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 1.92 1998/12/30 10:38:59 dfr 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; 120 121 /* 122 * Allocate temporary demand zeroed space for argument and 123 * environment strings 124 */ 125 imgp->stringbase = (char *)kmem_alloc_wait(exec_map, ARG_MAX + PAGE_SIZE); 126 if (imgp->stringbase == NULL) { 127 error = ENOMEM; 128 goto exec_fail; 129 } 130 imgp->stringp = imgp->stringbase; 131 imgp->stringspace = ARG_MAX; 132 imgp->image_header = imgp->stringbase + ARG_MAX; 133 134 /* 135 * Translate the file name. namei() returns a vnode pointer 136 * in ni_vp amoung other things. 137 */ 138 ndp = &nd; 139 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 140 UIO_USERSPACE, uap->fname, p); 141 142 interpret: 143 144 error = namei(ndp); 145 if (error) { 146 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 147 ARG_MAX + PAGE_SIZE); 148 goto exec_fail; 149 } 150 151 imgp->vp = ndp->ni_vp; 152 imgp->fname = uap->fname; 153 154 /* 155 * Check file permissions (also 'opens' file) 156 */ 157 error = exec_check_permissions(imgp); 158 if (error) { 159 VOP_UNLOCK(imgp->vp, 0, p); 160 goto exec_fail_dealloc; 161 } 162 163 error = exec_map_first_page(imgp); 164 VOP_UNLOCK(imgp->vp, 0, p); 165 if (error) 166 goto exec_fail_dealloc; 167 168 /* 169 * Loop through list of image activators, calling each one. 170 * If there is no match, the activator returns -1. If there 171 * is a match, but there was an error during the activation, 172 * the error is returned. Otherwise 0 means success. If the 173 * image is interpreted, loop back up and try activating 174 * the interpreter. 175 */ 176 for (i = 0; execsw[i]; ++i) { 177 if (execsw[i]->ex_imgact) 178 error = (*execsw[i]->ex_imgact)(imgp); 179 else 180 continue; 181 if (error == -1) 182 continue; 183 if (error) 184 goto exec_fail_dealloc; 185 if (imgp->interpreted) { 186 exec_unmap_first_page(imgp); 187 /* free old vnode and name buffer */ 188 vrele(ndp->ni_vp); 189 zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 190 /* set new name to that of the interpreter */ 191 NDINIT(ndp, LOOKUP, LOCKLEAF | FOLLOW | SAVENAME, 192 UIO_SYSSPACE, imgp->interpreter_name, p); 193 goto interpret; 194 } 195 break; 196 } 197 /* If we made it through all the activators and none matched, exit. */ 198 if (error == -1) { 199 error = ENOEXEC; 200 goto exec_fail_dealloc; 201 } 202 203 /* 204 * Copy out strings (args and env) and initialize stack base 205 */ 206 stack_base = exec_copyout_strings(imgp); 207 p->p_vmspace->vm_minsaddr = (char *)stack_base; 208 209 /* 210 * If custom stack fixup routine present for this process 211 * let it do the stack setup. 212 * Else stuff argument count as first item on stack 213 */ 214 if (p->p_sysent->sv_fixup) 215 (*p->p_sysent->sv_fixup)(&stack_base, imgp); 216 else 217 suword(--stack_base, imgp->argc); 218 219 /* 220 * For security and other reasons, the file descriptor table cannot 221 * be shared after an exec. 222 */ 223 if (p->p_fd->fd_refcnt > 1) { 224 struct filedesc *tmp; 225 226 tmp = fdcopy(p); 227 fdfree(p); 228 p->p_fd = tmp; 229 } 230 231 /* close files on exec */ 232 fdcloseexec(p); 233 234 /* reset caught signals */ 235 execsigs(p); 236 237 /* name this process - nameiexec(p, ndp) */ 238 len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); 239 bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); 240 p->p_comm[len] = 0; 241 242 /* 243 * mark as execed, wakeup the process that vforked (if any) and tell 244 * it that it now has its own resources back 245 */ 246 p->p_flag |= P_EXEC; 247 if (p->p_pptr && (p->p_flag & P_PPWAIT)) { 248 p->p_flag &= ~P_PPWAIT; 249 wakeup((caddr_t)p->p_pptr); 250 } 251 252 /* 253 * Implement image setuid/setgid. 