1#===- gen-msvc-exports.py - Generate C API export file -------*- python -*--===#
2#
3# Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4# See https://llvm.org/LICENSE.txt for license information.
5# SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6#
7#===------------------------------------------------------------------------===#
8#
9# Generate an export file from a list of given LIB files. This only exports symbols
10# that start with LLVM, so it only exports the LLVM C API.
11#
12# To have CMake run this, set LLVM_BUILD_LLVM_C_DYLIB to on while
13# building on Windows.
14#
15# To run manually, build LLVM with Visual Studio, use a Command prompt
16# to navigate to the directory with the .lib files (Debug\lib etc). Then run
17#     python C:\Path\To\gen-msvc-exports.py --nm ..\bin\llvm-nm.exe LLVM*.lib
18#
19# If you're generating a 32 bit DLL, use the `--underscore` flag.
20# If you want to use a different `llvm-nm` executable, pass the path
21# with the `--nm` flag.
22#
23# You can use the --output flag to set the name of the export file.
24#
25#===------------------------------------------------------------------------===#
26from tempfile import mkstemp
27from contextlib import contextmanager
28from subprocess import check_call
29import argparse
30import os
31import re
32
33
34_UNDERSCORE_REGEX = {
35    False: re.compile(r"^\w+\s+T\s+(LLVM.*)$"),
36    True:  re.compile(r"^\w+\s+T\s+_(LLVM.*)$")
37}
38
39
40@contextmanager
41def removing(path):
42    try:
43        yield path
44    finally:
45        os.unlink(path)
46
47
48def touch_tempfile(*args, **kwargs):
49    fd, name = mkstemp(*args, **kwargs)
50    os.close(fd)
51    return name
52
53
54def gen_llvm_c_export(output, underscore, libs, nm):
55    """Generate the export file for the LLVM-C DLL.
56
57    Run `nm` for each lib in `libs`, and output an export file
58    to `output`. If `underscore` is true, symbols will
59    be assumed to be prefixed with an underscore.
60    """
61    with removing(touch_tempfile(prefix='dumpout', suffix='.txt')) as dumpout:
62
63        # Get the right regex.
64        p = _UNDERSCORE_REGEX[underscore]
65
66        with open(output, 'w+t') as output_f:
67
68            # For each lib get the LLVM* functions it exports.
69            for lib in libs:
70                # Call dumpbin.
71                with open(dumpout, 'w+t') as dumpout_f:
72                    check_call([nm, '-g', lib], stdout=dumpout_f)
73
74                # Get the matching lines.
75                with open(dumpout) as dumpbin:
76                    for line in dumpbin:
77                        m = p.match(line)
78                        if m is not None:
79                            output_f.write(m.group(1) + '\n')
80
81
82def main():
83    parser = argparse.ArgumentParser('gen-msvc-exports')
84
85    parser.add_argument(
86        '-i', '--libsfile', help='file with list of libs, new line separated',
87        action='store', default=None
88    )
89    parser.add_argument(
90        '-o', '--output', help='output filename', default='LLVM-C.exports'
91    )
92    parser.add_argument('-u', '--underscore',
93        help='labels are prefixed with an underscore (use for 32 bit DLLs)',
94        action='store_true'
95    )
96    parser.add_argument(
97        '--nm', help='path to the llvm-nm executable', default='llvm-nm'
98    )
99    parser.add_argument(
100        'libs', metavar='LIBS', nargs='*', help='list of libraries to generate export from'
101    )
102
103    ns = parser.parse_args()
104
105    libs = ns.libs
106
107    # Add if we where given a libsfile add it to the libs.
108    if ns.libsfile:
109        with open(ns.libsfile) as f:
110            libs.extend(f.read().splitlines())
111
112    gen_llvm_c_export(ns.output, ns.underscore, libs, ns.nm)
113
114
115if __name__ == '__main__':
116    main()
117