1 /* $NetBSD: main.c,v 1.88 2021/10/26 10:07:20 kre Exp $ */ 2 3 /*- 4 * Copyright (c) 1991, 1993 5 * The Regents of the University of California. All rights reserved. 6 * 7 * This code is derived from software contributed to Berkeley by 8 * Kenneth Almquist. 9 * 10 * Redistribution and use in source and binary forms, with or without 11 * modification, are permitted provided that the following conditions 12 * are met: 13 * 1. Redistributions of source code must retain the above copyright 14 * notice, this list of conditions and the following disclaimer. 15 * 2. Redistributions in binary form must reproduce the above copyright 16 * notice, this list of conditions and the following disclaimer in the 17 * documentation and/or other materials provided with the distribution. 18 * 3. Neither the name of the University nor the names of its contributors 19 * may be used to endorse or promote products derived from this software 20 * without specific prior written permission. 21 * 22 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 23 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 24 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 25 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 26 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 27 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 28 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 29 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 30 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 31 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 32 * SUCH DAMAGE. 33 */ 34 35 #include <sys/cdefs.h> 36 #ifndef lint 37 __COPYRIGHT("@(#) Copyright (c) 1991, 1993\ 38 The Regents of the University of California. All rights reserved."); 39 #endif /* not lint */ 40 41 #ifndef lint 42 #if 0 43 static char sccsid[] = "@(#)main.c 8.7 (Berkeley) 7/19/95"; 44 #else 45 __RCSID("$NetBSD: main.c,v 1.88 2021/10/26 10:07:20 kre Exp $"); 46 #endif 47 #endif /* not lint */ 48 49 #include <errno.h> 50 #include <stdio.h> 51 #include <signal.h> 52 #include <sys/stat.h> 53 #include <unistd.h> 54 #include <stdbool.h> 55 #include <stdlib.h> 56 #include <locale.h> 57 #include <fcntl.h> 58 59 60 #include "shell.h" 61 #include "main.h" 62 #include "mail.h" 63 #include "options.h" 64 #include "builtins.h" 65 #include "output.h" 66 #include "parser.h" 67 #include "nodes.h" 68 #include "expand.h" 69 #include "eval.h" 70 #include "jobs.h" 71 #include "input.h" 72 #include "trap.h" 73 #include "var.h" 74 #include "show.h" 75 #include "memalloc.h" 76 #include "error.h" 77 #include "init.h" 78 #include "mystring.h" 79 #include "exec.h" 80 #include "cd.h" 81 #include "redir.h" 82 83 #define PROFILE 0 84 85 int rootpid; 86 int rootshell; 87 struct jmploc main_handler; 88 int max_user_fd; 89 long user_fd_limit; 90 bool privileged; 91 #if PROFILE 92 short profile_buf[16384]; 93 extern int etext(); 94 #endif 95 96 STATIC void read_profile(const char *); 97 98 /* 99 * Main routine. We initialize things, parse the arguments, execute 100 * profiles if we're a login shell, and then call cmdloop to execute 101 * commands. The setjmp call sets up the location to jump to when an 102 * exception occurs. When an exception occurs the variable "state" 103 * is used to figure out how far we had gotten. 