/* * Copyright (c) 1993, David Greenman * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * $FreeBSD: src/sys/kern/kern_exec.c,v 1.107.2.15 2002/07/30 15:40:46 nectar Exp $ * $DragonFly: src/sys/kern/kern_exec.c,v 1.27 2004/05/13 17:40:15 dillon Exp $ */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include MALLOC_DEFINE(M_PARGS, "proc-args", "Process arguments"); static register_t *exec_copyout_strings (struct image_params *); /* XXX This should be vm_size_t. */ static u_long ps_strings = PS_STRINGS; SYSCTL_ULONG(_kern, KERN_PS_STRINGS, ps_strings, CTLFLAG_RD, &ps_strings, 0, ""); /* XXX This should be vm_size_t. */ static u_long usrstack = USRSTACK; SYSCTL_ULONG(_kern, KERN_USRSTACK, usrstack, CTLFLAG_RD, &usrstack, 0, ""); u_long ps_arg_cache_limit = PAGE_SIZE / 16; SYSCTL_LONG(_kern, OID_AUTO, ps_arg_cache_limit, CTLFLAG_RW, &ps_arg_cache_limit, 0, ""); int ps_argsopen = 1; SYSCTL_INT(_kern, OID_AUTO, ps_argsopen, CTLFLAG_RW, &ps_argsopen, 0, ""); void print_execve_args(struct image_args *args); int debug_execve_args = 0; SYSCTL_INT(_kern, OID_AUTO, debug_execve_args, CTLFLAG_RW, &debug_execve_args, 0, ""); void print_execve_args(struct image_args *args) { char *cp; int ndx; cp = args->begin_argv; for (ndx = 0; ndx < args->argc; ndx++) { printf("\targv[%d]: %s\n", ndx, cp); while (*cp++ != '\0'); } for (ndx = 0; ndx < args->envc; ndx++) { printf("\tenvv[%d]: %s\n", ndx, cp); while (*cp++ != '\0'); } } /* * Each of the items is a pointer to a `const struct execsw', hence the * double pointer here. */ static const struct execsw **execsw; int kern_execve(struct nameidata *ndp, struct image_args *args) { struct thread *td = curthread; struct proc *p = td->td_proc; register_t *stack_base; int error, len, i; struct image_params image_params, *imgp; struct vattr attr; int (*img_first) (struct image_params *); if (debug_execve_args) { printf("%s()\n", __func__); print_execve_args(args); } KKASSERT(p); imgp = &image_params; /* * Lock the process and set the P_INEXEC flag to indicate that * it should be left alone until we're done here. This is * necessary to avoid race conditions - e.g. in ptrace() - * that might allow a local user to illicitly obtain elevated * privileges. */ p->p_flag |= P_INEXEC; /* * Initialize part of the common data */ imgp->proc = p; imgp->args = args; imgp->attr = &attr; imgp->entry_addr = 0; imgp->resident = 0; imgp->vmspace_destroyed = 0; imgp->interpreted = 0; imgp->interpreter_name[0] = 0; imgp->auxargs = NULL; imgp->vp = NULL; imgp->firstpage = NULL; imgp->ps_strings = 0; imgp->image_header = NULL; interpret: /* * Translate the file name. namei() returns a vnode pointer * in ni_vp amoung other things. */ if ((error = namei(ndp)) != 0) goto exec_fail; imgp->vp = ndp->ni_vp; /* * Check file permissions (also 'opens' file) */ error = exec_check_permissions(imgp); if (error) { VOP_UNLOCK(imgp->vp, NULL, 0, td); goto exec_fail_dealloc; } error = exec_map_first_page(imgp); VOP_UNLOCK(imgp->vp, NULL, 0, td); if (error) goto exec_fail_dealloc; if (debug_execve_args && imgp->interpreted) { printf(" target is interpreted -- recursive pass\n"); printf(" interpreter: %s\n", imgp->interpreter_name); print_execve_args(args); } /* * If the current process has a special image activator it * wants to try first, call it. For example, emulating shell * scripts differently. */ error = -1; if ((img_first = imgp->proc->p_sysent->sv_imgact_try) != NULL) error = img_first(imgp); /* * If