Upgrade mdev to allow commands to be run on create/delete.
Both Jason Schoon and Giuseppe Ciotta deserve credit for this, I used elements of both. It's been upgraded so that you can specify that a given command should run at create, at delete, or at both using different special characters (@, $, and * respectively). It uses the system() method of running command lines which means you can use environment variables on the command line (it sets $MDEV to the name of the current device being created/deleted, which is useful if you matched it via regex), and the documentation warns that you need a /bin/sh to make that work, so you probably want to pick a default shell.
This commit is contained in:
Rob Landley
parent
cf7577d417
commit
ef10d52745
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@ -1799,19 +1799,25 @@ USE_FEATURE_DATE_ISOFMT( \
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"\t-s\tScan /sys and populate /dev during system boot\n\n" \
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"Called with no options (via hotplug) it uses environment variables\n" \
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"to determine which device to add/remove."
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#ifdef CONFIG_FEATURE_MDEV_CONFIG
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#define mdev_notes_usage \
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#define mdev_notes_usage "" \
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USE_FEATURE_MDEV_CONFIG( \
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"The mdev config file contains lines that look like:\n" \
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" hd[a-z][0-9]* 0:3 660\n\n" \
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"That's device name (with regex match), uid:gid, and permissions.\n\n" \
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"Optionally, that can be followed (on the same line) by an asterisk\n" \
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"and a command line to run after creating the corresponding device(s),\n"\
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"ala:\n\n" \
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" hdc root:cdrom 660 *ln -s hdc cdrom\n\n" \
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USE_FEATURE_MDEV_EXEC( \
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"Optionally, that can be followed (on the same line) by a special character\n" \
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"and a command line to run after creating/before deleting the corresponding\n" \
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"device(s). The environment variable $MDEV indicates the active device node\n" \
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"(which is useful if it's a regex match). For example:\n\n" \
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" hdc root:cdrom 660 *ln -s $MDEV cdrom\n\n" \
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"The special characters are @ (run after creating), $ (run before deleting),\n" \
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"and * (run both after creating and before deleting). The commands run in\n" \
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"the /dev directory, and use system() which calls /bin/sh.\n\n" \
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) \
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"Config file parsing stops on the first matching line. If no config\n"\
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"entry is matched, devices are created with default 0:0 660. (Make\n"\
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"the last line match .* to override this.)\n\n"
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#endif
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"the last line match .* to override this.)\n\n" \
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)
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#define mesg_trivial_usage \
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"[y|n]"
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@ -265,16 +265,31 @@ config CONFIG_FEATURE_MDEV_CONF
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That's device name (with regex match), uid:gid, and permissions.
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Optionally, that can be followed (on the same line) by an asterisk
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and a command line to run after creating the corresponding device(s),
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ala:
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hdc root:cdrom 660 *ln -s hdc cdrom
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Config file parsing stops on the first matching line. If no config
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entry is matched, devices are created with default 0:0 660. (Make
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the last line match .* to override this.)
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config CONFIG_FEATURE_MDEV_EXEC
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bool "Support command execution at device addition/removal"
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default n
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depends on CONFIG_FEATURE_MDEV_CONF
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help
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This adds support for an optional field to /etc/mdev.conf, consisting
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of a special character and a command line to run after creating the
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corresponding device(s) and before removing, ala:
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hdc root:cdrom 660 *ln -s $MDEV cdrom
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The $MDEV environment variable is set to the name of the device.
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The special characters and their meanings are:
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@ Run after creating the device.
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$ Run before removing the device.
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* Run both after creating and before removing the device.
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Commands are executed via system() so you need /bin/sh, meaning you
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probably want to select a default shell in the Shells menu.
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config CONFIG_MKSWAP
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bool "mkswap"
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default n
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@ -8,25 +8,14 @@
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* Licensed under GPLv2 or later, see file LICENSE in this tarball for details.