104 */ 105 106 int 107 main(int argc, char **argv) 108 { 109 struct stackmark smark; 110 volatile int state; 111 char *shinit; 112 uid_t uid; 113 gid_t gid; 114 sigset_t mask; 115 bool waspriv; 116 117 /* 118 * If we happen to be invoked with SIGCHLD ignored, we cannot 119 * successfully do almost anything. Perhaps we should remember 120 * its state and pass it on ignored to children if it was ignored 121 * on entry, but that seems like just leaving the shit on the 122 * footpath for someone else to fall into... 123 */ 124 (void)signal(SIGCHLD, SIG_DFL); 125 /* 126 * Similarly, SIGCHLD must not be blocked 127 */ 128 sigemptyset(&mask); 129 sigaddset(&mask, SIGCHLD); 130 sigprocmask(SIG_UNBLOCK, &mask, NULL); 131 132 uid = getuid(); 133 gid = getgid(); 134 135 waspriv = privileged = (uid != geteuid()) || (gid != getegid()); 136 137 max_user_fd = fcntl(0, F_MAXFD); 138 if (max_user_fd < 2) 139 max_user_fd = 2; 140 user_fd_limit = sysconf(_SC_OPEN_MAX); 141 142 setlocale(LC_ALL, ""); 143 144 posix = getenv("POSIXLY_CORRECT") != NULL; 145 #if PROFILE 146 monitor(4, etext, profile_buf, sizeof profile_buf, 50); 147 #endif 148 state = 0; 149 if (setjmp(main_handler.loc)) { 150 /* 151 * When a shell procedure is executed, we raise the 152 * exception EXSHELLPROC to clean up before executing 153 * the shell procedure. 154 */ 155 switch (exception) { 156 case EXSHELLPROC: 157 rootpid = getpid(); 158 rootshell = 1; 159 minusc = NULL; 160 state = 3; 161 break; 162 163 case EXEXEC: 164 exitstatus = exerrno; 165 break; 166 167 case EXERROR: 168 exitstatus = 2; 169 break; 170 171 default: 172 break; 173 } 174 175 if (exception != EXSHELLPROC) { 176 if (state == 0 || iflag == 0 || ! rootshell || 177 exception == EXEXIT) 178 exitshell(exitstatus); 179 } 180 reset(); 181 if (exception == EXINT) { 182 out2c('\n'); 183 flushout(&errout); 184 } 185 popstackmark(&smark); 186 FORCEINTON; /* enable interrupts */ 187 if (state == 1) 188 goto state1; 189 else if (state == 2) 190 goto state2; 191 else if (state == 3) 192 goto state3; 193 else 194 goto state4; 195 } 196 handler = &main_handler; 197 #ifdef DEBUG 198 #if DEBUG >= 2 199 debug = 1; /* this may be reset by procargs() later */ 200 #endif 201 opentrace(); 202 if (privileged) 203 trputs("Privileged "); 204 trputs("Shell args: "); trargs(argv); 205 #if DEBUG >= 3 206 set_debug(((DEBUG)==3 ? "_@" : "++"), 1); 207 #endif 208 #endif 209 rootpid = getpid(); 210 rootshell = 1; 211 init(); 212 initpwd(); 213 setstackmark(&smark); 214 procargs(argc, argv); 215 216 #if 0 /* This now happens (indirectly) in the procargs() just above */ 217 /* 218 * Limit bogus system(3) or popen(3) calls in setuid binaries, 219 * by requiring the -p flag 220 */ 221 if (!pflag && (uid != geteuid() || gid != getegid())) { 222 setuid(uid); 223 setgid(gid); 224 /* PS1 might need to be changed accordingly. */ 225 choose_ps1(); 226 } 227 #else /* except for this one little bit */ 228 if (waspriv && !privileged) 229 choose_ps1(); 230 #endif 231 232 if (argv[0] && argv[0][0] == '-') { 233 state = 1; 234 read_profile("/etc/profile"); 235 state1: 236 state = 2; 237 if (!privileged) { 238 char *profile; 239 const char *home; 240 241 home = lookupvar("HOME"); 242 if (home == NULL) 243 home = nullstr; 244 profile = ststrcat(NULL, home, "/.profile", STSTRC_END); 245 read_profile(profile); 246 stunalloc(profile); 247 } 248 #if 0 /* FreeBSD does (effectively) ...*/ 249 else 250 read_profile("/etc/suid_profile"); 251 #endif 252 } 253 state2: 254 state = 3; 255 if ((iflag || !posix) && !privileged) { 256 struct stackmark env_smark; 257 258 setstackmark(&env_smark); 259 if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') { 260 state = 3; 261 read_profile(expandenv(shinit)); 262 } 263 popstackmark(&env_smark); 264 } 265 state3: 266 state = 4; 267 line_number = 1; /* undo anything from profile files */ 268 269 if (sflag == 0 || minusc) { 270 static int sigs[] = { 271 SIGINT, SIGQUIT, SIGHUP, 272 #ifdef SIGTSTP 273 SIGTSTP, 274 #endif 275 SIGPIPE 276 }; 277 #define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0])) 278 size_t i; 279 280 for (i = 0; i < SIGSSIZE; i++) 281 setsignal(sigs[i], 0); 282 } 283 284 rststackmark(&smark); /* this one is never popped */ 285 286 if (minusc) 287 evalstring(minusc, sflag ? 