On Sun, Jan 18, 2015 at 01:11:15PM +0100, k...@aspodata.se wrote: > Isaac Dunham: > > On Sat, Jan 17, 2015 at 08:06:05PM +0100, k...@aspodata.se wrote: > > > Also a lib that maps major/minor to /dev/name and the like, a command > > > that "scans lspci" and the like, and suggests kernel modules, > > > which I then at my own discretion can add to /etc/modules. > > > I.e. an udev that instead of taking over the system, gives me some > > > tools I could use to examine a system. > > > > To map major/minor/devtype to /dev/name (note: /dev/zero has the same > > major/minor as /dev/ram5; one is char, the other is block) you really > > need to recurse through /dev and find the first file that matches. > > > > I could write a non-threadsafe version of said function using nftw() > > in a day, I suppose; if I lift the dirtree code from toybox and patch > > it to fit, it might be not be much more work... > > > > So does "libsysdev" sound like a good name, and > > char * sysdev_getdevname(int major, int minor, int ischar); > > seem like a good prototype? > > Yes. > > Mesa uses the name sysfs, which might be better than sysdev. > The following two might be a good start: > > $ grep ^sysfs src/loader/loader.c > sysfs_get_pci_id_for_fd(int fd, int *vendor_id, int *chip_id) > sysfs_get_device_name_for_fd(int fd) > > and > > dev_node_from_fd(int fd, unsigned int *maj, unsigned int *min) > > libsysfs seems to be taken: > http://linux-diag.sourceforge.net/Sysfsutils.html > http://storage.jak-stik.ac.id/linux/doc/sysfsutils/libsysfs.pdf
libsysfs, which is used by udev, has already taken the sysfs_ namespace. I don't want to collide with that. I'd like to provide something that can be utilized as a fallback when libudev is missing/udev doesn't start. Optimally, the API will be simple enough that developers then say "And why aren't we using this *instead* of libudev?" A preview is available at https://github.com/idunham/libsysdev There's a basic example at util/devinfo.c, and the header has comments tersely explaining what inputs each function takes. I wrote it so that the udev usage in xf86-input-evdev can be replaced with more or less this: devfd = open(devicenode, O_RDONLY); if (devfd < 0) goto out; devpath = sysdev_devfd_to_syspath(devfd); if (devpath) { if (strstr(devpath, "LNXSYSTM")) rc = TRUE; free(devpath); } close(devfd); out: return rc; I have not yet tested that, however. It builds with "make" (no ./configure). It will build and install into /usr/{bin,lib,include} by default. On debian, devuan, and related distros, you will need to install with: make LIBDIR="/usr/lib/$TRIPLET" install On non-pure64 64-bit installs of other distros, you will need to set LIBDIR to point to the appropriate directory (lib32 or lib64). Before I fix that, I'd like some pointers on how to pick up the right triplet on multiarch and the right libdir on multilib. (as a shell snippet). I want to add a .pc file for pkg-config; I've delayed that to get the code out as soon as possible. Comments, requests, patches welcome; flames to /dev/null. Thanks, Isaac Dunham _______________________________________________ Dng mailing list Dng@lists.dyne.org https://mailinglists.dyne.org/cgi-bin/mailman/listinfo/dng
