I/O permissions

Imyrryr · 12-03-2003, 08:15 PM

When trying to run either seejpeg Screenshot.jpg and/or links -g I receive the following error: svgalib: Cannot get I/O permission as a regular user.

I understand this is a permission to the file that controls 'svgalib' but I'm not real sure which file I need to adjust permissions.

I've tried changing /dev/video* to chmod 666 this didn't help much either, same error

Any assistance would be greatly appreciated as well as passed on to those that may be having the same problem.

teval · 12-03-2003, 08:22 PM

strace is your friend.
probably with -f option. It'll give you pages of output, just look twoards the end, and see what fails. It'll show you what syscall the program is making (you'll see the file it's trying to get I/O rights on)
I usually do..

strace -f <program> &> programdump

Then just open programdump in your favourite editor, and look twoards the end.

Imyrryr · 12-03-2003, 09:06 PM

Well here is what I got:
tail c10 svga_io_dump

munmap(0x40016000, 4096) = 0
open("/home/gelnven/.svgalibrc", O_RDONLY) = -1 ENOENT (No such file or directory)
ioperm(0x3b4, 0x2c, 0x1) = -1 EPERM (Operation not permitted)
fstat64(1, {st_mode=S_IFCHR|0620, st_rdev=makedev(136, 0), ...}) = 0old_mmap(NULL, 4096, PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, -1, 0) = 0x40016000
write(1, "svgalib: Cannot get I/O permissi"..., 37svgalib: Cannot get I/O permissions.
) = 37
munmap(0x40016000, 4096) = 0
exit_group(1) = ?

okay, not exactly sure what I'm looking for but I'm guessing it's either the line that says no such file or the one that says operation not permitted? But from what I understand (although I could be wrong) if the file /etc/vga/vgalib.config exists there is not a requirement for the .svgalibrc.

teval · 12-03-2003, 10:04 PM

Create it anyway, and just see what happens.
Just..
touch /home/gelnven/.svgalibrc

Imyrryr · 05-16-2004, 07:21 AM

Whoa! completely forgot about this post but I found the fix for it: you have to chmod u+s seejpeg

rignes · 08-03-2004, 05:39 PM

That works but I'd call that a security risk. Espcially if it's done with links for using graphics mode.

I'm trying to find out if I can manage to use links -g and seejpeg as a non-root user without having to suid root.

Brian