内核中访问文件系统中的文件

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

#include

MODULE_LICENSE("GPL");

/**

** \fn openFile

** \brief Open a file

** \param pathname the path to the file to be opened

*\param flags permision flags to open the file with

* * \param mode mode flags to open the file with

* * \param uid owner user id

* * \param gid owner group id

* * \return file_ptr pointer to the opened file

* * NULL - err_code error opening as indicated by the error code

* */

static struct file *openFile (const char *filename, int32_t flags, int32_t mode, uid_t uid, gid_t gid) {

struct file *file;

do {

struct dentry *saved_root = current->fs->pwd.dentry;

struct vfsmount *saved_mnt = current->fs->pwd.mnt;

current->fs->pwd.dentry = init_task.fs->pwd.dentry;

current->fs->pwd.mnt = init_task.fs->pwd.mnt;

if (NULL == (file = filp_open (filename, flags, mode)))

printk(KERN_ERR "kermit: can't open file %s!\n", filename);

current->fs->pwd.mnt = saved_mnt;

current->fs->pwd.dentry = saved_root;

} while (0);

return file;

}

/**

* * \fn closeFile

* * \brief Close a file

* * \param file pointer to the file to be closed

* * \return 0 success

* * != 0 error closing the file as indicated by the error code * */

static int32_t closeFile (struct file *file)

{

return filp_close (file, current->files);

}

/**

* * \fn readFile

* * \brief Read from a file

* * \param file pointer to the file to be read from

* * \param addr buffer to hold the read data

* * \param len number of bytes to read

* * \param pos starting position

* * \return number of bytes read

* *

* * \warning file should be a valid file pointer

* * and the corresponding file should

* * be opened, i.e. the file should

* * located be on the linked node

* */

static int32_t readFile(struct file *file, char *addr, size_t len, loff_t *pos) {

int32_t re t;

do {

mm_segment_t old_fs;

old_fs = get_fs();

set_fs(KERNEL_DS); /* Enable to read in kernel memory */

ret = vfs_read(file, addr, len, pos);

set_fs(old_fs); /* Disable to read in kernel memory */ } while (0);

return ret;

}

static int __init hello_init (void)

{

char cbuf[128] = {0};

printk("Hello module init\n");

struct file *lut_fp = openFile("/tmp/1.txt", 0, 0, 0, 0);

if (NULL == lut_fp ) {

return 0;

}

lut_fp->f_pos = 0;

readFile(lut_fp, cbuf, sizeof(cbuf), &lut_fp->f_pos);

printk("%s \n", cbuf);

closeFile (lut_fp);

return 0;

}

static void __exit hello_exit (void)

{

printk("Hello module exit\n");

}

module_init(hello_init);

module_exit(hello_exit);