From 7856bf3569cc448fe3b360c3fca836593a0c0c7d Mon Sep 17 00:00:00 2001
From: guowenxue <guowenxue@gmail.com>
Date: Mon, 06 Nov 2023 17:01:27 +0800
Subject: [PATCH] format c source code
---
ch6_ipc/semaphore.c | 100 ++++++++++++++++++++++++++++++++++++++++++++++---
1 files changed, 93 insertions(+), 7 deletions(-)
diff --git a/ch6_ipc/semaphore.c b/ch6_ipc/semaphore.c
index 5b77416..b64987f 100644
--- a/ch6_ipc/semaphore.c
+++ b/ch6_ipc/semaphore.c
@@ -9,7 +9,7 @@
#include <sys/sem.h>
#define FTOK_PATH "/dev/zero"
-#define FTOK_PROJID 0x666
+#define FTOK_PROJID 0x22
union semun
{
@@ -18,18 +18,52 @@
unsigned short *arry;
};
+int semaphore_init(void);
+int semaphore_p(int semid);
+int semaphore_v(int semid);
+void semaphore_term(int semid);
+
int main(int argc, char **argv)
{
int semid;
+ pid_t pid;
+ int i;
- if( (semid=init_set(1)) < 0)
+ if( (semid=semaphore_init()) < 0)
{
-
+ printf("semaphore initial failure: %s\n", strerror(errno));
+ return -1;
}
+ if( (pid=fork()) < 0)
+ {
+ printf("fork() failure: %s\n", strerror(errno));
+ return -2;
+ }
+ else if( 0 == pid) /* child process */
+ {
+ printf("Child process start running and do something now...\n");
+ sleep(3);
+ printf("Child process do something over...\n");
+ semaphore_v(semid);
+
+ sleep(1);
+
+ printf("Child process exit now\n");
+ exit(0);
+ }
+
+ printf("Parent process P operator wait child process over\n");
+ semaphore_p(semid);
+ printf("Parent start do something now...\n");
+ sleep(2);
+ printf("Perent process destroy semaphore and exit\n");
+
+ semaphore_term(semid);
+ return 0;
}
-int init_set(int nums)
+int semaphore_init(void)
{
key_t key;
int semid;
@@ -41,20 +75,72 @@
return -1;
}
- semid = semget(key, nums, IPC_CREAT|IPC_EXCL|0644);
+ semid = semget(key, 1, IPC_CREAT|0644);
if( semid < 0)
{
printf("semget() get semid failure: %s\n", strerror(errno));
return -2;
}
-
- sem_union.val = 1;
+ sem_union.val = 0;
if( semctl(semid, 0, SETVAL, sem_union)<0 )
{
printf("semctl() set initial value failure: %s\n", strerror(errno));
return -3;
}
+ printf("Semaphore get key_t[0x%x] and semid[%d]\n", key, semid);
+
return semid;
}
+
+void semaphore_term(int semid)
+{
+ union semun sem_union;
+
+ if( semctl(semid, 0, IPC_RMID, sem_union)<0 )
+ {
+ printf("semctl() delete semaphore ID failure: %s\n", strerror(errno));
+ }
+
+ return ;
+}
+
+
+
+int semaphore_p(int semid)
+{
+ struct sembuf _sembuf;
+
+ _sembuf.sem_num = 0;
+ _sembuf.sem_op = -1;
+ _sembuf.sem_flg = SEM_UNDO; // IPC_NOWAIT SEM_UNDO
+
+
+ if( semop(semid, &_sembuf, 1) < 0 )
+ {
+ printf("semop P operator failure: %s\n", strerror(errno));
+ return -1;
+ }
+
+ return 0;
+}
+
+int semaphore_v(int semid)
+{
+ struct sembuf _sembuf;
+
+ _sembuf.sem_num = 0;
+ _sembuf.sem_op = 1;
+ _sembuf.sem_flg = SEM_UNDO; // IPC_NOWAIT SEM_UNDO
+
+ if( semop(semid, &_sembuf, 1) < 0 )
+ {
+ printf("semop V operator failure: %s\n", strerror(errno));
+ return -1;
+ }
+
+ return 0;
+}
+
+
--
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