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*/
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#include <ctype.h>
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#include <dirent.h>
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#include <errno.h>
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#include <fcntl.h>
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#include <stdio.h>
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#include <string.h>
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#include <sys/mman.h>
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#include <sys/stat.h>
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#include <sys/sysmacros.h>
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#include <sys/types.h>
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#include <unistd.h>
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#include <stdlib.h>
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#include "busybox.h"
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#include <ctype.h>
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#include <errno.h>
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#include <sys/mman.h>
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#include <sys/sysmacros.h>
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#include "xregex.h"
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#define DEV_PATH "/dev"
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#define MDEV_CONF "/etc/mdev.conf"
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#include <busybox.h>
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struct mdev_globals
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{
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@ -36,14 +25,15 @@ struct mdev_globals
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#define bbg mdev_globals
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/* mknod in /dev based on a path like "/sys/block/hda/hda1" */
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static void make_device(char *path)
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static void make_device(char *path, int delete)
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{
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char *device_name, *s;
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char *device_name;
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int major, minor, type, len, fd;
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int mode = 0660;
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uid_t uid = 0;
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gid_t gid = 0;
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char *temp = path + strlen(path);
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char *command = NULL;
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/* Try to read major/minor string. Note that the kernel puts \n after
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* the data, so we don't need to worry about null terminating the string
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@ -69,7 +59,7 @@ static void make_device(char *path)
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char *conf, *pos, *end;
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/* mmap the config file */
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if (-1 != (fd=open(MDEV_CONF,O_RDONLY))) {
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if (-1 != (fd=open("/etc/mdev.conf",O_RDONLY))) {
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len = lseek(fd, 0, SEEK_END);
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conf = mmap(NULL, len, PROT_READ, MAP_PRIVATE, fd, 0);
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if (conf) {
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@ -86,88 +76,89 @@ static void make_device(char *path)
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;
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/* Three fields: regex, uid:gid, mode */
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for (field=3; field; field--) {
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for (field=0; field < (3 + ENABLE_FEATURE_MDEV_EXEC);
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field++)
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{
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/* Skip whitespace */
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while (pos<end && isspace(*pos))
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pos++;
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if (pos==end || *pos=='#')
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break;
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for (end2=pos; end2<end && !isspace(*end2) && *end2!='#'; end2++)
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while (pos<end && isspace(*pos)) pos++;
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if (pos==end || *pos=='#') break;
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for (end2=pos;
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end2<end && !isspace(*end2) && *end2!='#'; end2++)
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;
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switch (field) {
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if (!field) {
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/* Regex to match this device */
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case 3:
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{
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char *regex = strndupa(pos,end2-pos);
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regex_t match;
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regmatch_t off;
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int result;
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/* Is this it? */
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xregcomp(&match,regex,REG_EXTENDED);
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result = regexec(&match,device_name,1,&off,0);
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regfree(&match);
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char *regex = strndupa(pos, end2-pos);
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regex_t match;
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regmatch_t off;
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int result;
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/* If not this device, skip rest of line */
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if (result || off.rm_so || off.rm_eo!=strlen(device_name))
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goto end_line;
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/* Is this it? */
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xregcomp(&match,regex, REG_EXTENDED);
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result = regexec(&match, device_name, 1, &off, 0);
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regfree(&match);
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/* If not this device, skip rest of line */
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if (result || off.rm_so
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|| off.rm_eo != strlen(device_name))
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break;
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}
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} else if (field == 1) {
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/* uid:gid */
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case 2:
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{
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char *s2;
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/* Find : */
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for(s=pos; s<end2 && *s!=':'; s++)
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;
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if (s == end2)
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goto end_line;
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char *s, *s2;
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/* Parse UID */
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uid = strtoul(pos,&s2,10);
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if (s != s2) {
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struct passwd *pass;
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pass = getpwnam(strndupa(pos,s-pos));
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if (!pass)
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goto end_line;
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uid = pass->pw_uid;
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}
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s++;
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/* parse GID */
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gid = strtoul(s,&s2,10);
