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         int tmp_size;
  98
  99         if (!PyArg_Parse(key, "s#", &krec.dptr, &tmp_size) )
 100                 return NULL;
 101
 102         krec.dsize = tmp_size;
 103         check_dbmobject_open(dp);
 104         drec = dbm_fetch(dp->di_dbm, krec);
 105         if ( drec.dptr == 0 ) {
 106                 PyErr_SetString(PyExc_KeyError,
 107                                 PyString_AS_STRING((PyStringObject *)key));
 108                 return NULL;
 109         }
 110         if ( dbm_error(dp->di_dbm) ) {
 111                 dbm_clearerr(dp->di_dbm);
 112                 PyErr_SetString(DbmError, "");
 113                 return NULL;
 114         }
 115         return PyString_FromStringAndSize(drec.dptr, drec.dsize);
 116 }
 117
 118 static int
 119 dbm_ass_sub(dbmobject *dp, PyObject *v, PyObject *w)
 120 {
 121         datum krec, drec;
 122         int tmp_size;
 123
 124         if ( !PyArg_Parse(v, "s#", &krec.dptr, &tmp_size) ) {
 125                 PyErr_SetString(PyExc_TypeError,
 126                                 "dbm mappings have string indices only");
 127                 return -1;
 128         }
 129         krec.dsize = tmp_size;
 130         if (dp->di_dbm == NULL) {
 131                  PyErr_SetString(DbmError, "DBM object has already been closed");
 132                  return -1;
 133         }
 134         dp->di_size = -1;
 135         if (w == NULL) {
 136                 if ( dbm_delete(dp->di_dbm, krec) < 0 ) {
 137                         dbm_clearerr(dp->di_dbm);
 138                         PyErr_SetString(PyExc_KeyError,
 139                                       PyString_AS_STRING((PyStringObject *)v));
 140                         return -1;
 141                 }
 142         } else {
 143                 if ( !PyArg_Parse(w, "s#", &drec.dptr, &tmp_size) ) {
 144                         PyErr_SetString(PyExc_TypeError,
 145                                      "dbm mappings have string elements only");
 146                         return -1;
 147                 }
 148                 drec.dsize = tmp_size;
 149                 if ( dbm_store(dp->di_dbm, krec, drec, DBM_REPLACE) < 0 ) {
 150                         dbm_clearerr(dp->di_dbm);
 151                         PyErr_SetString(DbmError,
 152                                         "cannot add item to database");
 153                         return -1;
 154                 }
 155         }
 156         if ( dbm_error(dp->di_dbm) ) {
 157                 dbm_clearerr(dp->di_dbm);
 158                 PyErr_SetString(DbmError, "");
 159                 return -1;
 160         }
 161         return 0;
 162 }
 163
 164 static PyMappingMethods dbm_as_mapping = {
 165         (inquiry)dbm_length,            /*mp_length*/
 166         (binaryfunc)dbm_subscript,      /*mp_subscript*/
 167         (objobjargproc)dbm_ass_sub,     /*mp_ass_subscript*/
 168 };
 169
 170 static PyObject *
 171 dbm__close(register dbmobject *dp, PyObject *args)
 172 {
 173         if (!PyArg_ParseTuple(args, ":close"))
 174                 return NULL;
 175         if (dp->di_dbm)
 176                 dbm_close(dp->di_dbm);
 177         dp->di_dbm = NULL;
 178         Py_INCREF(Py_None);
 179         return Py_None;
 180 }
 181
 182 static PyObject *
 183 dbm_keys(register dbmobject *dp, PyObject *args)
 184 {
 185         register PyObject *v, *item;
 186         datum key;
 187         int err;
 188
 189         if (!PyArg_ParseTuple(args, ":keys"))
 190                 return NULL;
 191         check_dbmobject_open(dp);
 192         v = PyList_New(0);
 193         if (v == NULL)
 194                 return NULL;
 195         for (key = dbm_firstkey(dp->di_dbm); key.dptr;
 196              key = dbm_nextkey(dp->di_dbm)) {
 197                 item = PyString_FromStringAndSize(key.dptr, key.dsize);
 198                 if (item == NULL) {
 199                         Py_DECREF(v);
 200                         return NULL;
 201                 }
 202                 err = PyList_Append(v, item);
 203                 Py_DECREF(item);
 204                 if (err != 0) {
 205                         Py_DECREF(v);
 206                         return NULL;
 207                 }
 208         }
 209         return v;
 210 }
 211
 212 static PyObject *
 213 dbm_has_key(register dbmobject *dp, PyObject *args)
 214 {
 215         datum key, val;
 216         int tmp_size;
 217
 218         if (!PyArg_ParseTuple(args, "s#:has_key", &key.dptr, &tmp_size))
 219                 return NULL;
 220         key.dsize = tmp_size;
 221         check_dbmobject_open(dp);
 222         val = dbm_fetch(dp->di_dbm, key);
 223         return PyInt_FromLong(val.dptr != NULL);
 224 }
 225
 226 static PyObject *
 227 dbm_get(register dbmobject *dp, PyObject *args)
 228 {
 229         datum key, val;
 230         PyObject *defvalue = Py_None;
 231         int tmp_size;
 232
 233         if (!PyArg_ParseTuple(args, "s#|O:get",
 234                               &key.dptr, &tmp_size, &defvalue))
 235                 return NULL;
 236         key.dsize = tmp_size;
 237         check_dbmobject_open(dp);
 238         val = dbm_fetch(dp->di_dbm, key);
 239         if (val.dptr != NULL)
