// SPDX-License-Identifier: GPL-2.0
/*
* seq_buf.c
*
* Copyright (C) 2014 Red Hat Inc, Steven Rostedt <[email protected]>
*
* The seq_buf is a handy tool that allows you to pass a descriptor around
* to a buffer that other functions can write to. It is similar to the
* seq_file functionality but has some differences.
*
* To use it, the seq_buf must be initialized with seq_buf_init().
* This will set up the counters within the descriptor. You can call
* seq_buf_init() more than once to reset the seq_buf to start
* from scratch.
*/
#include <linux/bug.h>
#include <linux/err.h>
#include <linux/export.h>
#include <linux/hex.h>
#include <linux/minmax.h>
#include <linux/printk.h>
#include <linux/seq_buf.h>
#include <linux/seq_file.h>
#include <linux/sprintf.h>
#include <linux/string.h>
#include <linux/types.h>
#include <linux/uaccess.h>
/**
* seq_buf_can_fit - can the new data fit in the current buffer?
* @s: the seq_buf descriptor
* @len: The length to see if it can fit in the current buffer
*
* Returns: true if there's enough unused space in the seq_buf buffer
* to fit the amount of new data according to @len.
*/
static bool seq_buf_can_fit(struct seq_buf *s, size_t len)
{
return s->len + len <= s->size;
}
/**
* seq_buf_print_seq - move the contents of seq_buf into a seq_file
* @m: the seq_file descriptor that is the destination
* @s: the seq_buf descriptor that is the source.
*
* Returns: zero on success, non-zero otherwise.
*/
int seq_buf_print_seq(struct seq_file *m, struct seq_buf *s)
{
unsigned int len = seq_buf_used(s);
return seq_write(m, s->buffer, len);
}
/**
* seq_buf_vprintf - sequence printing of information.
* @s: seq_buf descriptor
* @fmt: printf format string
* @args: va_list of arguments from a printf() type function
*
* Writes a vnprintf() format into the sequence buffer.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_vprintf(struct seq_buf *s, const char *fmt, va_list args)
{
int len;
WARN_ON(s->size == 0);
if (s->len < s->size) {
len = vsnprintf(s->buffer + s->len, s->size - s->len, fmt, args);
if (s->len + len < s->size) {
s->len += len;
return 0;
}
}
seq_buf_set_overflow(s);
return -1;
}
/**
* seq_buf_printf - sequence printing of information
* @s: seq_buf descriptor
* @fmt: printf format string
*
* Writes a printf() format into the sequence buffer.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_printf(struct seq_buf *s, const char *fmt, ...)
{
va_list ap;
int ret;
va_start(ap, fmt);
ret = seq_buf_vprintf(s, fmt, ap);
va_end(ap);
return ret;
}
EXPORT_SYMBOL_GPL(seq_buf_printf);
/**
* seq_buf_do_printk - printk() seq_buf line by line
* @s: seq_buf descriptor
* @lvl: printk level
*
* printk()-s a multi-line sequential buffer line by line. The function
* makes sure that the buffer in @s is NUL-terminated and safe to read
* as a string.
*/
void seq_buf_do_printk(struct seq_buf *s, const char *lvl)
{
const char *start, *lf;
if (s->size == 0 || s->len == 0)
return;
start = seq_buf_str(s);
while ((lf = strchr(start, '\n'))) {
int len = lf - start + 1;
printk("%s%.*s", lvl, len, start);
start = ++lf;
}
/* No trailing LF */
if (start < s->buffer + s->len)
printk("%s%s\n", lvl, start);
}
EXPORT_SYMBOL_GPL(seq_buf_do_printk);
#ifdef CONFIG_BINARY_PRINTF
/**
* seq_buf_bprintf - Write the printf string from binary arguments
* @s: seq_buf descriptor
* @fmt: The format string for the @binary arguments
* @binary: The binary arguments for @fmt.
*
* When recording in a fast path, a printf may be recorded with just
* saving the format and the arguments as they were passed to the
* function, instead of wasting cycles converting the arguments into
* ASCII characters. Instead, the arguments are saved in a 32 bit
* word array that is defined by the format string constraints.
