调用 LockFileEx() 时发生访问冲突
我有一个 FileMapping 类，它允许我使用 Win32 API 函数 LockFileEx()。
bool FileMapping::lockFile(bool wait) {
if (isFileLocked())
return true;
// We want an exclusive lock.
DWORD flags = LOCKFILE_EXCLUSIVE_LOCK;
// If we don't want the thread to block, we have to set the appropriate flag.
if (!wait)
flags |= LOCKFILE_FAIL_IMMEDIATELY;
m_isFileLocked = LockFileEx(m_fileDesc, flags, 0, (DWORD) m_mappingLength, (DWORD) (((uint64_t) m_mappingLength) >> 32), NULL);
return m_isFileLocked;
}
每当我进行 LockFileEx() 调用时，我都会遇到访问冲突：
tftpServer.exe 中 0x7466c2ec 处未处理的异常：0xC0000005：
访问冲突读取位置 0x00000008。
文件句柄m_fileDesc绝对是一个有效的句柄（使用该句柄将文件映射到内存中）并且m_mappingLength只是一个包含长度的size_t映射文件部分的字节数。
有人知道如何解决这个问题吗？
I have a FileMapping class that allows me to also lock a file for exclusive use by my process by using the Win32 API function LockFileEx().
bool FileMapping::lockFile(bool wait) {
if (isFileLocked())
return true;
// We want an exclusive lock.
DWORD flags = LOCKFILE_EXCLUSIVE_LOCK;
// If we don't want the thread to block, we have to set the appropriate flag.
if (!wait)
flags |= LOCKFILE_FAIL_IMMEDIATELY;
m_isFileLocked = LockFileEx(m_fileDesc, flags, 0, (DWORD) m_mappingLength, (DWORD) (((uint64_t) m_mappingLength) >> 32), NULL);
return m_isFileLocked;
}
Whenever I get to the LockFileEx() call I get an access violation:
Unhandled exception at 0x7466c2ec in tftpServer.exe: 0xC0000005:
Access violation reading location 0x00000008.
The file handle m_fileDesc is definitely a valid handle (mapping the file into memory with that handle works) and m_mappingLength is just a size_t containing the length of the mapped file portion in bytes.
Does anybody have an idea how to fix this?
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您的最后一个参数是 NULL，而它应该是指向 OVERLAPPED 结构的指针。有关读取位置 0x00000008 的错误可能对应于记录的要求：
鉴于
hEvent成员位于两个指针之后，在 32 位编译中，它将距结构开头 8 个字节。因此 LockFileEx 可能正在尝试读取 hEvent 成员，然后崩溃。Your last argument is
NULL, while it should be a pointer to aOVERLAPPEDstructure. The error about reading location 0x00000008 probably corresponds to the documented requirement that:Given the
hEventmember comes after two pointers, in 32 bit compilation it'd be 8 bytes from the beginning of the structure. SoLockFileExis probably trying to read the hEvent member, and crashes.引用您链接到的文档：
所以你最后的论点是错误的。
Quoting the docs you link to:
So your last argument is wrong.