 240                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 241         else {
 242                 Py_INCREF(defvalue);
 243                 return defvalue;
 244         }
 245 }
 246
 247 static PyObject *
 248 dbm_setdefault(register dbmobject *dp, PyObject *args)
 249 {
 250         datum key, val;
 251         PyObject *defvalue = NULL;
 252         int tmp_size;
 253
 254         if (!PyArg_ParseTuple(args, "s#|S:setdefault",
 255                               &key.dptr, &tmp_size, &defvalue))
 256                 return NULL;
 257         key.dsize = tmp_size;
 258         check_dbmobject_open(dp);
 259         val = dbm_fetch(dp->di_dbm, key);
 260         if (val.dptr != NULL)
 261                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 262         if (defvalue == NULL) {
 263                 defvalue = PyString_FromStringAndSize(NULL, 0);
 264                 if (defvalue == NULL)
 265                         return NULL;
 266         }
 267         else
 268                 Py_INCREF(defvalue);
 269         val.dptr = PyString_AS_STRING(defvalue);
 270         val.dsize = PyString_GET_SIZE(defvalue);
 271         if (dbm_store(dp->di_dbm, key, val, DBM_INSERT) < 0) {
 272                 dbm_clearerr(dp->di_dbm);
 273                 PyErr_SetString(DbmError, "cannot add item to database");
 274                 return NULL;
 275         }
 276         return defvalue;
 277 }
 278
 279 static PyMethodDef dbm_methods[] = {
 280         {"close",       (PyCFunction)dbm__close,        METH_VARARGS,
 281          "close()\nClose the database."},
 282         {"keys",        (PyCFunction)dbm_keys,          METH_VARARGS,
 283          "keys() -> list\nReturn a list of all keys in the database."},
 284         {"has_key",     (PyCFunction)dbm_has_key,       METH_VARARGS,
 285          "has_key(key} -> boolean\nReturn true iff key is in the database."},
 286         {"get",         (PyCFunction)dbm_get,           METH_VARARGS,
 287          "get(key[, default]) -> value\n"
 288          "Return the value for key if present, otherwise default."},
 289         {"setdefault",  (PyCFunction)dbm_setdefault,    METH_VARARGS,
 290          "setdefault(key[, default]) -> value\n"
 291          "Return the value for key if present, otherwise default.  If key\n"
 292          "is not in the database, it is inserted with default as the value."},
 293         {NULL,          NULL}           /* sentinel */
 294 };
 295
 296 static PyObject *
 297 dbm_getattr(dbmobject *dp, char *name)
 298 {
 299         return Py_FindMethod(dbm_methods, (PyObject *)dp, name);
 300 }
 301
 302 static PyTypeObject Dbmtype = {
 303         PyObject_HEAD_INIT(NULL)
 304         0,
 305         "dbm.dbm",
 306         sizeof(dbmobject),
 307         0,
 308         (destructor)dbm_dealloc,  /*tp_dealloc*/
 309         0,                        /*tp_print*/
 310         (getattrfunc)dbm_getattr, /*tp_getattr*/
 311         0,                        /*tp_setattr*/
 312         0,                        /*tp_compare*/
 313         0,                        /*tp_repr*/
 314         0,                        /*tp_as_number*/
 315         0,                        /*tp_as_sequence*/
 316         &dbm_as_mapping,          /*tp_as_mapping*/
 317 };
 318
 319 /* ----------------------------------------------------------------- */
 320
 321 static PyObject *
 322 dbmopen(PyObject *self, PyObject *args)
 323 {
 324         char *name;
 325         char *flags = "r";
 326         int iflags;
 327         int mode = 0666;
 328
 329         if ( !PyArg_ParseTuple(args, "s|si:open", &name, &flags, &mode) )
 330                 return NULL;
 331         if ( strcmp(flags, "r") == 0 )
 332                 iflags = O_RDONLY;
 333         else if ( strcmp(flags, "w") == 0 )
 334                 iflags = O_RDWR;
 335         else if ( strcmp(flags, "rw") == 0 ) /* B/W compat */
 336                 iflags = O_RDWR|O_CREAT;
 337         else if ( strcmp(flags, "c") == 0 )
 338                 iflags = O_RDWR|O_CREAT;
 339         else if ( strcmp(flags, "n") == 0 )
 340                 iflags = O_RDWR|O_CREAT|O_TRUNC;
 341         else {
 342                 PyErr_SetString(DbmError,
 343                                 "arg 2 to open should be 'r', 'w', 'c', or 'n'");
 344                 return NULL;
 345         }
 346         return newdbmobject(name, iflags, mode);
 347 }
 348
 349 static PyMethodDef dbmmodule_methods[] = {
 350         { "open", (PyCFunction)dbmopen, METH_VARARGS,
 351           "open(path[, flag[, mode]]) -> mapping\n"
 352           "Return a database object."},
 353         { 0, 0 },
 354 };
 355
 356 PyMODINIT_FUNC
 357 initdbm(void) {
 358         PyObject *m, *d, *s;
 359
 360         Dbmtype.ob_type = &PyType_Type;
 361         m = Py_InitModule("dbm", dbmmodule_methods);
 362         d = PyModule_GetDict(m);
 363         if (DbmError == NULL)
 364                 DbmError = PyErr_NewException("dbm.error", NULL, NULL);
 365         s = PyString_FromString(which_dbm);
 366         if (s != NULL) {
 367                 PyDict_SetItemString(d, "library", s);
 368                 Py_DECREF(s);
 369         }
 370         if (DbmError != NULL)
 371                 PyDict_SetItemString(d, "error", DbmError);
 372 }