两层Makefile的书写方法，可以一次生成在X86和ARM运行的程序

首先，看下整个工程文件的结构图：

（1）主文件包含一个Makefile，一起对应的c源文件，还有子文件夹arm_client



（2）子文件夹arm_client



（3）先看一下子文件夹arm_client各个文件的内容：

client.c

/*
client.c
[root@FriendlyARM /home]# ./client
Response from server:
TCP TRANSPORTATION TEST!
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include "../wrap.h"

#define MAXLINE 80
#define SERV_PORT 8888

int main(int argc, char *argv[])
{
struct sockaddr_in servaddr;
char buf[MAXLINE];
int sockfd, n;
char *str="TCP transportation test!";

sockfd = Socket(AF_INET, SOCK_STREAM, 0);
bzero(&servaddr, sizeof(servaddr));
servaddr.sin_family = AF_INET;
inet_pton(AF_INET, "192.168.1.108", &servaddr.sin_addr);
servaddr.sin_port = htons(SERV_PORT);

Connect(sockfd, (struct sockaddr *)&servaddr, sizeof(servaddr));
Write(sockfd, str, strlen(str));
n = Read(sockfd, buf, MAXLINE);
printf("Response from server:\n");
Write(STDOUT_FILENO, buf, n);
printf("\n");
Close(sockfd);
return 0;
}

Makefile文件

CC = gcc
ARMCC = arm-linux-gcc

OTHER_HEADER = ../wrap.h
OTHER_SOURCE = ../wrap.c

all: client
client: client.c arm_wrap.o
$(ARMCC) -o $@ client.c arm_wrap.o

arm_wrap.o:  $(OTHER_SOURCE) $(OTHER_HEADER)
$(ARMCC) -c -o $@ $(OTHER_SOURCE)

clean:
rm -f *.a *.o server client *~

说明：

Makefile文件依靠的是三个文件：client.c,还有上一级目录的wrap.c和wrap.h

不理解这个makefile写法的原理请参考我上篇文章：Makefile：依赖多个c文件的书写方式

/article/7877140.html

（4）主文件各文件的内容

wrap.h

#ifndef _WRAP_H
#define _WRAP_H
/*
#include <termios.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <termios.h>
#include <errno.h>
#include <pthread.h>
#include <string.h>
#include <ctype.h>
*/
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
void perr_exit(const char *s);
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr);
int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr);
void Bind(int fd, const struct sockaddr *sa, socklen_t salen);
void Connect(int fd, const struct sockaddr *sa, socklen_t salen);
void Listen(int fd, int backlog);
int Socket(int family, int type, int protocol);
ssize_t Read(int fd, void *ptr, size_t nbytes);
ssize_t Write(int fd, const void *ptr, size_t nbytes);
void Close(int fd);
ssize_t Readn(int fd, void *vptr, size_t n);
ssize_t Writen(int fd, const void *vptr, size_t n);
static ssize_t my_read(int fd, char *ptr);
ssize_t Readline(int fd, void *vptr, size_t maxlen);

#endif

wrap.c

/*
#include <stdlib.h>
#include <errno.h>
#include <sys/socket.h>
*/
#include "wrap.h"

void perr_exit(const char *s)
{
perror(s);
exit(1);
}

int Accept(int fd, struct sockaddr *sa, socklen_t *salenptr)
{
int n;
again:
if ( (n = accept(fd, sa, salenptr)) < 0) {
if ((errno == ECONNABORTED) || (errno == EINTR))
goto again;
else
perr_exit("accept error");
}
return n;
}

void Bind(int fd, const struct sockaddr *sa, socklen_t salen)
{
if (bind(fd, sa, salen) < 0)
perr_exit("bind error");
}

void Connect(int fd, const struct sockaddr *sa, socklen_t salen)
{
if (connect(fd, sa, salen) < 0)
perr_exit("connect error");
}

void Listen(int fd, int backlog)
{
if (listen(fd, backlog) < 0)
perr_exit("listen error");
}

int Socket(int family, int type, int protocol)
{
int n;
if ( (n = socket(family, type, protocol)) < 0)
perr_exit("socket error");
return n;
}

ssize_t Read(int fd, void *ptr, size_t nbytes)
{
ssize_t n;
again:
if ( (n = read(fd, ptr, nbytes)) == -1) {
if (errno == EINTR)
goto again;
else
return -1;
}
return n;
}

ssize_t Write(int fd, const void *ptr, size_t nbytes)
{
ssize_t n;
again:
if ( (n = write(fd, ptr, nbytes)) == -1) {
if (errno == EINTR)
goto again;
else
return -1;
}
return n;
}

