The Android Open Source Project | 8b23a6c | 2009-03-03 19:30:32 -0800 | [diff] [blame] | 1 | /* Copyright (c) 2008 The Android Open Source Project |
| 2 | * |
| 3 | * Permission is hereby granted, free of charge, to any person obtaining a copy |
| 4 | * of this software and associated documentation files (the "Software"), to deal |
| 5 | * in the Software without restriction, including without limitation the rights |
| 6 | * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell |
| 7 | * copies of the Software, and to permit persons to whom the Software is |
| 8 | * furnished to do so, subject to the following conditions: |
| 9 | * |
| 10 | * The above copyright notice and this permission notice shall be included in |
| 11 | * all copies or substantial portions of the Software. |
| 12 | * |
| 13 | * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR |
| 14 | * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, |
| 15 | * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL |
| 16 | * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER |
| 17 | * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, |
| 18 | * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN |
| 19 | * THE SOFTWARE. |
| 20 | */ |
| 21 | |
| 22 | /* |
| 23 | * Lazy Dynamic Linking Support |
| 24 | * |
| 25 | * This header file is meant to be included multiple times. |
| 26 | * |
| 27 | * It is used to define function pointers to symbols in external |
| 28 | * shared objects (Unix dynamic libraries) which will be lazily resolved |
| 29 | * at runtime, by calling a specific initialization function. |
| 30 | * |
| 31 | * You must define, before including this header, a DYNLINK_FUNCTIONS |
| 32 | * macro which must contain a sequence of DYNLINK_FUNC(ret,name,sig) |
| 33 | * statements. |
| 34 | * |
| 35 | * In each statement, 'ret' is a function return type, 'name' is |
| 36 | * the function's name as provided by the library, and 'sig' is |
| 37 | * the function signature, including enclosing parentheses. |
| 38 | * |
| 39 | * Here's an example: |
| 40 | * |
| 41 | * #define DYNLINK_FUNCTIONS \ |
| 42 | * DYNLINK_FUNC(int,open,(const char*, int)) \ |
| 43 | * DYNLINK_FUNC(int,read,(int,char*,int)) \ |
| 44 | * DYNLINK_FUNC(int,close,(int)) \ |
| 45 | * |
| 46 | * |
| 47 | * You must also define a DYNLINK_FUNCTIONS_INIT macro which contains the |
| 48 | * name of a generated function used to initialize the function pointers. |
| 49 | * (see below) |
| 50 | */ |
| 51 | |
| 52 | #ifndef DYNLINK_FUNCTIONS |
| 53 | #error DYNLINK_FUNCTIONS should be defined when including this file |
| 54 | #endif |
| 55 | |
| 56 | #ifndef DYNLINK_FUNCTIONS_INIT |
| 57 | #error DYNLINK_FUNCTIONS_INIT should be defined when including this file |
| 58 | #endif |
| 59 | |
| 60 | /* just in case */ |
| 61 | #undef DYNLINK_FUNC |
| 62 | |
| 63 | /* define pointers to dynamic library functions as static pointers. |
| 64 | */ |
| 65 | #define DYNLINK_FUNC(ret,name,sig) \ |
| 66 | static ret (*_dynlink_##name) sig ; |
| 67 | |
| 68 | #define DYNLINK_STR(name) DYNLINK_STR_(name) |
| 69 | #define DYNLINK_STR_(name) #name |
| 70 | |
| 71 | DYNLINK_FUNCTIONS |
| 72 | #undef DYNLINK_FUNC |
| 73 | |
| 74 | /* now define a function that tries to load all dynlink function |
| 75 | * pointers. returns 0 on success, or -1 on error (i.e. if any of |
| 76 | * the functions could not be loaded). |
| 77 | * |
| 78 | * 'library' must be the result of a succesful dlopen() call |
| 79 | * |
| 80 | * You must define DYNLINK_FUNCTIONS_INIT |
| 81 | */ |
| 82 | static int |
| 83 | DYNLINK_FUNCTIONS_INIT(void* library) |
| 84 | { |
| 85 | #define DYNLINK_FUNC(ret,name,sig) \ |
| 86 | do { \ |
| 87 | _dynlink_##name = dlsym( library, DYNLINK_STR(name) ); \ |
| 88 | if (_dynlink_##name == NULL) goto Fail; \ |
| 89 | } while (0); |
| 90 | |
| 91 | DYNLINK_FUNCTIONS |
| 92 | #undef DYNLINK_FUNC |
| 93 | |
| 94 | return 0; |
| 95 | Fail: |
| 96 | return -1; |
| 97 | } |
| 98 | |
| 99 | /* in user code, use FF(function_name) to invoke the |
| 100 | * corresponding dynamic function named 'function_name' |
| 101 | * after initialization succeeded. |
| 102 | */ |
| 103 | #ifndef FF |
| 104 | #define FF(name) (*_dynlink_##name) |
| 105 | #endif |
| 106 | |
| 107 | /* clear macros */ |
| 108 | #undef DYNLINK_FUNC |
| 109 | #undef DYNLINK_FUNCTIONS |
| 110 | #undef DYNLINK_FUNCTIONS_INIT |