Juergen,
I was looking at your Linux code here and thought
the technique of trying lseek(SEEK_END) might work.
Unfortunately, it doesn't: lseek(fd, 0, SEEK_END) gives
zero for both /dev/sa0 (a tape drive) and /dev/cd0
(an optical drive). Are you sure it works on Linux?
Tim
P.S. Here's the program I used to test. Running it
against regular files and various device
nodes is quite illuminating.
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
int
main(int argc, char **argv)
{
int fd;
if (argv[1] == NULL) {
fprintf(stderr, "Need to specify a pathname.\n");
exit(1);
}
fd = open(argv[1], O_RDWR);
printf("fd=%d\n", fd);
printf("lseek(fd, 0, SEEK_SET)=%d\n",
(int)lseek(fd, 0, SEEK_SET));
printf("lseek(fd, 10240, SEEK_SET)=%d\n",
(int)lseek(fd, 10240, SEEK_SET));
printf("lseek(fd, 10240, SEEK_CUR)=%d\n",
(int)lseek(fd, 10240, SEEK_CUR));
printf("lseek(fd, 0, SEEK_END)=%d\n",
(int)lseek(fd, 0, SEEK_END));
printf("lseek(fd, 0, SEEK_SET)=%d\n",
(int)lseek(fd, 0, SEEK_SET));
return (0);
}
Juergen Lock wrote:
On Thu, Feb 18, 2010 at 10:12:24PM -0800, Garrett Cooper wrote:
On Thu, Feb 18, 2010 at 10:34 AM, Juergen Lock <n...@jelal.kn-bremen.de> wrote:
On Wed, Feb 17, 2010 at 10:38:30PM -0800, Tim Kientzle wrote:
Juergen Lock wrote:
... since bsdtar/libarchive know iso9660 I just did the command in the
Subject. It worked, but it was sloow... :( Apparently it read all of
the disc without seeking. The following patch fixes this, is something
like this desired? If yes I could look how to do the same for Linux,
Juergen,
This is great! If you can figure out how to get this
right, I would really appreciate it. If you have a
tape drive handy, definitely test with that. My first
attempts here actually broke reading from tape drives,
which is why the current code is so conservative.
Hmm I can't test on a tape atm but if I look at the kernel,
http://fxr.watson.org/fxr/ident?i=DIOCGMEDIASIZE
DIOCGMEDIASIZE is only handled for geom, xen block devices, old CD drives
and pc98 floppies, and I'm pretty sure tapes don't use geom. :)
Minor style comments:
else if (S_ISCHR(st.st_mode) &&
!ioctl(fd, DIOCGMEDIASIZE, &mediasize) && mediasize) {
Please be explicit: S_ISCHR() && ioctl() == 0 && mediasize > 0
archive_read_extract_set_skip_file(a, st.st_dev, st.st_ino);
extract_skip_file isn't needed here; we don't read the
contents of device nodes.
Let me know as soon as you have something you're confident of.
Ok here is a new version of the patch with these things fixed and the
Linux case added: (Linux case not tested yet, and yes I did this on
stable/8.)
Index: src/lib/libarchive/archive_read_open_filename.c
===================================================================
RCS file: /home/scvs/src/lib/libarchive/archive_read_open_filename.c,v
retrieving revision 1.25.2.1
diff -u -p -r1.25.2.1 archive_read_open_filename.c
--- src/lib/libarchive/archive_read_open_filename.c 3 Aug 2009 08:13:06
-0000 1.25.2.1
+++ src/lib/libarchive/archive_read_open_filename.c 18 Feb 2010 18:14:16
-0000
@@ -44,6 +44,10 @@ __FBSDID("$FreeBSD: src/lib/libarchive/a
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
+#ifdef __FreeBSD__
+#include <sys/ioctl.h>
+#include <sys/disk.h>
+#endif
#include "archive.h"
@@ -83,6 +87,9 @@ archive_read_open_filename(struct archiv
struct read_file_data *mine;
void *b;
int fd;
+#ifdef __FreeBSD__
+ off_t mediasize = 0;
+#endif
archive_clear_error(a);
if (filename == NULL || filename[0] == '\0') {
@@ -143,6 +150,27 @@ archive_read_open_filename(struct archiv
*/
mine->can_skip = 1;
}
+#ifdef __FreeBSD__
+ /*
+ * on FreeBSD if a device supports the DIOCGMEDIASIZE ioctl
+ * it is a disk-like device and should be seekable.
