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Merge pull request #163 from linD026/read-write

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procfs{2, 3}: Change to use offset parameter
This commit is contained in:
Jim Huang 2022-09-08 22:24:20 +08:00 committed by GitHub
commit c69eff9d1f
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2 changed files with 9 additions and 11 deletions
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1
examples/procfs2.c
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@ -55,6 +55,7 @@ static ssize_t procfile_write(struct file *file, const char __user *buff,
return -EFAULT; return -EFAULT;
procfs_buffer[procfs_buffer_size & (PROCFS_MAX_SIZE - 1)] = '\0'; procfs_buffer[procfs_buffer_size & (PROCFS_MAX_SIZE - 1)] = '\0';
*off += procfs_buffer_size;
pr_info("procfile write %s\n", procfs_buffer); pr_info("procfile write %s\n", procfs_buffer);
return procfs_buffer_size; return procfs_buffer_size;

19
examples/procfs3.c
View File

@ -8,12 +8,13 @@
#include <linux/sched.h> #include <linux/sched.h>
#include <linux/uaccess.h> #include <linux/uaccess.h>
#include <linux/version.h> #include <linux/version.h>
#include <linux/minmax.h>
#if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0) #if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0)
#define HAVE_PROC_OPS #define HAVE_PROC_OPS
#endif #endif
#define PROCFS_MAX_SIZE 2048 #define PROCFS_MAX_SIZE 2048UL
#define PROCFS_ENTRY_FILENAME "buffer2k" #define PROCFS_ENTRY_FILENAME "buffer2k"
static struct proc_dir_entry *our_proc_file; static struct proc_dir_entry *our_proc_file;
@ -23,17 +24,15 @@ static unsigned long procfs_buffer_size = 0;
static ssize_t procfs_read(struct file *filp, char __user *buffer, static ssize_t procfs_read(struct file *filp, char __user *buffer,
size_t length, loff_t *offset) size_t length, loff_t *offset)
{ {
static int finished = 0; if (*offset || procfs_buffer_size == 0) {
if (finished) {
pr_debug("procfs_read: END\n"); pr_debug("procfs_read: END\n");
finished = 0; *offset = 0;
return 0; return 0;
} }
finished = 1; procfs_buffer_size = min(procfs_buffer_size, length);
if (copy_to_user(buffer, procfs_buffer, procfs_buffer_size)) if (copy_to_user(buffer, procfs_buffer, procfs_buffer_size))
return -EFAULT; return -EFAULT;
*offset += procfs_buffer_size;
pr_debug("procfs_read: read %lu bytes\n", procfs_buffer_size); pr_debug("procfs_read: read %lu bytes\n", procfs_buffer_size);
return procfs_buffer_size; return procfs_buffer_size;
@ -41,12 +40,10 @@ static ssize_t procfs_read(struct file *filp, char __user *buffer,
static ssize_t procfs_write(struct file *file, const char __user *buffer, static ssize_t procfs_write(struct file *file, const char __user *buffer,
size_t len, loff_t *off) size_t len, loff_t *off)
{ {
if (len > PROCFS_MAX_SIZE) procfs_buffer_size = min(PROCFS_MAX_SIZE, len);
procfs_buffer_size = PROCFS_MAX_SIZE;
else
procfs_buffer_size = len;
if (copy_from_user(procfs_buffer, buffer, procfs_buffer_size)) if (copy_from_user(procfs_buffer, buffer, procfs_buffer_size))
return -EFAULT; return -EFAULT;
*off += procfs_buffer_size;
pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size); pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size);
return procfs_buffer_size; return procfs_buffer_size;