the vnode has a registered vmspace, exec the vmspace */ if (error == -1 && imgp->vp->v_resident) { error = exec_resident_imgact(imgp); } /* * Loop through the list of image activators, calling each one. * An activator returns -1 if there is no match, 0 on success, * and an error otherwise. */ for (i = 0; error == -1 && execsw[i]; ++i) { if (execsw[i]->ex_imgact == NULL || execsw[i]->ex_imgact == img_first) { continue; } error = (*execsw[i]->ex_imgact)(imgp); } if (error) { if (error == -1) error = ENOEXEC; goto exec_fail_dealloc; } /* * Special interpreter operation, cleanup and loop up to try to * activate the interpreter. */ if (imgp->interpreted) { exec_unmap_first_page(imgp); /* free name buffer and old vnode */ NDFREE(ndp, NDF_ONLY_PNBUF); vrele(ndp->ni_vp); /* set new name to that of the interpreter */ NDINIT(ndp, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, UIO_SYSSPACE, imgp->interpreter_name, td); goto interpret; } /* * Copy out strings (args and env) and initialize stack base */ stack_base = exec_copyout_strings(imgp); p->p_vmspace->vm_minsaddr = (char *)stack_base; /* * If custom stack fixup routine present for this process * let it do the stack setup. If we are running a resident * image there is no auxinfo or other image activator context * so don't try to add fixups to the stack. * * Else stuff argument count as first item on stack */ if (p->p_sysent->sv_fixup && imgp->resident == 0) (*p->p_sysent->sv_fixup)(&stack_base, imgp); else suword(--stack_base, imgp->args->argc); /* * For security and other reasons, the file descriptor table cannot * be shared after an exec. */ if (p->p_fd->fd_refcnt > 1) { struct filedesc *tmp; tmp = fdcopy(p); fdfree(p); p->p_fd = tmp; } /* * For security and other reasons, signal handlers cannot * be shared after an exec. The new proces gets a copy of the old * handlers. In execsigs(), the new process will have its signals * reset. */ if (p->p_procsig->ps_refcnt > 1) { struct procsig *newprocsig; MALLOC(newprocsig, struct procsig *, sizeof(struct procsig), M_SUBPROC, M_WAITOK); bcopy(p->p_procsig, newprocsig, sizeof(*newprocsig)); p->p_procsig->ps_refcnt--; p->p_procsig = newprocsig; p->p_procsig->ps_refcnt = 1; if (p->p_sigacts == &p->p_addr->u_sigacts) panic("shared procsig but private sigacts?"); p->p_addr->u_sigacts = *p->p_sigacts; p->p_sigacts = &p->p_addr->u_sigacts; } /* Stop profiling */ stopprofclock(p); /* close files on exec */ fdcloseexec(p); /* reset caught signals */ execsigs(p); /* name this process - nameiexec(p, ndp) */ len = min(ndp->ni_cnd.cn_namelen,MAXCOMLEN); bcopy(ndp->ni_cnd.cn_nameptr, p->p_comm, len); p->p_comm[len] = 0; /* * mark as execed, wakeup the process that vforked (if any) and tell * it that it now has its own resources back */ p->p_flag |= P_EXEC; if (p->p_pptr && (p->p_flag & P_PPWAIT)) { p->p_flag &= ~P_PPWAIT; wakeup((caddr_t)p->p_pptr); } /* * Implement image setuid/setgid. * * Don't honor setuid/setgid if the filesystem prohibits it or if * the process is being traced. */ if ((((attr.va_mode & VSUID) && p->p_ucred->cr_uid != attr.va_uid) || ((attr.va_mode & VSGID) && p->p_ucred->cr_gid != attr.va_gid)) && (imgp->vp->v_mount->mnt_flag & MNT_NOSUID) == 0 && (p->p_flag & P_TRACED) == 0) { /* * Turn off syscall tracing for set-id programs, except for * root. Record any set-id flags first to make sure that * we do not regain any tracing during a possible block. */ setsugid(); if (p->p_tracep && suser(td)) { struct vnode *vtmp; if ((vtmp = p->p_tracep) != NULL) { p->p_tracep = NULL; p->p_traceflag = 0; vrele(vtmp); } } /* Close any file descriptors 0..2 that reference procfs */ setugidsafety(p); /* Make sure file descriptors 0..2 are in use. */ error = fdcheckstd(p); if (error != 0) goto exec_fail_dealloc; /* * Set the new credentials. */ cratom(&p->p_ucred); if (attr.va_mode & VSUID) change_euid(attr.va_uid); if (attr.va_mode & VSGID) p->p_ucred->cr_gid = attr.va_gid; /* * Clear local varsym variables */ varsymset_clean(&p->p_varsymset); } else { if (p->p_ucred->cr_uid == p->p_ucred->cr_ruid && p->p_ucred->cr_gid == p->p_ucred->cr_rgid) p->p_flag &= ~P_SUGID; } /* * Implement correct POSIX saved-id behavior. */ if (p->p_ucred->cr_svuid != p->p_ucred->cr_uid || p->p_ucred->cr_svgid != p->p_ucred->cr_gid) { cratom(&p->p_ucred); p->p_ucred->cr_svuid = p->p_ucred->cr_uid; p->p_ucred->cr_svgid = p->p_ucred->cr_gid; } /* * Store the vp for use in procfs */ if (p->p_textvp) /* release old reference */ vrele(p->p_textvp); vref(ndp->ni_vp); p->p_textvp = ndp->ni_vp; /* * Notify others that we exec'd, and clear the P_INEXEC flag * as we're now a bona fide freshly-execed process. */ KNOTE(&p->p_klist, NOTE_EXEC); p->p_flag &= ~P_INEXEC; /* * If tracing the process, trap to debugger so breakpoints * can be set before the program executes. */ STOPEVENT(p, S_EXEC, 0); if (p->p_flag & P_TRACED) psignal(p, SIGTRAP); /* clear "fork but no exec" flag, as we _are_ execing */ p->p_acflag &= ~AFORK; /* Set values passed into the program in registers. */ setregs(p, imgp->entry_addr, (u_long)(uintptr_t)stack_base, imgp->ps_strings); /* Free any previous argument cache */ if (p->p_args && --p->p_args->ar_ref == 0) FREE(p->p_args, M_PARGS); p->p_args = NULL; /* Cache arguments if they fit inside our allowance */ i = imgp->args->begin_envv - imgp->args->begin_argv; if (ps_arg_cache_limit >= i + sizeof(struct pargs)) { MALLOC(p->p_args, struct pargs *, sizeof(struct pargs) + i, M_PARGS, M_WAITOK); p->p_args->ar_ref = 1; p->p_args->ar_length = i; bcopy(imgp->args->begin_argv, p->p_args->ar_args, i); } exec_fail_dealloc: /* * free various allocated resources */ if (imgp->firstpage) exec_unmap_first_page(imgp); if (imgp->vp) { NDFREE(ndp, NDF_ONLY_PNBUF); vrele(imgp->vp); } if (error == 0) { ++mycpu->gd_cnt.v_exec; return (0); } exec_fail: /* we're done here, clear P_INEXEC */ p->p_flag &= ~P_INEXEC; if (imgp->vmspace_destroyed) { /* sorry, no more process anymore. exit gracefully */ exit1(W_EXITCODE(0, SIGABRT)); /* NOT REACHED */ return(0); } else { return(error); } } /* * execve() system call. */ int execve(struct execve_args *uap) { struct thread *td = curthread; struct nameidata nd; struct image_args args; int error; NDINIT(&nd, NAMEI_LOOKUP, CNP_LOCKLEAF | CNP_FOLLOW | CNP_SAVENAME, UIO_USERSPACE, uap->fname, td); error = exec_copyin_args(&args, uap->fname, PATH_USERSPACE, uap->argv, uap->envv); if (error == 0) error = kern_execve(&nd, &args); exec_free_args(&args); /* * The syscall result is returned in registers to the new program. * Linux will register %edx as an atexit function and we must be * sure to set it to 0. XXX */ if (error == 0) uap->sysmsg_result64 = 0; return (error); } int exec_map_first_page(struct image_params *imgp) { int s, rv, i; int initial_pagein; vm_page_t ma[VM_INITIAL_PAGEIN]; vm_page_t m; vm_object_t object; if (imgp->firstpage) exec_unmap_first_page(imgp); VOP_GETVOBJECT(imgp->vp, &object); /* * We