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Fix read_at() in SEFS if offset beyond the end of the file

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LI Qing 2020-02-13 04:02:43 +00:00
parent bd56504b20
commit 76b90efa8f
1 changed files with 10 additions and 2 deletions
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12
src/libos/src/fs/sefs/sgx_storage.rs
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@ -172,6 +172,14 @@ impl File for LockedFile {
return Ok(0); return Ok(0);
} }
let mut file = self.0.lock().unwrap(); let mut file = self.0.lock().unwrap();
// SgxFile does not support to seek a position beyond the end.
// So check if file_size < offset and return zero(indicates end of file).
let file_size = file.seek(SeekFrom::End(0)).expect("failed to tell SgxFile") as usize;
if file_size < offset {
return Ok(0);
}
let offset = offset as u64; let offset = offset as u64;
file.seek(SeekFrom::Start(offset)) file.seek(SeekFrom::Start(offset))
.expect("failed to seek SgxFile"); .expect("failed to seek SgxFile");
@ -185,8 +193,8 @@ impl File for LockedFile {
} }
let mut file = self.0.lock().unwrap(); let mut file = self.0.lock().unwrap();
// SgxFile do not support seek a position after the end. // SgxFile does not support to seek a position beyond the end.
// So check the size and padding zeros if necessary. // So check if file_size < offset and padding null bytes.
let file_size = file.seek(SeekFrom::End(0)).expect("failed to tell SgxFile") as usize; let file_size = file.seek(SeekFrom::End(0)).expect("failed to tell SgxFile") as usize;
if file_size < offset { if file_size < offset {
static ZEROS: [u8; 0x1000] = [0; 0x1000]; static ZEROS: [u8; 0x1000] = [0; 0x1000];