\n', '', stream.read()))
if not isinstance(data, list):
data = [ data ]
for item in data:
header_files.append(item['file'])
for name, data in item['structs'].items():
if name in structs:
show('WARN: Description of struct "' + name + '" in file "' + item['file'] + '" replaces an existing description!')
structs[name] = data
for part in item['defines']:
if not isinstance(part, list):
# If no type is specified, assume integer.
part = ['i', part]
if part[1] in defines:
show('WARN: Description of define "' + part[1] + '" in file "' + item['file'] + '" replaces an existing description!')
defines[part[1]] = part[0]
def output_json(obj, compressed=True, stream=None):
if stream == None:
stream = sys.stdout
elif isinstance(stream, str):
stream = open(stream, 'w')
if compressed:
json.dump(obj, stream, separators=(',', ':'))
else:
json.dump(obj, stream, indent=4, sort_keys=True)
stream.close()
def filter_opts(opts):
# Only apply compiler options regarding syntax, includes and defines.
# We have to compile for the current system, we aren't compiling to bitcode after all.
out = []
for flag in opts:
if flag[:2] in ('-f', '-I', '-i', '-D', '-U'):
out.append(flag)
return out
def main(args):
global QUIET
parser = argparse.ArgumentParser(description='Generate JSON infos for structs.')
parser.add_argument('headers', nargs='+', help='A header (.h) file or a JSON file with a list of structs and their fields')
parser.add_argument('-q', dest='quiet', action='store_true', default=False, help='Don\'t output anything besides error messages.')
parser.add_argument('-f', dest='list_fields', action='store_true', default=False, help='Output a list of structs and fields for the given headers.')
parser.add_argument('-p', dest='pretty_print', action='store_true', default=False, help='Pretty print the outputted JSON.')
parser.add_argument('-o', dest='output', metavar='path', default=None, help='Path to the JSON file that will be written. If omitted, the generated data will be printed to stdout.')
parser.add_argument('-I', dest='includes', metavar='dir', action='append', default=[], help='Add directory to include search path')
parser.add_argument('-D', dest='defines', metavar='define', action='append', default=[], help='Pass a define to the preprocessor')
parser.add_argument('-U', dest='undefines', metavar='undefine', action='append', default=[], help='Pass an undefine to the preprocessor')
args = parser.parse_args(args)
QUIET = args.quiet
# Avoid parsing problems due to gcc specifc syntax.
cpp_opts = ['-D_GNU_SOURCE'] + shared.COMPILER_OPTS
# Add the user options to the list as well.
for path in args.includes:
cpp_opts.append('-I' + path)
for arg in args.defines:
cpp_opts.append('-D' + arg)
for arg in args.undefines:
cpp_opts.append('-U' + arg)
if args.list_fields:
# Just parse the given headers and output the result.
data = []
for path in args.headers:
if path[-5:] == '.json':
show('WARN: Skipping "' + path + '" because it\'s already a JSON file!')
else:
data.append(parse_header(path, cpp_opts))
output_json(data, not args.pretty_print, args.output)
sys.exit(0)
# Look for structs in all passed headers.
header_files = []
structs = {}
defines = {}
for header in args.headers:
if header[-5:] == '.json':
# This is a JSON file, parse it.
parse_json(header, header_files, structs, defines)
else:
# If the passed file isn't a JSON file, assume it's a header.
header_files.append(header)
data = parse_header(header, cpp_opts)
structs.update(data['structs'])
defines.extend(data['defines'])
# Inspect all collected structs.
struct_info = inspect_code(header_files, cpp_opts, structs, defines)
output_json(struct_info, not args.pretty_print, args.output)
if __name__ == '__main__':
main(sys.argv[1:])
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