um/kernel/exitcode.c

0001 // SPDX-License-Identifier: GPL-2.0
0002 /*
0003  * Copyright (C) 2002 - 2007 Jeff Dike (jdike@{addtoit,linux.intel}.com)
0004  */
0005
0006 #include <linux/ctype.h>
0007 #include <linux/init.h>
0008 #include <linux/kernel.h>
0009 #include <linux/module.h>
0010 #include <linux/proc_fs.h>
0011 #include <linux/seq_file.h>
0012 #include <linux/types.h>
0013 #include <linux/uaccess.h>
0014
0015 /*
0016  * If read and write race, the read will still atomically read a valid
0017  * value.
0018  */
0019 int uml_exitcode = 0;
0020
0021 static int exitcode_proc_show(struct seq_file *m, void *v)
0022 {
0023     int val;
0024
0025     /*
0026      * Save uml_exitcode in a local so that we don't need to guarantee
0027      * that sprintf accesses it atomically.
0028      */
0029     val = uml_exitcode;
0030     seq_printf(m, "%d\n", val);
0031     return 0;
0032 }
0033
0034 static int exitcode_proc_open(struct inode *inode, struct file *file)
0035 {
0036     return single_open(file, exitcode_proc_show, NULL);
0037 }
0038
0039 static ssize_t exitcode_proc_write(struct file *file,
0040         const char __user *buffer, size_t count, loff_t *pos)
0041 {
0042     char *end, buf[sizeof("nnnnn\0")];
0043     size_t size;
0044     int tmp;
0045
0046     size = min(count, sizeof(buf));
0047     if (copy_from_user(buf, buffer, size))
0048         return -EFAULT;
0049
0050     tmp = simple_strtol(buf, &end, 0);
0051     if ((*end != '\0') && !isspace(*end))
0052         return -EINVAL;
0053
0054     uml_exitcode = tmp;
0055     return count;
0056 }
0057
0058 static const struct proc_ops exitcode_proc_ops = {
0059     .proc_open  = exitcode_proc_open,
0060     .proc_read  = seq_read,
0061     .proc_lseek = seq_lseek,
0062     .proc_release   = single_release,
0063     .proc_write = exitcode_proc_write,
0064 };
0065
0066 static int make_proc_exitcode(void)
0067 {
0068     struct proc_dir_entry *ent;
0069
0070     ent = proc_create("exitcode", 0600, NULL, &exitcode_proc_ops);
0071     if (ent == NULL) {
0072         printk(KERN_WARNING "make_proc_exitcode : Failed to register "
0073                "/proc/exitcode\n");
0074         return 0;
0075     }
0076     return 0;
0077 }
0078
0079 __initcall(make_proc_exitcode);