Modules/dbmmodule.c

   1
   2 /* DBM module using dictionary interface */
   3
   4
   5 #include "Python.h"
   6
   7 #include <sys/types.h>
   8 #include <sys/stat.h>
   9 #include <fcntl.h>
  10
  11 /* Some Linux systems install gdbm/ndbm.h, but not ndbm.h.  This supports
  12  * whichever configure was able to locate.
  13  */
  14 #if defined(HAVE_NDBM_H)
  15 #include <ndbm.h>
  16 #if defined(PYOS_OS2) && !defined(PYCC_GCC)
  17 static char *which_dbm = "ndbm";
  18 #else
  19 static char *which_dbm = "GNU gdbm";  /* EMX port of GDBM */
  20 #endif
  21 #elif defined(HAVE_GDBM_NDBM_H)
  22 #include <gdbm/ndbm.h>
  23 static char *which_dbm = "GNU gdbm";
  24 #elif defined(HAVE_BERKDB_H)
  25 #include <db.h>
  26 static char *which_dbm = "Berkeley DB";
  27 #else
  28 #error "No ndbm.h available!"
  29 #endif
  30
  31 typedef struct {
  32         PyObject_HEAD
  33         int di_size;    /* -1 means recompute */
  34         DBM *di_dbm;
  35 } dbmobject;
  36
  37 static PyTypeObject Dbmtype;
  38
  39 #define is_dbmobject(v) ((v)->ob_type == &Dbmtype)
  40 #define check_dbmobject_open(v) if ((v)->di_dbm == NULL) \
  41                { PyErr_SetString(DbmError, "DBM object has already been closed"); \
  42                  return NULL; }
  43
  44 static PyObject *DbmError;
  45
  46 static PyObject *
  47 newdbmobject(char *file, int flags, int mode)
  48 {
  49         dbmobject *dp;
  50
  51         dp = PyObject_New(dbmobject, &Dbmtype);
  52         if (dp == NULL)
  53                 return NULL;
  54         dp->di_size = -1;
  55         if ( (dp->di_dbm = dbm_open(file, flags, mode)) == 0 ) {
  56                 PyErr_SetFromErrno(DbmError);
  57                 Py_DECREF(dp);
  58                 return NULL;
  59         }
  60         return (PyObject *)dp;
  61 }
  62
  63 /* Methods */
  64
  65 static void
  66 dbm_dealloc(register dbmobject *dp)
  67 {
  68         if ( dp->di_dbm )
  69                 dbm_close(dp->di_dbm);
  70         PyObject_Del(dp);
  71 }
  72
  73 static int
  74 dbm_length(dbmobject *dp)
  75 {
  76         if (dp->di_dbm == NULL) {
  77                  PyErr_SetString(DbmError, "DBM object has already been closed");
  78                  return -1;
  79         }
  80         if ( dp->di_size < 0 ) {
  81                 datum key;
  82                 int size;
  83
  84                 size = 0;
  85                 for ( key=dbm_firstkey(dp->di_dbm); key.dptr;
  86                       key = dbm_nextkey(dp->di_dbm))
  87                         size++;
  88                 dp->di_size = size;
  89         }
  90         return dp->di_size;
  91 }
  92
  93 static PyObject *
  94 dbm_subscript(dbmobject *dp, register PyObject *key)
  95 {
  96         datum drec, krec;
  97
  98         if (!PyArg_Parse(key, "s#", &krec.dptr, &krec.dsize) )
  99                 return NULL;
 100
 101         check_dbmobject_open(dp);
 102         drec = dbm_fetch(dp->di_dbm, krec);
 103         if ( drec.dptr == 0 ) {
 104                 PyErr_SetString(PyExc_KeyError,
 105                                 PyString_AS_STRING((PyStringObject *)key));
 106                 return NULL;
 107         }
 108         if ( dbm_error(dp->di_dbm) ) {
 109                 dbm_clearerr(dp->di_dbm);
 110                 PyErr_SetString(DbmError, "");
 111                 return NULL;
 112         }
 113         return PyString_FromStringAndSize(drec.dptr, drec.dsize);
 114 }
 115
 116 static int
 117 dbm_ass_sub(dbmobject *dp, PyObject *v, PyObject *w)
 118 {
 119         datum krec, drec;
 120
 121         if ( !PyArg_Parse(v, "s#", &krec.dptr, &krec.dsize) ) {
 122                 PyErr_SetString(PyExc_TypeError,
 123                                 "dbm mappings have string indices only");
 124                 return -1;
 125         }
 126         if (dp->di_dbm == NULL) {
 127                  PyErr_SetString(DbmError, "DBM object has already been closed");
 128                  return -1;
 129         }
 130         dp->di_size = -1;
 131         if (w == NULL) {
 132                 if ( dbm_delete(dp->di_dbm, krec) < 0 ) {
 133                         dbm_clearerr(dp->di_dbm);
 134                         PyErr_SetString(PyExc_KeyError,
 135                                       PyString_AS_STRING((PyStringObject *)v));
