lib/hexdump.c

/*
 * lib/hexdump.c
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation. See README and COPYING for
 * more details.
 */

#include <linux/types.h>
#include <linux/ctype.h>
#include <linux/kernel.h>
#include <linux/module.h>

const char hex_asc[] = "0123456789abcdef";
EXPORT_SYMBOL(hex_asc);

/**
 * hex_dump_to_buffer - convert a blob of data to "hex ASCII" in memory
 * @buf: data blob to dump
 * @len: number of bytes in the @buf
 * @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)
 * @linebuf: where to put the converted data
 * @linebuflen: total size of @linebuf, including space for terminating NUL
 * @ascii: include ASCII after the hex output
 *
 * hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
 * 16 or 32 bytes of input data converted to hex + ASCII output.
 *
 * Given a buffer of u8 data, hex_dump_to_buffer() converts the input data
 * to a hex + ASCII dump at the supplied memory location.
 * The converted output is always NUL-terminated.
 *
 * E.g.:
 *   hex_dump_to_buffer(frame->data, frame->len, 16, 1,
 *			linebuf, sizeof(linebuf), true);
 *
 * example output buffer:
 * 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f  @ABCDEFGHIJKLMNO
 */
void hex_dump_to_buffer(const void *buf, size_t len, int rowsize,
			int groupsize, char *linebuf, size_t linebuflen,
			bool ascii)
{
	const u8 *ptr = buf;
	u8 ch;
	int j, lx = 0;
	int ascii_column;

	if (rowsize != 16 && rowsize != 32)
		rowsize = 16;

	if (!len)
		goto nil;
	if (len > rowsize)		/* limit to one line at a time */
		len = rowsize;
	if ((len % groupsize) != 0)	/* no mixed size output */
		groupsize = 1;

	switch (groupsize) {
	case 8: {
		const u64 *ptr8 = buf;
		int ngroups = len / groupsize;

		for (j = 0; j < ngroups; j++)
			lx += scnprintf(linebuf + lx, linebuflen - lx,
					"%s%16.16llx", j ? " " : "",
					(unsigned long long)*(ptr8 + j));
		ascii_column = 17 * ngroups + 2;
		break;
	}

	case 4: {
		const u32 *ptr4 = buf;
		int ngroups = len / groupsize;

		for (j = 0; j < ngroups; j++)
			lx += scnprintf(linebuf + lx, linebuflen - lx,
					"%s%8.8x", j ? " " : "", *(ptr4 + j));
		ascii_column = 9 * ngroups + 2;
		break;
	}

	case 2: {
		const u16 *ptr2 = buf;
		int ngroups = len / groupsize;

		for (j = 0; j < ngroups; j++)
			lx += scnprintf(linebuf + lx, linebuflen - lx,
					"%s%4.4x", j ? " " : "", *(ptr2 + j));
		ascii_column = 5 * ngroups + 2;
		break;
	}

	default:
		for (j = 0; (j < len) && (lx + 3) <= linebuflen; j++) {
			ch = ptr[j];
			linebuf[lx++] = hex_asc_hi(ch);
			linebuf[lx++] = hex_asc_lo(ch);
			linebuf[lx++] = ' ';
		}
		if (j)
			lx--;

		ascii_column = 3 * rowsize + 2;
		break;
	}
	if (!ascii)
		goto nil;

	while (lx < (linebuflen - 1) && lx < (ascii_column - 1))
		linebuf[lx++] = ' ';
	for (j = 0; (j < len) && (lx + 2) < linebuflen; j++) {
		ch = ptr[j];
		linebuf[lx++] = (isascii(ch) && isprint(ch)) ? ch : '.';
	}
nil:
	linebuf[lx++] = '\0';
}
EXPORT_SYMBOL(hex_dump_to_buffer);

/**
 * print_hex_dump - print a text hex dump to syslog for a binary blob of data
 * @level: kernel log level (e.g. KERN_DEBUG)
 * @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
 *
 * Given a buffer of u8 data, print_hex_dump() prints a hex + ASCII dump
 * to the kernel log at the specified kernel log level, with an optional
 * leading prefix.
 *
 * print_hex_dump() works on one "line" of output at a time, i.e.,
 * 16 or 32 bytes of input data converted to hex + ASCII output.
 * print_hex_dump() iterates over the entire input @buf, breaking it into
 * "line size" chunks to format and print.
 *
 * E.g.:
 *   print_hex_dump(KERN_DEBUG, "raw data: ", DUMP_PREFIX_ADDRESS,
 *		    16, 1, frame->data, frame->len, true);
 *
 * Example output using %DUMP_PREFIX_OFFSET and 1-byte mode:
 * 0009ab42: 40 41 42 43 44 45 46 47 48 49 4a 4b 4c 4d 4e 4f  @ABCDEFGHIJKLMNO
 * Example output using %DUMP_PREFIX_ADDRESS and 4-byte mode:
 * ffffffff88089af0: 73727170 77767574 7b7a7978 7f7e7d7c  pqrstuvwxyz{|}~.
 */
void print_hex_dump(const char *level, 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];

	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:
			printk("%s%s%p: %s\n",
			       level, prefix_str, ptr + i, linebuf);
			break;
		case DUMP_PREFIX_OFFSET:
			printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
			break;
		default:
			printk("%s%s%s\n", level, prefix_str, linebuf);
			break;
		}
	}
}
EXPORT_SYMBOL(print_hex_dump);

/**
 * print_hex_dump_bytes - shorthand form of print_hex_dump() with default params
 * @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)
 * @buf: data blob to dump
 * @len: number of bytes in the @buf
 *
 * Calls print_hex_dump(), with log level of KERN_DEBUG,
 * rowsize of 16, groupsize of 1, and ASCII output included.
 */
void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
			  const void *buf, size_t len)
{
	print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1,
		       buf, len, true);
}
EXPORT_SYMBOL(print_hex_dump_bytes);