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if (end2 != s2) {
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struct group *grp;
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grp = getgrnam(strndupa(s,end2-s));
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if (!grp)
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goto end_line;
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gid = grp->gr_gid;
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}
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/* Find : */
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for(s=pos; s<end2 && *s!=':'; s++)
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;
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if (s == end2) break;
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/* Parse UID */
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uid = strtoul(pos,&s2,10);
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if (s != s2) {
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struct passwd *pass;
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pass = getpwnam(strndupa(pos, s-pos));
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if (!pass) break;
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uid = pass->pw_uid;
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}
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s++;
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/* parse GID */
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gid = strtoul(s, &s2, 10);
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if (end2 != s2) {
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struct group *grp;
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grp = getgrnam(strndupa(s, end2-s));
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if (!grp) break;
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gid = grp->gr_gid;
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}
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} else if (field == 2) {
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/* mode */
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mode = strtoul(pos, &pos, 8);
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if (pos != end2) break;
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} else if (ENABLE_FEATURE_MDEV_EXEC && field == 3) {
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// Command to run
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char *s = "@$*", *s2;
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if (!(s2 = strchr(s, *pos++))) {
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// Force error
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field = 1;
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break;
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}
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/* mode */
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case 1:
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{
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mode = strtoul(pos,&pos,8);
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if (pos != end2)
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goto end_line;
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else
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goto found_device;
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}
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if ((s2-s+1) & (1<<delete))
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command = bb_xstrndup(pos, end-pos);
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}
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pos = end2;
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}
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end_line:
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/* Did everything parse happily? */
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if (field && field!=3)
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bb_error_msg_and_die("Bad line %d",line);
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if (field > 2) break;
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if (field) bb_error_msg_and_die("Bad line %d",line);
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/* Next line */
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pos = ++end;
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}
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found_device:
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munmap(conf, len);
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}
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close(fd);
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@ -175,13 +166,29 @@ found_device:
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}
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umask(0);
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if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
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bb_perror_msg_and_die("mknod %s failed", device_name);
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if (!delete) {
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if (mknod(device_name, mode | type, makedev(major, minor)) && errno != EEXIST)
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bb_perror_msg_and_die("mknod %s failed", device_name);
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if (major==bbg.root_major && minor==bbg.root_minor)
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symlink(device_name, "root");
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if (major == bbg.root_major && minor == bbg.root_minor)
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symlink(device_name, "root");
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if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
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if (ENABLE_FEATURE_MDEV_CONF) chown(device_name, uid, gid);
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}
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if (command) {
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int rc;
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char *s;
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s=bb_xasprintf("MDEV=%s",device_name);
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putenv(s);
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rc = system(command);
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s[4]=0;
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putenv(s);
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free(s);
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free(command);
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if (rc == -1) bb_perror_msg_and_die("Couldn't run %s", command);
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}
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if (delete) unlink(device_name);
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}
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/* Recursive search of /sys/block or /sys/class. path must be a writeable
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@ -212,7 +219,7 @@ static void find_dev(char *path)
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/* If there's a dev entry, mknod it */
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if (!strcmp(entry->d_name, "dev")) make_device(path);
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if (!strcmp(entry->d_name, "dev")) make_device(path, 0);
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}
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closedir(dir);
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@ -247,12 +254,9 @@ int mdev_main(int argc, char *argv[])
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if (!action || !env_path)
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bb_show_usage();
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if (!strcmp(action, "add")) {
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sprintf(temp, "/sys%s", env_path);
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make_device(temp);
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} else if (!strcmp(action, "remove")) {
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unlink(strrchr(env_path, '/') + 1);
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}
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sprintf(temp, "/sys%s", env_path);
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if (!strcmp(action, "add")) make_device(temp,0);
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else if (!strcmp(action, "remove")) make_device(temp,1);
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}
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if (ENABLE_FEATURE_CLEAN_UP) RELEASE_CONFIG_BUFFER(temp);
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