1 /* 2 * Copyright (c) 1993, David Greenman 3 * All rights reserved. 4 * 5 * Redistribution and use in source and binary forms, with or without 6 * modification, are permitted provided that the following conditions 7 * are met: 8 * 1. Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * 2. Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in the 12 * documentation and/or other materials provided with the distribution. 13 * 14 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 15 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 16 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 17 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 18 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 19 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 20 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 21 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 22 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 23 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 24 * SUCH DAMAGE. 25 * 26 * $Id: kern_exec.c,v 1.98 1999/04/19 14:14:09 peter Exp $ 27 */ 28 29 #include <sys/param.h> 30 #include <sys/systm.h> 31 #include <sys/sysproto.h> 32 #include <sys/signalvar.h> 33 #include <sys/kernel.h> 34 #include <sys/mount.h> 35 #include <sys/filedesc.h> 36 #include <sys/fcntl.h> 37 #include <sys/acct.h> 38 #include <sys/exec.h> 39 #include <sys/imgact.h> 40 #include <sys/imgact_elf.h> 41 #include <sys/wait.h> 42 #include <sys/proc.h> 43 #include <sys/pioctl.h> 44 #include <sys/malloc.h> 45 #include <sys/namei.h> 46 #include <sys/sysent.h> 47 #include <sys/shm.h> 48 #include <sys/sysctl.h> 49 #include <sys/vnode.h> 50 #include <sys/buf.h> 51 52 #include <vm/vm.h> 53 #include <vm/vm_param.h> 54 #include <vm/vm_prot.h> 55 #include <sys/lock.h> 56 #include <vm/pmap.h> 57 #include <vm/vm_page.h> 58 #include <vm/vm_map.h> 59 #include <vm/vm_kern.h> 60 #include <vm/vm_extern.h> 61 #include <vm/vm_object.h> 62 #include <vm/vm_zone.h> 63 #include <vm/vm_pager.h> 64 65 #include <machine/reg.h> 66 67 static long *exec_copyout_strings __P((struct image_params *)); 68 69 static long ps_strings = PS_STRINGS; 70 SYSCTL_LONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, ""); 71 72 static long usrstack = USRSTACK; 73 SYSCTL_LONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, ""); 74 75 /* 76 * Each of the items is a pointer to a `const struct execsw', hence the 77 * double pointer here. 78 */ 79 static const struct execsw **execsw; 80 81 #ifndef _SYS_SYSPROTO_H_ 82 struct execve_args { 83 char *fname; 84 char **argv; 85 char **envv; 86 }; 87 #endif 88 89 /* 90 * execve() system call. 91 */ 92 int 93 execve(p, uap) 94 struct proc *p; 95 register struct execve_args *uap; 96 { 97 struct nameidata nd, *ndp; 98 long *stack_base; 99 int error, len, i; 100 struct image_params image_params, *imgp; 101 struct vattr attr; 102 103 imgp = &image_params; 104 105 /* 106 * Initialize part of the common data 107 */ 108 imgp->proc = p; 109 imgp->uap = uap; 110 imgp->attr = &attr; 111 imgp->argc = imgp->envc = 0; 112 imgp->argv0 = NULL; 113 imgp->entry_addr = 0; 114 imgp->vmspace_destroyed = 0; 115 imgp->interpreted = 0; 116 imgp->interpreter_name[0] = '\0'; 117 imgp->auxargs = NULL; 118 imgp->vp = NULL; 119 imgp->firstpage = NULL; 120 imgp->ps_strings = 0; 121 122 /* 123 * Allocate temporary demand zeroed space for argument and 124 * environment strings 125 */ 126 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 127 if (imgp->stringbase == NULL) { 128 error = ENOMEM; 129 goto exec_fail; 130 } 131 imgp->stringp = imgp->stringbase; 132 imgp->stringspace = ARG_MAX; 133 imgp->image_header = imgp->stringbase + ARG_MAX; 134 135 /* 136 * Translate the file name. namei() returns a vnode pointer 137 * in ni_vp amoung other things. 