shouldn't need protection for vm_page_grab() but we certainly * need it for the lookup loop below (lookup/busy race), since * an interrupt can unbusy and free the page before our busy check. */ s = splvm(); m = vm_page_grab(object, 0, VM_ALLOC_NORMAL | VM_ALLOC_RETRY); if ((m->valid & VM_PAGE_BITS_ALL) != VM_PAGE_BITS_ALL) { ma[0] = m; initial_pagein = VM_INITIAL_PAGEIN; if (initial_pagein > object->size) initial_pagein = object->size; for (i = 1; i < initial_pagein; i++) { if ((m = vm_page_lookup(object, i)) != NULL) { if ((m->flags & PG_BUSY) || m->busy) break; if (m->valid) break; vm_page_busy(m); } else { m = vm_page_alloc(object, i, VM_ALLOC_NORMAL); if (m == NULL) break; } ma[i] = m; } initial_pagein = i; /* * get_pages unbusies all the requested pages except the * primary page (at index 0 in this case). */ rv = vm_pager_get_pages(object, ma, initial_pagein, 0); m = vm_page_lookup(object, 0); if (rv != VM_PAGER_OK || m == NULL || m->valid == 0) { if (m) { vm_page_protect(m, VM_PROT_NONE); vm_page_free(m); } splx(s); return EIO; } } vm_page_hold(m); vm_page_wakeup(m); /* unbusy the page */ splx(s); imgp->firstpage = sf_buf_alloc(m, SFBA_QUICK); imgp->image_header = (void *)sf_buf_kva(imgp->firstpage); return 0; } void exec_unmap_first_page(imgp) struct image_params *imgp; { vm_page_t m; int s; s = splvm(); if (imgp->firstpage != NULL) { m = sf_buf_page(imgp->firstpage); sf_buf_free(imgp->firstpage); imgp->firstpage = NULL; imgp->image_header = NULL; vm_page_unhold(m); } splx(s); } /* * Destroy old address space, and allocate a new stack * The new stack is only SGROWSIZ large because it is grown * automatically in trap.c. */ int exec_new_vmspace(struct image_params *imgp, struct vmspace *vmcopy) { int error; struct vmspace *vmspace = imgp->proc->p_vmspace; vm_offset_t stack_addr = USRSTACK - maxssiz; vm_map_t map; imgp->vmspace_destroyed = 1; /* * Prevent a pending AIO from modifying the new address space. */ aio_proc_rundown(imgp->proc); /* * Blow away entire process VM, if address space not shared, * otherwise, create a new VM space so that other threads are * not disrupted. If we are execing a resident vmspace we * create a duplicate of it and remap the stack. * * The exitingcnt test is not strictly necessary but has been * included for code sanity (to make the code more deterministic). */ map = &vmspace->vm_map; if (vmcopy) { vmspace_exec(imgp->proc, vmcopy); vmspace = imgp->proc->p_vmspace; pmap_remove_pages(vmspace_pmap(vmspace), stack_addr, USRSTACK); map = &vmspace->vm_map; } else if (vmspace->vm_refcnt == 1 && vmspace->vm_exitingcnt == 0) { shmexit(vmspace); if (vmspace->vm_upcalls) upc_release(vmspace, imgp->proc); pmap_remove_pages(vmspace_pmap(vmspace), 0, VM_MAXUSER_ADDRESS); vm_map_remove(map, 0, VM_MAXUSER_ADDRESS); } else { vmspace_exec(imgp->proc, NULL); vmspace = imgp->proc->p_vmspace; map = &vmspace->vm_map; } /* Allocate a new stack */ error = vm_map_stack(&vmspace->vm_map, stack_addr, (vm_size_t)maxssiz, VM_PROT_ALL, VM_PROT_ALL, 0); if (error) return (error); /* vm_ssize and vm_maxsaddr are somewhat antiquated concepts in the * VM_STACK case, but they are still used to monitor the size of the * process stack so we can check the stack rlimit. */ vmspace->vm_ssize = sgrowsiz >> PAGE_SHIFT; vmspace->vm_maxsaddr = (char *)USRSTACK - maxssiz; return(0); } /* * Copy out argument and environment strings from the old process * address space into the