linux C 调用系统接口安装模块 范例

#include <stdio.h>
#include <stdlib.h>
# include <sys/syscall.h>    // syscall() , __NR_init_module
#include <sys/stat.h>
#include <errno.h>               // ENOEXEC

#include <fcntl.h>        // O_RDONLY 
#include <sys/mman.h>    // PROT_READ , MAP_PRIVATE , MAP_FAILED

# define init_module(mod, len, opts) syscall(__NR_init_module, mod, len, opts)
# define delete_module(mod, flags) syscall(__NR_delete_module, mod, flags)

#define MPI_NAME "cc_def.ko"

void moderror(int err)
{
    switch (err) {
    case -1: /* btw: it's -EPERM */
        printf("no such module");
        return;
    case ENOEXEC:
        printf( "invalid module format");
        return;
    case ENOENT:
        printf( "unknown symbol in module, or unknown parameter");
        return;
    case ESRCH:
        printf("module has wrong symbol version");
        return ;
    case ENOSYS:
        printf("kernel does not support requested operation");
        return ;
    default :
        printf("unknown errcode");
        return ;
    }
}

int main(void )
{
    int len;
    char *image;
    const char *options;
    struct stat st;
    int fd;
    int ret;

    //if (!options)
    options = "";
    if ((fd = open(MPI_NAME, O_RDONLY, 0)) < 0) {
                    printf("cannot open module `%s'", MPI_NAME);
        }
            fstat(fd, &st);
            len = st.st_size;
    printf(" size : %d",len);
            image = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
            if (image == MAP_FAILED) {
        printf("cannot mmap `%s'", MPI_NAME);
        }
    errno=0;
    ret= init_module(image, len, options);
           if (ret != 0) { 
        printf("cannot insert ");
        moderror(errno);
        printf("\n ");
    }
    munmap(image,len);
    return 0;
}