From 39a313dc2039591fca5de3e149824d897884ff2c Mon Sep 17 00:00:00 2001 From: linD026 Date: Thu, 8 Sep 2022 06:51:14 +0800 Subject: [PATCH] procfs{2, 3}: Change to use offset parameter To make sure the behavior of the read and write operations are correct with offset, update it each time. Also, since it is using the offset, modify the part of read for removing unnecessary variable. --- examples/procfs2.c | 1 + examples/procfs3.c | 19 ++++++++----------- 2 files changed, 9 insertions(+), 11 deletions(-) diff --git a/examples/procfs2.c b/examples/procfs2.c index bb2aa61..896a777 100644 --- a/examples/procfs2.c +++ b/examples/procfs2.c @@ -55,6 +55,7 @@ static ssize_t procfile_write(struct file *file, const char __user *buff, return -EFAULT; procfs_buffer[procfs_buffer_size & (PROCFS_MAX_SIZE - 1)] = '\0'; + *off += procfs_buffer_size; pr_info("procfile write %s\n", procfs_buffer); return procfs_buffer_size; diff --git a/examples/procfs3.c b/examples/procfs3.c index bbf40ce..6d41417 100644 --- a/examples/procfs3.c +++ b/examples/procfs3.c @@ -8,12 +8,13 @@ #include #include #include +#include #if LINUX_VERSION_CODE >= KERNEL_VERSION(5, 6, 0) #define HAVE_PROC_OPS #endif -#define PROCFS_MAX_SIZE 2048 +#define PROCFS_MAX_SIZE 2048UL #define PROCFS_ENTRY_FILENAME "buffer2k" 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, size_t length, loff_t *offset) { - static int finished = 0; - - if (finished) { + if (*offset || procfs_buffer_size == 0) { pr_debug("procfs_read: END\n"); - finished = 0; + *offset = 0; return 0; } - finished = 1; - + procfs_buffer_size = min(procfs_buffer_size, length); if (copy_to_user(buffer, procfs_buffer, procfs_buffer_size)) return -EFAULT; + *offset += procfs_buffer_size; pr_debug("procfs_read: read %lu bytes\n", 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, size_t len, loff_t *off) { - if (len > PROCFS_MAX_SIZE) - procfs_buffer_size = PROCFS_MAX_SIZE; - else - procfs_buffer_size = len; + procfs_buffer_size = min(PROCFS_MAX_SIZE, len); if (copy_from_user(procfs_buffer, buffer, procfs_buffer_size)) return -EFAULT; + *off += procfs_buffer_size; pr_debug("procfs_write: write %lu bytes\n", procfs_buffer_size); return procfs_buffer_size; -- 2.39.5