temporary string buffer. */ int exec_copyin_args(struct image_args *args, char *fname, enum exec_path_segflg segflg, char **argv, char **envv) { char *argp, *envp; int error = 0; size_t length; bzero(args, sizeof(*args)); args->buf = (char *) kmem_alloc_wait(exec_map, PATH_MAX + ARG_MAX); if (args->buf == NULL) return (ENOMEM); args->begin_argv = args->buf; args->endp = args->begin_argv; args->space = ARG_MAX; args->fname = args->buf + ARG_MAX; /* * Copy the file name. */ if (segflg == PATH_SYSSPACE) { error = copystr(fname, args->fname, PATH_MAX, &length); } else if (segflg == PATH_USERSPACE) { error = copyinstr(fname, args->fname, PATH_MAX, &length); } /* * extract argument strings */ if (argv && error == 0) { /* * The argv0 argument for execv() is allowed to be NULL, * in which case we use our filename as argv[0]. * This guarantees that * the interpreter knows what file to open in the case * that we exec an interpreted file. */ argp = (caddr_t) (intptr_t) fuword(argv); if (argp == NULL) { length = strlen(args->fname) + 1; KKASSERT(length <= args->space); bcopy(args->fname, args->endp, length); args->space -= length; args->endp += length; args->argc++; argv++; } while ((argp = (caddr_t) (intptr_t) fuword(argv++))) { if (argp == (caddr_t) -1) { error = EFAULT; goto cleanup; } error = copyinstr(argp, args->endp, args->space, &length); if (error == ENAMETOOLONG) error = E2BIG; if (error) goto cleanup; args->space -= length; args->endp += length; args->argc++; } } args->begin_envv = args->endp; /* * extract environment strings */ if (envv && error == 0) { while ((envp = (caddr_t) (intptr_t) fuword(envv++))) { if (envp == (caddr_t) -1) { error = EFAULT; goto cleanup; } error = copyinstr(envp, args->endp, args->space, &length); if (error == ENAMETOOLONG) error = E2BIG; if (error) goto cleanup; args->space -= length; args->endp += length; args->envc++; } } cleanup: return (error); } void exec_free_args(struct image_args *args) { if (args->buf) { kmem_free_wakeup(exec_map, (vm_offset_t)args->buf, PATH_MAX + ARG_MAX); args->buf = NULL; } } /* * Copy strings out to the new process address space, constructing * new arg and env vector tables. Return a pointer to the base * so that it can be used as the initial stack pointer. */ register_t * exec_copyout_strings(struct image_params *imgp) { int argc, envc; char **vectp; char *stringp, *destp; register_t *stack_base; struct ps_strings *arginfo; int szsigcode; /* * Calculate string base and vector table pointers. * Also deal with signal trampoline code for this exec type. */ arginfo = (struct ps_strings *)PS_STRINGS; szsigcode = *(imgp->proc->p_sysent->sv_szsigcode); destp = (caddr_t)arginfo - szsigcode - SPARE_USRSPACE - roundup((ARG_MAX - imgp->args->space), sizeof(char *)); /* * install sigcode */ if (szsigcode) copyout(imgp->proc->p_sysent->sv_sigcode, ((caddr_t)arginfo - szsigcode), szsigcode); /* * If we have a valid auxargs ptr, prepare some room * on the stack. * * The '+ 2' is for the null pointers at the end of each of the * arg and env vector sets, and 'AT_COUNT*2' is room for the * ELF Auxargs data. */ if (imgp->auxargs) { vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2 + AT_COUNT * 2) * sizeof(char*)); } else { vectp = (char **)(destp - (imgp->args->argc + imgp->args->envc + 2) * sizeof(char*)); } /* * NOTE: don't bother aligning the stack here for GCC 2.x, it will * be done in crt1.o. Note that GCC 3.x aligns the stack in main. */ /* * vectp also becomes our initial stack base */ stack_base = (register_t *)vectp; stringp = imgp->args->begin_argv; argc = imgp->args->argc; envc = imgp->args->envc; /* * Copy out strings - arguments and environment. */ copyout(stringp, destp, ARG_MAX - imgp->args->space); /* * Fill in "ps_strings" struct for ps, w, etc. */ suword(&arginfo->ps_argvstr, (long)(intptr_t)vectp); suword(&arginfo->ps_nargvstr, argc); /* * Fill in argument portion of vector table. */ for (; argc > 0; --argc) { suword(vectp++, (long)(intptr_t)destp); while (*stringp++ != 0) destp++; destp++; } /* a null vector table pointer separates the argp's from the envp's */ suword(vectp++, 0); suword(&arginfo->ps_envstr, (long)(intptr_t)vectp); suword(&arginfo->ps_nenvstr, envc); /* * Fill in environment portion of vector table. */ for (; envc > 0; --envc) { suword(vectp++, (long)(intptr_t)destp); while (*stringp++ != 0) destp++; destp++; } /* end of vector table is a null pointer */ suword(vectp, 0); return (stack_base); } /* * Check permissions of file to execute. * Return 0 for success or error code on failure. */ int exec_check_permissions(imgp) struct image_params *imgp; { struct proc *p = imgp->proc; struct vnode *vp = imgp->vp; struct vattr *attr = imgp->attr; struct thread *td = p->p_thread; int error; /* Get file attributes */ error = VOP_GETATTR(vp, attr, td); if (error) return (error); /* * 1) Check if file execution is disabled for the filesystem that this * file resides on. * 2) Insure that at least one execute bit is on - otherwise root * will always succeed, and we don't want to happen unless the * file really is executable. * 3) Insure that the file is a regular file. */ if ((vp->v_mount->mnt_flag & MNT_NOEXEC) || ((attr->va_mode & 0111) == 0) || (attr->va_type != VREG)) { return (EACCES); } /* * Zero length files can't be exec'd */ if (attr->va_size == 0) return (ENOEXEC); /* * Check for execute permission to file based on current credentials. */ error = VOP_ACCESS(vp, VEXEC, p->p_ucred, td); if (error) return (error); /* * Check number of open-for-writes on the file and deny execution * if there are any. */ if (vp->v_writecount) return (ETXTBSY); /* * Call filesystem specific open routine (which does nothing in the * general case). */ error = VOP_OPEN(vp, FREAD, p->p_ucred, td); if (error) return (error); return (0); } /* * Exec handler registration */ int exec_register(execsw_arg) const struct execsw *execsw_arg; { const struct execsw **es, **xs, **newexecsw; int count = 2; /* New slot and trailing NULL */ if (execsw) for (es = execsw; *es; es++) count++; newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); if (newexecsw == NULL) return ENOMEM; xs = newexecsw; if (execsw) for (es = execsw; *es; es++) *xs++ = *es; *xs++ = execsw_arg; *xs = NULL; if (execsw) free(execsw, M_TEMP); execsw = newexecsw; return 0; } int exec_unregister(execsw_arg) const struct execsw *execsw_arg; { const struct execsw **es, **xs, **newexecsw; int count = 1; if (execsw == NULL) panic("unregister with no handlers left?"); for (es = execsw; *es; es++) { if (*es == execsw_arg) break; } if (*es == NULL) return ENOENT; for (es = execsw; *es; es++) if (*es != execsw_arg) count++; newexecsw = malloc(count * sizeof(*es), M_TEMP, M_WAITOK); if (newexecsw == NULL) return ENOMEM; xs = newexecsw; for (es = execsw; *es; es++) if (*es != execsw_arg) *xs++ = *es; *xs = NULL; if (execsw) free(execsw, M_TEMP); execsw = newexecsw; return 0; }