lib/hexdump

Based on ace_dump_mem() from Grant Likely for the Xilinx SystemACE
CompactFlash interface.

Add print_hex_dump() & hex_dumper() to lib/hexdump.c and linux/kernel.h.

This patch adds the functions print_hex_dump() & hex_dumper().
print_hex_dump() can be used to perform a hex + ASCII dump of data to
syslog, in an easily viewable format, thus providing a common text hex dump
format.

hex_dumper() provides a dump-to-memory function. It converts one "line" of
output (16 bytes of input) at a time.

Example usages:
print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame->data, frame->len);
hex_dumper(frame->data, frame->len, linebuf, sizeof(linebuf));

Example output using %DUMP_PREFIX_OFFSET:
0009ab42: 40414243 44454647 48494a4b 4c4d4e4f-@ABCDEFG HIJKLMNO
Example output using %DUMP_PREFIX_ADDRESS:
ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f-pqrstuvw xyz{|}~.

[[e-mail]: cleanups, add export]
Signed-off-by: Randy Dunlap <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

include/linux/kernel.h

···
 
 extern void dump_stack(void);
 
+enum {
+	DUMP_PREFIX_NONE,
+	DUMP_PREFIX_ADDRESS,
+	DUMP_PREFIX_OFFSET
+};
+extern void hex_dump_to_buffer(const void *buf, size_t len, char *linebuf,
+				size_t linebuflen);
+extern void print_hex_dump(const char *level, int prefix_type,
+				void *buf, size_t len);
+#define hex_asc(x)	"0123456789abcdef"[x]
+
 #ifdef DEBUG
 /* If you are writing a driver, please use dev_dbg instead */
 #define pr_debug(fmt,arg...) \

lib/Makefile

···
 lib-y	+= kobject.o kref.o kobject_uevent.o klist.o
 
 obj-y += div64.o sort.o parser.o halfmd4.o debug_locks.o random32.o \
-	 bust_spinlocks.o
+	 bust_spinlocks.o hexdump.o
 
 ifeq ($(CONFIG_DEBUG_KOBJECT),y)
 CFLAGS_kobject.o += -DDEBUG

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>
+
+/**
+ * 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
+ * @linebuf: where to put the converted data
+ * @linebuflen: total size of @linebuf, including space for terminating NUL
+ *
+ * hex_dump_to_buffer() works on one "line" of output at a time, i.e.,
+ * 16 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, linebuf, sizeof(linebuf));
+ *
+ * example output buffer:
+ * 40414243 44454647 48494a4b 4c4d4e4f  @ABCDEFGHIJKLMNO
+ */
+void hex_dump_to_buffer(const void *buf, size_t len, char *linebuf,
+			size_t linebuflen)
+{
+	const u8 *ptr = buf;
+	u8 ch;
+	int j, lx = 0;
+
+	for (j = 0; (j < 16) && (j < len) && (lx + 3) < linebuflen; j++) {
+		if (j && !(j % 4))
+			linebuf[lx++] = ' ';
+		ch = ptr[j];
+		linebuf[lx++] = hex_asc(ch >> 4);
+		linebuf[lx++] = hex_asc(ch & 0x0f);
+	}
+	if ((lx + 2) < linebuflen) {
+		linebuf[lx++] = ' ';
+		linebuf[lx++] = ' ';
+	}
+	for (j = 0; (j < 16) && (j < len) && (lx + 2) < linebuflen; j++)
+		linebuf[lx++] = isprint(ptr[j]) ? ptr[j] : '.';
+	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_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
+ *
+ * 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.
+ *
+ * E.g.:
+ *   print_hex_dump(KERN_DEBUG, DUMP_PREFIX_ADDRESS, frame->data, frame->len);
+ *
+ * Example output using %DUMP_PREFIX_OFFSET:
+ * 0009ab42: 40414243 44454647 48494a4b 4c4d4e4f  @ABCDEFGHIJKLMNO
+ * Example output using %DUMP_PREFIX_ADDRESS:
+ * ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f  pqrstuvwxyz{|}~.
+ */
+void print_hex_dump(const char *level, int prefix_type, void *buf, size_t len)
+{
+	u8 *ptr = buf;
+	int i, linelen, remaining = len;
+	unsigned char linebuf[100];
+
+	for (i = 0; i < len; i += 16) {
+		linelen = min(remaining, 16);
+		remaining -= 16;
+		hex_dump_to_buffer(ptr + i, linelen, linebuf, sizeof(linebuf));
+
+		switch (prefix_type) {
+		case DUMP_PREFIX_ADDRESS:
+			printk("%s%*p: %s\n", level,
+				(int)(2 * sizeof(void *)), ptr + i, linebuf);
+			break;
+		case DUMP_PREFIX_OFFSET:
+			printk("%s%.8x: %s\n", level, i, linebuf);
+			break;
+		default:
+			printk("%s%s\n", level, linebuf);
+			break;
+		}
+	}
+}
+EXPORT_SYMBOL(print_hex_dump);