src/vm/properties.c

   1 /* src/vm/properties.c - handling commandline properties
   2
   3    Copyright (C) 1996-2005, 2006, 2007, 2008
   4    CACAOVM - Verein zur Foerderung der freien virtuellen Maschine CACAO
   5
   6    This file is part of CACAO.
   7
   8    This program is free software; you can redistribute it and/or
   9    modify it under the terms of the GNU General Public License as
  10    published by the Free Software Foundation; either version 2, or (at
  11    your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful, but
  14    WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  16    General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program; if not, write to the Free Software
  20    Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
  21    02110-1301, USA.
  22
  23 */
  24
  25
  26 #include "config.h"
  27
  28 #include <errno.h>
  29 #include <stdlib.h>
  30 #include <string.h>
  31 #include <time.h>
  32 #include <unistd.h>
  33 #include <sys/utsname.h>
  34
  35 #include "vm/types.h"
  36
  37 #include "mm/memory.h"
  38
  39 #include "native/jni.h"
  40 #include "native/llni.h"
  41
  42 #include "vm/global.h"                      /* required by java_lang_String.h */
  43 #include "native/include/java_lang_String.h"
  44
  45 #include "toolbox/list.h"
  46 #include "toolbox/util.h"
  47
  48 #include "vm/properties.h"
  49 #include "vm/stringlocal.h"
  50 #include "vm/vm.h"
  51
  52 #include "vm/jit/asmpart.h"
  53
  54 #include "vmcore/class.h"
  55 #include "vmcore/method.h"
  56 #include "vmcore/options.h"
  57 #include "vmcore/system.h"
  58
  59
  60 /* internal property structure ************************************************/
  61
  62 typedef struct list_properties_entry_t list_properties_entry_t;
  63
  64 struct list_properties_entry_t {
  65         char       *key;
  66         char       *value;
  67         listnode_t  linkage;
  68 };
  69
  70
  71 /* global variables ***********************************************************/
  72
  73 static list_t *list_properties = NULL;
  74
  75
  76 /* properties_init *************************************************************
  77
  78    Initialize the properties list and fill the list with default
  79    values.
  80
  81 *******************************************************************************/
  82
  83 void properties_init(void)
  84 {
  85         TRACESUBSYSTEMINITIALIZATION("properties_init");
  86
  87         list_properties = list_create(OFFSET(list_properties_entry_t, linkage));
  88 }
  89
  90
  91 /* properties_set **************************************************************
  92
  93    Fill the properties list with default values.
  94
  95 *******************************************************************************/
  96
  97 void properties_set(void)
  98 {
  99         int             len;
 100         char           *p;
 101
 102         char           *java_home;
 103         char           *boot_class_path;
 104
 105 #if defined(ENABLE_JAVASE)
 106         char           *class_path;
 107         char           *boot_library_path;
 108         char           *extdirs;
 109         char           *endorseddirs;
 110
 111 # if defined(WITH_CLASSPATH_GNU)
 112         char           *cwd;
 113         char           *env_user;
 114         char           *env_home;
 115         char           *env_lang;
 116         char           *lang;
 117         char           *country;
 118         struct utsname *utsnamebuf;
 119
 120         char           *java_library_path;
 121 # endif
 122 #endif
 123
 124 #if defined(ENABLE_JRE_LAYOUT)
 125         /* SUN also uses a buffer of 4096-bytes (strace is your friend). */
 126
 127         p = MNEW(char, 4096);
 128
 129         if (readlink("/proc/self/exe", p, 4095) == -1)
 130                 vm_abort("properties_set: readlink failed: %s\n", strerror(errno));
 131
 132         /* We have a path like:
 133
 134            /path/to/executable/bin/java
 135
 136            or
 137
 138            /path/to/executeable/jre/bin/java
 139
 140            Now let's strip two levels. */
 141
 142         p = system_dirname(p);
 143         p = system_dirname(p);
 144
 145 # if defined(WITH_CLASSPATH_GNU)
 146
 147         /* Set java.home. */
 148
 149         java_home = strdup(p);
