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extmod/vfs_fat_file: Implement SEEK_CUR for non-zero offset. 

CPython doesn't allow SEEK_CUR with non-zero offset for files in text mode,
and uPy inherited this behaviour for both text and binary files.  It makes
sense to provide full support for SEEK_CUR of binary-mode files in uPy, and
to do this in a minimal way means also allowing to use SEEK_CUR with
non-zero offsets on text-mode files.  That seems to be a fair compromise.
This commit is contained in:
Ayke van Laethem 2017-12-19 23:47:07 +01:00 committed by Jeff Epler
parent 9ab39eb2d2
commit fa55b15ac6
3 changed files with 4 additions and 10 deletions
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6
extmod/vfs_fat_file.c
View File

@ -125,11 +125,7 @@ STATIC mp_uint_t file_obj_ioctl(mp_obj_t o_in, mp_uint_t request, uintptr_t arg,
break;
case 1: // SEEK_CUR
if (s->offset != 0) {
*errcode = MP_EOPNOTSUPP;
return MP_STREAM_ERROR;
}
// no-operation
f_lseek(&self->fp, f_tell(&self->fp) + s->offset);
break;
case 2: // SEEK_END

6
tests/extmod/vfs_fat_fileio1.py
View File

@ -91,10 +91,8 @@ with open("foo_file.txt") as f2:
f2.seek(0, 1) # SEEK_CUR
print(f2.read(1))
try:
f2.seek(1, 1) # SEEK_END
except OSError as e:
print(e.args[0] == uerrno.EOPNOTSUPP)
f2.seek(2, 1) # SEEK_CUR
print(f2.read(1))
f2.seek(-2, 2) # SEEK_END
print(f2.read(1))

2
tests/extmod/vfs_fat_fileio1.py.exp
View File

@ -7,7 +7,7 @@ hello!world!
12
h
e
True
o
d
True
[('foo_dir', 16384, 0)]