 136                         return -1;
 137                 }
 138         } else {
 139                 if ( !PyArg_Parse(w, "s#", &drec.dptr, &drec.dsize) ) {
 140                         PyErr_SetString(PyExc_TypeError,
 141                                      "dbm mappings have string elements only");
 142                         return -1;
 143                 }
 144                 if ( dbm_store(dp->di_dbm, krec, drec, DBM_REPLACE) < 0 ) {
 145                         dbm_clearerr(dp->di_dbm);
 146                         PyErr_SetString(DbmError,
 147                                         "cannot add item to database");
 148                         return -1;
 149                 }
 150         }
 151         if ( dbm_error(dp->di_dbm) ) {
 152                 dbm_clearerr(dp->di_dbm);
 153                 PyErr_SetString(DbmError, "");
 154                 return -1;
 155         }
 156         return 0;
 157 }
 158
 159 static PyMappingMethods dbm_as_mapping = {
 160         (inquiry)dbm_length,            /*mp_length*/
 161         (binaryfunc)dbm_subscript,      /*mp_subscript*/
 162         (objobjargproc)dbm_ass_sub,     /*mp_ass_subscript*/
 163 };
 164
 165 static PyObject *
 166 dbm__close(register dbmobject *dp, PyObject *args)
 167 {
 168         if (!PyArg_ParseTuple(args, ":close"))
 169                 return NULL;
 170         if (dp->di_dbm)
 171                 dbm_close(dp->di_dbm);
 172         dp->di_dbm = NULL;
 173         Py_INCREF(Py_None);
 174         return Py_None;
 175 }
 176
 177 static PyObject *
 178 dbm_keys(register dbmobject *dp, PyObject *args)
 179 {
 180         register PyObject *v, *item;
 181         datum key;
 182         int err;
 183
 184         if (!PyArg_ParseTuple(args, ":keys"))
 185                 return NULL;
 186         check_dbmobject_open(dp);
 187         v = PyList_New(0);
 188         if (v == NULL)
 189                 return NULL;
 190         for (key = dbm_firstkey(dp->di_dbm); key.dptr;
 191              key = dbm_nextkey(dp->di_dbm)) {
 192                 item = PyString_FromStringAndSize(key.dptr, key.dsize);
 193                 if (item == NULL) {
 194                         Py_DECREF(v);
 195                         return NULL;
 196                 }
 197                 err = PyList_Append(v, item);
 198                 Py_DECREF(item);
 199                 if (err != 0) {
 200                         Py_DECREF(v);
 201                         return NULL;
 202                 }
 203         }
 204         return v;
 205 }
 206
 207 static PyObject *
 208 dbm_has_key(register dbmobject *dp, PyObject *args)
 209 {
 210         datum key, val;
 211
 212         if (!PyArg_ParseTuple(args, "s#:has_key", &key.dptr, &key.dsize))
 213                 return NULL;
 214         check_dbmobject_open(dp);
 215         val = dbm_fetch(dp->di_dbm, key);
 216         return PyInt_FromLong(val.dptr != NULL);
 217 }
 218
 219 static PyObject *
 220 dbm_get(register dbmobject *dp, PyObject *args)
 221 {
 222         datum key, val;
 223         PyObject *defvalue = Py_None;
 224
 225         if (!PyArg_ParseTuple(args, "s#|O:get",
 226                               &key.dptr, &key.dsize, &defvalue))
 227                 return NULL;
 228         check_dbmobject_open(dp);
 229         val = dbm_fetch(dp->di_dbm, key);
 230         if (val.dptr != NULL)
 231                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 232         else {
 233                 Py_INCREF(defvalue);
 234                 return defvalue;
 235         }
 236 }
 237
 238 static PyObject *
 239 dbm_setdefault(register dbmobject *dp, PyObject *args)
 240 {
 241         datum key, val;
 242         PyObject *defvalue = NULL;
 243
 244         if (!PyArg_ParseTuple(args, "s#|S:setdefault",
 245                               &key.dptr, &key.dsize, &defvalue))
 246                 return NULL;
 247         check_dbmobject_open(dp);
 248         val = dbm_fetch(dp->di_dbm, key);
 249         if (val.dptr != NULL)
 250                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 251         if (defvalue == NULL) {
 252                 defvalue = PyString_FromStringAndSize(NULL, 0);
 253                 if (defvalue == NULL)
 254                         return NULL;
 255         }