 150
 151         /* Set the path to Java core native libraries. */
 152
 153         len = strlen(java_home) + strlen("/lib/classpath") + strlen("0");
 154
 155         boot_library_path = MNEW(char, len);
 156
 157         strcpy(boot_library_path, java_home);
 158         strcat(boot_library_path, "/lib/classpath");
 159
 160 # elif defined(WITH_CLASSPATH_SUN)
 161
 162         /* Find correct java.home.  We check if there is a JRE
 163            co-located. */
 164
 165         /* NOTE: We use the server VM here as it should be available on
 166            all architectures. */
 167
 168         len =
 169                 strlen(p) +
 170                 strlen("/jre/lib/"JAVA_ARCH"/server/libjvm.so") +
 171                 strlen("0");
 172
 173         java_home = MNEW(char, len);
 174
 175         strcpy(java_home, p);
 176         strcat(java_home, "/jre/lib/"JAVA_ARCH"/server/libjvm.so");
 177
 178         /* Check if that libjvm.so exists. */
 179
 180         if (system_access(java_home, F_OK) == 0) {
 181                 /* Yes, we add /jre to java.home. */
 182
 183                 strcpy(java_home, p);
 184                 strcat(java_home, "/jre");
 185         }
 186         else {
 187                 /* No, java.home is parent directory. */
 188
 189                 strcpy(java_home, p);
 190         }
 191
 192         /* Set the path to Java core native libraries. */
 193
 194         len = strlen(java_home) + strlen("/lib/"JAVA_ARCH) + strlen("0");
 195
 196         boot_library_path = MNEW(char, len);
 197
 198         strcpy(boot_library_path, java_home);
 199         strcat(boot_library_path, "/lib/"JAVA_ARCH);
 200
 201 # else
 202 #  error unknown classpath configuration
 203 # endif
 204
 205         /* Free path. */
 206
 207         MFREE(p, char, len);
 208
 209 #else
 210         java_home         = CACAO_PREFIX;
 211
 212 # if defined(WITH_CLASSPATH_GNU)
 213
 214         boot_library_path = CLASSPATH_LIBDIR"/classpath";
 215
 216 # elif defined(WITH_CLASSPATH_SUN)
 217
 218         boot_library_path = CLASSPATH_LIBDIR;
 219
 220 # elif defined(WITH_CLASSPATH_CLDC1_1)
 221
 222         /* No boot_library_path required. */
 223
 224 # else
 225 #  error unknown classpath configuration
 226 # endif
 227 #endif
 228
 229         properties_add("java.home", java_home);
 230
 231         /* Set the bootclasspath. */
 232
 233         p = getenv("BOOTCLASSPATH");
 234
 235         if (p != NULL) {
 236                 boot_class_path = MNEW(char, strlen(p) + strlen("0"));
 237                 strcpy(boot_class_path, p);
 238         }
 239         else {
 240 #if defined(ENABLE_JRE_LAYOUT)
 241 # if defined(WITH_CLASSPATH_GNU)
 242
 243                 len =
 244                         strlen(java_home) + strlen("/share/cacao/vm.zip:") +
 245                         strlen(java_home) + strlen("/share/classpath/glibj.zip") +
 246                         strlen("0");
 247
 248                 boot_class_path = MNEW(char, len);
 249
 250                 strcpy(boot_class_path, java_home);
 251                 strcat(boot_class_path, "/share/cacao/vm.zip");
 252                 strcat(boot_class_path, ":");
 253                 strcat(boot_class_path, java_home);
 254                 strcat(boot_class_path, "/share/classpath/glibj.zip");
 255
 256 # elif defined(WITH_CLASSPATH_SUN)
 257
 258                 /* This is the bootclasspath taken from HotSpot (see
 259                    hotspot/src/share/vm/runtime/os.cpp
 260                    (os::set_boot_path)). */
 261
 262                 len =
 263                         strlen(java_home) + strlen("/lib/resources.jar:") +
 264                         strlen(java_home) + strlen("/lib/rt.jar:") +
 265                         strlen(java_home) + strlen("/lib/sunrsasign.jar:") +
 266                         strlen(java_home) + strlen("/lib/jsse.jar:") +
 267                         strlen(java_home) + strlen("/lib/jce.jar:") +
 268                         strlen(java_home) + strlen("/lib/charsets.jar:") +
 269                         strlen(java_home) + strlen("/classes") +
 270                         strlen("0");
 271
 272                 boot_class_path = MNEW(char, len);
 273
 274                 strcpy(boot_class_path, java_home);
 275                 strcat(boot_class_path, "/lib/resources.jar:");