254 * 255 * Don't honor setuid/setgid if the filesystem prohibits it or if 256 * the process is being traced. 257 */ 258 if ((attr.va_mode & VSUID && p->p_ucred->cr_uid != attr.va_uid || 259 attr.va_mode & VSGID && p->p_ucred->cr_gid != attr.va_gid) && 260 (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && 261 (p->p_flag & P_TRACED) == 0) { 262 /* 263 * Turn off syscall tracing for set-id programs, except for 264 * root. 265 */ 266 if (p->p_tracep && suser(p->p_ucred, &p->p_acflag)) { 267 p->p_traceflag = 0; 268 vrele(p->p_tracep); 269 p->p_tracep = NULL; 270 } 271 /* 272 * Set the new credentials. 273 */ 274 p->p_ucred = crcopy(p->p_ucred); 275 if (attr.va_mode & VSUID) 276 p->p_ucred->cr_uid = attr.va_uid; 277 if (attr.va_mode & VSGID) 278 p->p_ucred->cr_gid = attr.va_gid; 279 setsugid(p); 280 } else { 281 if (p->p_ucred->cr_uid == p->p_cred->p_ruid && 282 p->p_ucred->cr_gid == p->p_cred->p_rgid) 283 p->p_flag &= ~P_SUGID; 284 } 285 286 /* 287 * Implement correct POSIX saved-id behavior. 288 */ 289 p->p_cred->p_svuid = p->p_ucred->cr_uid; 290 p->p_cred->p_svgid = p->p_ucred->cr_gid; 291 292 /* 293 * Store the vp for use in procfs 294 */ 295 if (p->p_textvp) /* release old reference */ 296 vrele(p->p_textvp); 297 VREF(ndp->ni_vp); 298 p->p_textvp = ndp->ni_vp; 299 300 /* 301 * If tracing the process, trap to debugger so breakpoints 302 * can be set before the program executes. 303 */ 304 STOPEVENT(p, S_EXEC, 0); 305 306 if (p->p_flag & P_TRACED) 307 psignal(p, SIGTRAP); 308 309 /* clear "fork but no exec" flag, as we _are_ execing */ 310 p->p_acflag &= ~AFORK; 311 312 /* Set entry address */ 313 setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base); 314 315 exec_fail_dealloc: 316 317 /* 318 * free various allocated resources 319 */ 320 if (imgp->firstpage) 321 exec_unmap_first_page(imgp); 322 323 if (imgp->stringbase != NULL) 324 kmem_free_wakeup(exec_map, (vm_offset_t)imgp->stringbase, 325 ARG_MAX + PAGE_SIZE); 326 327 if (imgp->vp) { 328 vrele(imgp->vp); 329 zfree(namei_zone, ndp->ni_cnd.cn_pnbuf); 330 } 331 332 if (error == 0) 333 return (0); 334 335 exec_fail: 336 if (imgp->vmspace_destroyed) { 337 /* sorry, no more process anymore. exit gracefully */ 338 exit1(p, W_EXITCODE(0, SIGABRT)); 339 /* NOT REACHED */ 340 return(0); 341 } else { 342 return(error); 343 } 344 } 345 346 int 347 exec_map_first_page(imgp) 348 struct image_params *imgp; 349 { 350 int s, rv, i; 351 int initial_pagein; 352 vm_page_t ma[VM_INITIAL_PAGEIN]; 353 vm_object_t object; 354 355 356 if (imgp->firstpage) { 357 exec_unmap_first_page(imgp); 358 } 359 360 object = imgp->vp->v_object; 361 s = splvm(); 362 363 ma[0] = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); 364 365 if ((ma[0]->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { 366 initial_pagein = VM_INITIAL_PAGEIN; 367 if (initial_pagein > object->size) 368 initial_pagein = object->size; 369 for (i = 1; i < initial_pagein; i++) { 370 if (ma[i] = vm_page_lookup(object, i)) { 