Windows System Programming Third Edition

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CHAPTER 3 ADVANCED FILE AND DIRECTORY PROCESSING, AND THE REGISTRY

Using File Locks

File locking examples are deferred until Chapter 6, which covers process manage-

ment. Programs 4–2, 6–4, 6–5, and 6–6 use locks to ensure that only one process

at a time can modify a file.

UNIX has advisory file locking; an attempt to obtain a lock may fail (the logic is

the same as in Table 3–1), but the process can still perform the I/O. Therefore,

UNIX can achieve locking between cooperating processes, but any other process

can violate the protocol.

To obtain an advisory lock, use options to the

function. The commands (the

second parameter) are

, (to wait),