From 5d6ed5e5437304eb81eb6a4c435322636f53ea96 Mon Sep 17 00:00:00 2001
From: Guo Wenxue <guowenxue@gmail.com>
Date: Sat, 10 Nov 2018 13:58:33 +0800
Subject: [PATCH] Update fork_var.c source code
---
ch3_fork/fork_var.c | 111 ++++++++++---------------------------------------------
1 files changed, 21 insertions(+), 90 deletions(-)
diff --git a/ch3_fork/fork_var.c b/ch3_fork/fork_var.c
index 1489039..0fddba7 100644
--- a/ch3_fork/fork_var.c
+++ b/ch3_fork/fork_var.c
@@ -1,109 +1,40 @@
#include <stdio.h>
+#include <errno.h>
#include <unistd.h>
#include <string.h>
-#include <errno.h>
-#include <sys/types.h>
-#include <sys/stat.h>
-#include <fcntl.h>
-#include <ctype.h>
-#define TMP_FILE "/tmp/.ifconfig.log"
-
-int main(int argc, char **argv)
+int g_var = 6;
+char g_buf[]="A string write to stdout.\n";
+int main (int argc, char **argv)
{
- pid_t pid;
- int fd;
- char buf[1024];
- int rv;
- char *ptr;
- FILE *fp;
- char *ip_start;
- char *ip_end;
- char ipaddr[16];
+ int var = 88;
+ pid_t pid;
- if( (fd=open(TMP_FILE, O_RDWR|O_CREAT|O_TRUNC, 0644)) < 0 )
+ if( write(STDOUT_FILENO, g_buf, sizeof(g_buf)-1) < 0)
{
- printf("Redirect standard output to file failure: %s\n", strerror(errno));
+ printf("Write string to stdout error: %s\n", strerror(errno));
return -1;
}
- pid = fork();
- if(pid < 0)
+ printf("Befor fork\n");
+
+ if( (pid=fork()) < 0)
{
- printf("fork() create child process failure: %s\n", strerror(errno));
- return -1;
+ printf("fork() error: %s\n", strerror(errno));
+ return -2;
}
- else if( pid == 0 )
+ else if( 0 == pid)
{
- printf("Child process start excute ifconfig program\n");
- dup2(fd, STDOUT_FILENO);
- execl("/sbin/ifconfig", "ifconfig", "eth0", NULL);
- printf("Child process start excute ifconfig program over\n");
- return 0;
+ printf("Child process PID[%d] running...\n", getpid());
+ g_var ++;
+ var ++;
}
- else
+ else
{
- sleep(3);
+ printf("Parent process PID[%d] waiting...\n", getpid());
+ sleep(1);
}
- memset(buf, 0, sizeof(buf));
-
- rv=read(fd, buf, sizeof(buf));
- printf("Read %d bytes data dierectly read after child process write\n", rv);
-
- lseek(fd, 0, SEEK_SET);
- rv=read(fd, buf, sizeof(buf));
- printf("Read %d bytes data after lseek:\n %s\n ", rv, buf);
-
- fp = fdopen(fd, "r");
- fseek(fp, 0, SEEK_SET);
-
- memset(buf, 0, sizeof(buf));
-
- rv=read(fd, buf, sizeof(buf));
- printf("Read %d bytes data dierectly read after child process write\n", rv);
- printf("Read %d bytes data dierectly read after child process write\n", rv);
-
- lseek(fd, 0, SEEK_SET);
- rv=read(fd, buf, sizeof(buf));
- printf("Read %d bytes data after lseek:\n %s\n ", rv, buf);
-
- fp = fdopen(fd, "r");
- fseek(fp, 0, SEEK_SET);
-
- while( fgets(buf, sizeof(buf), fp) )
- {
- if( strstr(buf, "netmask") )
- {
- ptr=strstr(buf, "inet");
- if( !ptr )
- {
- break;
- }
- ptr += strlen("inet");
-
- while( isblank(*ptr) )
- ptr++;
-
- ip_start = ptr;
-
- while( !isblank(*ptr) )
- ptr++;
-
- ip_end = ptr;
-
- memset(ipaddr, 0, sizeof(ipaddr));
- memcpy(ipaddr, ip_start, ip_end-ip_start);
-
- break;
- }
- }
-
- printf("Parser and get IP address: %s\n", ipaddr);
-
- fclose(fp);
-
- unlink(TMP_FILE);
-
+ printf("PID=%ld, g_var=%d, var=%d\n", (long) getpid(), g_var, var);
return 0;
}
--
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