371 if ((ma[i]->flags & PG_BUSY) || ma[i]->busy) 372 break; 373 if (ma[i]->valid) 374 break; 375 vm_page_busy(ma[i]); 376 } else { 377 ma[i] = vm_page_alloc(object, i, VM_ALLOC_NORMAL); 378 if (ma[i] == NULL) 379 break; 380 } 381 } 382 initial_pagein = i; 383 384 rv = vm_pager_get_pages(object, ma, initial_pagein, 0); 385 ma[0] = vm_page_lookup(object, 0); 386 387 if ((rv != VM_PAGER_OK) || (ma[0] == NULL) || (ma[0]->valid == 0)) { 388 if (ma[0]) { 389 vm_page_protect(ma[0], VM_PROT_NONE); 390 vm_page_free(ma[0]); 391 } 392 splx(s); 393 return EIO; 394 } 395 } 396 397 vm_page_wire(ma[0]); 398 vm_page_wakeup(ma[0]); 399 splx(s); 400 401 pmap_kenter((vm_offset_t) imgp->image_header, VM_PAGE_TO_PHYS(ma[0])); 402 imgp->firstpage = ma[0]; 403 404 return 0; 405 } 406 407 void 408 exec_unmap_first_page(imgp) 409 struct image_params *imgp; 410 { 411 if (imgp->firstpage) { 412 pmap_kremove((vm_offset_t) imgp->image_header); 413 vm_page_unwire(imgp->firstpage, 1); 414 imgp->firstpage = NULL; 415 } 416 } 417 418 /* 419 * Destroy old address space, and allocate a new stack 420 * The new stack is only SGROWSIZ large because it is grown 421 * automatically in trap.c. 422 */ 423 int 424 exec_new_vmspace(imgp) 425 struct image_params *imgp; 426 { 427 int error; 428 struct vmspace *vmspace = imgp->proc->p_vmspace; 429 #ifdef VM_STACK 430 caddr_t stack_addr = (caddr_t) (USRSTACK - MAXSSIZ); 431 #else 432 caddr_t stack_addr = (caddr_t) (USRSTACK - SGROWSIZ); 433 #endif 434 vm_map_t map = &vmspace->vm_map; 435 436 imgp->vmspace_destroyed = 1; 437 438 /* 439 * Blow away entire process VM, if address space not shared, 440 * otherwise, create a new VM space so that other threads are 441 * not disrupted 442 */ 443 if (vmspace->vm_refcnt == 1) { 444 if (vmspace->vm_shm) 445 shmexit(imgp->proc); 446 pmap_remove_pages(&vmspace->vm_pmap, 0, VM_MAXUSER_ADDRESS); 447 vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); 448 } else { 449 vmspace_exec(imgp->proc); 450 vmspace = imgp->proc->p_vmspace; 451 map = &vmspace->vm_map; 452 } 453 454 /* Allocate a new stack */ 455 #ifdef VM_STACK 456 error = vm_map_stack (&vmspace->vm_map, (vm_offset_t)stack_addr, 457 (vm_size_t)MAXSSIZ, VM_PROT_ALL, VM_PROT_ALL, 0); 458 if (error) 459 return (error); 460 461 /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the 462 * VM_STACK case, but they are still used to monitor the size of the 463 * process stack so we can check the stack rlimit. 464 */ 465 vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT; 466 vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ; 467 #else 468 error = vm_map_insert(&vmspace->vm_map, NULL, 0, 469 (vm_offset_t) stack_addr, (vm_offset_t) USRSTACK, 470 VM_PROT_ALL, VM_PROT_ALL, 0); 471 if (error) 472 return (error); 473 474 vmspace->vm_ssize = SGROWSIZ >> PAGE_SHIFT; 475 476 /* Initialize maximum stack address */ 477 vmspace->vm_maxsaddr = (char *)USRSTACK - MAXSSIZ; 478 #endif 479 480 return(0); 481 } 482 483 /* 484 * Copy out argument and environment strings from the old process 485 * address space into the temporary string buffer. 