Support gethostbyname_r_ERANGE.
[android-sdk/platform-bionic.git] / linker / linker_allocator.cpp
1 /*
2  * Copyright (C) 2014 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 #include "linker_allocator.h"
17 #include <inttypes.h>
18 #include <sys/mman.h>
19 #include <unistd.h>
21 #include "private/bionic_prctl.h"
23 struct LinkerAllocatorPage {
24   LinkerAllocatorPage* next;
25   uint8_t bytes[PAGE_SIZE-sizeof(LinkerAllocatorPage*)];
26 };
28 struct FreeBlockInfo {
29   void* next_block;
30   size_t num_free_blocks;
31 };
33 LinkerBlockAllocator::LinkerBlockAllocator(size_t block_size)
34   : block_size_(block_size < sizeof(FreeBlockInfo) ? sizeof(FreeBlockInfo) : block_size),
35     page_list_(nullptr),
36     free_block_list_(nullptr)
37 {}
39 void* LinkerBlockAllocator::alloc() {
40   if (free_block_list_ == nullptr) {
41     create_new_page();
42   }
44   FreeBlockInfo* block_info = reinterpret_cast<FreeBlockInfo*>(free_block_list_);
45   if (block_info->num_free_blocks > 1) {
46     FreeBlockInfo* next_block_info = reinterpret_cast<FreeBlockInfo*>(
47       reinterpret_cast<char*>(free_block_list_) + block_size_);
48     next_block_info->next_block = block_info->next_block;
49     next_block_info->num_free_blocks = block_info->num_free_blocks - 1;
50     free_block_list_ = next_block_info;
51   } else {
52     free_block_list_ = block_info->next_block;
53   }
55   memset(block_info, 0, block_size_);
57   return block_info;
58 }
60 void LinkerBlockAllocator::free(void* block) {
61   if (block == nullptr) {
62     return;
63   }
65   LinkerAllocatorPage* page = find_page(block);
67   if (page == nullptr) {
68     abort();
69   }
71   ssize_t offset = reinterpret_cast<uint8_t*>(block) - page->bytes;
73   if (offset % block_size_ != 0) {
74     abort();
75   }
77   memset(block, 0, block_size_);
79   FreeBlockInfo* block_info = reinterpret_cast<FreeBlockInfo*>(block);
81   block_info->next_block = free_block_list_;
82   block_info->num_free_blocks = 1;
84   free_block_list_ = block_info;
85 }
87 void LinkerBlockAllocator::protect_all(int prot) {
88   for (LinkerAllocatorPage* page = page_list_; page != nullptr; page = page->next) {
89     if (mprotect(page, PAGE_SIZE, prot) == -1) {
90       abort();
91     }
92   }
93 }
95 void LinkerBlockAllocator::create_new_page() {
96   LinkerAllocatorPage* page = reinterpret_cast<LinkerAllocatorPage*>(mmap(nullptr, PAGE_SIZE,
97       PROT_READ|PROT_WRITE, MAP_PRIVATE|MAP_ANONYMOUS, 0, 0));
98   if (page == MAP_FAILED) {
99     abort(); // oom
100   }
102   prctl(PR_SET_VMA, PR_SET_VMA_ANON_NAME, page, PAGE_SIZE, "linker_alloc");
104   memset(page, 0, PAGE_SIZE);
106   FreeBlockInfo* first_block = reinterpret_cast<FreeBlockInfo*>(page->bytes);
107   first_block->next_block = free_block_list_;
108   first_block->num_free_blocks = (PAGE_SIZE - sizeof(LinkerAllocatorPage*))/block_size_;
110   free_block_list_ = first_block;
112   page->next = page_list_;
113   page_list_ = page;
116 LinkerAllocatorPage* LinkerBlockAllocator::find_page(void* block) {
117   if (block == nullptr) {
118     abort();
119   }
121   LinkerAllocatorPage* page = page_list_;
122   while (page != nullptr) {
123     const uint8_t* page_ptr = reinterpret_cast<const uint8_t*>(page);
124     if (block >= (page_ptr + sizeof(page->next)) && block < (page_ptr + PAGE_SIZE)) {
125       return page;
126     }
128     page = page->next;
129   }
131   abort();