138 */ 139 ndp = &nd; 140 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 141 UIO_USERSPACE, uap->fname, p); 142 143 interpret: 144 145 error = namei(ndp); 146 if (error) { 147 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 148 ARG_MAX + PAGE_SIZE); 149 goto exec_fail; 150 } 151 152 imgp->vp = ndp->ni_vp; 153 imgp->fname = uap->fname; 154 155 /* 156 * Check file permissions (also 'opens' file) 157 */ 158 error = exec_check_permissions(imgp); 159 if (error) { 160 VOP_UNLOCK(imgp->vp, 0, p); 161 goto exec_fail_dealloc; 162 } 163 164 error = exec_map_first_page(imgp); 165 VOP_UNLOCK(imgp->vp, 0, p); 166 if (error) 167 goto exec_fail_dealloc; 168 169 /* 170 * Loop through list of image activators, calling each one. 171 * If there is no match, the activator returns -1. If there 172 * is a match, but there was an error during the activation, 173 * the error is returned. Otherwise 0 means success. If the 174 * image is interpreted, loop back up and try activating 175 * the interpreter. 176 */ 177 for (i = 0; execsw[i]; ++i) { 178 if (execsw[i]->ex_imgact) 179 error = (*execsw[i]->ex_imgact)(imgp); 180 else 181 continue; 182 if (error == -1) 183 continue; 184 if (error) 185 goto exec_fail_dealloc; 186 if (imgp->interpreted) { 187 exec_unmap_first_page(imgp); 188 /* free old vnode and name buffer */ 189 vrele(ndp->ni_vp); 190 zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 191 /* set new name to that of the interpreter */ 192 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 193 UIO_SYSSPACE, imgp->interpreter_name, p); 194 goto interpret; 195 } 196 break; 197 } 198 /* If we made it through all the activators and none matched, exit. */ 199 if (error == -1) { 200 error = ENOEXEC; 201 goto exec_fail_dealloc; 202 } 203 204 /* 205 * Copy out strings (args and env) and initialize stack base 206 */ 207 stack_base = exec_copyout_strings(imgp); 208 p->p_vmspace->vm_minsaddr = (char *)stack_base; 209 210 /* 211 * If custom stack fixup routine present for this process 212 * let it do the stack setup. 213 * Else stuff argument count as first item on stack 214 */ 215 if (p->p_sysent->sv_fixup) 216 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 217 else 218 suword(--stack_base, imgp->argc); 219 220 /* 221 * For security and other reasons, the file descriptor table cannot 222 * be shared after an exec. 223 */ 224 if (p->p_fd->fd_refcnt > 1) { 225 struct filedesc *tmp; 226 227 tmp = fdcopy(p); 228 fdfree(p); 229 p->p_fd = tmp; 230 } 231 232 /* close files on exec */ 233 fdcloseexec(p); 234 235 /* reset caught signals */ 236 execsigs(p); 237 238 /* name this process - nameiexec(p, ndp) */ 239 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 240 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 241 p->p_comm[len] = 0; 242 243 /* 244 * mark as execed, wakeup the process that vforked (if any) and tell 245 * it that it now has its own resources back 246 */ 247 p->p_flag |= P_EXEC; 248 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 249 p->p_flag &= ~P_PPWAIT; 250 wakeup((caddr_t)p->p_pptr); 251 } 252 253 /* 254 * Implement image setuid/setgid. 255 * 256 * Don't honor setuid/setgid if the filesystem prohibits it or if 257 * the process is being traced. 258 */ 259 if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || 260 ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && 261 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 262 (p->p_flag & P_TRACED) == 0) { 263 /* 264 * Turn off syscall tracing for set-id programs, except for 265 * root. 266 */ 267 if (p->p_tracep && suser(p)) { 268 p->p_traceflag = 0; 269 vrele(p->p_tracep); 270 p->p_tracep = NULL; 271 } 272 /* 273 * Set the new credentials. 274 */ 275 p->p_ucred = crcopy(p->p_ucred); 276 if (attr.va_mode & VSUID) 277 p->p_ucred->cr_uid = attr.va_uid; 278 if (attr.va_mode & VSGID) 279 p->p_ucred->cr_gid = attr.va_gid; 280 setsugid(p); 281 } else { 282 if (p->p_ucred->cr_uid == p->p_cred->p_ruid && 283 p->p_ucred->cr_gid == p->p_cred->p_rgid) 284 p->p_flag &= ~P_SUGID; 285 } 286 287 /* 288 * Implement correct POSIX saved-id behavior. 