Files
GoogleDriveManagement/src/gam/fileutils.py
2022-01-11 11:05:02 -05:00

184 lines
5.7 KiB
Python

"""Common file operations."""
import io
import os
import sys
from gam import controlflow
from gam import display
from gam.var import GM_Globals
from gam.var import GM_SYS_ENCODING
from gam.var import UTF8_SIG
def _open_file(filename, mode, encoding=None, newline=None):
"""Opens a file with no error handling."""
# Determine which encoding to use
if 'b' in mode:
encoding = None
elif not encoding:
encoding = GM_Globals[GM_SYS_ENCODING]
elif 'r' in mode and encoding.lower().replace('-', '') == 'utf8':
encoding = UTF8_SIG
return open(os.path.expanduser(filename),
mode,
newline=newline,
encoding=encoding)
def open_file(filename,
mode='r',
encoding=None,
newline=None,
strip_utf_bom=False):
"""Opens a file.
Args:
filename: String, the name of the file to open, or '-' to use stdin/stdout,
to read/write, depending on the mode param, respectively.
mode: String, the common file mode to open the file with. Default is read.
encoding: String, the name of the encoding used to decode or encode the
file. This should only be used in text mode.
newline: See param description in
https://docs.python.org/3.7/library/functions.html#open
strip_utf_bom: Boolean, True if the file being opened should seek past the
UTF Byte Order Mark before being returned.
See more: https://en.wikipedia.org/wiki/UTF-8#Byte_order_mark
Returns:
The opened file.
"""
try:
if filename == '-':
# Read from stdin, rather than a file
if 'r' in mode:
return io.StringIO(str(sys.stdin.read()))
return sys.stdout
# Open a file on disk
f = _open_file(filename, mode, newline=newline, encoding=encoding)
if strip_utf_bom:
utf_bom = '\ufeff'
has_bom = False
if 'b' in mode:
has_bom = f.read(3).decode('UTF-8') == utf_bom
elif f.encoding and not f.encoding.lower().startswith('utf'):
# Convert UTF BOM into ISO-8859-1 via Bytes
utf8_bom_bytes = utf_bom.encode('UTF-8')
iso_8859_1_bom = utf8_bom_bytes.decode('iso-8859-1').encode(
'iso-8859-1')
has_bom = f.read(3).encode('iso-8859-1',
'replace') == iso_8859_1_bom
else:
has_bom = f.read(1) == utf_bom
if not has_bom:
f.seek(0)
return f
except OSError as e:
controlflow.system_error_exit(6, e)
def close_file(f, force_flush=False):
"""Closes a file.
Args:
f: The file to close
force_flush: Flush file to disk emptying Python and OS caches. See:
https://stackoverflow.com/a/13762137/1503886
Returns:
Boolean, True if the file was successfully closed. False if an error
was encountered while closing.
"""
if force_flush:
f.flush()
os.fsync(f.fileno())
try:
f.close()
return True
except OSError as e:
display.print_error(e)
return False
def read_file(filename,
mode='r',
encoding=None,
newline=None,
continue_on_error=False,
display_errors=True):
"""Reads a file from disk.
Args:
filename: String, the path of the file to open from disk, or "-" to read
from stdin.
mode: String, the mode in which to open the file.
encoding: String, the name of the encoding used to decode or encode the
file. This should only be used in text mode.
newline: See param description in
https://docs.python.org/3.7/library/functions.html#open
continue_on_error: Boolean, If True, suppresses any IO errors and returns to
the caller without any externalities.
display_errors: Boolean, If True, prints error messages when errors are
encountered and continue_on_error is True.
Returns:
The contents of the file, or stdin if filename == "-". Returns None if
an error is encountered and continue_on_errors is True.
"""
try:
if filename == '-':
# Read from stdin, rather than a file.
return str(sys.stdin.read())
with _open_file(filename, mode, newline=newline,
encoding=encoding) as f:
return f.read()
except OSError as e:
if continue_on_error:
if display_errors:
display.print_warning(e)
return None
controlflow.system_error_exit(6, e)
except (LookupError, UnicodeDecodeError, UnicodeError) as e:
controlflow.system_error_exit(2, str(e))
def write_file(filename,
data,
mode='w',
continue_on_error=False,
display_errors=True):
"""Writes data to a file.
Args:
filename: String, the path of the file to write to disk.
data: Serializable data to write to the file.
mode: String, the mode in which to open the file and write to it.
continue_on_error: Boolean, If True, suppresses any IO errors and returns to
the caller without any externalities.
display_errors: Boolean, If True, prints error messages when errors are
encountered and continue_on_error is True.
Returns:
Boolean, True if the write operation succeeded, or False if not.
"""
try:
with _open_file(filename, mode) as f:
f.write(data)
return True
except OSError as e:
if continue_on_error:
if display_errors:
display.print_error(e)
return False
else:
controlflow.system_error_exit(6, e)