def _delete_bytes_no_mmap(fobj, size, offset, BUFFER_SIZE=2**16):
"""Delete size bytes of empty space starting at offset.
fobj must be an open file object, open rb+ or
equivalent. Mutagen tries to use mmap to resize the file, but
falls back to a significantly slower method if mmap fails.
"""
locked = False
assert 0 < size
assert 0 <= offset
fobj.seek(0, 2)
filesize = fobj.tell()
movesize = filesize - offset - size
assert 0 <= movesize
try:
if movesize > 0:
fobj.flush()
locked = _util.lock(fobj)
fobj.seek(offset + size)
buf = fobj.read(BUFFER_SIZE)
while buf:
fobj.seek(offset)
fobj.write(buf)
offset += len(buf)
fobj.seek(offset + size)
buf = fobj.read(BUFFER_SIZE)
fobj.truncate(filesize - size)
fobj.flush()
finally:
if locked:
_util.unlock(fobj)
def _delete_bytes_no_mmap(fobj, size, offset, BUFFER_SIZE=2**16):
"""Delete size bytes of empty space starting at offset.
fobj must be an open file object, open rb+ or
equivalent. Mutagen tries to use mmap to resize the file, but
falls back to a significantly slower method if mmap fails.
"""
locked = False
assert 0 < size
assert 0 <= offset
fobj.seek(0, 2)
filesize = fobj.tell()
movesize = filesize - offset - size
assert 0 <= movesize
try:
if movesize > 0:
fobj.flush()
locked = _util.lock(fobj)
fobj.seek(offset + size)
buf = fobj.read(BUFFER_SIZE)
while buf:
fobj.seek(offset)
fobj.write(buf)
offset += len(buf)
fobj.seek(offset + size)
buf = fobj.read(BUFFER_SIZE)
fobj.truncate(filesize - size)
fobj.flush()
finally:
if locked:
_util.unlock(fobj)
def _insert_bytes_no_mmap(fobj, size, offset, BUFFER_SIZE=2**16):
"""Insert size bytes of empty space starting at offset.
fobj must be an open file object, open rb+ or
equivalent. Mutagen tries to use mmap to resize the file, but
falls back to a significantly slower method if mmap fails.
"""
assert 0 < size
assert 0 <= offset
locked = False
fobj.seek(0, 2)
filesize = fobj.tell()
movesize = filesize - offset
fobj.write('\x00' * size)
fobj.flush()
try:
locked = _util.lock(fobj)
fobj.truncate(filesize)
fobj.seek(0, 2)
padsize = size
# Don't generate an enormous string if we need to pad
# the file out several megs.
while padsize:
addsize = min(BUFFER_SIZE, padsize)
fobj.write("\x00" * addsize)
padsize -= addsize
fobj.seek(filesize, 0)
while movesize:
# At the start of this loop, fobj is pointing at the end
# of the data we need to move, which is of movesize length.
thismove = min(BUFFER_SIZE, movesize)
# Seek back however much we're going to read this frame.
fobj.seek(-thismove, 1)
nextpos = fobj.tell()
# Read it, so we're back at the end.
data = fobj.read(thismove)
# Seek back to where we need to write it.
fobj.seek(-thismove + size, 1)
# Write it.
fobj.write(data)
# And seek back to the end of the unmoved data.
fobj.seek(nextpos)
movesize -= thismove
fobj.flush()
finally:
if locked:
_util.unlock(fobj)
def _insert_bytes_no_mmap(fobj, size, offset, BUFFER_SIZE=2**16):
"""Insert size bytes of empty space starting at offset.
fobj must be an open file object, open rb+ or
equivalent. Mutagen tries to use mmap to resize the file, but
falls back to a significantly slower method if mmap fails.
"""
assert 0 < size
assert 0 <= offset
locked = False
fobj.seek(0, 2)
filesize = fobj.tell()
movesize = filesize - offset
fobj.write('\x00' * size)
fobj.flush()
try:
locked = _util.lock(fobj)
fobj.truncate(filesize)
fobj.seek(0, 2)
padsize = size
# Don't generate an enormous string if we need to pad
# the file out several megs.
while padsize:
addsize = min(BUFFER_SIZE, padsize)
fobj.write("\x00" * addsize)
padsize -= addsize
fobj.seek(filesize, 0)
while movesize:
# At the start of this loop, fobj is pointing at the end
# of the data we need to move, which is of movesize length.
thismove = min(BUFFER_SIZE, movesize)
# Seek back however much we're going to read this frame.
fobj.seek(-thismove, 1)
nextpos = fobj.tell()
# Read it, so we're back at the end.
data = fobj.read(thismove)
# Seek back to where we need to write it.
fobj.seek(-thismove + size, 1)
# Write it.
fobj.write(data)
# And seek back to the end of the unmoved data.
fobj.seek(nextpos)
movesize -= thismove
fobj.flush()
finally:
if locked:
_util.unlock(fobj)