486 */ 487 int 488 exec_extract_strings(imgp) 489 struct image_params *imgp; 490 { 491 char **argv, **envv; 492 char *argp, *envp; 493 int error; 494 size_t length; 495 496 /* 497 * extract arguments first 498 */ 499 500 argv = imgp->uap->argv; 501 502 if (argv) { 503 argp = (caddr_t) (intptr_t) fuword(argv); 504 if (argp == (caddr_t) -1) 505 return (EFAULT); 506 if (argp) 507 argv++; 508 if (imgp->argv0) 509 argp = imgp->argv0; 510 if (argp) { 511 do { 512 if (argp == (caddr_t) -1) 513 return (EFAULT); 514 if ((error = copyinstr(argp, imgp->stringp, 515 imgp->stringspace, &length))) { 516 if (error == ENAMETOOLONG) 517 return(E2BIG); 518 return (error); 519 } 520 imgp->stringspace -= length; 521 imgp->stringp += length; 522 imgp->argc++; 523 } while ((argp = (caddr_t) (intptr_t) fuword(argv++))); 524 } 525 } 526 527 /* 528 * extract environment strings 529 */ 530 531 envv = imgp->uap->envv; 532 533 if (envv) { 534 while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { 535 if (envp == (caddr_t) -1) 536 return (EFAULT); 537 if ((error = copyinstr(envp, imgp->stringp, 538 imgp->stringspace, &length))) { 539 if (error == ENAMETOOLONG) 540 return(E2BIG); 541 return (error); 542 } 543 imgp->stringspace -= length; 544 imgp->stringp += length; 545 imgp->envc++; 546 } 547 } 548 549 return (0); 550 } 551 552 /* 553 * Copy strings out to the new process address space, constructing 554 * new arg and env vector tables. Return a pointer to the base 555 * so that it can be used as the initial stack pointer. 556 */ 557 long * 558 exec_copyout_strings(imgp) 559 struct image_params *imgp; 560 { 561 int argc, envc; 562 char **vectp; 563 char *stringp, *destp; 564 long *stack_base; 565 struct ps_strings *arginfo; 566 int szsigcode; 567 568 /* 569 * Calculate string base and vector table pointers. 570 * Also deal with signal trampoline code for this exec type. 571 */ 572 arginfo = (struct ps_strings *)PS_STRINGS; 573 szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); 574 destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - 575 roundup((ARG_MAX - imgp->stringspace), sizeof(char *)); 576 577 /* 578 * install sigcode 579 */ 580 if (szsigcode) 581 copyout(imgp->proc->p_sysent->sv_sigcode, 582 ((caddr_t)arginfo - szsigcode), szsigcode); 583 584 /* 585 * If we have a valid auxargs ptr, prepare some room 586 * on the stack. 587 */ 588 if (imgp->auxargs) 589 /* 590 * The '+ 2' is for the null pointers at the end of each of the 591 * arg and env vector sets, and 'AT_COUNT*2' is room for the 592 * ELF Auxargs data. 593 */ 594 vectp = (char **)(destp - (imgp->argc + imgp->envc + 2 + 595 AT_COUNT*2) * sizeof(char*)); 596 else 597 /* 598 * The '+ 2' is for the null pointers at the end of each of the 599 * arg and env vector sets 600 */ 601 vectp = (char **) 602 (destp - (imgp->argc + imgp->envc + 2) * sizeof(char*)); 603 604 /* 605 * vectp also becomes our initial stack base 606 */ 607 stack_base = (long *)vectp; 608 609 stringp = imgp->stringbase; 610 argc = imgp->argc; 611 envc = imgp->envc; 612 613 /* 614 * Copy out strings - arguments and environment. 615 */ 616 copyout(stringp, destp, ARG_MAX - imgp->stringspace); 617 618 /* 619 * Fill in "ps_strings" struct for ps, w, etc. 620 */ 621 suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); 622 suword(&arginfo->ps_nargvstr, argc); 623 624 /* 625 * Fill in argument portion of vector table. 626 */ 627 for (; argc > 0; --argc) { 628 suword(vectp++, (long)(intptr_t)destp); 629 while (*stringp++ != 0) 630 destp++; 631 destp++; 632 } 633 634 /* a null vector table pointer seperates the argp's from the envp's */ 635 suword(vectp++, 0); 636 637 suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); 638 suword(&arginfo->ps_nenvstr, envc); 639 640 /* 641 * Fill in environment portion of vector table. 