 256         else
 257                 Py_INCREF(defvalue);
 258         val.dptr = PyString_AS_STRING(defvalue);
 259         val.dsize = PyString_GET_SIZE(defvalue);
 260         if (dbm_store(dp->di_dbm, key, val, DBM_INSERT) < 0) {
 261                 dbm_clearerr(dp->di_dbm);
 262                 PyErr_SetString(DbmError, "cannot add item to database");
 263                 return NULL;
 264         }
 265         return defvalue;
 266 }
 267
 268 static PyMethodDef dbm_methods[] = {
 269         {"close",       (PyCFunction)dbm__close,        METH_VARARGS,
 270          "close()\nClose the database."},
 271         {"keys",        (PyCFunction)dbm_keys,          METH_VARARGS,
 272          "keys() -> list\nReturn a list of all keys in the database."},
 273         {"has_key",     (PyCFunction)dbm_has_key,       METH_VARARGS,
 274          "has_key(key} -> boolean\nReturn true iff key is in the database."},
 275         {"get",         (PyCFunction)dbm_get,           METH_VARARGS,
 276          "get(key[, default]) -> value\n"
 277          "Return the value for key if present, otherwise default."},
 278         {"setdefault",  (PyCFunction)dbm_setdefault,    METH_VARARGS,
 279          "setdefault(key[, default]) -> value\n"
 280          "Return the value for key if present, otherwise default.  If key\n"
 281          "is not in the database, it is inserted with default as the value."},
 282         {NULL,          NULL}           /* sentinel */
 283 };
 284
 285 static PyObject *
 286 dbm_getattr(dbmobject *dp, char *name)
 287 {
 288         return Py_FindMethod(dbm_methods, (PyObject *)dp, name);
 289 }
 290
 291 static PyTypeObject Dbmtype = {
 292         PyObject_HEAD_INIT(NULL)
 293         0,
 294         "dbm.dbm",
 295         sizeof(dbmobject),
 296         0,
 297         (destructor)dbm_dealloc,  /*tp_dealloc*/
 298         0,                        /*tp_print*/
 299         (getattrfunc)dbm_getattr, /*tp_getattr*/
 300         0,                        /*tp_setattr*/
 301         0,                        /*tp_compare*/
 302         0,                        /*tp_repr*/
 303         0,                        /*tp_as_number*/
 304         0,                        /*tp_as_sequence*/
 305         &dbm_as_mapping,          /*tp_as_mapping*/
 306 };
 307
 308 /* ----------------------------------------------------------------- */
 309
 310 static PyObject *
 311 dbmopen(PyObject *self, PyObject *args)
 312 {
 313         char *name;
 314         char *flags = "r";
 315         int iflags;
 316         int mode = 0666;
 317
 318         if ( !PyArg_ParseTuple(args, "s|si:open", &name, &flags, &mode) )
 319                 return NULL;
 320         if ( strcmp(flags, "r") == 0 )
 321                 iflags = O_RDONLY;
 322         else if ( strcmp(flags, "w") == 0 )
 323                 iflags = O_RDWR;
 324         else if ( strcmp(flags, "rw") == 0 ) /* B/W compat */
 325                 iflags = O_RDWR|O_CREAT;
 326         else if ( strcmp(flags, "c") == 0 )
 327                 iflags = O_RDWR|O_CREAT;
 328         else if ( strcmp(flags, "n") == 0 )
 329                 iflags = O_RDWR|O_CREAT|O_TRUNC;
 330         else {
 331                 PyErr_SetString(DbmError,
 332                                 "arg 2 to open should be 'r', 'w', 'c', or 'n'");
 333                 return NULL;
 334         }
 335         return newdbmobject(name, iflags, mode);
 336 }
 337
 338 static PyMethodDef dbmmodule_methods[] = {
 339         { "open", (PyCFunction)dbmopen, METH_VARARGS,
 340           "open(path[, flag[, mode]]) -> mapping\n"
 341           "Return a database object."},
 342         { 0, 0 },
 343 };
 344
 345 PyMODINIT_FUNC
 346 initdbm(void) {
 347         PyObject *m, *d, *s;
 348
 349         Dbmtype.ob_type = &PyType_Type;
 350         m = Py_InitModule("dbm", dbmmodule_methods);
 351         d = PyModule_GetDict(m);
 352         if (DbmError == NULL)
 353                 DbmError = PyErr_NewException("dbm.error", NULL, NULL);
 354         s = PyString_FromString(which_dbm);
 355         if (s != NULL) {
 356                 PyDict_SetItemString(d, "library", s);
 357                 Py_DECREF(s);
 358         }
 359         if (DbmError != NULL)
 360                 PyDict_SetItemString(d, "error", DbmError);
 361 }