 276                 strcat(boot_class_path, java_home);
 277                 strcat(boot_class_path, "/lib/rt.jar:");
 278                 strcat(boot_class_path, java_home);
 279                 strcat(boot_class_path, "/lib/sunrsasign.jar:");
 280                 strcat(boot_class_path, java_home);
 281                 strcat(boot_class_path, "/lib/jsse.jar:");
 282                 strcat(boot_class_path, java_home);
 283                 strcat(boot_class_path, "/lib/jce.jar:");
 284                 strcat(boot_class_path, java_home);
 285                 strcat(boot_class_path, "/lib/charsets.jar:");
 286                 strcat(boot_class_path, java_home);
 287                 strcat(boot_class_path, "/classes");
 288
 289 # else
 290 #  error unknown classpath configuration
 291 # endif
 292 #else
 293 # if defined(WITH_CLASSPATH_GNU)
 294
 295                 len =
 296                         strlen(CACAO_VM_ZIP) +
 297                         strlen(":") +
 298                         strlen(CLASSPATH_CLASSES) +
 299                         strlen("0");
 300
 301                 boot_class_path = MNEW(char, len);
 302
 303                 strcpy(boot_class_path, CACAO_VM_ZIP);
 304                 strcat(boot_class_path, ":");
 305                 strcat(boot_class_path, CLASSPATH_CLASSES);
 306
 307 # elif defined(WITH_CLASSPATH_SUN)
 308
 309                 /* This is the bootclasspath taken from HotSpot (see
 310                    hotspot/src/share/vm/runtime/os.cpp
 311                    (os::set_boot_path)). */
 312
 313                 len =
 314                         strlen(CLASSPATH_PREFIX"/lib/resources.jar:") +
 315                         strlen(CLASSPATH_PREFIX"/lib/rt.jar:") +
 316                         strlen(CLASSPATH_PREFIX"/lib/sunrsasign.jar:") +
 317                         strlen(CLASSPATH_PREFIX"/lib/jsse.jar:") +
 318                         strlen(CLASSPATH_PREFIX"/lib/jce.jar:") +
 319                         strlen(CLASSPATH_PREFIX"/lib/charsets.jar:") +
 320                         strlen(CLASSPATH_PREFIX"/classes") +
 321                         strlen("0");
 322
 323                 boot_class_path = MNEW(char, len);
 324
 325                 strcpy(boot_class_path, CLASSPATH_PREFIX"/lib/resources.jar:");
 326                 strcat(boot_class_path, CLASSPATH_PREFIX"/lib/rt.jar:");
 327                 strcat(boot_class_path, CLASSPATH_PREFIX"/lib/sunrsasign.jar:");
 328                 strcat(boot_class_path, CLASSPATH_PREFIX"/lib/jsse.jar:");
 329                 strcat(boot_class_path, CLASSPATH_PREFIX"/lib/jce.jar:");
 330                 strcat(boot_class_path, CLASSPATH_PREFIX"/lib/charsets.jar:");
 331                 strcat(boot_class_path, CLASSPATH_PREFIX"/classes");
 332
 333 # elif defined(WITH_CLASSPATH_CLDC1_1)
 334
 335                 len =
 336                         strlen(CLASSPATH_CLASSES) +
 337                         strlen("0");
 338
 339                 boot_class_path = MNEW(char, len);
 340
 341                 strcpy(boot_class_path, CLASSPATH_CLASSES);
 342
 343 # else
 344 #  error unknown classpath configuration
 345 # endif
 346 #endif
 347         }
 348
 349         properties_add("sun.boot.class.path", boot_class_path);
 350         properties_add("java.boot.class.path", boot_class_path);
 351
 352 #if defined(ENABLE_JAVASE)
 353
 354         /* Set the classpath. */
 355
 356         p = getenv("CLASSPATH");
 357
 358         if (p != NULL) {
 359                 class_path = MNEW(char, strlen(p) + strlen("0"));
 360                 strcpy(class_path, p);
 361         }
 362         else {
 363                 class_path = MNEW(char, strlen(".") + strlen("0"));
 364                 strcpy(class_path, ".");
 365         }
 366
 367         properties_add("java.class.path", class_path);
 368
 369         /* Add java.vm properties. */
 370
 371         properties_add("java.vm.specification.version", "1.0");
 372         properties_add("java.vm.specification.vendor", "Sun Microsystems Inc.");
 373         properties_add("java.vm.specification.name", "Java Virtual Machine Specification");
 374         properties_add("java.vm.version", VERSION);
 375         properties_add("java.vm.vendor", "CACAO Team");
 376         properties_add("java.vm.name", "CACAO");
 377
