rmmod.c

   1 /* rmmod.c: remove a module from the kernel.
   2     Copyright (C) 2001  Rusty Russell.
   3     Copyright (C) 2002  Rusty Russell, IBM Corporation.
   4
   5     This program is free software; you can redistribute it and/or modify
   6     it under the terms of the GNU General Public License as published by
   7     the Free Software Foundation; either version 2 of the License, or
   8     (at your option) any later version.
   9
  10     This program is distributed in the hope that it will be useful,
  11     but WITHOUT ANY WARRANTY; without even the implied warranty of
  12     MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  13     GNU General Public License for more details.
  14
  15     You should have received a copy of the GNU General Public License
  16     along with this program; if not, write to the Free Software
  17     Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
  18 */
  19 #include <stdio.h>
  20 #include <stdlib.h>
  21 #include <string.h>
  22 #include <unistd.h>
  23 #include <errno.h>
  24 #include <fcntl.h>
  25 #include <asm/unistd.h>
  26 #include <stdarg.h>
  27 #include <getopt.h>
  28 #include <syslog.h>
  29
  30 #include "util.h"
  31 #include "logging.h"
  32 #include "testing.h"
  33 #include "backwards_compat.c"
  34
  35 extern long delete_module(const char *, unsigned int);
  36
  37 static char *next_field(const char *line)
  38 {
  39         const char *rest;
  40
  41         rest = line + strcspn(line, " ");
  42         rest += strspn(rest, " ");
  43         return (char *)rest;
  44 }
  45
  46 /* Report that the module is in use. */
  47 static void mod_in_use(const char *modname, char *usedby)
  48 {
  49         /* New /proc/modules uses a single "-" to mean "nothing".  Old
  50            one just puts nothing there. */
  51         if (usedby[0] == '-' || streq(usedby, "")) {
  52                 error("Module %s is in use\n", modname);
  53                 return;
  54         }
  55
  56         /* New /proc/modules *always* prints commas (even if only one) */
  57         if (strchr(usedby, ','))
  58                 /* Blatt over trailing comma for neatness */
  59                 usedby[strcspn(usedby, " \n")-1] = '\0';
  60         else {
  61                 /* Older /proc/modules just put them as
  62                    space-separated names.  Blatt over trailing \n */
  63                 usedby[strlen(usedby)-1] = '\0';
  64         }
  65
  66         error("Module %s is in use by %s\n", modname, usedby);
  67 }
  68
  69 /* If we can check usage without entering kernel, do so. */
  70 static int check_usage(const char *modname)
  71 {
  72         FILE *module_list;
  73         char line[10240], name[64];
  74         unsigned long size, refs;
  75         int scanned;
  76
  77         module_list = fopen("/proc/modules", "r");
  78         if (!module_list) {
  79                 if (errno == ENOENT) /* /proc may not be mounted. */
  80                         return 0;
  81                 fatal("can't open /proc/modules: %s\n", strerror(errno));
  82         }
  83         while (fgets(line, sizeof(line)-1, module_list) != NULL) {
  84                 if (strchr(line, '\n') == NULL) {
  85                         fatal("V. v. long line broke rmmod.\n");
  86                         exit(1);
  87                 }
  88
  89                 scanned = sscanf(line, "%s %lu %lu", name, &size, &refs);
  90                 if (strcmp(name, modname) != 0)
  91                         continue;
  92
  93                 if (scanned < 2)
  94                         fatal("Unknown format in /proc/modules: %s\n", line);
  95
  96                 if (scanned == 2)
  97                         fatal("Kernel does not have unload support.\n");
  98
  99                 /* Hand it fields 3 onwards. */
 100                 if (refs != 0)
 101                         mod_in_use(modname,
 102                                    next_field(next_field(next_field(line))));
 103                 goto out;
 104         }
 105         error("Module %s does not exist in /proc/modules\n", modname);
 106         refs = 1;
 107  out:
 108         fclose(module_list);