void Close(int fd)
{
if (close(fd) == -1)
perr_exit("close error");
}

ssize_t Readn(int fd, void *vptr, size_t n)
{
size_t  nleft;
ssize_t nread;
char   *ptr;
ptr = vptr;
nleft = n;
while (nleft > 0) {
if ( (nread = read(fd, ptr, nleft)) < 0) {
if (errno == EINTR)
nread = 0;
else
return -1;
} else if (nread == 0)
break;
nleft -= nread;
ptr += nread;
}
return n - nleft;
}

ssize_t Writen(int fd, const void *vptr, size_t n)
{
size_t nleft;
ssize_t nwritten;
const char *ptr;
ptr = vptr;
nleft = n;
while (nleft > 0) {
if ( (nwritten = write(fd, ptr, nleft)) <= 0) {
if (nwritten < 0 && errno == EINTR)
nwritten = 0;
else
return -1;
}
nleft -= nwritten;
ptr += nwritten;
}
return n;
}

static ssize_t my_read(int fd, char *ptr)
{
static int read_cnt;
static char *read_ptr;
static char read_buf[100];
if (read_cnt <= 0) {
again:
if ( (read_cnt = read(fd, read_buf,
sizeof(read_buf))) < 0) {
if (errno == EINTR)
goto again;
return -1;
} else if (read_cnt == 0)
return 0;
read_ptr = read_buf;
}
read_cnt--;
*ptr = *read_ptr++;
return 1;
}

ssize_t Readline(int fd, void *vptr, size_t maxlen)
{
ssize_t n, rc;
char    c, *ptr;
ptr = vptr;
for (n = 1; n < maxlen; n++) {
if ( (rc = my_read(fd, &c)) == 1) {
*ptr++ = c;
if (c  == '\n')
break;
} else if (rc == 0) {
*ptr = 0;
return n - 1;
} else
return -1;
}
*ptr  = 0;
return n;
}

以上两个文件被编译的两次，在子文件里面被编译成目标文件arm_wrap.o，在主文件里面被编译成wrap.o

server.c

/*
server.c
bind error: Address already in use
发生这种问题是由于端口被程序绑定而没有释放造成.
可以使用netstat -lp命令查询当前处于连接的程序以及对应的进程信息。
然后用ps pid 察看对应的进程，并使用kill pid 关闭该进程即可。
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/socket.h>
#include <netinet/in.h>

#include "wrap.h"

#define MAXLINE 80
#define SERV_PORT 8888
int DEBUG=1;

int main(void)
{
struct sockaddr_in servaddr, cliaddr;
socklen_t cliaddr_len;
int listenfd, connfd;
char buf[MAXLINE];
char str[INET_ADDRSTRLEN];
int i, n;

listenfd = Socket(AF_INET, SOCK_STREAM, 0);//open a network connection(IPV4 ,TCP)
if(DEBUG){
int on=1;//允许地址重用,端口可以马上重用
setsockopt(listenfd, SOL_SOCKET,SO_REUSEADDR, &on, sizeof(on) );
}
bzero(&servaddr, sizeof(servaddr));//clear the struct
servaddr.sin_family = AF_INET;
servaddr.sin_addr.s_addr = htonl(INADDR_ANY);
servaddr.sin_port = htons(SERV_PORT);

Bind(listenfd, (struct sockaddr *)&servaddr, sizeof(servaddr));//bind servaddr to socket
Listen(listenfd, 20);//The maximum of clients who are waiting for connection is 20
printf("Accepting connections ...\n");
while (1) {
cliaddr_len = sizeof(cliaddr);//cliaddr_len 是传入传出参数，每次调用accept前重新赋初值
connfd = Accept(listenfd, (struct sockaddr *)&cliaddr, &cliaddr_len);
n = Read(connfd, buf, MAXLINE);

printf("received from %s at Client PORT %d\n",
inet_ntop(AF_INET, &cliaddr.sin_addr, str, sizeof(str)),
ntohs(cliaddr.sin_port));//客户端的端口号是自动分配的
printf("Response from client:\n");
Write(STDOUT_FILENO, buf, n);
printf("\n");
for (i = 0; i < n; i++){
//printf("%x",buf[i]);// if add this ,bind error
buf[i] = toupper(buf[i]);//把收到的字符转换成大写字母发回去
}

Write(connfd, buf, n);
Close(connfd);
}
}

Makefile文件

CC = gcc
ARMCC = arm-linux-gcc

all: server client

client: wrap.h
make -C arm_client/ all	CC=$(ARMCC)
cp arm_client/client .

server: server.c wrap.o
$(CC) -o server server.c wrap.o

wrap.o:  wrap.c wrap.h
$(CC) -c -o $@ wrap.c

clean:
make -C arm_client/ $@
rm -f *.a *.o server client *~

这个Makefile文件做两件事：

第一：生成能在X86上运行的server可执行文件

第二：生成能在ARM上运行的client可执行文件，并吧client从arm_client文件里面复制到当前文件夹