From d4a286bdfd61be9381b0c5199c0a637b8372df1c Mon Sep 17 00:00:00 2001
From: Guo Wenxue <guowenxue@gmail.com>
Date: Thu, 08 Nov 2018 11:00:27 +0800
Subject: [PATCH] Add Ch3_fork sample code
---
ch3_fork/fork_exec.c | 96 ++++++++++
ch3_fork/memory_layout.c | 42 ++++
ch3_fork/socket_server.c | 162 ++++++++++++++++++
ch3_fork/popen.c | 88 +++++++++
ch3_fork/fork.c | 28 +++
ch3_fork/fork_var.c | 109 ++++++++++++
6 files changed, 525 insertions(+), 0 deletions(-)
diff --git a/ch3_fork/fork.c b/ch3_fork/fork.c
new file mode 100644
index 0000000..4dbb728
--- /dev/null
+++ b/ch3_fork/fork.c
@@ -0,0 +1,28 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+
+int main(int argc, char **argv)
+{
+ pid_t pid;
+
+ printf("Parent process PID[%d] start running...\n", getpid() );
+
+ pid = fork();
+ if(pid < 0)
+ {
+ printf("fork() create child process failure: %s\n", strerror(errno));
+ return -1;
+ }
+ else if( pid == 0 )
+ {
+ printf("Child process PID[%d] start running, my parent PID is [%d]\n", getpid(), getppid());
+ return 0;
+ }
+ else // if( pid > 0 )
+ {
+ printf("Parent process PID[%d] continue running, and child process PID is [%d]\n", getpid(), pid);
+ return 0;
+ }
+}
diff --git a/ch3_fork/fork_exec.c b/ch3_fork/fork_exec.c
new file mode 100644
index 0000000..e009f47
--- /dev/null
+++ b/ch3_fork/fork_exec.c
@@ -0,0 +1,96 @@
+#include <stdio.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)
+{
+ pid_t pid;
+ int fd;
+ char buf[1024];
+ int rv;
+ char *ptr;
+ FILE *fp;
+ char *ip_start;
+ char *ip_end;
+ char ipaddr[16];
+
+ if( (fd=open(TMP_FILE, O_RDWR|O_CREAT|O_TRUNC, 0644)) < 0 )
+ {
+ printf("Redirect standard output to file failure: %s\n", strerror(errno));
+ return -1;
+ }
+
+ pid = fork();
+ if(pid < 0)
+ {
+ printf("fork() create child process failure: %s\n", strerror(errno));
+ return -1;
+ }
+ else if( pid == 0 )
+ {
+ printf("Child process start excute ifconfig program\n");
+ dup2(fd, STDOUT_FILENO);
+ execl("/sbin/ifconfig", "ifconfig", "eth0", NULL);
+ printf("Child process excute another program, will not return here. Return here means execl() error\n");
+ return -1;
+ }
+ else
+ {
+ sleep(3);
+ }
+
+ memset(buf, 0, sizeof(buf));
+
+ rv=read(fd, buf, sizeof(buf));
+ printf("Read %d bytes data dierectly read after child process write\n", rv);
+
+ memset(buf, 0, sizeof(buf));
+ lseek(fd, 0, SEEK_SET);
+ rv=read(fd, buf, sizeof(buf));
+ printf("Read %d bytes data after lseek:\n %s", 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);
+
+ return 0;
+}
diff --git a/ch3_fork/fork_var.c b/ch3_fork/fork_var.c
new file mode 100644
index 0000000..1489039
--- /dev/null
+++ b/ch3_fork/fork_var.c
@@ -0,0 +1,109 @@
+#include <stdio.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)
+{
+ pid_t pid;
+ int fd;
+ char buf[1024];
+ int rv;
+ char *ptr;
+ FILE *fp;
+ char *ip_start;
+ char *ip_end;
+ char ipaddr[16];
+
+ if( (fd=open(TMP_FILE, O_RDWR|O_CREAT|O_TRUNC, 0644)) < 0 )
+ {
+ printf("Redirect standard output to file failure: %s\n", strerror(errno));
+ return -1;
+ }
+
+ pid = fork();
+ if(pid < 0)
+ {
+ printf("fork() create child process failure: %s\n", strerror(errno));
+ return -1;
+ }
+ else if( pid == 0 )
