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Chapter 48. System V Shared Memory > Example: Transferring Data via Shared Memo...
48.4. Example: Transferring Data via Shared Memory
We now look at an example application that uses System V shared memory and semaphores. The application consists of two programs: the writer and the reader. The writer reads blocks of data from standard input and copies (“writes”) them into a shared memory segment. The reader copies (“reads”) blocks of data from the shared memory segment to standard output. In effect, the programs treat the shared memory somewhat like a pipe.
The two programs employ a pair of System V semaphores in a binary semaphore protocol (the initSemAvailable(), initSemInUse(), reserveSem(), and releaseSem() functions defined in Section 47.9) to ensure that:
