On 2017-07-12 14:38, [ext] Reichel Andreas wrote:
> If the user manually creates a loopback device node
> in /dev, for example /dev/NAME and uses it to setup a
> loopback device, the resulting base name of /sys/block/loop*
> does not match that of /dev/NAME. On some systems,
> /dev/loop* gets created automatically by using losetup, on
> others not.
> The solution is to read the major and minor revision
> out of /sys/block/NAME/dev and look for the same
> in /dev. Thus, the correct block device node in /dev
> can be found.
>
> Signed-off-by: Andreas Reichel <[email protected]>
> ---
> tools/ebgpart.c | 105
> ++++++++++++++++++++++++++++++++++++++++++++++++--------
> tools/ebgpart.h | 5 ++-
> 2 files changed, 95 insertions(+), 15 deletions(-)
>
> diff --git a/tools/ebgpart.c b/tools/ebgpart.c
> index 07edb05..940652f 100644
> --- a/tools/ebgpart.c
> +++ b/tools/ebgpart.c
> @@ -353,27 +353,104 @@ bool check_partition_table(PedDevice *dev)
> return true;
> }
>
> -void ped_device_probe_all()
> +int scan_devdir(unsigned int fmajor, unsigned int fminor, char *fullname,
> + unsigned int maxlen)
static - the compiler should complain about lacking prototype, or didn't
we enable that check?
> {
> - struct dirent *devfile;
> - char fullname[256];
> + int result = -1;
>
> - DIR *devdir = opendir(DEVDIRNAME);
> + DIR *devdir = opendir(DEVDIR);
> if (!devdir) {
> - VERBOSE(stderr, "Could not open %s\n", DEVDIRNAME);
> + VERBOSE(stderr, "Failed to open %s\n", DEVDIR);
> + return result;
> + }
> + struct dirent *devfile;
> + do {
> + devfile = readdir(devdir);
> + if (!devfile) {
> + break;
> + }
> + snprintf(fullname, maxlen, "%s/%s", DEVDIR, devfile->d_name);
> + struct stat fstat;
> + if (stat(fullname, &fstat) == -1) {
> + VERBOSE(stderr, "stat failed on %s\n", fullname);
> + break;
> + }
> + if (major(fstat.st_rdev) == fmajor &&
> + minor(fstat.st_rdev) == fminor) {
> + VERBOSE(stdout, "Node found: %s\n", fullname);
> + result = 0;
> + break;
> + }
> + } while (devfile);
> + closedir(devdir);
> +
> + return result;
> +}
> +
> +int get_major_minor(char *filename, unsigned int *major, unsigned int *minor)
static
> +{
> + if (!filename || !major || !minor) {
Really possible or just over-defensive programming? Specifically when
the caller is local, I'm reluctant to sprinkle such checks.
Looking at the caller, it's impossible. So drop these pointless checks.
> + return -1;
> + }
> + FILE *fh = fopen(filename, "r");
> + if (fh == 0) {
> + VERBOSE(stderr, "Error opening %s for read", filename);
> + return -1;
> + }
> + int res = fscanf(fh, "%u:%u", major, minor);
> + fclose(fh);
> + if (res < 2) {
> + VERBOSE(stderr,
> + "Error reading major/minor of device entry. (%s)\n",
> + strerror(errno));
> + return -1;
> + };
> + return 0;
> +}
> +
> +void ped_device_probe_all()
> +{
> + struct dirent *sysblockfile;
> + char fullname[DEV_FILENAME_LEN];
> +
> + DIR *sysblockdir = opendir(SYSBLOCKDIR);
> + if (!sysblockdir) {
> + VERBOSE(stderr, "Could not open %s\n", SYSBLOCKDIR);
> return;
> }
>
> - /* get all files from devdir */
> + /* get all files from sysblockdir */
> do {
> - devfile = readdir(devdir);
> - if (!devfile)
> + sysblockfile = readdir(sysblockdir);
> + if (!sysblockfile) {
> break;
> - if (strcmp(devfile->d_name, ".") == 0 ||
> - strcmp(devfile->d_name, "..") == 0)
> + }
> + if (strcmp(sysblockfile->d_name, ".") == 0 ||
> + strcmp(sysblockfile->d_name, "..") == 0) {
> continue;
> -
> - snprintf(fullname, 255, "/dev/%s", devfile->d_name);
> + }
> + snprintf(fullname, DEV_FILENAME_LEN, "/sys/block/%s/dev",
sizeof(fullname) would be better, here and below.
> + sysblockfile->d_name);
> + /* Get major and minor revision from /sys/block/sdX/dev */
> + unsigned int fmajor, fminor;
> + if (get_major_minor(fullname, &fmajor, &fminor) < 0) {
> + continue;
> + }
> + VERBOSE(stdout,
> + "Trying device with: Major = %d, Minor = %d, (%s)\n",
> + fmajor, fminor, fullname);
> + /* Check if this file is really in the dev directory */
> + snprintf(fullname, DEV_FILENAME_LEN, "%s/%s", DEVDIR,
> + sysblockfile->d_name);
> + struct stat fstat;
> + if (stat(fullname, &fstat) == -1) {
> + /* Node with same name not found in /dev, thus search
> + * for node with identical Major and Minor revision */
> + if (scan_devdir(fmajor, fminor, fullname,
> + DEV_FILENAME_LEN) != 0) {
> + continue;
> + }
> + }
> /* This is a block device, so add it to the list*/
> PedDevice *dev = calloc(sizeof(PedDevice), 1);
> asprintf(&dev->model, "N/A");
> @@ -385,9 +462,9 @@ void ped_device_probe_all()
> free(dev->path);
> free(dev);
> }
> - } while (devfile);
> + } while (sysblockfile);
>
> - closedir(devdir);
> + closedir(sysblockdir);
> }
>
> void ped_partition_destroy(PedPartition *p)
> diff --git a/tools/ebgpart.h b/tools/ebgpart.h
> index 76fee9d..fbaa77c 100644
> --- a/tools/ebgpart.h
> +++ b/tools/ebgpart.h
> @@ -25,6 +25,8 @@
> #define _GNU_SOURCE
> #endif
>
> +#define DEV_FILENAME_LEN 256
> +
> #ifndef VERBOSE
> #define VERBOSE(o, ...)
> \
> if (verbosity) fprintf(o, __VA_ARGS__)
> @@ -41,7 +43,8 @@
> #include <string.h>
> #include <stdlib.h>
>
> -#define DEVDIRNAME "/sys/block"
> +#define SYSBLOCKDIR "/sys/block"
> +#define DEVDIR "/dev"
>
> #define LB_SIZE 512
>
>
Jan
--
Siemens AG, Corporate Technology, CT RDA ITP SES-DE
Corporate Competence Center Embedded Linux
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