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 "testing.h"
  31 #include "backwards_compat.c"
  32
  33 extern long delete_module(const char *, unsigned int);
  34
  35 #define error(log, fmt, ...) message(log, "ERROR: ", fmt , ## __VA_ARGS__)
  36 #define warn(log, fmt, ...) message(log, "WARNING: ", fmt , ## __VA_ARGS__)
  37 #define info(log, fmt, ...) \
  38         do { if (verbose) message(log, "", fmt , ## __VA_ARGS__); } while(0)
  39 #define fatal(log, fmt, ...) \
  40         do { message(log, "FATAL: ", fmt , ## __VA_ARGS__); exit(1); } while(0)
  41
  42 static void message(int log, const char *prefix, const char *fmt, ...)
  43 __attribute__ ((format (printf, 3, 4)));
  44
  45 static int getlen(const char *fmt, va_list ap)
  46 {
  47         int ret;
  48
  49         /* glibcs before 2.1 return -1 on "can't fit". */
  50         ret = vsnprintf(NULL, 0, fmt, ap);
  51         if (ret >= 0)
  52                 return ret;
  53         return 4096;
  54 }
  55
  56 static void message(int log, const char *prefix, const char *fmt, ...)
  57 {
  58         char *buf;
  59         va_list arglist;
  60         int len;
  61
  62         va_start(arglist, fmt);
  63         len = strlen(prefix) + getlen(fmt, arglist) + 1;
  64         buf = malloc(len);
  65
  66         /* Must restart args on some archs */
  67         va_start(arglist, fmt);
  68         strcpy(buf, prefix);
  69         vsnprintf(buf + strlen(buf), len, fmt, arglist);
  70
  71         if (log)
  72                 // modutils-2.4 would buffer these up
  73                 syslog(LOG_INFO, "%s", buf);
  74         else
  75                 fprintf(stderr, "%s", buf);
  76
  77         free(buf);
  78 }
  79
  80 static char *next_field(const char *line)
  81 {
  82         const char *rest;
  83
  84         rest = line + strcspn(line, " ");
  85         rest += strspn(rest, " ");
  86         return (char *)rest;
  87 }
  88
  89 /* Report that the module is in use. */
  90 static void mod_in_use(int log, const char *modname, char *usedby)
  91 {
  92         /* New /proc/modules uses a single "-" to mean "nothing".  Old
  93            one just puts nothing there. */
  94         if (usedby[0] == '-' || strcmp(usedby, "") == 0) {
  95                 error(log, "Module %s is in use\n", modname);
  96                 return;
  97         }
  98
  99         /* New /proc/modules *always* prints commas (even if only one) */
 100         if (strchr(usedby, ','))
 101                 /* Blatt over trailing comma for neatness */
 102                 usedby[strcspn(usedby, " \n")-1] = '\0';
 103         else {
 104                 /* Older /proc/modules just put them as
 105                    space-separated names.  Blatt over trailing \n */
 106                 usedby[strlen(usedby)-1] = '\0';
 107         }
 108
 109         error(log, "Module %s is in use by %s\n", modname, usedby);
 110 }
 111
 112 /* If we can check usage without entering kernel, do so. */
 113 static int check_usage(int log, const char *modname)
 114 {
 115         FILE *module_list;
 116         char line[10240], name[64];
 117         unsigned long size, refs;
 118         int scanned;
 119
 120         module_list = fopen("/proc/modules", "r");
 121         if (!module_list) {
 122                 if (errno == ENOENT) /* /proc may not be mounted. */
 123                         return 0;
 124                 fatal(log, "can't open /proc/modules: %s\n", strerror(errno));
 125         }
 126         while (fgets(line, sizeof(line)-1, module_list) != NULL) {
 127                 if (strchr(line, '\n') == NULL) {
 128                         fatal(log, "V. v. long line broke rmmod.\n");
 129                         exit(1);
 130                 }
 131
 132                 scanned = sscanf(line, "%s %lu %lu", name, &size, &refs);
 133                 if (strcmp(name, modname) != 0)
 134                         continue;
 135
 136                 if (scanned < 2)
 137                         fatal(log, "Unknown format in /proc/modules: %s\n",
 138                               line);
 139
 140                 if (scanned == 2)
 141                         fatal(log, "Kernel does not have unload support.\n");
 142
 143                 /* Hand it fields 3 onwards. */
 144                 if (refs != 0)
 145                         mod_in_use(log, modname,
 146                                    next_field(next_field(next_field(line))));
 147                 goto out;
 148         }
 149         error(log, "Module %s does not exist in /proc/modules\n", modname);
 150         refs = 1;
 151  out:
 152         fclose(module_list);
 153         return (refs == 0) ? 0 : -EINVAL;
 154 }
 155
 156 static void filename2modname(char *modname, const char *filename)
 157 {
 158         const char *afterslash;
 159         unsigned int i;
 160
 161         afterslash = strrchr(filename, '/');
