aboutsummaryrefslogtreecommitdiff
path: root/svg-flatten/svg_flatten_wasi/__init__.py
blob: 85d5657cc4c59db59214d35a5b11d6531375fbd0 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
import os
import sys
import subprocess
import tempfile
import wasmtime
import platform
import click
from pathlib import Path
import hashlib
import lzma
import appdirs
from importlib import resources as importlib_resources
try:
    importlib_resources.files # py3.9+ stdlib
except AttributeError:
    import importlib_resources # py3.8- shim


# ==============================
# Note on wasmtime path handling
# ==============================
#
# Hack: Right now, wasmtime's preopen_dir / --map functionality is completely borked. AFAICT only the first mapping is
# even considered, and preopening both / and . simply does not work: Either all paths open'ed by the executable must be
# absolute, or all paths must be relative. I spent some hours trying to track down where exactly this borkage originates
# from, but I found the code confusing and did not succeed.
# 
# FOR NOW we work around this issue the dumb way: We simply have click parse enough of the command line to transform any
# paths given on the command line to absolute paths. The actual path resolution is done by click because of
# resolve_path=True.
# 


def _run_wasm_app(wasm_filename, argv, cachedir="svg-flatten-wasi"):

    module_binary = importlib_resources.read_binary(__package__, wasm_filename)

    module_path_digest = hashlib.sha256(__file__.encode()).hexdigest()
    module_digest = hashlib.sha256(module_binary).hexdigest()
    cache_path = Path(os.getenv("SVG_FLATTEN_WASI_CACHE_DIR", appdirs.user_cache_dir(cachedir)))
    cache_path.mkdir(parents=True, exist_ok=True)
    cache_filename = (cache_path / f'{wasm_filename}-{module_path_digest[:8]}-{module_digest[:16]}')
    
    wasi_cfg = wasmtime.WasiConfig()
    wasi_cfg.argv = argv
    wasi_cfg.preopen_dir('/', '/')
    wasi_cfg.inherit_stdin()
    wasi_cfg.inherit_stdout()
    wasi_cfg.inherit_stderr()
    engine = wasmtime.Engine()

    import time
    try:
        with cache_filename.open("rb") as cache_file:
            module = wasmtime.Module.deserialize(engine, lzma.decompress(cache_file.read()))
    except:
        print("Preparing to run {}. This might take a while...".format(argv[0]), file=sys.stderr)
        module = wasmtime.Module(engine, module_binary)
        with cache_filename.open("wb") as cache_file:
            cache_file.write(lzma.compress(module.serialize(), preset=0))

    linker = wasmtime.Linker(engine)
    linker.define_wasi()
    store = wasmtime.Store(engine)
    store.set_wasi(wasi_cfg)
    app = linker.instantiate(store, module)
    linker.define_instance(store, "app", app)

    try:
        app.exports(store)["_start"](store)
        return 0
    except wasmtime.ExitTrap as trap:
        return trap.code


def run_usvg(input_file, output_file, **usvg_args):

    args = []
    for key, value in usvg_args.items():
        if value is not None:
            if value is False:
                continue

            args.append(f'--{key.replace("_", "-")[5:]}')

            if value is not True:
                args.append(value)

    args += [input_file, output_file]
    print(args)

    # By default, try a number of options:
    candidates = [
        # somewhere in $PATH
        'usvg',
        'wasi-usvg',
        # in user-local cargo installation
        Path.home() / '.cargo' / 'bin' / 'usvg',
        # wasi-usvg in user-local pip installation
        Path.home() / '.local' / 'bin' / 'wasi-usvg',
        # next to our current python interpreter (e.g. in virtualenv)
        str(Path(sys.executable).parent / 'wasi-usvg')
        ]

    # if USVG envvar is set, try that first.
    if 'USVG' in os.environ:
        candidates = [os.environ['USVG'], *candidates]

    for candidate in candidates:
        try:
            res = subprocess.run([candidate, *args], check=True)
            print('used usvg:', candidate)
            break
        except FileNotFoundError:
            continue
    else:
        raise SystemError('usvg executable not found')


@click.command(context_settings={'ignore_unknown_options': True})
@click.option('--no-usvg', is_flag=True)
# Options forwarded to USVG
@click.option('--usvg-dpi')
@click.option('--usvg-font-family')
@click.option('--usvg-font-size')
@click.option('--usvg-serif-family')
@click.option('--usvg-sans-serif-family')
@click.option('--usvg-cursive-family')
@click.option('--usvg-fantasy-family')
@click.option('--usvg-monospace-family')
@click.option('--usvg-use-font-file')
@click.option('--usvg-use-fonts-dir')
@click.option('--usvg-skip-system-fonts', is_flag=True)
# Catch-all argument to forward options to svg-flatten
@click.argument('other_args', nargs=-1, type=click.UNPROCESSED)
# Input/output file
@click.argument('input_file',  type=click.Path(resolve_path=True, dir_okay=False))
@click.argument('output_file', type=click.Path(resolve_path=True, dir_okay=False, writable=True))
def run_svg_flatten(input_file, output_file, other_args, no_usvg, **usvg_args):

    with tempfile.NamedTemporaryFile() as f:
        if not no_usvg:
            run_usvg(input_file, f.name, **usvg_args)
            input_file = f.name

        cmdline = ['svg-flatten', '--force-svg', '--no-usvg', *other_args, input_file, output_file]
        exit_code = _run_wasm_app("svg-flatten.wasm", cmdline)
        if exit_code:
            exc = click.ClickException(f'Process returned exit code {exit_code}')
            exc.exit_code = exit_code
            raise exc