From 9e2354ec432f40e212e8d9ac54f1efb8567aef8b Mon Sep 17 00:00:00 2001
From: Guo Wenxue <guowenxue@gmail.com>
Date: Fri, 07 Dec 2018 20:50:07 +0800
Subject: [PATCH] Add IPC semaphore sample code, not finish yet
---
ch6_ipc/semaphore.c | 60 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
1 files changed, 60 insertions(+), 0 deletions(-)
diff --git a/ch6_ipc/semaphore.c b/ch6_ipc/semaphore.c
new file mode 100644
index 0000000..5b77416
--- /dev/null
+++ b/ch6_ipc/semaphore.c
@@ -0,0 +1,60 @@
+#include <stdio.h>
+#include <string.h>
+#include <errno.h>
+#include <unistd.h>
+#include <stdlib.h>
+
+#include <sys/types.h>
+#include <sys/ipc.h>
+#include <sys/sem.h>
+
+#define FTOK_PATH "/dev/zero"
+#define FTOK_PROJID 0x666
+
+union semun
+{
+ int val;
+ struct semid_ds *buf;
+ unsigned short *arry;
+};
+
+int main(int argc, char **argv)
+{
+ int semid;
+
+ if( (semid=init_set(1)) < 0)
+ {
+
+ }
+
+}
+
+int init_set(int nums)
+{
+ key_t key;
+ int semid;
+ union semun sem_union;
+
+ if( (key=ftok(FTOK_PATH, FTOK_PROJID)) < 0 )
+ {
+ printf("ftok() get IPC token failure: %s\n", strerror(errno));
+ return -1;
+ }
+
+ semid = semget(key, nums, IPC_CREAT|IPC_EXCL|0644);
+ if( semid < 0)
+ {
+ printf("semget() get semid failure: %s\n", strerror(errno));
+ return -2;
+ }
+
+
+ sem_union.val = 1;
+ if( semctl(semid, 0, SETVAL, sem_union)<0 )
+ {
+ printf("semctl() set initial value failure: %s\n", strerror(errno));
+ return -3;
+ }
+
+ return semid;
+}
--
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