289 */ 290 p->p_cred->p_svuid = p->p_ucred->cr_uid; 291 p->p_cred->p_svgid = p->p_ucred->cr_gid; 292 293 /* 294 * Store the vp for use in procfs 295 */ 296 if (p->p_textvp) /* release old reference */ 297 vrele(p->p_textvp); 298 VREF(ndp->ni_vp); 299 p->p_textvp = ndp->ni_vp; 300 301 /* 302 * If tracing the process, trap to debugger so breakpoints 303 * can be set before the program executes. 304 */ 305 STOPEVENT(p, S_EXEC, 0); 306 307 if (p->p_flag & P_TRACED) 308 psignal(p, SIGTRAP); 309 310 /* clear "fork but no exec" flag, as we _are_ execing */ 311 p->p_acflag &= ~AFORK; 312 313 /* Set values passed into the program in registers. */ 314 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, 315 imgp->ps_strings); 316 317 exec_fail_dealloc: 318 319 /* 320 * free various allocated resources 321 */ 322 if (imgp->firstpage) 323 exec_unmap_first_page(imgp); 324 325 if (imgp->stringbase != NULL) 326 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 327 ARG_MAX + PAGE_SIZE); 328 329 if (imgp->vp) { 330 vrele(imgp->vp); 331 zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 332 } 333 334 if (error == 0) 335 return (0); 336 337 exec_fail: 338 if (imgp->vmspace_destroyed) { 339 /* sorry, no more process anymore. exit gracefully */ 340 exit1(p, W_EXITCODE(0, SIGABRT)); 341 /* NOT REACHED */ 342 return(0); 343 } else { 344 return(error); 345 } 346 } 347 348 int 349 exec_map_first_page(imgp) 350 struct image_params *imgp; 351 { 352 int s, rv, i; 353 int initial_pagein; 354 vm_page_t ma[VM_INITIAL_PAGEIN]; 355 vm_object_t object; 356 357 358 if (imgp->firstpage) { 359 exec_unmap_first_page(imgp); 360 } 361 362 object = imgp->vp->v_object; 363 s = splvm(); 364 365 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 366 367 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 368 initial_pagein = VM_INITIAL_PAGEIN; 369 if (initial_pagein > object->size) 370 initial_pagein = object->size; 371 for (i = 1; i < initial_pagein; i++) { 372 if ((ma[i] = vm_page_lookup(object, i)) != NULL) { 373 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 374 break; 375 if (ma[i]->valid) 376 break; 377 vm_page_busy(ma[i]); 378 } else { 379 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 380 if (ma[i] == NULL) 381 break; 382 } 383 } 384 initial_pagein = i; 385 386 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 387 ma[0] = vm_page_lookup(object, 0); 388 389 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 390 if (ma[0]) { 391 vm_page_protect(ma[0], VM_PROT_NONE); 392 vm_page_free(ma[0]); 393 } 394 splx(s); 395 return EIO; 396 } 397 } 398 399 vm_page_wire(ma[0]); 400 vm_page_wakeup(ma[0]); 401 splx(s); 402 403 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 404 imgp->firstpage = ma[0]; 405 406 return 0; 407 } 408 409 void 410 exec_unmap_first_page(imgp) 411 struct image_params *imgp; 412 { 413 if (imgp->firstpage) { 414 pmap_kremove((vm_offset_t) imgp->image_header); 415 vm_page_unwire(imgp->firstpage, 1); 416 imgp->firstpage = NULL; 417 } 418 } 419 420 /* 421 * Destroy old address space, and allocate a new stack 422 * The new stack is only SGROWSIZ large because it is grown 423 * automatically in trap.c. 424 */ 425 int 426 exec_new_vmspace(imgp) 427 struct image_params *imgp; 428 { 429 int error; 430 struct vmspace *vmspace = imgp->proc->p_vmspace; 431 caddr_t stack_addr = (caddr_t) (USRSTACK - MAXSSIZ); 432 vm_map_t map = &vmspace->vm_map; 433 434 imgp->vmspace_destroyed = 1; 435 436 /* 437 * Blow away entire process VM, if address space not shared, 438 * otherwise, create a new VM space so that other threads are 439 * not disrupted 440 */ 441 if (vmspace->vm_refcnt == 1) { 442 if (vmspace->vm_shm) 443 shmexit(imgp->proc); 444 pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); 445 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 446 } else { 447 vmspace_exec(imgp->proc); 448 vmspace = imgp->proc->p_vmspace; 449 map = &vmspace->vm_map; 450 } 451 452 /* Allocate a new stack */ 453 error = vm_map_stack (&vmspace->vm_map, (vm_offset_t)stack_addr, 454 (vm_size_t)MAXSSIZ, VM_PROT_ALL, VM_PROT_ALL, 0); 455 if (error) 456 return (error); 457 458 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 459 * VM_STACK case, but they are still used to monitor the size of the 460 * process stack so we can check the stack rlimit. 