Message385692
Seeking past the end of a file with file objects does not match the same code implemented in terms of file descriptors. Is this the intended behavior?
Smallest example I could find:
f = open('new_file', 'ab')
print(f.seek(1))
print(f.write(b'foo'))
print(f.tell())
f.close()
This program outputs: 1, 3, 4 as expected, but only creates a 3-byte file:
and creates a 3-byte file:
$ hexdump -C new_file
00000000 66 6f 6f |foo|
00000003
If I use open(..., buffering=0), or flush before the tell, it outputs: 1, 3, 3.
The obvious code with file descriptors:
fd = os.open('log', os.O_WRONLY | os.O_CREAT)
print(os.lseek(fd, 1, os.SEEK_SET))
os.write(fd, b'foo')
os.close(fd)
works as expected, creating a 4-byte file.
Could this be related this issue:
https://bugs.python.org/issue36411
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Date |
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2021-01-26 05:29:12 | cotton.seed | set | recipients:
+ cotton.seed |
2021-01-26 05:29:12 | cotton.seed | set | messageid: <1611638952.77.0.560549779185.issue43028@roundup.psfhosted.org> |
2021-01-26 05:29:12 | cotton.seed | link | issue43028 messages |
2021-01-26 05:29:12 | cotton.seed | create | |
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