def run(input_file, output_file, dpi, mode_args):
args_unpaper = ['unpaper', '-v', '--dpi', str(round(dpi, 6))] + mode_args
with TemporaryDirectory() as tmpdir:
input_pnm, output_pnm = _setup_unpaper_io(Path(tmpdir), input_file)
# To prevent any shenanigans from accepting arbitrary parameters in
# --unpaper-args, we:
# 1) run with cwd set to a tmpdir with only unpaper's files
# 2) forbid the use of '/' in arguments, to prevent changing paths
# 3) append absolute paths for the input and output file
# This should ensure that a user cannot clobber some other file with
# their unpaper arguments (whether intentionally or otherwise)
args_unpaper.extend([os.fspath(input_pnm), os.fspath(output_pnm)])
external_run(
args_unpaper,
close_fds=True,
check=True,
stderr=STDOUT, # unpaper writes logging output to stdout and stderr
stdout=PIPE, # and cannot send file output to stdout
cwd=tmpdir,
logs_errors_to_stdout=True,
)
try:
with Image.open(output_pnm) as imout:
imout.save(output_file, dpi=(dpi, dpi))
except (FileNotFoundError, OSError):
raise SubprocessOutputError(
"unpaper: failed to produce the expected output file. " +
" Called with: " + str(args_unpaper)) from None
def run(input_file, output_file, dpi, mode_args):
args_unpaper = ['unpaper', '-v', '--dpi', str(dpi)] + mode_args
SUFFIXES = {'1': '.pbm', 'L': '.pgm', 'RGB': '.ppm'}
with TemporaryDirectory() as tmpdir, Image.open(input_file) as im:
if im.mode not in SUFFIXES.keys():
log.info("Converting image to other colorspace")
try:
if im.mode == 'P' and len(im.getcolors()) == 2:
im = im.convert(mode='1')
else:
im = im.convert(mode='RGB')
except IOError as e:
im.close()
raise MissingDependencyError(
"Could not convert image with type " + im.mode) from e
try:
suffix = SUFFIXES[im.mode]
except KeyError:
raise MissingDependencyError(
"Failed to convert image to a supported format.") from e
input_pnm = Path(tmpdir) / f'input{suffix}'
output_pnm = Path(tmpdir) / f'output{suffix}'
im.save(input_pnm, format='PPM')
# To prevent any shenanigans from accepting arbitrary parameters in
# --unpaper-args, we:
# 1) run with cwd set to a tmpdir with only unpaper's files
# 2) forbid the use of '/' in arguments, to prevent changing paths
# 3) append absolute paths for the input and output file
# This should ensure that a user cannot clobber some other file with
# their unpaper arguments (whether intentionally or otherwise)
args_unpaper.extend([os.fspath(input_pnm), os.fspath(output_pnm)])
try:
proc = external_run(
args_unpaper,
check=True,
close_fds=True,
universal_newlines=True,
stderr=STDOUT,
cwd=tmpdir,
stdout=PIPE,
)
except CalledProcessError as e:
log.debug(e.output)
raise e from e
else:
log.debug(proc.stdout)
# unpaper sets dpi to 72; fix this
try:
with Image.open(output_pnm) as imout:
imout.save(output_file, dpi=(dpi, dpi))
except (FileNotFoundError, OSError):
raise SubprocessOutputError(
"unpaper: failed to produce the expected output file. " +
" Called with: " + str(args_unpaper)) from None