1 /*- 2 * SPDX-License-Identifier: BSD-2-Clause 3 * 4 * Copyright (c) 2018 Mark Johnston <markj@FreeBSD.org> 5 * 6 * Redistribution and use in source and binary forms, with or without 7 * modification, are permitted provided that the following conditions 8 * are met: 9 * 1. Redistributions of source code must retain the above copyright 10 * notice, this list of conditions and the following disclaimer. 11 * 2. Redistributions in binary form must reproduce the above copyright 12 * notice, this list of conditions and the following disclaimer in the 13 * documentation and/or other materials provided with the distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND 16 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 17 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 18 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE 19 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 20 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 21 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 22 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 23 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 24 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 25 * SUCH DAMAGE. 26 */ 27 28 #include <sys/types.h> 29 #include <sys/syscall.h> 30 #include <errno.h> 31 #include <stdint.h> 32 #include <stdlib.h> 33 34 void *__sys_break(char *nsize); 35 36 static uintptr_t curbrk, minbrk; 37 static int curbrk_initted; 38 39 static int 40 initbrk(void) 41 { 42 void *newbrk; 43 44 if (!curbrk_initted) { 45 newbrk = __sys_break(NULL); 46 if (newbrk == (void *)-1) 47 return (-1); 48 curbrk = minbrk = (uintptr_t)newbrk; 49 curbrk_initted = 1; 50 } 51 return (0); 52 } 53 54 static void * 55 mvbrk(void *addr) 56 { 57 uintptr_t oldbrk; 58 59 if ((uintptr_t)addr < minbrk) { 60 /* Emulate legacy error handling in the syscall. */ 61 errno = EINVAL; 62 return ((void *)-1); 63 } 64 if (__sys_break(addr) == (void *)-1) 65 return ((void *)-1); 66 oldbrk = curbrk; 67 curbrk = (uintptr_t)addr; 68 return ((void *)oldbrk); 69 } 70 71 int 72 brk(const void *addr) 73 { 74 75 if (initbrk() == -1) 76 return (-1); 77 if ((uintptr_t)addr < minbrk) 78 addr = (void *)minbrk; 79 return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0); 80 } 81 82 int 83 _brk(const void *addr) 84 { 85 86 if (initbrk() == -1) 87 return (-1); 88 return (mvbrk(__DECONST(void *, addr)) == (void *)-1 ? -1 : 0); 89 } 90 91 void * 92 sbrk(intptr_t incr) 93 { 94 95 if (initbrk() == -1) 96 return ((void *)-1); 97 if ((incr > 0 && curbrk + incr < curbrk) || 98 (incr < 0 && curbrk + incr > curbrk)) { 99 /* Emulate legacy error handling in the syscall. */ 100 errno = EINVAL; 101 return ((void *)-1); 102 } 103 return (mvbrk((void *)(curbrk + incr))); 104 } 105