Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 1 | /* Error handling -- see also run.c */ |
| 2 | |
| 3 | /* New error handling interface. |
| 4 | |
| 5 | The following problem exists (existed): methods of built-in modules |
| 6 | are called with 'self' and 'args' arguments, but without a context |
| 7 | argument, so they have no way to raise a specific exception. |
| 8 | The same is true for the object implementations: no context argument. |
| 9 | The old convention was to set 'errno' and to return NULL. |
| 10 | The caller (usually call_function() in eval.c) detects the NULL |
| 11 | return value and then calls puterrno(ctx) to turn the errno value |
| 12 | into a true exception. Problems with this approach are: |
| 13 | - it used standard errno values to indicate Python-specific errors, |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 14 | but this means that when such an error code is reported by a system |
| 15 | call (e.g., in module posix), the user gets a confusing message |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 16 | - errno is a global variable, which makes extensions to a multi- |
| 17 | threading environment difficult; e.g., in IRIX, multi-threaded |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 18 | programs must use the function oserror() instead of looking in errno |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 19 | - there is no portable way to add new error numbers for specic |
| 20 | situations -- the value space for errno is reserved to the OS, yet |
| 21 | the way to turn module-specific errors into a module-specific |
| 22 | exception requires module-specific values for errno |
| 23 | - there is no way to add a more situation-specific message to an |
| 24 | error. |
| 25 | |
| 26 | The new interface solves all these problems. To return an error, a |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 27 | built-in function calls err_set(exception), err_setval(exception, |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 28 | value) or err_setstr(exception, string), and returns NULL. These |
| 29 | functions save the value for later use by puterrno(). To adapt this |
| 30 | scheme to a multi-threaded environment, only the implementation of |
| 31 | err_setval() has to be changed. |
| 32 | */ |
| 33 | |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 34 | #include "allobjects.h" |
| 35 | |
Guido van Rossum | f22120a | 1990-12-20 23:05:40 +0000 | [diff] [blame^] | 36 | #include <errno.h> |
| 37 | #ifndef errno |
| 38 | extern int errno; |
| 39 | #endif |
| 40 | |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 41 | #include "errcode.h" |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 42 | |
Guido van Rossum | f5401bd | 1990-11-02 17:50:28 +0000 | [diff] [blame] | 43 | extern char *strerror PROTO((int)); |
| 44 | |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 45 | /* Last exception stored by err_setval() */ |
| 46 | |
| 47 | static object *last_exception; |
| 48 | static object *last_exc_val; |
| 49 | |
| 50 | void |
| 51 | err_setval(exception, value) |
| 52 | object *exception; |
| 53 | object *value; |
| 54 | { |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 55 | XDECREF(last_exception); |
| 56 | XINCREF(exception); |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 57 | last_exception = exception; |
| 58 | |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 59 | XDECREF(last_exc_val); |
| 60 | XINCREF(value); |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 61 | last_exc_val = value; |
| 62 | } |
| 63 | |
| 64 | void |
| 65 | err_set(exception) |
| 66 | object *exception; |
| 67 | { |
| 68 | err_setval(exception, (object *)NULL); |
| 69 | } |
| 70 | |
| 71 | void |
| 72 | err_setstr(exception, string) |
| 73 | object *exception; |
| 74 | char *string; |
| 75 | { |
| 76 | object *value = newstringobject(string); |
| 77 | err_setval(exception, value); |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 78 | XDECREF(value); |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 79 | } |
| 80 | |
| 81 | int |
| 82 | err_occurred() |
| 83 | { |
| 84 | return last_exception != NULL; |
| 85 | } |
| 86 | |
| 87 | void |
| 88 | err_get(p_exc, p_val) |
| 89 | object **p_exc; |
| 90 | object **p_val; |
| 91 | { |
| 92 | *p_exc = last_exception; |
| 93 | last_exception = NULL; |
| 94 | *p_val = last_exc_val; |
| 95 | last_exc_val = NULL; |
| 96 | } |
| 97 | |
| 98 | void |
| 99 | err_clear() |
| 100 | { |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 101 | XDECREF(last_exception); |
| 102 | last_exception = NULL; |
| 103 | XDECREF(last_exc_val); |
| 104 | last_exc_val = NULL; |
Guido van Rossum | 85a5fbb | 1990-10-14 12:07:46 +0000 | [diff] [blame] | 105 | } |
Guido van Rossum | 7d310eb | 1990-10-14 20:00:05 +0000 | [diff] [blame] | 106 | |
| 107 | /* Convenience functions to set a type error exception and return 0 */ |
| 108 | |
| 109 | int |
| 110 | err_badarg() |
| 111 | { |
Guido van Rossum | f1ac403 | 1990-11-09 15:05:53 +0000 | [diff] [blame] | 112 | err_setstr(TypeError, "illegal argument type for built-in operation"); |
Guido van Rossum | 7d310eb | 1990-10-14 20:00:05 +0000 | [diff] [blame] | 113 | return 0; |
| 114 | } |
| 115 | |
| 116 | object * |
| 117 | err_nomem() |
| 118 | { |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 119 | err_set(MemoryError); |
Guido van Rossum | 7d310eb | 1990-10-14 20:00:05 +0000 | [diff] [blame] | 120 | return NULL; |
| 121 | } |
| 122 | |
| 123 | object * |
| 124 | err_errno(exc) |
| 125 | object *exc; |
| 126 | { |
| 127 | object *v = newtupleobject(2); |
| 128 | if (v != NULL) { |
| 129 | settupleitem(v, 0, newintobject((long)errno)); |
| 130 | settupleitem(v, 1, newstringobject(strerror(errno))); |
| 131 | } |
| 132 | err_setval(exc, v); |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 133 | XDECREF(v); |
Guido van Rossum | 7d310eb | 1990-10-14 20:00:05 +0000 | [diff] [blame] | 134 | return NULL; |
| 135 | } |
Guido van Rossum | 683a072 | 1990-10-21 22:09:12 +0000 | [diff] [blame] | 136 | |
| 137 | void |
| 138 | err_badcall() |
| 139 | { |
| 140 | err_setstr(SystemError, "bad argument to internal function"); |
| 141 | } |
Guido van Rossum | 3f5da24 | 1990-12-20 15:06:42 +0000 | [diff] [blame] | 142 | |
| 143 | /* Set the error appropriate to the given input error code (see errcode.h) */ |
| 144 | |
| 145 | void |
| 146 | err_input(err) |
| 147 | int err; |
| 148 | { |
| 149 | switch (err) { |
| 150 | case E_DONE: |
| 151 | case E_OK: |
| 152 | break; |
| 153 | case E_SYNTAX: |
| 154 | err_setstr(RuntimeError, "syntax error"); |
| 155 | break; |
| 156 | case E_TOKEN: |
| 157 | err_setstr(RuntimeError, "illegal token"); |
| 158 | break; |
| 159 | case E_INTR: |
| 160 | err_set(KeyboardInterrupt); |
| 161 | break; |
| 162 | case E_NOMEM: |
| 163 | err_nomem(); |
| 164 | break; |
| 165 | case E_EOF: |
| 166 | err_set(EOFError); |
| 167 | break; |
| 168 | default: |
| 169 | err_setstr(RuntimeError, "unknown input error"); |
| 170 | break; |
| 171 | } |
| 172 | } |