1 /* $NetBSD: main.c,v 1.90 2023/04/07 10:34:13 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 1.90 2023/04/07 10:34:13 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 setvar_invocation(argc, argv); 216 217 #if 0 /* This now happens (indirectly) in the procargs() just above */ 218 /* 219 * Limit bogus system(3) or popen(3) calls in setuid binaries, 220 * by requiring the -p flag 221 */ 222 if (!pflag && (uid != geteuid() || gid != getegid())) { 223 setuid(uid); 224 setgid(gid); 225 /* PS1 might need to be changed accordingly. */ 226 choose_ps1(); 227 } 228 #else /* except for this one little bit */ 229 if (waspriv && !privileged) 230 choose_ps1(); 231 #endif 232 233 if (loginsh) { 234 state = 1; 235 read_profile("/etc/profile"); 236 state1: 237 state = 2; 238 if (!privileged) { 239 char *profile; 240 const char *home; 241 242 home = lookupvar("HOME"); 243 if (home == NULL) 244 home = nullstr; 245 profile = ststrcat(NULL, home, "/.profile", STSTRC_END); 246 read_profile(profile); 247 stunalloc(profile); 248 } 249 #if 0 /* FreeBSD does (effectively) ...*/ 250 else 251 read_profile("/etc/suid_profile"); 252 #endif 253 } 254 state2: 255 state = 3; 256 if ((iflag || !posix) && !privileged) { 257 struct stackmark env_smark; 258 259 setstackmark(&env_smark); 260 if ((shinit = lookupvar("ENV")) != NULL && *shinit != '\0') { 261 state = 3; 262 read_profile(expandenv(shinit)); 263 } 264 popstackmark(&env_smark); 265 } 266 state3: 267 state = 4; 268 line_number = 1; /* undo anything from profile files */ 269 270 if (sflag == 0 || minusc) { 271 static int sigs[] = { 272 SIGINT, SIGQUIT, SIGHUP, 273 #ifdef SIGTSTP 274 SIGTSTP, 275 #endif 276 SIGPIPE 277 }; 278 #define SIGSSIZE (sizeof(sigs)/sizeof(sigs[0])) 279 size_t i; 280 281 for (i = 0; i < SIGSSIZE; i++) 282 setsignal(sigs[i], 0); 283 } 284 285 rststackmark(&smark); /* this one is never popped */ 286 287 if (minusc) 288 evalstring(minusc, sflag ? 0 : EV_EXIT); 289 290 if (sflag || minusc == NULL) { 291 state4: /* XXX ??? - why isn't this before the "if" statement */ 292 cmdloop(1); 293 if (iflag) { 294 out2str("\n"); 295 flushout(&errout); 296 } 297 } 298 #if PROFILE 299 monitor(0); 300 #endif 301 line_number = plinno; 302 exitshell(exitstatus); 303 /* NOTREACHED */ 304 } 305 306 307 /* 308 * Read and execute commands. "Top" is nonzero for the top level command 309 * loop; it turns on prompting if the shell is interactive. 310 */ 311 312 void 313 cmdloop(int top) 314 { 315 union node *n; 316 struct stackmark smark; 317 int inter; 318 int numeof = 0; 319 enum skipstate skip; 320 321 CTRACE(DBG_ALWAYS, ("cmdloop(%d) called\n", top)); 322 setstackmark(&smark); 323 for (;;) { 324 if (pendingsigs) 325 dotrap(); 326 inter = 0; 327 if (iflag == 1 && top) { 328 inter = 1; 329 showjobs(out2, SHOW_CHANGED); 330 chkmail(0); 331 flushout(&errout); 332 nflag = 0; 333 } 334 n = parsecmd(inter); 335 VXTRACE(DBG_PARSE|DBG_EVAL|DBG_CMDS,("cmdloop: "),showtree(n)); 336 if (n == NEOF) { 337 if (!top || numeof >= 50) 338 break; 339 if (nflag) 340 break; 341 if (!stoppedjobs()) { 342 if (!iflag || !Iflag) 343 break; 344 out2str("\nUse \"exit\" to leave shell.\n"); 345 } 346 numeof++; 347 } else if (n != NULL && nflag == 0) { 348 job_warning = (job_warning == 2) ? 1 : 0; 349 numeof = 0; 350 evaltree(n, 0); 351 } 352 rststackmark(&smark); 353 354 /* 355 * Any SKIP* can occur here! SKIP(FUNC|BREAK|CONT) occur when 356 * a dotcmd is in a loop or a function body and appropriate 357 * built-ins occurs in file scope in the sourced file. Values 358 * other than SKIPFILE are reset by the appropriate eval*() 359 * that contained the dotcmd() call. 360 */ 361 skip = current_skipstate(); 362 if (skip != SKIPNONE) { 363 if (skip == SKIPFILE) 364 stop_skipping(); 365 break; 366 } 367 } 368 popstackmark(&smark); 369 } 370 371 372 373 /* 374 * Read /etc/profile or .profile. Return on error. 375 */ 376 377 STATIC void 378 read_profile(const char *name) 379 { 380 int fd; 381 int xflag_set = 0; 382 int vflag_set = 0; 383 384 if (*name == '\0') 385 return; 386 387 INTOFF; 388 if ((fd = open(name, O_RDONLY)) >= 0) 389 setinputfd(fd, 1); 390 INTON; 391 if (fd < 0) 392 return; 393 /* -q turns off -x and -v just when executing init files */ 394 if (qflag) { 395 if (xflag) 396 xflag = 0, xflag_set = 1; 397 if (vflag) 398 vflag = 0, vflag_set = 1; 399 } 400 (void)set_dot_funcnest(1); /* allow profile to "return" */ 401 cmdloop(0); 402 (void)set_dot_funcnest(0); 403 if (qflag) { 404 if (xflag_set) 405 xflag = 1; 406 if (vflag_set) 407 vflag = 1; 408 } 409 popfile(); 410 } 411 412 413 414 /* 415 * Read a file containing shell functions. 416 */ 417 418 void 419 readcmdfile(char *name) 420 { 421 int fd; 422 423 INTOFF; 424 if ((fd = open(name, O_RDONLY)) >= 0) 425 setinputfd(fd, 1); 426 else 427 error("Can't open %s", name); 428 INTON; 429 cmdloop(0); 430 popfile(); 431 } 432 433 434 435 int 436 exitcmd(int argc, char **argv) 437 { 438 if (stoppedjobs()) 439 return 0; 440 if (argc > 1) 441 exitshell(number(argv[1])); 442 else 443 exitshell_savedstatus(); 444 /* NOTREACHED */ 445 } 446