我正在编写一个NFS V4客户端，并使用Wireshark调试结果。我无法读取文件。
通过OPEN和GETATTR，我打开了文件，并通过匹配的长度(1001字节(确认它是所需的文件。
然后，我尝试READ文件中偏移量为0、长度为1的单个字节。即使EOF为false，得到的回复也会返回0字节的数据。重复调用read命令会产生相同的结果。
打开或读取中是否有我实际读取文件时缺少的参数？
Wireshark输出
Open Call
Operations (count: 5): SEQUENCE, PUTROOTFH, OPEN, GETFH, GETATTR
Opcode: SEQUENCE (53)
Opcode: PUTROOTFH (24)
Opcode: OPEN (18)
seqid: 0x00000000
share_access: OPEN4_SHARE_ACCESS_READ (1)
share_deny: OPEN4_SHARE_DENY_NONE (0)
clientid: 0x13f5c375a578cd7c
owner: <DATA>
Open Type: OPEN4_NOCREATE (0)
Claim Type: CLAIM_NULL (0)
Opcode: GETFH (10)
Opcode: GETATTR (9)
打开回复
Operations (count: 5)
Opcode: SEQUENCE (53)
Opcode: PUTROOTFH (24)
Opcode: OPEN (18)
Status: NFS4_OK (0)
StateID
[StateID Hash: 0x91a9]
StateID seqid: 1
StateID Other: 13f5c375a578cd7c00000000
[StateID Other hash: 0x5b73]
change_info
Atomic: Yes
changeid (before): 110
changeid (after): 110
result flags: 0x00000004, locktype posix
.... .... .... .... .... .... .... ..0. = confirm: False
.... .... .... .... .... .... .... .1.. = locktype posix: True
.... .... .... .... .... .... .... 0... = preserve unlinked: False
.... .... .... .... .... .... ..0. .... = may notify lock: False
Delegation Type: OPEN_DELEGATE_NONE (0)
Opcode: GETFH (10)
Status: NFS4_OK (0)
Filehandle
length: 128
[hash (CRC-32): 0xc5dcd623]
FileHandle: 2b3e5cee938ee2b6afff448601a384b8ffc30bab28b5e2a4...
Opcode: GETATTR (9)
Status: NFS4_OK (0)
Attr mask: 0x00000010 (Size)
reqd_attr: Size (4)
size: 1001
读取呼叫
Operations (count: 3): SEQUENCE, PUTFH, READ
Opcode: SEQUENCE (53)
Opcode: PUTFH (22)
FileHandle
length: 128
[hash (CRC-32): 0xc5dcd623]
FileHandle: 2b3e5cee938ee2b6afff448601a384b8ffc30bab28b5e2a4...
Opcode: READ (25)
StateID
[StateID Hash: 0x91a9]
StateID seqid: 1
StateID Other: 13f5c375a578cd7c00000000
[StateID Other hash: 0x5b73]
offset: 0
count: 1
读取回复
Operations (count: 3)
Opcode: SEQUENCE (53)
Opcode: PUTFH (22)
Status: NFS4_OK (0)
Opcode: READ (25)
Status: NFS4_OK (0)
eof: 0
Read length: 0
Data: <EMPTY>
对于遇到类似情况的人，我可以通过将READ调用的SEQUENCE操作中的cachethis标志从true更改为false来解决问题。
struct SEQUENCE4args {
sessionid4 sa_sessionid;
sequenceid4 sa_sequenceid;
slotid4 sa_slotid;
slotid4 sa_highest_slotid;
bool sa_cachethis; // ensure this is false
};
cachethis标志的一些行为在RFC 5661中有描述，但该信息不包括发生这种行为的原因。
一种可能性是，Amazon对NFS规范的实现在sa_cachethis的行为中存在错误。