461 */ 462 vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT; 463 vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ; 464 465 return(0); 466 } 467 468 /* 469 * Copy out argument and environment strings from the old process 470 * address space into the temporary string buffer. 471 */ 472 int 473 exec_extract_strings(imgp) 474 struct image_params *imgp; 475 { 476 char **argv, **envv; 477 char *argp, *envp; 478 int error; 479 size_t length; 480 481 /* 482 * extract arguments first 483 */ 484 485 argv = imgp->uap->argv; 486 487 if (argv) { 488 argp = (caddr_t) (intptr_t) fuword(argv); 489 if (argp == (caddr_t) -1) 490 return (EFAULT); 491 if (argp) 492 argv++; 493 if (imgp->argv0) 494 argp = imgp->argv0; 495 if (argp) { 496 do { 497 if (argp == (caddr_t) -1) 498 return (EFAULT); 499 if ((error = copyinstr(argp, imgp->stringp, 500 imgp->stringspace, &length))) { 501 if (error == ENAMETOOLONG) 502 return(E2BIG); 503 return (error); 504 } 505 imgp->stringspace -= length; 506 imgp->stringp += length; 507 imgp->argc++; 508 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 509 } 510 } 511 512 /* 513 * extract environment strings 514 */ 515 516 envv = imgp->uap->envv; 517 518 if (envv) { 519 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 520 if (envp == (caddr_t) -1) 521 return (EFAULT); 522 if ((error = copyinstr(envp, imgp->stringp, 523 imgp->stringspace, &length))) { 524 if (error == ENAMETOOLONG) 525 return(E2BIG); 526 return (error); 527 } 528 imgp->stringspace -= length; 529 imgp->stringp += length; 530 imgp->envc++; 531 } 532 } 533 534 return (0); 535 } 536 537 /* 538 * Copy strings out to the new process address space, constructing 539 * new arg and env vector tables. Return a pointer to the base 540 * so that it can be used as the initial stack pointer. 541 */ 542 long * 543 exec_copyout_strings(imgp) 544 struct image_params *imgp; 545 { 546 int argc, envc; 547 char **vectp; 548 char *stringp, *destp; 549 long *stack_base; 550 struct ps_strings *arginfo; 551 int szsigcode; 552 553 /* 554 * Calculate string base and vector table pointers. 555 * Also deal with signal trampoline code for this exec type. 556 */ 557 arginfo = (struct ps_strings *)PS_STRINGS; 558 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 559 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 560 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 561 562 /* 563 * install sigcode 564 */ 565 if (szsigcode) 566 copyout(imgp->proc->p_sysent->sv_sigcode, 567 ((caddr_t)arginfo - szsigcode), szsigcode); 568 569 /* 570 * If we have a valid auxargs ptr, prepare some room 571 * on the stack. 572 */ 573 if (imgp->auxargs) 574 /* 575 * The '+ 2' is for the null pointers at the end of each of the 576 * arg and env vector sets, and 'AT_COUNT*2' is room for the 577 * ELF Auxargs data. 578 */ 579 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 + 580 AT_COUNT*2) * sizeof(char*)); 581 else 582 /* 583 * The '+ 2' is for the null pointers at the end of each of the 584 * arg and env vector sets 585 */ 586 vectp = (char **) 587 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*)); 588 589 /* 590 * vectp also becomes our initial stack base 591 */ 592 stack_base = (long *)vectp; 593 594 stringp = imgp->stringbase; 595 argc = imgp->argc; 596 envc = imgp->envc; 597 598 /* 599 * Copy out strings - arguments and environment. 