 378 # if defined(ENABLE_INTRP)
 379         if (opt_intrp) {
 380                 /* XXX We don't support java.lang.Compiler */
 381 /*              properties_add("java.compiler", "cacao.intrp"); */
 382                 properties_add("java.vm.info", "interpreted mode");
 383         }
 384         else
 385 # endif
 386         {
 387                 /* XXX We don't support java.lang.Compiler */
 388 /*              properties_add("java.compiler", "cacao.jit"); */
 389                 properties_add("java.vm.info", "JIT mode");
 390         }
 391
 392 # if defined(WITH_CLASSPATH_GNU)
 393
 394         /* Get properties from system. */
 395
 396         cwd      = _Jv_getcwd();
 397
 398         env_user = getenv("USER");
 399         env_home = getenv("HOME");
 400         env_lang = getenv("LANG");
 401
 402         utsnamebuf = NEW(struct utsname);
 403
 404         uname(utsnamebuf);
 405
 406         properties_add("java.runtime.version", VERSION);
 407         properties_add("java.runtime.name", "CACAO");
 408
 409         properties_add("java.specification.version", "1.5");
 410         properties_add("java.specification.vendor", "Sun Microsystems Inc.");
 411         properties_add("java.specification.name", "Java Platform API Specification");
 412
 413         properties_add("java.version", JAVA_VERSION);
 414         properties_add("java.vendor", "GNU Classpath");
 415         properties_add("java.vendor.url", "http://www.gnu.org/software/classpath/");
 416
 417         properties_add("java.class.version", CLASS_VERSION);
 418
 419         properties_add("gnu.classpath.boot.library.path", boot_library_path);
 420
 421         /* Get and set java.library.path. */
 422
 423         java_library_path = getenv("LD_LIBRARY_PATH");
 424
 425         if (java_library_path == NULL)
 426                 java_library_path = "";
 427
 428         properties_add("java.library.path", java_library_path);
 429
 430         properties_add("java.io.tmpdir", "/tmp");
 431
 432 #  if defined(ENABLE_INTRP)
 433         if (opt_intrp) {
 434                 properties_add("gnu.java.compiler.name", "cacao.intrp");
 435         }
 436         else
 437 #  endif
 438         {
 439                 properties_add("gnu.java.compiler.name", "cacao.jit");
 440         }
 441
 442         /* Set the java.ext.dirs property. */
 443
 444         len = strlen(java_home) + strlen("/jre/lib/ext") + strlen("0");
 445
 446         extdirs = MNEW(char, len);
 447
 448         sprintf(extdirs, "%s/jre/lib/ext", java_home);
 449
 450         properties_add("java.ext.dirs", extdirs);
 451
 452         /* Set the java.ext.endorsed property. */
 453
 454         len = strlen(java_home) + strlen("/jre/lib/endorsed") + strlen("0");
 455
 456         endorseddirs = MNEW(char, len);
 457
 458         sprintf(endorseddirs, "%s/jre/lib/endorsed", java_home);
 459
 460         properties_add("java.endorsed.dirs", endorseddirs);
 461
 462 #  if defined(DISABLE_GC)
 463         /* When we disable the GC, we mmap the whole heap to a specific
 464            address, so we can compare call traces. For this reason we have
 465            to add the same properties on different machines, otherwise
 466            more memory may be allocated (e.g. strlen("i386")
 467            vs. strlen("alpha"). */
 468
 469         properties_add("os.arch", "unknown");
 470         properties_add("os.name", "unknown");
 471         properties_add("os.version", "unknown");
 472 #  else
 473         properties_add("os.arch", JAVA_ARCH);
 474         properties_add("os.name", utsnamebuf->sysname);
 475         properties_add("os.version", utsnamebuf->release);
 476 #  endif
 477
 478 #  if WORDS_BIGENDIAN == 1
 479         properties_add("gnu.cpu.endian", "big");
 480 #  else
 481         properties_add("gnu.cpu.endian", "little");
 482 #  endif
 483
 484         properties_add("file.separator", "/");
 485         properties_add("path.separator", ":");
 486         properties_add("line.separator", "\n");
 487
 488         properties_add("user.name", env_user ? env_user : "null");
 489         properties_add("user.home", env_home ? env_home : "null");
 490         properties_add("user.dir", cwd ? cwd : "null");
 491
 492         /* get locale */
 493
 494         if (env_lang != NULL) {