+ */
+ else if (S_ISCHR(st.st_mode) &&
+ ioctl(fd, DIOCGMEDIASIZE, &mediasize) == 0 && mediasize > 0) {
+ mine->can_skip = 1;
+ }
+#endif
+#ifdef __linux__
Is there any reason why a) you wouldn't check for other BSDs? b) you
aren't doing something of the flavor...
#if defined(__FreeBSD__)
#elif defined(__linux__)
#endif
Okok, here's a new version of the patch that now also knows about
other BSDs and switched to #elif: (only NetBSD actually tested tho
since I had a VM lying around, more testing welcome!)
(Also if anyone wants to switch this to autoconf-style HAVE_FOO
handling they are welcome too... :)
Enjoy,
Juergen
Index: src/lib/libarchive/archive_read_open_filename.c
===================================================================
RCS file: /home/scvs/src/lib/libarchive/archive_read_open_filename.c,v
retrieving revision 1.25.2.1
diff -u -p -u -p -r1.25.2.1 archive_read_open_filename.c
--- src/lib/libarchive/archive_read_open_filename.c 3 Aug 2009 08:13:06
-0000 1.25.2.1
+++ src/lib/libarchive/archive_read_open_filename.c 19 Feb 2010 18:18:24
-0000
@@ -44,6 +44,17 @@ __FBSDID("$FreeBSD: src/lib/libarchive/a
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+#include <sys/ioctl.h>
+#include <sys/disk.h>
+#elif defined(__NetBSD__) || defined(__OpenBSD__)
+#include <sys/ioctl.h>
+#include <sys/disklabel.h>
+#include <sys/dkio.h>
+#elif defined(__DragonFly__)
+#include <sys/ioctl.h>
+#include <sys/diskslice.h>
+#endif
#include "archive.h"
@@ -83,6 +94,13 @@ archive_read_open_filename(struct archiv
struct read_file_data *mine;
void *b;
int fd;
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+ off_t mediasize = 0;
+#elif defined(__NetBSD__) || defined(__OpenBSD__)
+ struct disklabel dl;
+#elif defined(__DragonFly__)
+ struct partinfo pi;
+#endif
archive_clear_error(a);
if (filename == NULL || filename[0] == '\0') {
@@ -143,6 +161,45 @@ archive_read_open_filename(struct archiv
*/
mine->can_skip = 1;
}
+#if defined(__FreeBSD__) || defined(__FreeBSD_kernel__)
+ /*
+ * on FreeBSD if a device supports the DIOCGMEDIASIZE ioctl
+ * it is a disk-like device and should be seekable.
+ */
+ else if (S_ISCHR(st.st_mode) &&
+ ioctl(fd, DIOCGMEDIASIZE, &mediasize) == 0 && mediasize > 0) {
+ mine->can_skip = 1;
+ }
+#elif defined(__NetBSD__) || defined(__OpenBSD__)
+ /*
+ * on Net/OpenBSD if a device supports the DIOCGDINFO ioctl
+ * it is a disk-like device and should be seekable.
+ */
+ else if ((S_ISCHR(st.st_mode) || S_ISBLK(st.st_mode)) &&
+ ioctl(fd, DIOCGDINFO, &dl) == 0 &&
+ dl.d_partitions[DISKPART(st.st_rdev)].p_size > 0) {
+ mine->can_skip = 1;
+ }
+#elif defined(__DragonFly__)
+ /*
+ * on DragonFly BSD if a device supports the DIOCGPART ioctl
+ * it is a disk-like device and should be seekable.
+ */
+ else if (S_ISCHR(st.st_mode) &&
+ ioctl(fd, DIOCGPART, &pi) == 0 && pi.media_size > 0) {
+ mine->can_skip = 1;
+ }
+#elif defined(__linux__)
+ /*
+ * on Linux just check whether its a block device and that
+ * lseek works. (Tapes are character devices there.)
+ */
+ else if (S_ISBLK(st.st_mode) &&
+ lseek(fd, 0, SEEK_CUR) == 0 && lseek(fd, 0, SEEK_SET) == 0 &&
+ lseek(fd, 0, SEEK_END) > 0 && lseek(fd, 0, SEEK_SET) == 0) {
+ mine->can_skip = 1;
+ }
+#endif
return (archive_read_open2(a, mine,
NULL, file_read, file_skip, file_close));
}
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