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hexdump: more output formatting
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Add a prefix string parameter.  Callers are responsible for any string
length/alignment that they want to see in the output.  I.e., callers should
pad strings to achieve alignment if they want that.

Add rowsize parameter.  This is the number of raw data bytes to be printed
per line.  Must be 16 or 32.

Add a groupsize parameter.  This allows callers to dump values as 1-byte,
2-byte, 4-byte, or 8-byte numbers.  Default is 1-byte numbers.  If the
total length is not an even multiple of groupsize, 1-byte numbers are
printed.

Add an "ascii" output parameter.  This causes ASCII data output following
the hex data output.

Clean up some doc examples.

Align the ASCII output on all lines that are produced by one call.

Add a new interface, print_hex_dump_bytes(), that is a shortcut to
print_hex_dump(), using default parameter values to print 16 bytes in
byte-size chunks of hex + ASCII output, using printk level KERN_DEBUG.

Signed-off-by: Randy Dunlap <[email protected]>
Cc: Christoph Lameter <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>
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@rddunlap
rddunlap authored and Linus Torvalds committed Jun 9, 2007
1 parent abb4920 commit c790923
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Showing 2 changed files with 129 additions and 32 deletions.
12 changes: 8 additions & 4 deletions include/linux/kernel.h
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Original file line number Diff line number Diff line change
Expand Up @@ -218,10 +218,14 @@ enum {
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);
extern void hex_dump_to_buffer(const void *buf, size_t len,
int rowsize, int groupsize,
char *linebuf, size_t linebuflen, bool ascii);
extern void print_hex_dump(const char *level, const char *prefix_str,
int prefix_type, int rowsize, int groupsize,
void *buf, size_t len, bool ascii);
extern void print_hex_dump_bytes(const char *prefix_str, int prefix_type,
void *buf, size_t len);
#define hex_asc(x) "0123456789abcdef"[x]

#ifdef DEBUG
Expand Down
149 changes: 121 additions & 28 deletions lib/hexdump.c
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Original file line number Diff line number Diff line change
Expand Up @@ -16,89 +16,182 @@
* 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 bytes of input data converted to hex + ASCII output.
* 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, linebuf, sizeof(linebuf));
* hex_dump_to_buffer(frame->data, frame->len, 16, 1,
* linebuf, sizeof(linebuf), 1);
*
* example output buffer:
* 40414243 44454647 48494a4b 4c4d4e4f @ABCDEFGHIJKLMNO
* 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, char *linebuf,
size_t linebuflen)
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;

for (j = 0; (j < 16) && (j < len) && (lx + 3) < linebuflen; j++) {
if (j && !(j % 4))
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,
"%16.16llx ", (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,
"%8.8x ", *(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,
"%4.4x ", *(ptr2 + j));
ascii_column = 5 * ngroups + 2;
break;
}

default:
for (j = 0; (j < rowsize) && (j < len) && (lx + 4) < linebuflen;
j++) {
ch = ptr[j];
linebuf[lx++] = hex_asc(ch >> 4);
linebuf[lx++] = hex_asc(ch & 0x0f);
linebuf[lx++] = ' ';
ch = ptr[j];
linebuf[lx++] = hex_asc(ch >> 4);
linebuf[lx++] = hex_asc(ch & 0x0f);
}
ascii_column = 3 * rowsize + 2;
break;
}
if ((lx + 2) < linebuflen) {
linebuf[lx++] = ' ';
if (!ascii)
goto nil;

while (lx < (linebuflen - 1) && lx < (ascii_column - 1))
linebuf[lx++] = ' ';
}
for (j = 0; (j < 16) && (j < len) && (lx + 2) < linebuflen; j++)
for (j = 0; (j < rowsize) && (j < len) && (lx + 2) < linebuflen; j++)
linebuf[lx++] = isprint(ptr[j]) ? ptr[j] : '.';
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, DUMP_PREFIX_ADDRESS, frame->data, frame->len);
* print_hex_dump(KERN_DEBUG, "raw data: ", DUMP_PREFIX_ADDRESS,
* 16, 1, frame->data, frame->len, 1);
*
* Example output using %DUMP_PREFIX_OFFSET:
* 0009ab42: 40414243 44454647 48494a4b 4c4d4e4f @ABCDEFGHIJKLMNO
* Example output using %DUMP_PREFIX_ADDRESS:
* ffffffff88089af0: 70717273 74757677 78797a7b 7c7d7e7f pqrstuvwxyz{|}~.
* 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, int prefix_type, void *buf, size_t len)
void print_hex_dump(const char *level, const char *prefix_str, int prefix_type,
int rowsize, int groupsize,
void *buf, size_t len, bool ascii)
{
u8 *ptr = buf;
int i, linelen, remaining = len;
unsigned char linebuf[100];
unsigned char linebuf[200];

for (i = 0; i < len; i += 16) {
linelen = min(remaining, 16);
remaining -= 16;
hex_dump_to_buffer(ptr + i, linelen, linebuf, sizeof(linebuf));
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%*p: %s\n", level,
printk("%s%s%*p: %s\n", level, prefix_str,
(int)(2 * sizeof(void *)), ptr + i, linebuf);
break;
case DUMP_PREFIX_OFFSET:
printk("%s%.8x: %s\n", level, i, linebuf);
printk("%s%s%.8x: %s\n", level, prefix_str, i, linebuf);
break;
default:
printk("%s%s\n", level, linebuf);
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,
void *buf, size_t len)
{
print_hex_dump(KERN_DEBUG, prefix_str, prefix_type, 16, 1,
buf, len, 1);
}
EXPORT_SYMBOL(print_hex_dump_bytes);

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