 495                 /* get the local stuff from the environment */
 496
 497                 if (strlen(env_lang) <= 2) {
 498                         properties_add("user.language", env_lang);
 499                 }
 500                 else {
 501                         if ((env_lang[2] == '_') && (strlen(env_lang) >= 5)) {
 502                                 lang = MNEW(char, 3);
 503                                 strncpy(lang, (char *) &env_lang[0], 2);
 504                                 lang[2] = '\0';
 505
 506                                 country = MNEW(char, 3);
 507                                 strncpy(country, (char *) &env_lang[3], 2);
 508                                 country[2] = '\0';
 509
 510                                 properties_add("user.language", lang);
 511                                 properties_add("user.country", country);
 512                         }
 513                 }
 514         }
 515         else {
 516                 /* if no default locale was specified, use `en_US' */
 517
 518                 properties_add("user.language", "en");
 519                 properties_add("user.country", "US");
 520         }
 521
 522 # elif defined(WITH_CLASSPATH_SUN)
 523
 524         /* Actually this property is set by OpenJDK, but we need it in
 525            nativevm_preinit(). */
 526
 527         properties_add("sun.boot.library.path", boot_library_path);
 528
 529         /* Set the java.ext.dirs property. */
 530
 531         len =
 532                 strlen(java_home) + strlen("/lib/ext") +
 533                 strlen(":") +
 534                 strlen("/usr/java/packages/lib/ext") +
 535                 strlen("0");
 536
 537         extdirs = MNEW(char, len);
 538
 539         sprintf(extdirs, "%s/lib/ext:/usr/java/packages/lib/ext", java_home);
 540
 541         properties_add("java.ext.dirs", extdirs);
 542
 543         /* Set the java.ext.endorsed property. */
 544
 545         len = strlen(java_home) + strlen("/lib/endorsed") + strlen("0");
 546
 547         endorseddirs = MNEW(char, len);
 548
 549         sprintf(endorseddirs, "%s/lib/endorsed", java_home);
 550
 551         properties_add("java.endorsed.dirs", endorseddirs);
 552
 553 # else
 554
 555 #  error unknown classpath configuration
 556
 557 # endif
 558
 559 #elif defined(ENABLE_JAVAME_CLDC1_1)
 560
 561     properties_add("microedition.configuration", "CLDC-1.1");
 562     properties_add("microedition.platform", "generic");
 563     properties_add("microedition.encoding", "ISO8859_1");
 564     properties_add("microedition.profiles", "");
 565
 566 #else
 567
 568 # error unknown Java configuration
 569
 570 #endif
 571 }
 572
 573
 574 /* properties_add **************************************************************
 575
 576    Adds a property entry to the internal property list.  If there's
 577    already an entry with the same key, replace it.
 578
 579 *******************************************************************************/
 580
 581 void properties_add(char *key, char *value)
 582 {
 583         list_properties_entry_t *pe;
 584
 585         /* search for the entry */
 586
 587         for (pe = list_first(list_properties); pe != NULL;
 588                  pe = list_next(list_properties, pe)) {
 589                 if (strcmp(pe->key, key) == 0) {
 590                         /* entry was found, replace the value */
 591
 592 #if !defined(NDEBUG)
 593                         if (opt_DebugProperties) {
 594                                 printf("[properties_add: key=%s, old value=%s, new value=%s]\n",
 595                                            key, pe->value, value);
 596                         }
 597 #endif
 598
 599                         pe->value = value;
 600
 601                         return;
 602                 }
 603         }
 604
 605         /* entry was not found, insert a new one */
 606
 607 #if !defined(NDEBUG)
 608         if (opt_DebugProperties) {
 609                 printf("[properties_add: key=%s, value=%s]\n", key, value);
 610         }
 611 #endif
 612
 613         pe = NEW(list_properties_entry_t);
 614
 615         pe->key   = key;
 616         pe->value = value;
 617
 618         list_add_last(list_properties, pe);
 619 }
 620
 621
 622 /* properties_get **************************************************************
