我开发了这个函数:
bool execc(char *cmd, char *r)
{
FILE *fp;
char t1[1024];
char *t2;
memset(r, 0, sizeof(r));
fp = popen(cmd, "r");
if (fp == NULL)
{
return false;
}
t1 = r;
while (fgets(t1, sizeof(t1), fp) != NULL)
{
r = &r[strlen(r)];
memcpy(r, t1, strlen(t1));
}
r = t2;
r[strlen(r)] = '\0';
pclose(fp);
return true;
}
int main()
{
char r[4096];
int i = 51;
execc("ls -l /", r);
printf("result of cmd: \n %s", r);
return 0;
}
当我执行这个程序时,我得到了一些奇怪的字符,比如:
result of command:
total xxx
drwxr-xr-x 7 1001 root 4096 août 25 16:06 xxx
drwxr-xr-x 3 root root 4096 juin 30 11:45 xxx
drwxr-xr-x 2 root root 12288 oct. 9 15:26 bin
drwxr-xr-x 3 root root 1024 août 28 11:48 boot
drwxr-xr-x 3 root root 4096 août 26 10:51 boot-files
drwxrwxr-x 2 root root 4096 janv. 12 2015 cdrom
drwxr-xr-x 7 xxxx xxxx 4096 juil. 14 16:43 data
drwxr-xr-x 20 root root 4640 oct. 20 15:06 dev
drwxr-xr-x 174 root root 12288 oct. 9 17:43 etc
drwxr-xr-x 5 root root 4096 sept. 28 17:19 home
lrwxrwxrwx 1 root root 33 août 26 10:50 initrd.img -> boot/initrd.img-xxxx-generic
lrwxrwxrwx 1 root root 33 août 26 10:49 initrd.img.old -> boot/initrd.img-xxxx-generic
drwxr-xr-x 27 root root 4096 avril 28 16:08 lib
drwxr-xr-x 2 root root 4096 mai 7 17:35 lib32
drwxr-xr-x 2 root root 4096 avril 28 15:33 lib64
drwx------ 2 root root 16384 janv. 12 2015 lost+found
drwxr-xr-x 3 root root 4096 janv. 16 2015 media
drwxr-xr-x 2 root root 4096 oct. 16 2014 mnt
drwxr-xr-x 7 root root 4096 août 24 13:18 opt
dr-xr-xr-x 299 root root 0 oct. 19 08:54 proc
drwx------ 10 root root 4096 oct. 5 18:03 root
drwxr-xr-x 27 root root 940 oct. 20 14:38 run
drwxr-xr-x 2 root root 12288 août 13 09:57 sbin
h�rwxr-xr-x 2 root root 4096 oct. 22 2014 srv
dr-xr-xr-x 13 root root 0 oct. 20 14:34 sys
drwxrwxrwx 2 nobody xxxx 4096 oct. 12 12:08 tftpboot
drwxrwxrwt 19 root root 20480 oct. 20 15:30 tmp
drwxr-xr-x 12 root root 4096 août 27 10:24 usr
drwxr-xr-x 14 root root 4096 avril 7 2015 var
lrwxrwxrwx 1 root root 30 août 26 10:46 vmlinuz -> boot/vmlinuz-xxxx-generic
3B�lrwxrwxrwx 1 root root 30 août 13 10:01 vmlinuz.old -> boot/vmlinuz-xxxx-generic
如何修复此错误?我不觉得有问题
最佳答案
sizeof(r)
返回指针的大小清空r
的最简单方法是将main更改为具有…
char r[4096] = ""; /* initialize to '\0' */
代码可能应该遍历读取的数据量,而不是缓冲区溢出。
memcpy(r, t1, strlen(t1));
r = &r[strlen(t1)]; /* walk by amount added */
密码好像弄乱了。
t1 = r; /* << == doesn't compile */
r = t2;
创建未定义的行为,因为从未分配过t2
。r = t2;
r[strlen(r)] = '\0';
在循环中尝试。
memcpy(r, t1, strlen(t1));
r = &r[strlen(t1)]; /* walk by amount added */
r[0] = '\0'; /* terminate the string */
一般来说,如果你得到的数据超过4k,就会发生不好的事情。
bool execc(char *cmd, char *r)
{
FILE *fp;
char t1[1024];
fp = popen(cmd, "r");
if (fp == NULL)
{
return false;
}
while (fgets(t1, sizeof(t1), fp) != NULL)
{
memcpy(r, t1, strlen(t1));
r = &r[strlen(t1)]; /* walk by amount added */
r[0] = '\0'; /* terminate the string */
}
pclose(fp);
return true;
}