 162         if (!afterslash)
 163                 afterslash = filename;
 164         else
 165                 afterslash++;
 166
 167         /* Convert to underscores, stop at first . */
 168         for (i = 0; afterslash[i] && afterslash[i] != '.'; i++) {
 169                 if (afterslash[i] == '-')
 170                         modname[i] = '_';
 171                 else
 172                         modname[i] = afterslash[i];
 173         }
 174         modname[i] = '\0';
 175 }
 176
 177 static int rmmod(int log, int verbose, const char *path, int flags)
 178 {
 179         long ret;
 180         char name[strlen(path) + 1];
 181
 182         filename2modname(name, path);
 183
 184         if ((flags & O_NONBLOCK) && !(flags & O_TRUNC)) {
 185                 if (check_usage(log, name) != 0)
 186                         return 1;
 187         }
 188
 189         info(log, "rmmod %s, wait=%s%s\n", name,
 190              (flags & O_NONBLOCK) ? "no" : "yes",
 191              (flags & O_TRUNC) ? " force" : "");
 192
 193         ret = delete_module(name, flags);
 194         if (ret != 0)
 195                 error(log, "Removing '%s': %s\n", name, strerror(errno));
 196         return ret;
 197 }
 198
 199 static struct option options[] = { { "all", 0, NULL, 'a' },
 200                                    { "force", 0, NULL, 'f' },
 201                                    { "help", 0, NULL, 'h' },
 202                                    { "syslog", 0, NULL, 's' },
 203                                    { "verbose", 0, NULL, 'v' },
 204                                    { "version", 0, NULL, 'V' },
 205                                    { "wait", 0, NULL, 'w' },
 206                                    { NULL, 0, NULL, 0 } };
 207
 208 static void print_usage(const char *progname)
 209 {
 210         fprintf(stderr,
 211                 "Usage: %s [-fhswvV] modulename ...\n"
 212                 // " -a (or --all) to remove all modules (no names needed)\n"
 213                 " -f (or --force) forces a module unload, and may crash your\n"
 214                 "    machine.  This requires the Forced Module Removal option\n"
 215                 "    when the kernel was compiled.\n"
 216                 " -h (or --help) prints this help text\n"
 217                 " -s (or --syslog) says use syslog, not stderr\n"
 218                 " -v (or --verbose) enables more messages\n"
 219                 " -V (or --version) prints the version code\n"
 220                 " -w (or --wait) begins a module removal even if it is used\n"
 221                 "    and will stop new users from accessing the module (so it\n"
 222                 "    should eventually fall to zero).\n"
 223                 , progname);
 224         exit(1);
 225 }
 226
 227 int main(int argc, char *argv[])
 228 {
 229         /* O_EXCL so kernels can spot old rmmod versions */
 230         unsigned int flags = O_NONBLOCK|O_EXCL;
 231         int i, opt, all = 0, log = 0, verbose = 0;
 232         int ret, err;
 233
 234         try_old_version("rmmod", argv);
 235
 236         while ((opt = getopt_long(argc, argv,
 237                         "afh?swvV", options, NULL)) != EOF) {
 238                 switch (opt) {
 239                 case 'a':       // --all
 240                         all = 1;
 241                         break;
 242                 case 'f':       // --force
 243                         flags |= O_TRUNC;
 244                         break;
 245                 case 's':       // --syslog
 246                         openlog("rmmod", LOG_CONS, LOG_DAEMON);
 247                         log = 1;
 248                         break;
 249                 case 'w':       // --wait
 250                         flags &= ~O_NONBLOCK;
 251                         break;
 252                 case 'v':       // --verbose
 253                         verbose++;
 254                         break;
 255                 case 'V':       // --version
 256                         puts(PACKAGE " version " VERSION);
 257                         return 0;
 258
 259                 default:
 260                         print_usage(argv[0]);
 261                 }
 262         }
 263         if (!argv[optind]) {
 264                 if (all) {
 265                         /* FIXME implement */
 266                         exit(1);
 267                 }
 268                 fprintf(stderr, "no module names given\n");
 269                 print_usage(argv[0]);
 270         }
 271
 272         err = 0;
 273         /* remove each specified module */
 274         for (i = optind; i < argc; i++) {
 275                 ret = rmmod(log, verbose, argv[i], flags);
 276                 if (ret != 0)
 277                         err = 1;
 278         }
 279
 280         if (log)
 281                 closelog();
 282         exit(err);
 283 }