 623
 624    Get a property entry from the internal property list.
 625
 626 *******************************************************************************/
 627
 628 char *properties_get(char *key)
 629 {
 630         list_properties_entry_t *pe;
 631
 632         for (pe = list_first(list_properties); pe != NULL;
 633                  pe = list_next(list_properties, pe)) {
 634                 if (strcmp(pe->key, key) == 0)
 635                         return pe->value;
 636         }
 637
 638         return NULL;
 639 }
 640
 641
 642 /* properties_system_add *******************************************************
 643
 644    Adds a given property to the Java system properties.
 645
 646 *******************************************************************************/
 647
 648 void properties_system_add(java_handle_t *p, char *key, char *value)
 649 {
 650         classinfo     *c;
 651         methodinfo    *m;
 652         java_handle_t *k;
 653         java_handle_t *v;
 654
 655         /* search for method to add properties */
 656
 657         LLNI_class_get(p, c);
 658
 659         m = class_resolveclassmethod(c,
 660                                                                  utf_put,
 661                                                                  utf_new_char("(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;"),
 662                                                                  NULL,
 663                                                                  true);
 664
 665         if (m == NULL)
 666                 return;
 667
 668         /* add to the Java system properties */
 669
 670         k = javastring_new_from_utf_string(key);
 671         v = javastring_new_from_utf_string(value);
 672
 673         (void) vm_call_method(m, p, k, v);
 674 }
 675
 676
 677 /* properties_system_add_all ***************************************************
 678
 679    Adds all properties from the properties list to the Java system
 680    properties.
 681
 682    ARGUMENTS:
 683        p.... is actually a java_util_Properties structure
 684
 685 *******************************************************************************/
 686
 687 #if defined(ENABLE_JAVASE)
 688 void properties_system_add_all(java_handle_t *p)
 689 {
 690         list_properties_entry_t *pe;
 691         classinfo               *c;
 692         methodinfo              *m;
 693         java_handle_t           *key;
 694         java_handle_t           *value;
 695
 696         /* search for method to add properties */
 697
 698         LLNI_class_get(p, c);
 699
 700         m = class_resolveclassmethod(c,
 701                                                                  utf_put,
 702                                                                  utf_new_char("(Ljava/lang/Object;Ljava/lang/Object;)Ljava/lang/Object;"),
 703                                                                  NULL,
 704                                                                  true);
 705
 706         if (m == NULL)
 707                 return;
 708
 709         /* process all properties stored in the internal table */
 710
 711         for (pe = list_first(list_properties); pe != NULL;
 712                  pe = list_next(list_properties, pe)) {
 713                 /* add to the Java system properties */
 714
 715                 key   = javastring_new_from_utf_string(pe->key);
 716                 value = javastring_new_from_utf_string(pe->value);
 717
 718                 (void) vm_call_method(m, (java_handle_t *) p, key, value);
 719         }
 720 }
 721 #endif /* defined(ENABLE_JAVASE) */
 722
 723
 724 /* properties_dump *************************************************************
 725
 726    Dump all property entries.
 727
 728 *******************************************************************************/
 729
 730 void properties_dump(void)
 731 {
 732         list_t                  *l;
 733         list_properties_entry_t *pe;
 734
 735         /* For convenience. */
 736
 737         l = list_properties;
 738
 739         for (pe = list_first(l); pe != NULL; pe = list_next(l, pe)) {
 740                 log_println("[properties_dump: key=%s, value=%s]", pe->key, pe->value);
 741         }
 742 }
 743
 744
 745 /*
 746  * These are local overrides for various environment variables in Emacs.
 747  * Please do not remove this and leave it at the end of the file, where
 748  * Emacs will automagically detect them.
 749  * ---------------------------------------------------------------------
 750  * Local variables:
 751  * mode: c
 752  * indent-tabs-mode: t
 753  * c-basic-offset: 4
 754  * tab-width: 4
 755  * End:
 756  */