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Add -e and -E flags to od(1) and properly handle endianness 

The -e and -E flags allow the user to override the host endianness
and force od(1) to handle input according to a little (-e) or big (-E)
endian environment.
The previous handling was broken as bitshifts alone are already
endian-independent.
This commit is contained in:
FRIGN 2015-10-25 23:26:49 +01:00 committed by sin
parent c619e168c9
commit d03baf1697
2 changed files with 34 additions and 14 deletions
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13
od.1
View File

@ -1,4 +1,4 @@
.Dd 2015-10-09
.Dd 2015-10-25
.Dt OD 1
.Os sbase
.Sh NAME
@ -7,6 +7,7 @@
.Sh SYNOPSIS
.Nm
.Op Fl A Ar addrformat
.Op Fl E | e
.Op Fl t Ar outputformat...
.Op Fl v
.Op Ar file ...
@ -26,6 +27,12 @@ reads from stdin.
is one of d|o|x|n and sets the address to be
either in \fId\fRecimal, \fIo\fRctal, he\fIx\fRadecimal or \fIn\fRot
printed at all. The default is octal.
.It Fl E | e
Force Little Endian
.Fl ( e )
or Big Endian
.Fl ( E )
system-independently.
.It Fl t Ar outputformat
.Ar outputformat
is a list of a|c|d|o|u|x followed by a digit or C|S|I|L and sets
@ -49,3 +56,7 @@ The
flag is enabled by default and the 'd' parameter for the
.Op Fl t
flag is interpreted as 'u'.
.Pp
The
.Op Ee
flags are an extension to that specification.

35
od.c
View File

@ -1,5 +1,4 @@
/* See LICENSE file for copyright and license details. */
#include <endian.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
@ -8,6 +7,8 @@
#include "queue.h"
#include "util.h"
#define HOST_BIG_ENDIAN (*(uint16_t *)"\0\xff" == 0xff)
struct type {
unsigned char format;
unsigned int len;
@ -19,6 +20,7 @@ static unsigned char addr_format = 'o';
static off_t skip = 0;
static off_t max = -1;
static size_t linelen = 1;
static int big_endian;
static void
printaddress(off_t addr)
@ -37,7 +39,7 @@ static void
printchunk(unsigned char *s, unsigned char format, size_t len) {
long long res, basefac;
size_t i;
char fmt[] = " %0*ll#";
char fmt[] = " %#*ll#";
const char *namedict[] = {
"nul", "soh", "stx", "etx", "eot", "enq", "ack",
@ -70,17 +72,18 @@ printchunk(unsigned char *s, unsigned char format, size_t len) {
}
break;
default:
res = 0;
basefac = 1;
#if __BYTE_ORDER == __BIG_ENDIAN
for (i = len; i; i--) {
res += s[i - 1] * basefac;
#else
for (i = 0; i < len; i++) {
res += s[i] * basefac;
#endif
basefac <<= 8;
if (big_endian == HOST_BIG_ENDIAN) {
for (res = 0, basefac = 1, i = 0; i < len; i++) {
res += s[i] * basefac;
basefac <<= 8;
}
} else {
for (res = 0, basefac = 1, i = len; i; i--) {
res += s[i - 1] * basefac;
basefac <<= 8;
}
}
fmt[2] = big_endian ? '-' : '+';
fmt[6] = format;
printf(fmt, (int)(3 * len + len - 1), res);
}
@ -165,7 +168,7 @@ lcm(unsigned int a, unsigned int b)
static void
usage(void)
{
eprintf("usage: %s [-A addressformat] [-t outputformat] "
eprintf("usage: %s [-A addressformat] [-E | -e] [-t outputformat] "
"[-v] [file ...]\n", argv0);
}
@ -177,6 +180,8 @@ main(int argc, char *argv[])
int ret = 0;
char *s;
big_endian = HOST_BIG_ENDIAN;
ARGBEGIN {
case 'A':
s = EARGF(usage());
@ -184,6 +189,10 @@ main(int argc, char *argv[])
usage();
addr_format = s[0];
break;
case 'E':
case 'e':
big_endian = (ARGC() == 'E');
break;
case 'j':
if ((skip = parseoffset(EARGF(usage()))) < 0)
usage();