Date: Thu, 18 Jan 2018 21:59:13 +0000 (UTC) From: Kyle Evans <kevans@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-stable@freebsd.org, svn-src-stable-11@freebsd.org Subject: svn commit: r328149 - stable/11/usr.bin/hexdump Message-ID: <201801182159.w0ILxDSS019416@repo.freebsd.org>
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Author: kevans Date: Thu Jan 18 21:59:13 2018 New Revision: 328149 URL: https://svnweb.freebsd.org/changeset/base/328149 Log: MFC r327567: 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 Modified: stable/11/usr.bin/hexdump/display.c Directory Properties: stable/11/ (props changed) Modified: stable/11/usr.bin/hexdump/display.c ============================================================================== --- stable/11/usr.bin/hexdump/display.c Thu Jan 18 21:53:07 2018 (r328148) +++ stable/11/usr.bin/hexdump/display.c Thu Jan 18 21:59:13 2018 (r328149) @@ -36,6 +36,8 @@ static char sccsid[] = "@(#)display.c 8.1 (Berkeley) 6 __FBSDID("$FreeBSD$"); #include <sys/param.h> +#include <sys/conf.h> +#include <sys/ioctl.h> #include <sys/stat.h> #include <ctype.h> @@ -52,6 +54,7 @@ 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) @@ -368,7 +371,7 @@ next(char **argv) void doskip(const char *fname, int statok) { - int cnt; + int type; struct stat sb; if (statok) { @@ -380,16 +383,37 @@ 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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