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) (Py_TYPE(v) == &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 Py_ssize_t
  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         (lenfunc)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 *unused)
 172 {
 173         if (dp->di_dbm)
 174                 dbm_close(dp->di_dbm);
 175         dp->di_dbm = NULL;
 176         Py_INCREF(Py_None);
 177         return Py_None;
 178 }
 179
 180 static PyObject *
 181 dbm_keys(register dbmobject *dp, PyObject *unused)
 182 {
 183         register PyObject *v, *item;
 184         datum key;
 185         int err;
 186
 187         check_dbmobject_open(dp);
 188         v = PyList_New(0);
 189         if (v == NULL)
 190                 return NULL;
 191         for (key = dbm_firstkey(dp->di_dbm); key.dptr;
 192              key = dbm_nextkey(dp->di_dbm)) {
 193                 item = PyString_FromStringAndSize(key.dptr, key.dsize);
 194                 if (item == NULL) {
 195                         Py_DECREF(v);
 196                         return NULL;
 197                 }
 198                 err = PyList_Append(v, item);
 199                 Py_DECREF(item);
 200                 if (err != 0) {
 201                         Py_DECREF(v);
 202                         return NULL;
 203                 }
 204         }
 205         return v;
 206 }
 207
 208 static PyObject *
 209 dbm_has_key(register dbmobject *dp, PyObject *args)
 210 {
 211         char *tmp_ptr;
 212         datum key, val;
 213         int tmp_size;
 214
 215         if (!PyArg_ParseTuple(args, "s#:has_key", &tmp_ptr, &tmp_size))
 216                 return NULL;
 217         key.dptr = tmp_ptr;
 218         key.dsize = tmp_size;
 219         check_dbmobject_open(dp);
 220         val = dbm_fetch(dp->di_dbm, key);
 221         return PyInt_FromLong(val.dptr != NULL);
 222 }
 223
 224 static PyObject *
 225 dbm_get(register dbmobject *dp, PyObject *args)
 226 {
 227         datum key, val;
 228         PyObject *defvalue = Py_None;
 229         char *tmp_ptr;
 230         int tmp_size;
 231
 232         if (!PyArg_ParseTuple(args, "s#|O:get",
 233                               &tmp_ptr, &tmp_size, &defvalue))
 234                 return NULL;
 235         key.dptr = tmp_ptr;
 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         char *tmp_ptr;
 253         int tmp_size;
 254
 255         if (!PyArg_ParseTuple(args, "s#|S:setdefault",
 256                               &tmp_ptr, &tmp_size, &defvalue))
 257                 return NULL;
 258         key.dptr = tmp_ptr;
 259         key.dsize = tmp_size;
 260         check_dbmobject_open(dp);
 261         val = dbm_fetch(dp->di_dbm, key);
 262         if (val.dptr != NULL)
 263                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 264         if (defvalue == NULL) {
 265                 defvalue = PyString_FromStringAndSize(NULL, 0);
 266                 if (defvalue == NULL)
 267                         return NULL;
 268         }
 269         else
 270                 Py_INCREF(defvalue);
 271         val.dptr = PyString_AS_STRING(defvalue);
 272         val.dsize = PyString_GET_SIZE(defvalue);
 273         if (dbm_store(dp->di_dbm, key, val, DBM_INSERT) < 0) {
 274                 dbm_clearerr(dp->di_dbm);
 275                 PyErr_SetString(DbmError, "cannot add item to database");
 276                 return NULL;
 277         }
 278         return defvalue;
 279 }
 280
 281 static PyMethodDef dbm_methods[] = {
 282         {"close",       (PyCFunction)dbm__close,        METH_NOARGS,
 283          "close()\nClose the database."},
 284         {"keys",        (PyCFunction)dbm_keys,          METH_NOARGS,