 109         return (refs == 0) ? 0 : -EINVAL;
 110 }
 111
 112 static int rmmod(const char *path, int flags)
 113 {
 114         long ret;
 115         char name[strlen(path) + 1];
 116
 117         filename2modname(name, path);
 118
 119         if ((flags & O_NONBLOCK) && !(flags & O_TRUNC)) {
 120                 if (check_usage(name) != 0)
 121                         return 1;
 122         }
 123
 124         info("rmmod %s, wait=%s%s\n", name,
 125              (flags & O_NONBLOCK) ? "no" : "yes",
 126              (flags & O_TRUNC) ? " force" : "");
 127
 128         ret = delete_module(name, flags);
 129         if (ret != 0)
 130                 error("Removing '%s': %s\n", name, strerror(errno));
 131         return ret;
 132 }
 133
 134 static struct option options[] = { { "all", 0, NULL, 'a' },
 135                                    { "force", 0, NULL, 'f' },
 136                                    { "help", 0, NULL, 'h' },
 137                                    { "syslog", 0, NULL, 's' },
 138                                    { "verbose", 0, NULL, 'v' },
 139                                    { "version", 0, NULL, 'V' },
 140                                    { "wait", 0, NULL, 'w' },
 141                                    { NULL, 0, NULL, 0 } };
 142
 143 static void print_usage(const char *progname)
 144 {
 145         fprintf(stderr,
 146                 "Usage: %s [-fhswvV] modulename ...\n"
 147                 // " -a (or --all) to remove all modules (no names needed)\n"
 148                 " -f (or --force) forces a module unload, and may crash your\n"
 149                 "    machine.  This requires the Forced Module Removal option\n"
 150                 "    when the kernel was compiled.\n"
 151                 " -h (or --help) prints this help text\n"
 152                 " -s (or --syslog) says use syslog, not stderr\n"
 153                 " -v (or --verbose) enables more messages\n"
 154                 " -V (or --version) prints the version code\n"
 155                 " -w (or --wait) begins a module removal even if it is used\n"
 156                 "    and will stop new users from accessing the module (so it\n"
 157                 "    should eventually fall to zero).\n"
 158                 , progname);
 159         exit(1);
 160 }
 161
 162 int main(int argc, char *argv[])
 163 {
 164         /* O_EXCL so kernels can spot old rmmod versions */
 165         unsigned int flags = O_NONBLOCK|O_EXCL;
 166         int i, opt, all = 0;
 167         int ret, err;
 168
 169         try_old_version("rmmod", argv);
 170
 171         while ((opt = getopt_long(argc, argv,
 172                         "afh?swvV", options, NULL)) != EOF) {
 173                 switch (opt) {
 174                 case 'a':       // --all
 175                         all = 1;
 176                         break;
 177                 case 'f':       // --force
 178                         flags |= O_TRUNC;
 179                         break;
 180                 case 's':       // --syslog
 181                         openlog("rmmod", LOG_CONS, LOG_DAEMON);
 182                         logging = 1;
 183                         break;
 184                 case 'w':       // --wait
 185                         flags &= ~O_NONBLOCK;
 186                         break;
 187                 case 'v':       // --verbose
 188                         verbose++;
 189                         break;
 190                 case 'V':       // --version
 191                         puts(PACKAGE " version " VERSION);
 192                         return 0;
 193
 194                 default:
 195                         print_usage(argv[0]);
 196                 }
 197         }
 198         if (!argv[optind]) {
 199                 fprintf(stderr, "no module names given\n");
 200                 print_usage(argv[0]);
 201         }
 202
 203         err = 0;
 204         /* remove each specified module */
 205         for (i = optind; i < argc; i++) {
 206                 ret = rmmod(argv[i], flags);
 207                 if (ret != 0)
 208                         err = 1;
 209         }
 210
 211         if (logging)
 212                 closelog();
 213         exit(err);
 214 }