0 : EV_EXIT); 288 289 if (sflag || minusc == NULL) { 290 state4: /* XXX ??? - why isn't this before the "if" statement */ 291 cmdloop(1); 292 if (iflag) { 293 out2str("\n"); 294 flushout(&errout); 295 } 296 } 297 #if PROFILE 298 monitor(0); 299 #endif 300 line_number = plinno; 301 exitshell(exitstatus); 302 /* NOTREACHED */ 303 } 304 305 306 /* 307 * Read and execute commands. "Top" is nonzero for the top level command 308 * loop; it turns on prompting if the shell is interactive. 309 */ 310 311 void 312 cmdloop(int top) 313 { 314 union node *n; 315 struct stackmark smark; 316 int inter; 317 int numeof = 0; 318 enum skipstate skip; 319 320 CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top)); 321 setstackmark(&smark); 322 for (;;) { 323 if (pendingsigs) 324 dotrap(); 325 inter = 0; 326 if (iflag == 1 && top) { 327 inter = 1; 328 showjobs(out2, SHOW_CHANGED); 329 chkmail(0); 330 flushout(&errout); 331 nflag = 0; 332 } 333 n = parsecmd(inter); 334 VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n)); 335 if (n == NEOF) { 336 if (!top || numeof >= 50) 337 break; 338 if (nflag) 339 break; 340 if (!stoppedjobs()) { 341 if (!iflag || !Iflag) 342 break; 343 out2str("\nUse \"exit\" to leave shell.\n"); 344 } 345 numeof++; 346 } else if (n != NULL && nflag == 0) { 347 job_warning = (job_warning == 2) ? 1 : 0; 348 numeof = 0; 349 evaltree(n, 0); 350 } 351 rststackmark(&smark); 352 353 /* 354 * Any SKIP* can occur here! SKIP(FUNC|BREAK|CONT) occur when 355 * a dotcmd is in a loop or a function body and appropriate 356 * built-ins occurs in file scope in the sourced file. Values 357 * other than SKIPFILE are reset by the appropriate eval*() 358 * that contained the dotcmd() call. 359 */ 360 skip = current_skipstate(); 361 if (skip != SKIPNONE) { 362 if (skip == SKIPFILE) 363 stop_skipping(); 364 break; 365 } 366 } 367 popstackmark(&smark); 368 } 369 370 371 372 /* 373 * Read /etc/profile or .profile. Return on error. 374 */ 375 376 STATIC void 377 read_profile(const char *name) 378 { 379 int fd; 380 int xflag_set = 0; 381 int vflag_set = 0; 382 383 if (*name == '\0') 384 return; 385 386 INTOFF; 387 if ((fd = open(name, O_RDONLY)) >= 0) 388 setinputfd(fd, 1); 389 INTON; 390 if (fd < 0) 391 return; 392 /* -q turns off -x and -v just when executing init files */ 393 if (qflag) { 394 if (xflag) 395 xflag = 0, xflag_set = 1; 396 if (vflag) 397 vflag = 0, vflag_set = 1; 398 } 399 (void)set_dot_funcnest(1); /* allow profile to "return" */ 400 cmdloop(0); 401 (void)set_dot_funcnest(0); 402 if (qflag) { 403 if (xflag_set) 404 xflag = 1; 405 if (vflag_set) 406 vflag = 1; 407 } 408 popfile(); 409 } 410 411 412 413 /* 414 * Read a file containing shell functions. 415 */ 416 417 void 418 readcmdfile(char *name) 419 { 420 int fd; 421 422 INTOFF; 423 if ((fd = open(name, O_RDONLY)) >= 0) 424 setinputfd(fd, 1); 425 else 426 error("Can't open %s", name); 427 INTON; 428 cmdloop(0); 429 popfile(); 430 } 431 432 433 434 int 435 exitcmd(int argc, char **argv) 436 { 437 if (stoppedjobs()) 438 return 0; 439 if (argc > 1) 440 exitshell(number(argv[1])); 441 else 442 exitshell_savedstatus(); 443 /* NOTREACHED */ 444 } 445