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