*
* This function will take the format and the binary array and finish
* the conversion into the ASCII string within the buffer.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_bprintf(struct seq_buf *s, const char *fmt, const u32 *binary)
{
unsigned int len = seq_buf_buffer_left(s);
int ret;
WARN_ON(s->size == 0);
if (s->len < s->size) {
ret = bstr_printf(s->buffer + s->len, len, fmt, binary);
if (s->len + ret < s->size) {
s->len += ret;
return 0;
}
}
seq_buf_set_overflow(s);
return -1;
}
#endif /* CONFIG_BINARY_PRINTF */
/**
* seq_buf_puts - sequence printing of simple string
* @s: seq_buf descriptor
* @str: simple string to record
*
* Copy a simple string into the sequence buffer.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_puts(struct seq_buf *s, const char *str)
{
size_t len = strlen(str);
WARN_ON(s->size == 0);
/* Add 1 to len for the trailing null byte which must be there */
len += 1;
if (seq_buf_can_fit(s, len)) {
memcpy(s->buffer + s->len, str, len);
/* Don't count the trailing null byte against the capacity */
s->len += len - 1;
return 0;
}
seq_buf_set_overflow(s);
return -1;
}
EXPORT_SYMBOL_GPL(seq_buf_puts);
/**
* seq_buf_putc - sequence printing of simple character
* @s: seq_buf descriptor
* @c: simple character to record
*
* Copy a single character into the sequence buffer.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_putc(struct seq_buf *s, unsigned char c)
{
WARN_ON(s->size == 0);
if (seq_buf_can_fit(s, 1)) {
s->buffer[s->len++] = c;
return 0;
}
seq_buf_set_overflow(s);
return -1;
}
EXPORT_SYMBOL_GPL(seq_buf_putc);
/**
* seq_buf_putmem - write raw data into the sequence buffer
* @s: seq_buf descriptor
* @mem: The raw memory to copy into the buffer
* @len: The length of the raw memory to copy (in bytes)
*
* There may be cases where raw memory needs to be written into the
* buffer and a strcpy() would not work. Using this function allows
* for such cases.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_putmem(struct seq_buf *s, const void *mem, unsigned int len)
{
WARN_ON(s->size == 0);
if (seq_buf_can_fit(s, len)) {
memcpy(s->buffer + s->len, mem, len);
s->len += len;
return 0;
}
seq_buf_set_overflow(s);
return -1;
}
#define MAX_MEMHEX_BYTES 8U
#define HEX_CHARS (MAX_MEMHEX_BYTES*2 + 1)
/**
* seq_buf_putmem_hex - write raw memory into the buffer in ASCII hex
* @s: seq_buf descriptor
* @mem: The raw memory to write its hex ASCII representation of
* @len: The length of the raw memory to copy (in bytes)
*
* This is similar to seq_buf_putmem() except instead of just copying the
* raw memory into the buffer it writes its ASCII representation of it
* in hex characters.
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_putmem_hex(struct seq_buf *s, const void *mem,
unsigned int len)
{
unsigned char hex[HEX_CHARS];
const unsigned char *data = mem;
unsigned int start_len;
int i, j;
WARN_ON(s->size == 0);
BUILD_BUG_ON(MAX_MEMHEX_BYTES * 2 >= HEX_CHARS);
while (len) {
start_len = min(len, MAX_MEMHEX_BYTES);
#ifdef __BIG_ENDIAN
for (i = 0, j = 0; i < start_len; i++) {
#else
for (i = start_len-1, j = 0; i >= 0; i--) {
#endif
hex[j++] = hex_asc_hi(data[i]);
hex[j++] = hex_asc_lo(data[i]);
}
if (WARN_ON_ONCE(j == 0 || j/2 > len))
break;
/* j increments twice per loop */
hex[j++] = ' ';
seq_buf_putmem(s, hex, j);
if (seq_buf_has_overflowed(s))
return -1;
len -= start_len;
data += start_len;
}
return 0;
}
/**
* seq_buf_path - copy a path into the sequence buffer
* @s: seq_buf descriptor
* @path: path to write into the sequence buffer.
