C programming: My code is not running correctly and I amsure what's wrong. Please help. I have
Question:
C programming: My code is not running correctly and I amsure what's wrong. Please help. I have provided a screenshot andeverything below.
Assignment:
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Design a kernel module that creates a /proc filenamed /proc/jiffies that reports the current valueof jiffies when the /proc/jiffies file is read,such as with the command
cat /proc/jiffiesBe sure to remove /proc/jiffies when the module isremoved.
Source Code:
jiffies.c
/* This function is called when the module is loaded. */
int proc_init(void)
{
/* creates the /proc/jiffies entry */
proc_create(PROC_NAME, 0666, NULL, &proc_ops);
return 0;
}
/* This function is called when the module is removed. */
void proc_exit(void)
{
/* removes the /proc/jiffies entry */
remove_proc_entry(PROC_NAME, NULL);
}
/* This function is called each time /proc/jiffies is read*/
ssize_t proc_read(struct file *file, char __user *usr_buf,size_t count, loff_t *pos)
{
int rv = 0;
char buffer[BUFFER_SIZE];
static int completed = 0;
if (completed) {
completed = 0;
return 0;
}
completed = 1;
rv = sprintf(buffer, "%lu", jiffies);
/* copies kernel space buffer to user space usr buf */
copy_to_user(usr_buf, buffer, rv);
return rv;
}
Makefile
obj-m += jiffies.o
all:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD)modules
clean:
make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clean
Expert Answer:
Based on the provided source code it looks like the problem might be in the procread function Specif... View the full answer
Income Tax Fundamentals 2013
ISBN: 9781285586618
31st Edition
Authors: Gerald E. Whittenburg, Martha Altus Buller, Steven L Gill
