Messages in this thread | | | Date | Fri, 12 Jan 2007 15:47:32 +0800 | From | "congwen" <> | Subject | How can I create or read/write a file in linux device driver? |
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Hello everyone, I want to create and read/write a file in Linux kernel or device driver, I have write some code, the file could be created successfully, but it can not be wrote in anything, the function "write" always return a negative number, the content of the file is still empty. The following code is what I wrote in my device driver, the code reference the function sys_open() in open.c and sys_write() in read_write.c, please give me a help, thanks!
struct file *filp; char testbuf[100] = {0}; char *ptestbuf = NULL; ssize_t count = 0; ssize_t ret = 0; int ii = 0; filp = filp_open("/logfile", O_CREAT | O_WRONLY | O_TRUNC, 0666); if (IS_ERR(filp)) printk("<0>Create record file error!\n\r"); for(ii = 0; ii < 100; ii++) testbuf[ii] = 1; ptestbuf = testbuf;
if (filp->f_mode & FMODE_WRITE) { struct inode *inode = filp->f_dentry->d_inode; ret = locks_verify_area(FLOCK_VERIFY_WRITE, inode, filp, filp->f_pos, count); if (!ret) { ssize_t (*write)(struct file *, const char *, size_t, loff_t *); if (filp->f_op && (filp->f_op->write) != NULL) { write = filp->f_op->write; count = 99; ret = write(filp, (const char *)ptestbuf, count, &filp->f_pos); printk("<0>After write, ret = %d \n\r"); } } }
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