* @esc: set of characters to escape in the output
*
* Write a path name into the sequence buffer.
*
* Returns: the number of written bytes on success, -1 on overflow.
*/
int seq_buf_path(struct seq_buf *s, const struct path *path, const char *esc)
{
char *buf;
size_t size = seq_buf_get_buf(s, &buf);
int res = -1;
WARN_ON(s->size == 0);
if (size) {
char *p = d_path(path, buf, size);
if (!IS_ERR(p)) {
char *end = mangle_path(buf, p, esc);
if (end)
res = end - buf;
}
}
seq_buf_commit(s, res);
return res;
}
/**
* seq_buf_to_user - copy the sequence buffer to user space
* @s: seq_buf descriptor
* @ubuf: The userspace memory location to copy to
* @start: The first byte in the buffer to copy
* @cnt: The amount to copy
*
* Copies the sequence buffer into the userspace memory pointed to
* by @ubuf. It starts from @start and writes up to @cnt characters
* or until it reaches the end of the content in the buffer (@s->len),
* whichever comes first.
*
* Returns:
* On success, it returns a positive number of the number of bytes
* it copied.
*
* On failure it returns -EBUSY if all of the content in the
* sequence has been already read, which includes nothing in the
* sequence (@s->len == @start).
*
* Returns -EFAULT if the copy to userspace fails.
*/
int seq_buf_to_user(struct seq_buf *s, char __user *ubuf, size_t start, int cnt)
{
int len;
int ret;
if (!cnt)
return 0;
len = seq_buf_used(s);
if (len <= start)
return -EBUSY;
len -= start;
if (cnt > len)
cnt = len;
ret = copy_to_user(ubuf, s->buffer + start, cnt);
if (ret == cnt)
return -EFAULT;
return cnt - ret;
}
/**
* seq_buf_hex_dump - print formatted hex dump into the sequence buffer
* @s: seq_buf descriptor
* @prefix_str: string to prefix each line with;
* caller supplies trailing spaces for alignment if desired
* @prefix_type: controls whether prefix of an offset, address, or none
* is printed (%DUMP_PREFIX_OFFSET, %DUMP_PREFIX_ADDRESS, %DUMP_PREFIX_NONE)
* @rowsize: number of bytes to print per line; must be 16 or 32
* @groupsize: number of bytes to print at a time (1, 2, 4, 8; default = 1)
* @buf: data blob to dump
* @len: number of bytes in the @buf
* @ascii: include ASCII after the hex output
*
* Function is an analogue of print_hex_dump() and thus has similar interface.
*
* linebuf size is maximal length for one line.
* 32 * 3 - maximum bytes per line, each printed into 2 chars + 1 for
* separating space
* 2 - spaces separating hex dump and ASCII representation
* 32 - ASCII representation
* 1 - terminating '\0'
*
* Returns: zero on success, -1 on overflow.
*/
int seq_buf_hex_dump(struct seq_buf *s, const char *prefix_str, int prefix_type,
int rowsize, int groupsize,
const void *buf, size_t len, bool ascii)
{
const u8 *ptr = buf;
int i, linelen, remaining = len;
unsigned char linebuf[32 * 3 + 2 + 32 + 1];
int ret;
if (rowsize != 16 && rowsize != 32)
rowsize = 16;
for (i = 0; i < len; i += rowsize) {
linelen = min(remaining, rowsize);
remaining -= rowsize;
hex_dump_to_buffer(ptr + i, linelen, rowsize, groupsize,
linebuf, sizeof(linebuf), ascii);
switch (prefix_type) {
case DUMP_PREFIX_ADDRESS:
ret = seq_buf_printf(s, "%s%p: %s\n",
prefix_str, ptr + i, linebuf);
break;
case DUMP_PREFIX_OFFSET:
ret = seq_buf_printf(s, "%s%.8x: %s\n",
prefix_str, i, linebuf);
break;
default:
ret = seq_buf_printf(s, "%s%s\n", prefix_str, linebuf);
break;
}
if (ret)
return ret;
}
return 0;
}
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