/* * Copyright (C) 2008 The Android Open Source Project * * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. */ /* * Implementation of the user-space ashmem API for the simulator, which lacks * an ashmem-enabled kernel. See ashmem-dev.c for the real ashmem-based version. */ #include #include #include #include #include #include #include #include #include #include #include int ashmem_create_region(const char *ignored, size_t size) { static const char txt[] = "abcdefghijklmnopqrstuvwxyz" "ABCDEFGHIJKLMNOPQRSTUVWXYZ"; char name[64]; unsigned int retries = 0; pid_t pid = getpid(); int fd; srand(time(NULL) + pid); retry: /* not beautiful, its just wolf-like loop unrolling */ snprintf(name, sizeof(name), "/tmp/android-ashmem-%d-%c%c%c%c%c%c%c%c", pid, txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))], txt[(int) ((sizeof(txt) - 1) * (rand() / (RAND_MAX + 1.0)))]); /* open O_EXCL & O_CREAT: we are either the sole owner or we fail */ fd = open(name, O_RDWR | O_CREAT | O_EXCL, 0600); if (fd == -1) { /* unlikely, but if we failed because `name' exists, retry */ if (errno == EEXIST && ++retries < 6) goto retry; return -1; } /* truncate the file to `len' bytes */ if (ftruncate(fd, size) == -1) goto error; if (unlink(name) == -1) goto error; return fd; error: close(fd); return -1; } int ashmem_set_prot_region(int fd, int prot) { return 0; } int ashmem_pin_region(int fd, size_t offset, size_t len) { return ASHMEM_NOT_PURGED; } int ashmem_unpin_region(int fd, size_t offset, size_t len) { return ASHMEM_IS_UNPINNED; } int ashmem_get_size_region(int fd) { struct stat buf; int result; result = fstat(fd, &buf); if (result == -1) { return -1; } // Check if this is an "ashmem" region. // TODO: This is very hacky, and can easily break. We need some reliable indicator. if (!(buf.st_nlink == 0 && S_ISREG(buf.st_mode))) { errno = ENOTTY; return -1; } return (int)buf.st_size; // TODO: care about overflow (> 2GB file)? }