+ {
+ 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;
+ }
+ else
+ {
+ sleep(3);
+ }
+
+ 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);
+
+ return 0;
+}
diff --git a/ch3_fork/memory_layout.c b/ch3_fork/memory_layout.c
new file mode 100644
index 0000000..5a786cd
--- /dev/null
+++ b/ch3_fork/memory_layout.c
@@ -0,0 +1,42 @@
+#include <stdio.h>
+#include <stdlib.h>
+
+int g_var1;
+int g_var2=20;
+
+int main(int argc, char **argv)
+{
+ static int s_var1;
+ static int s_var2=10;
+
+ char *str="Hello";
+ char *ptr;
+
+ ptr = malloc(100);
+
+ printf("[cmd args]: argv address: %p\n", argv);
+ printf("\n");
+
+ printf("[ Stack]: str address: %p\n", &str);
+ printf("[ Stack]: ptr address: %p\n", &ptr);
+ printf("\n");
+
+ printf("[ Heap ]: malloc address: %p\n", ptr);
+ printf("\n");
+
+
+ printf("[ bss ]: s_var1 address: %p value: %d\n", &s_var1, g_var1);
+ printf("[ bss ]: g_var1 address: %p value: %d\n", &g_var1, g_var1);
+
+ printf("[ data ]: g_var2 address: %p value: %d\n", &g_var2, g_var2);
+ printf("[ data ]: s_var2 address: %p value: %d\n", &s_var2, s_var2);
+
+ printf("[rodata]: \"%s\" address: %p \n", str, str);
+ printf("\n");
+
+ printf("[ text ]: main() address: %p\n", main);
+ printf("\n");
+
+
+ return 0;
+}
diff --git a/ch3_fork/popen.c b/ch3_fork/popen.c
new file mode 100644
index 0000000..6a8e089
--- /dev/null
+++ b/ch3_fork/popen.c
@@ -0,0 +1,88 @@
+#include <stdio.h>
+#include <unistd.h>
+#include <string.h>
+#include <errno.h>
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <fcntl.h>
+#include <ctype.h>
+
+int get_ipaddr(char *interface, char *ipaddr, int ipaddr_size);
+
+int main(int argc, char **argv)
+{
+ char ipaddr[16];
+ char *interface="eth0";
+
+ memset(ipaddr, 0, sizeof(ipaddr));
+
+ if( get_ipaddr(interface, ipaddr, sizeof(ipaddr)) < 0 )
+ {
+ printf("ERROR: get IP address failure\n");
+ return -1;
+ }
+
+ printf("get network interface %s IP address [%s]\n", interface, ipaddr);
+ return 0;
+}
+
+int get_ipaddr(char *interface, char *ipaddr, int ipaddr_size)
+{
+ char buf[1024];
+ char *ptr;
+ char *ip_start;
+ char *ip_end;
+ FILE *fp;
+ int len;
+ int rv;
+
+ if( !interface || !ipaddr || ipaddr_size<16 )
+ {
+ printf("Invalid input arguments\n");
+ return -1;
+ }
+
+ memset(buf, 0, sizeof(buf));
+ snprintf(buf, sizeof(buf), "ifconfig %s", interface);
+ if( NULL == (fp=popen(buf, "r")) )
+ {
+ printf("popen() to excute command \"%s\" failure: %s\n", buf, strerror(errno));
+ return -2;
+ }
+
+ rv = -3; /* Set default return value to -3 means parser failure */
+
+ 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));
+
+ len = ip_end-ip_start;
+ len = len>ipaddr_size ? ipaddr_size : len;
+ memcpy(ipaddr, ip_start, len);
+
+ rv = 0; /* Parser IP address OK and set rv to 0 */
+
+ break;
+ }
+ }
+
+ return rv;
+}
diff --git a/ch3_fork/socket_server.c b/ch3_fork/socket_server.c
new file mode 100644
index 0000000..875386c
--- /dev/null
+++ b/ch3_fork/socket_server.c
@@ -0,0 +1,162 @@
+#include <stdio.h>
+#include <errno.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/types.h>
+#include <sys/socket.h>
+#include <arpa/inet.h>
+#include <stdlib.h>
+#include <getopt.h>
+
