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eb2c766da4
min()/max() splited from kernel.h to minmax.h since v5.10-rc1.
Before v5.10, minmax.h doesn't exist [1].
[1] b296a6d533
107 lines
2.8 KiB
C
107 lines
2.8 KiB
C
/*
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* procfs3.c
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*/
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#include <linux/kernel.h>
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#include <linux/module.h>
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#include <linux/proc_fs.h>
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#include <linux/sched.h>
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#include <linux/uaccess.h>
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#include <linux/version.h>
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 10, 0)
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#include <linux/minmax.h>
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#endif
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#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
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#define HAVE_PROC_OPS
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#endif
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#define PROCFS_MAX_SIZE 2048UL
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#define PROCFS_ENTRY_FILENAME "buffer2k"
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static struct proc_dir_entry *our_proc_file;
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static char procfs_buffer[PROCFS_MAX_SIZE];
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static unsigned long procfs_buffer_size = 0;
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static ssize_t procfs_read(struct file *filp, char __user *buffer,
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size_t length, loff_t *offset)
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{
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if (*offset || procfs_buffer_size == 0) {
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pr_debug("procfs_read: END\n");
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*offset = 0;
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return 0;
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}
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procfs_buffer_size = min(procfs_buffer_size, length);
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if (copy_to_user(buffer, procfs_buffer, procfs_buffer_size))
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return -EFAULT;
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*offset += procfs_buffer_size;
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pr_debug("procfs_read: read %lu bytes\n", procfs_buffer_size);
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return procfs_buffer_size;
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}
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static ssize_t procfs_write(struct file *file, const char __user *buffer,
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size_t len, loff_t *off)
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{
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procfs_buffer_size = min(PROCFS_MAX_SIZE, len);
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if (copy_from_user(procfs_buffer, buffer, procfs_buffer_size))
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return -EFAULT;
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*off += procfs_buffer_size;
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pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size);
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return procfs_buffer_size;
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}
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static int procfs_open(struct inode *inode, struct file *file)
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{
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try_module_get(THIS_MODULE);
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return 0;
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}
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static int procfs_close(struct inode *inode, struct file *file)
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{
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module_put(THIS_MODULE);
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return 0;
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}
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#ifdef HAVE_PROC_OPS
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static struct proc_ops file_ops_4_our_proc_file = {
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.proc_read = procfs_read,
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.proc_write = procfs_write,
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.proc_open = procfs_open,
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.proc_release = procfs_close,
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};
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#else
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static const struct file_operations file_ops_4_our_proc_file = {
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.read = procfs_read,
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.write = procfs_write,
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.open = procfs_open,
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.release = procfs_close,
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};
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#endif
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static int __init procfs3_init(void)
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{
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our_proc_file = proc_create(PROCFS_ENTRY_FILENAME, 0644, NULL,
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&file_ops_4_our_proc_file);
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if (our_proc_file == NULL) {
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remove_proc_entry(PROCFS_ENTRY_FILENAME, NULL);
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pr_debug("Error: Could not initialize /proc/%s\n",
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PROCFS_ENTRY_FILENAME);
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return -ENOMEM;
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}
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proc_set_size(our_proc_file, 80);
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proc_set_user(our_proc_file, GLOBAL_ROOT_UID, GLOBAL_ROOT_GID);
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pr_debug("/proc/%s created\n", PROCFS_ENTRY_FILENAME);
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return 0;
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}
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static void __exit procfs3_exit(void)
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{
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remove_proc_entry(PROCFS_ENTRY_FILENAME, NULL);
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pr_debug("/proc/%s removed\n", PROCFS_ENTRY_FILENAME);
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}
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module_init(procfs3_init);
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module_exit(procfs3_exit);
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MODULE_LICENSE("GPL");
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