1 /* 2 * Copyright (C) 2008 The Android Open Source Project 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 * * Redistributions of source code must retain the above copyright 9 * notice, this list of conditions and the following disclaimer. 10 * * Redistributions in binary form must reproduce the above copyright 11 * notice, this list of conditions and the following disclaimer in 12 * the documentation and/or other materials provided with the 13 * distribution. 14 * 15 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS 16 * "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT 17 * LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS 18 * FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE 19 * COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, 20 * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, 21 * BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS 22 * OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED 23 * AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, 24 * OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT 25 * OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 26 * SUCH DAMAGE. 27 */ 28 29 #include <errno.h> 30 #include <unistd.h> 31 32 #if defined(__LP64__) 33 static void* __bionic_brk; 34 #else 35 void* __bionic_brk; // Accidentally exported by the NDK. 36 #endif 37 38 extern "C" void* __brk(void* __addr); 39 40 int brk(void* end_data) { 41 __bionic_brk = __brk(end_data); 42 if (__bionic_brk < end_data) { 43 errno = ENOMEM; 44 return -1; 45 } 46 return 0; 47 } 48 49 void* sbrk(ptrdiff_t increment) { 50 // Initialize __bionic_brk if necessary. 51 if (__bionic_brk == NULL) { 52 __bionic_brk = __brk(NULL); 53 } 54 55 // Don't ask the kernel if we already know the answer. 56 if (increment == 0) { 57 return __bionic_brk; 58 } 59 60 // Avoid overflow. 61 uintptr_t old_brk = reinterpret_cast<uintptr_t>(__bionic_brk); 62 if ((increment > 0 && static_cast<uintptr_t>(increment) > (UINTPTR_MAX - old_brk)) || 63 (increment < 0 && static_cast<uintptr_t>(-increment) > old_brk)) { 64 errno = ENOMEM; 65 return reinterpret_cast<void*>(-1); 66 } 67 68 void* desired_brk = reinterpret_cast<void*>(old_brk + increment); 69 __bionic_brk = __brk(desired_brk); 70 if (__bionic_brk < desired_brk) { 71 errno = ENOMEM; 72 return reinterpret_cast<void*>(-1); 73 } 74 75 return reinterpret_cast<void*>(old_brk); 76 } 77