642 */ 643 for (; envc > 0; --envc) { 644 suword(vectp++, (long)(intptr_t)destp); 645 while (*stringp++ != 0) 646 destp++; 647 destp++; 648 } 649 650 /* end of vector table is a null pointer */ 651 suword(vectp, 0); 652 653 return (stack_base); 654 } 655 656 /* 657 * Check permissions of file to execute. 658 * Return 0 for success or error code on failure. 659 */ 660 int 661 exec_check_permissions(imgp) 662 struct image_params *imgp; 663 { 664 struct proc *p = imgp->proc; 665 struct vnode *vp = imgp->vp; 666 struct vattr *attr = imgp->attr; 667 int error; 668 669 /* Get file attributes */ 670 error = VOP_GETATTR(vp, attr, p->p_ucred, p); 671 if (error) 672 return (error); 673 674 /* 675 * 1) Check if file execution is disabled for the filesystem that this 676 * file resides on. 677 * 2) Insure that at least one execute bit is on - otherwise root 678 * will always succeed, and we don't want to happen unless the 679 * file really is executable. 680 * 3) Insure that the file is a regular file. 681 */ 682 if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || 683 ((attr->va_mode & 0111) == 0) || 684 (attr->va_type != VREG)) { 685 return (EACCES); 686 } 687 688 /* 689 * Zero length files can't be exec'd 690 */ 691 if (attr->va_size == 0) 692 return (ENOEXEC); 693 694 /* 695 * Check for execute permission to file based on current credentials. 696 */ 697 error = VOP_ACCESS(vp, VEXEC, p->p_ucred, p); 698 if (error) 699 return (error); 700 701 /* 702 * Check number of open-for-writes on the file and deny execution 703 * if there are any. 704 */ 705 if (vp->v_writecount) 706 return (ETXTBSY); 707 708 /* 709 * Call filesystem specific open routine (which does nothing in the 710 * general case). 711 */ 712 error = VOP_OPEN(vp, FREAD, p->p_ucred, p); 713 if (error) 714 return (error); 715 716 return (0); 717 } 718 719 /* 720 * Exec handler registration 721 */ 722 int 723 exec_register(execsw_arg) 724 const struct execsw *execsw_arg; 725 { 726 const struct execsw **es, **xs, **newexecsw; 727 int count = 2; /* New slot and trailing NULL */ 728 729 if (execsw) 730 for (es = execsw; *es; es++) 731 count++; 732 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 733 if (newexecsw == NULL) 734 return ENOMEM; 735 xs = newexecsw; 736 if (execsw) 737 for (es = execsw; *es; es++) 738 *xs++ = *es; 739 *xs++ = execsw_arg; 740 *xs = NULL; 741 if (execsw) 742 free(execsw, M_TEMP); 743 execsw = newexecsw; 744 return 0; 745 } 746 747 int 748 exec_unregister(execsw_arg) 749 const struct execsw *execsw_arg; 750 { 751 const struct execsw **es, **xs, **newexecsw; 752 int count = 1; 753 754 if (execsw == NULL) 755 panic("unregister with no handlers left?\n"); 756 757 for (es = execsw; *es; es++) { 758 if (*es == execsw_arg) 759 break; 760 } 761 if (*es == NULL) 762 return ENOENT; 763 for (es = execsw; *es; es++) 764 if (*es != execsw_arg) 765 count++; 766 newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); 767 if (newexecsw == NULL) 768 return ENOMEM; 769 xs = newexecsw; 770 for (es = execsw; *es; es++) 771 if (*es != execsw_arg) 772 *xs++ = *es; 773 *xs = NULL; 774 if (execsw) 775 free(execsw, M_TEMP); 776 execsw = newexecsw; 777 return 0; 778 } 779