Hi, I just tried to find the byte position of a string within a binary file using grep. Our base grep -bo let me down because it will only display the position of the '\n' delimited line, not the position of the pattern.
That's what our grep(1) says:
-b The offset in bytes of a matched pattern is displayed in
front of the respective matched line.
what it actually does is displaying the offset of the line, not the
pattern. I think it should read as following:
-b Each output line is preceded by its position (in bytes) in the
file. If option -o is also specified, the offset in bytes of
the actual matched pattern is displayed.
and here's the diff. Regression tests still pass. OK?
Christopher
Index: grep.1
===================================================================
RCS file: /cvs/src/usr.bin/grep/grep.1,v
retrieving revision 1.45
diff -u -p -r1.45 grep.1
--- grep.1 10 Dec 2017 09:17:24 -0000 1.45
+++ grep.1 16 Jul 2019 21:16:18 -0000
@@ -131,8 +131,11 @@ and
.Fl C
options.
.It Fl b
-The offset in bytes of a matched pattern is
-displayed in front of the respective matched line.
+Each output line is preceded by its position (in bytes) in the file.
+If option
+.Fl o
+is also specified, the offset in bytes of the actual matched pattern is
+displayed.
.It Fl C Ns Oo Ar num Oc , Fl -context Ns Op = Ns Ar num
Print
.Ar num
Index: util.c
===================================================================
RCS file: /cvs/src/usr.bin/grep/util.c,v
retrieving revision 1.59
diff -u -p -r1.59 util.c
--- util.c 23 Jan 2019 23:00:54 -0000 1.59
+++ util.c 16 Jul 2019 21:16:18 -0000
@@ -250,9 +250,9 @@ print:
if (Bflag > 0)
printqueue();
linesqueued = 0;
- printline(l, ':', oflag ? &pmatch : NULL);
+ printline(l, ':', &pmatch);
} else {
- printline(l, '-', oflag ? &pmatch : NULL);
+ printline(l, '-', &pmatch);
tail--;
}
}
@@ -651,12 +651,14 @@ printline(str_t *line, int sep, regmatch
if (bflag) {
if (n)
putchar(sep);
- printf("%lld", (long long)line->off);
+ printf("%lld",
+ (long long)line->off
+ + (pmatch && oflag ? pmatch->rm_so : 0));
++n;
}
if (n)
putchar(sep);
- if (pmatch)
+ if (oflag && pmatch)
fwrite(line->dat + pmatch->rm_so,
pmatch->rm_eo - pmatch->rm_so, 1, stdout);
else
--
http://gmerlin.de
OpenPGP: http://gmerlin.de/christopher.pub
CB07 DA40 B0B6 571D 35E2 0DEF 87E2 92A7 13E5 DEE1
--
http://gmerlin.de
OpenPGP: http://gmerlin.de/christopher.pub
CB07 DA40 B0B6 571D 35E2 0DEF 87E2 92A7 13E5 DEE1
pgp36UztoKX1k.pgp
Description: OpenPGP digital signature