600 */ 601 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 602 603 /* 604 * Fill in "ps_strings" struct for ps, w, etc. 605 */ 606 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 607 suword(&arginfo->ps_nargvstr, argc); 608 609 /* 610 * Fill in argument portion of vector table. 611 */ 612 for (; argc > 0; --argc) { 613 suword(vectp++, (long)(intptr_t)destp); 614 while (*stringp++ != 0) 615 destp++; 616 destp++; 617 } 618 619 /* a null vector table pointer seperates the argp's from the envp's */ 620 suword(vectp++, 0); 621 622 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 623 suword(&arginfo->ps_nenvstr, envc); 624 625 /* 626 * Fill in environment portion of vector table. 627 */ 628 for (; envc > 0; --envc) { 629 suword(vectp++, (long)(intptr_t)destp); 630 while (*stringp++ != 0) 631 destp++; 632 destp++; 633 } 634 635 /* end of vector table is a null pointer */ 636 suword(vectp, 0); 637 638 return (stack_base); 639 } 640 641 /* 642 * Check permissions of file to execute. 643 * Return 0 for success or error code on failure. 644 */ 645 int 646 exec_check_permissions(imgp) 647 struct image_params *imgp; 648 { 649 struct proc *p = imgp->proc; 650 struct vnode *vp = imgp->vp; 651 struct vattr *attr = imgp->attr; 652 int error; 653 654 /* Get file attributes */ 655 error = VOP_GETATTR(vp, attr, p->p_ucred, p); 656 if (error) 657 return (error); 658 659 /* 660 * 1) Check if file execution is disabled for the filesystem that this 661 * file resides on. 662 * 2) Insure that at least one execute bit is on - otherwise root 663 * will always succeed, and we don't want to happen unless the 664 * file really is executable. 665 * 3) Insure that the file is a regular file. 666 */ 667 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 668 ((attr->va_mode & 0111) == 0) || 669 (attr->va_type != VREG)) { 670 return (EACCES); 671 } 672 673 /* 674 * Zero length files can't be exec'd 675 */ 676 if (attr->va_size == 0) 677 return (ENOEXEC); 678 679 /* 680 * Check for execute permission to file based on current credentials. 681 */ 682 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p); 683 if (error) 684 return (error); 685 686 /* 687 * Check number of open-for-writes on the file and deny execution 688 * if there are any. 689 */ 690 if (vp->v_writecount) 691 return (ETXTBSY); 692 693 /* 694 * Call filesystem specific open routine (which does nothing in the 695 * general case). 696 */ 697 error = VOP_OPEN(vp, FREAD, p->p_ucred, p); 698 if (error) 699 return (error); 700 701 return (0); 702 } 703 704 /* 705 * Exec handler registration 706 */ 707 int 708 exec_register(execsw_arg) 709 const struct execsw *execsw_arg; 710 { 711 const struct execsw **es, **xs, **newexecsw; 712 int count = 2; /* New slot and trailing NULL */ 713 714 if (execsw) 715 for (es = execsw; *es; es++) 716 count++; 717 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 718 if (newexecsw == NULL) 719 return ENOMEM; 720 xs = newexecsw; 721 if (execsw) 722 for (es = execsw; *es; es++) 723 *xs++ = *es; 724 *xs++ = execsw_arg; 725 *xs = NULL; 726 if (execsw) 727 free(execsw, M_TEMP); 728 execsw = newexecsw; 729 return 0; 730 } 731 732 int 733 exec_unregister(execsw_arg) 734 const struct execsw *execsw_arg; 735 { 736 const struct execsw **es, **xs, **newexecsw; 737 int count = 1; 738 739 if (execsw == NULL) 740 panic("unregister with no handlers left?\n"); 741 742 for (es = execsw; *es; es++) { 743 if (*es == execsw_arg) 744 break; 745 } 746 if (*es == NULL) 747 return ENOENT; 748 for (es = execsw; *es; es++) 749 if (*es != execsw_arg) 750 count++; 751 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 752 if (newexecsw == NULL) 753 return ENOMEM; 754 xs = newexecsw; 755 for (es = execsw; *es; es++) 756 if (*es != execsw_arg) 757 *xs++ = *es; 758 *xs = NULL; 759 if (execsw) 760 free(execsw, M_TEMP); 761 execsw = newexecsw; 762 return 0; 763 } 764