 285          "keys() -> list\nReturn a list of all keys in the database."},
 286         {"has_key",     (PyCFunction)dbm_has_key,       METH_VARARGS,
 287          "has_key(key} -> boolean\nReturn true iff key is in the database."},
 288         {"get",         (PyCFunction)dbm_get,           METH_VARARGS,
 289          "get(key[, default]) -> value\n"
 290          "Return the value for key if present, otherwise default."},
 291         {"setdefault",  (PyCFunction)dbm_setdefault,    METH_VARARGS,
 292          "setdefault(key[, default]) -> value\n"
 293          "Return the value for key if present, otherwise default.  If key\n"
 294          "is not in the database, it is inserted with default as the value."},
 295         {NULL,          NULL}           /* sentinel */
 296 };
 297
 298 static PyObject *
 299 dbm_getattr(dbmobject *dp, char *name)
 300 {
 301         return Py_FindMethod(dbm_methods, (PyObject *)dp, name);
 302 }
 303
 304 static PyTypeObject Dbmtype = {
 305         PyVarObject_HEAD_INIT(NULL, 0)
 306         "dbm.dbm",
 307         sizeof(dbmobject),
 308         0,
 309         (destructor)dbm_dealloc,  /*tp_dealloc*/
 310         0,                        /*tp_print*/
 311         (getattrfunc)dbm_getattr, /*tp_getattr*/
 312         0,                        /*tp_setattr*/
 313         0,                        /*tp_compare*/
 314         0,                        /*tp_repr*/
 315         0,                        /*tp_as_number*/
 316         0,                        /*tp_as_sequence*/
 317         &dbm_as_mapping,          /*tp_as_mapping*/
 318 };
 319
 320 /* ----------------------------------------------------------------- */
 321
 322 static PyObject *
 323 dbmopen(PyObject *self, PyObject *args)
 324 {
 325         char *name;
 326         char *flags = "r";
 327         int iflags;
 328         int mode = 0666;
 329
 330         if ( !PyArg_ParseTuple(args, "s|si:open", &name, &flags, &mode) )
 331                 return NULL;
 332         if ( strcmp(flags, "r") == 0 )
 333                 iflags = O_RDONLY;
 334         else if ( strcmp(flags, "w") == 0 )
 335                 iflags = O_RDWR;
 336         else if ( strcmp(flags, "rw") == 0 ) /* B/W compat */
 337                 iflags = O_RDWR|O_CREAT;
 338         else if ( strcmp(flags, "c") == 0 )
 339                 iflags = O_RDWR|O_CREAT;
 340         else if ( strcmp(flags, "n") == 0 )
 341                 iflags = O_RDWR|O_CREAT|O_TRUNC;
 342         else {
 343                 PyErr_SetString(DbmError,
 344                                 "arg 2 to open should be 'r', 'w', 'c', or 'n'");
 345                 return NULL;
 346         }
 347         return newdbmobject(name, iflags, mode);
 348 }
 349
 350 static PyMethodDef dbmmodule_methods[] = {
 351         { "open", (PyCFunction)dbmopen, METH_VARARGS,
 352           "open(path[, flag[, mode]]) -> mapping\n"
 353           "Return a database object."},
 354         { 0, 0 },
 355 };
 356
 357 PyMODINIT_FUNC
 358 initdbm(void) {
 359         PyObject *m, *d, *s;
 360
 361         Dbmtype.ob_type = &PyType_Type;
 362         m = Py_InitModule("dbm", dbmmodule_methods);
 363         if (m == NULL)
 364                 return;
 365         d = PyModule_GetDict(m);
 366         if (DbmError == NULL)
 367                 DbmError = PyErr_NewException("dbm.error", NULL, NULL);
 368         s = PyString_FromString(which_dbm);
 369         if (s != NULL) {
 370                 PyDict_SetItemString(d, "library", s);
 371                 Py_DECREF(s);
 372         }
 373         if (DbmError != NULL)
 374                 PyDict_SetItemString(d, "error", DbmError);
 375 }