1 /* 2 * Copyright (C) 2008 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 17 /* 18 * Implementation of the user-space ashmem API for the simulator, which lacks 19 * an ashmem-enabled kernel. See ashmem-dev.c for the real ashmem-based version. 20 */ 21 22 #include <unistd.h> 23 #include <string.h> 24 #include <stdlib.h> 25 #include <sys/types.h> 26 #include <sys/stat.h> 27 #include <fcntl.h> 28 #include <stdio.h> 29 #include <errno.h> 30 #include <time.h> 31 #include <limits.h> 32 33 #include <cutils/ashmem.h> 34 35 int ashmem_create_region(const char *ignored, size_t size) 36 { 37 static const char txt[] = "abcdefghijklmnopqrstuvwxyz" 38 "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; 39 char name[64]; 40 unsigned int retries = 0; 41 pid_t pid = getpid(); 42 int fd; 43 44 srand(time(NULL) + pid); 45 46 retry: 47 /* not beautiful, its just wolf-like loop unrolling */ 48 snprintf(name, sizeof(name), "/tmp/android-ashmem-%d-%c%c%c%c%c%c%c%c", 49 pid, 50 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 51 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 52 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 53 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 54 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 55 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 56 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], 57 txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))]); 58 59 /* open O_EXCL & O_CREAT: we are either the sole owner or we fail */ 60 fd = open(name, O_RDWR | O_CREAT | O_EXCL, 0600); 61 if (fd == -1) { 62 /* unlikely, but if we failed because `name' exists, retry */ 63 if (errno == EEXIST && ++retries < 6) 64 goto retry; 65 return -1; 66 } 67 68 /* truncate the file to `len' bytes */ 69 if (ftruncate(fd, size) == -1) 70 goto error; 71 72 if (unlink(name) == -1) 73 goto error; 74 75 return fd; 76 error: 77 close(fd); 78 return -1; 79 } 80 81 int ashmem_set_prot_region(int fd, int prot) 82 { 83 return 0; 84 } 85 86 int ashmem_pin_region(int fd, size_t offset, size_t len) 87 { 88 return ASHMEM_NOT_PURGED; 89 } 90 91 int ashmem_unpin_region(int fd, size_t offset, size_t len) 92 { 93 return ASHMEM_IS_UNPINNED; 94 } 95 96 int ashmem_get_size_region(int fd) 97 { 98 struct stat buf; 99 int result; 100 101 result = fstat(fd, &buf); 102 if (result == -1) { 103 return -1; 104 } 105 106 // Check if this is an "ashmem" region. 107 // TODO: This is very hacky, and can easily break. We need some reliable indicator. 108 if (!(buf.st_nlink == 0 && S_ISREG(buf.st_mode))) { 109 errno = ENOTTY; 110 return -1; 111 } 112 113 return (int)buf.st_size; // TODO: care about overflow (> 2GB file)? 114 } 115
