svn commit: r327567 - head/usr.bin/hexdump
Kyle Evans
kevans at FreeBSD.org
Fri Jan 5 01:46:42 UTC 2018
Author: kevans
Date: Fri Jan 5 01:46:41 2018
New Revision: 327567
URL: https://svnweb.freebsd.org/changeset/base/327567
Log:
hexdump(1): Speed up -s flag on devices
Using the -s flag on devices is extraordinarily slow due to using fseek(3) a
little too conservatively. Address this by using fseek on character/block
devices as well, falling back to getchar(3) only if we fail to seek or we're
operating on tape drives, where fseek may succeed while not actually being
supported.
PR: 86485
Submitted by: arundel (originally; modified since then)
Reviewed by: cem
Differential Revision: https://reviews.freebsd.org/D10939
Modified:
head/usr.bin/hexdump/display.c
Modified: head/usr.bin/hexdump/display.c
==============================================================================
--- head/usr.bin/hexdump/display.c Thu Jan 4 23:07:51 2018 (r327566)
+++ head/usr.bin/hexdump/display.c Fri Jan 5 01:46:41 2018 (r327567)
@@ -39,6 +39,8 @@ __FBSDID("$FreeBSD$");
#include <sys/param.h>
#include <sys/capsicum.h>
+#include <sys/conf.h>
+#include <sys/ioctl.h>
#include <sys/stat.h>
#include <capsicum_helpers.h>
@@ -57,6 +59,7 @@ static off_t address; /* address/offset in stream */
static off_t eaddress; /* end address */
static void print(PR *, u_char *);
+static void noseek(void);
void
display(void)
@@ -386,7 +389,7 @@ next(char **argv)
void
doskip(const char *fname, int statok)
{
- int cnt;
+ int type;
struct stat sb;
if (statok) {
@@ -398,16 +401,37 @@ doskip(const char *fname, int statok)
return;
}
}
- if (statok && S_ISREG(sb.st_mode)) {
- if (fseeko(stdin, skip, SEEK_SET))
+ if (!statok || S_ISFIFO(sb.st_mode) || S_ISSOCK(sb.st_mode)) {
+ noseek();
+ return;
+ }
+ if (S_ISCHR(sb.st_mode) || S_ISBLK(sb.st_mode)) {
+ if (ioctl(fileno(stdin), FIODTYPE, &type))
err(1, "%s", fname);
- address += skip;
- skip = 0;
- } else {
- for (cnt = 0; cnt < skip; ++cnt)
- if (getchar() == EOF)
- break;
- address += cnt;
- skip -= cnt;
+ /*
+ * Most tape drives don't support seeking,
+ * yet fseek() would succeed.
+ */
+ if (type & D_TAPE) {
+ noseek();
+ return;
+ }
}
+ if (fseeko(stdin, skip, SEEK_SET)) {
+ noseek();
+ return;
+ }
+ address += skip;
+ skip = 0;
+}
+
+static void
+noseek(void)
+{
+ int count;
+ for (count = 0; count < skip; ++count)
+ if (getchar() == EOF)
+ break;
+ address += count;
+ skip -= count;
}
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