+#define MSG_STR "Hello LingYun IoT Studio Client\n"
+
+void print_usage(char *progname)
+{
+ printf("%s usage: \n", progname);
+ printf("-p(--port): sepcify server listen port.\n");
+ printf("-h(--Help): print this help information.\n");
+
+ return ;
+}
+
+int main(int argc, char **argv)
+{
+ int sockfd = -1;
+ int rv = -1;
+ struct sockaddr_in servaddr;
+ struct sockaddr_in cliaddr;
+ socklen_t len;
+ int port = 0;
+ int clifd;
+ int ch;
+ int on = 1;
+ pid_t pid;
+
+ struct option opts[] = {
+ {"port", required_argument, NULL, 'p'},
+ {"help", no_argument, NULL, 'h'},
+ {NULL, 0, NULL, 0}
+ };
+
+ while( (ch=getopt_long(argc, argv, "p:h", opts, NULL)) != -1 )
+ {
+ switch(ch)
+ {
+ case 'p':
+ port=atoi(optarg);
+ break;
+
+ case 'h':
+ print_usage(argv[0]);
+ return 0;
+ }
+
+ }
+
+ if( !port )
+ {
+ print_usage(argv[0]);
+ return 0;
+ }
+
+ sockfd=socket(AF_INET, SOCK_STREAM, 0);
+ if(sockfd < 0)
+ {
+ printf("Create socket failure: %s\n", strerror(errno));
+ return -1;
+ }
+ printf("Create socket[%d] successfully!\n", sockfd);
+
+ setsockopt(sockfd, SOL_SOCKET, SO_REUSEADDR, &on, sizeof(on));
+
+ memset(&servaddr, 0, sizeof(servaddr));
+ servaddr.sin_family=AF_INET;
+ servaddr.sin_port = htons(port);
+ servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
+ //inet_aton("192.168.0.16", &servaddr.sin_addr);
+
+ rv=bind(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
+ if(rv < 0)
+ {
+ printf("Socket[%d] bind on port[%d] failure: %s\n", sockfd, port, strerror(errno));
+ return -2;
+ }
+
+ listen(sockfd, 13);
+ printf("Start to listen on port [%d]\n", port);
+
+ while(1)
+ {
+ printf("Start accept new client incoming...\n");
+
+ clifd=accept(sockfd, (struct sockaddr *)&cliaddr, &len);
+ if(clifd < 0)
+ {
+ printf("Accept new client failure: %s\n", strerror(errno));
+ continue;
+ }
+
+ printf("Accept new client[%s:%d] successfully\n",
+ inet_ntoa(cliaddr.sin_addr), ntohs(cliaddr.sin_port));
+
+ pid = fork();
+ if( pid < 0 )
+ {
+ printf("fork() create child process failure: %s\n", strerror(errno));
+ close(clifd);
+ continue;
+ }
+ else if( pid > 0 )
+ {
+ /* Parent process close client fd and goes to accept new socket client again */
+ close(clifd);
+ continue;
+ }
+ else if ( 0 == pid )
+ {
+ char buf[1024];
+
+ /* Child process close the listen socket fd */
+ close(sockfd);
+
+ printf("Child process start to commuicate with socket client...\n");
+ memset(buf, 0, sizeof(buf));
+ rv=read(clifd, buf, sizeof(buf));
+ if( rv < 0)
+ {
+ printf("Read data from client sockfd[%d] failure: %s\n", clifd, strerror(errno));
+ close(clifd);
+ exit(0);
+ }
+ else if( rv == 0)
+ {
+ printf("Socket[%d] get disconnected\n", clifd);
+ close(clifd);
+ exit(0);
+ }
+ else if( rv > 0 )
+ {
+ printf("Read %d bytes data from Server: %s\n", rv, buf);
+ }
+
+ rv=write(clifd, MSG_STR, strlen(MSG_STR));
+ if(rv < 0)
+ {
+ printf("Write to client by sockfd[%d] failure: %s\n", sockfd, strerror(errno));
+ close(clifd);
+ exit(0);
+ }
+
+ sleep(1);
+
+ printf("close client socket[%d] and child process exit\n", clifd);
+ close(clifd);
+ exit(0);
+ }
+ }
+
+
+ close(sockfd);
+
+ return 0;
+}
--
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