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 static char *which_dbm = "ndbm";
  17 #elif defined(HAVE_DB1_NDBM_H)
  18 #include <db1/ndbm.h>
  19 static char *which_dbm = "BSD db";
  20 #elif defined(HAVE_GDBM_NDBM_H)
  21 #include <gdbm/ndbm.h>
  22 static char *which_dbm = "GNU gdbm";
  23 #else
  24 #error "No ndbm.h available!"
  25 #endif
  26
  27 typedef struct {
  28         PyObject_HEAD
  29         int di_size;    /* -1 means recompute */
  30         DBM *di_dbm;
  31 } dbmobject;
  32
  33 staticforward PyTypeObject Dbmtype;
  34
  35 #define is_dbmobject(v) ((v)->ob_type == &Dbmtype)
  36 #define check_dbmobject_open(v) if ((v)->di_dbm == NULL) \
  37                { PyErr_SetString(DbmError, "DBM object has already been closed"); \
  38                  return NULL; }
  39
  40 static PyObject *DbmError;
  41
  42 static PyObject *
  43 newdbmobject(char *file, int flags, int mode)
  44 {
  45         dbmobject *dp;
  46
  47         dp = PyObject_New(dbmobject, &Dbmtype);
  48         if (dp == NULL)
  49                 return NULL;
  50         dp->di_size = -1;
  51         if ( (dp->di_dbm = dbm_open(file, flags, mode)) == 0 ) {
  52                 PyErr_SetFromErrno(DbmError);
  53                 Py_DECREF(dp);
  54                 return NULL;
  55         }
  56         return (PyObject *)dp;
  57 }
  58
  59 /* Methods */
  60
  61 static void
  62 dbm_dealloc(register dbmobject *dp)
  63 {
  64         if ( dp->di_dbm )
  65                 dbm_close(dp->di_dbm);
  66         PyObject_Del(dp);
  67 }
  68
  69 static int
  70 dbm_length(dbmobject *dp)
  71 {
  72         if (dp->di_dbm == NULL) {
  73                  PyErr_SetString(DbmError, "DBM object has already been closed");
  74                  return -1;
  75         }
  76         if ( dp->di_size < 0 ) {
  77                 datum key;
  78                 int size;
  79
  80                 size = 0;
  81                 for ( key=dbm_firstkey(dp->di_dbm); key.dptr;
  82                       key = dbm_nextkey(dp->di_dbm))
  83                         size++;
  84                 dp->di_size = size;
  85         }
  86         return dp->di_size;
  87 }
  88
  89 static PyObject *
  90 dbm_subscript(dbmobject *dp, register PyObject *key)
  91 {
  92         datum drec, krec;
  93
  94         if (!PyArg_Parse(key, "s#", &krec.dptr, &krec.dsize) )
  95                 return NULL;
  96
  97         check_dbmobject_open(dp);
  98         drec = dbm_fetch(dp->di_dbm, krec);
  99         if ( drec.dptr == 0 ) {
 100                 PyErr_SetString(PyExc_KeyError,
 101                                 PyString_AS_STRING((PyStringObject *)key));
 102                 return NULL;
 103         }
 104         if ( dbm_error(dp->di_dbm) ) {
 105                 dbm_clearerr(dp->di_dbm);
 106                 PyErr_SetString(DbmError, "");
 107                 return NULL;
 108         }
 109         return PyString_FromStringAndSize(drec.dptr, drec.dsize);
 110 }
 111
 112 static int
 113 dbm_ass_sub(dbmobject *dp, PyObject *v, PyObject *w)
 114 {
 115         datum krec, drec;
 116
 117         if ( !PyArg_Parse(v, "s#", &krec.dptr, &krec.dsize) ) {
 118                 PyErr_SetString(PyExc_TypeError,
 119                                 "dbm mappings have string indices only");
 120                 return -1;
 121         }
 122         if (dp->di_dbm == NULL) {
 123                  PyErr_SetString(DbmError, "DBM object has already been closed");
 124                  return -1;
 125         }
 126         dp->di_size = -1;
 127         if (w == NULL) {
 128                 if ( dbm_delete(dp->di_dbm, krec) < 0 ) {
 129                         dbm_clearerr(dp->di_dbm);
 130                         PyErr_SetString(PyExc_KeyError,
 131                                       PyString_AS_STRING((PyStringObject *)v));
 132                         return -1;
 133                 }
 134         } else {
 135                 if ( !PyArg_Parse(w, "s#", &drec.dptr, &drec.dsize) ) {
 136                         PyErr_SetString(PyExc_TypeError,
 137                                      "dbm mappings have string elements only");
 138                         return -1;
 139                 }
 140                 if ( dbm_store(dp->di_dbm, krec, drec, DBM_REPLACE) < 0 ) {
 141                         dbm_clearerr(dp->di_dbm);
 142                         PyErr_SetString(DbmError,
 143                                         "cannot add item to database");
 144                         return -1;
 145                 }
 146         }
 147         if ( dbm_error(dp->di_dbm) ) {
 148                 dbm_clearerr(dp->di_dbm);
 149                 PyErr_SetString(DbmError, "");
 150                 return -1;
 151         }
 152         return 0;
 153 }
 154
 155 static PyMappingMethods dbm_as_mapping = {
 156         (inquiry)dbm_length,            /*mp_length*/
 157         (binaryfunc)dbm_subscript,      /*mp_subscript*/
 158         (objobjargproc)dbm_ass_sub,     /*mp_ass_subscript*/
 159 };
 160
 161 static PyObject *
 162 dbm__close(register dbmobject *dp, PyObject *args)
 163 {
 164         if (!PyArg_ParseTuple(args, ":close"))
 165                 return NULL;
 166         if (dp->di_dbm)
 167                 dbm_close(dp->di_dbm);
 168         dp->di_dbm = NULL;
 169         Py_INCREF(Py_None);
 170         return Py_None;
 171 }
 172
 173 static PyObject *
 174 dbm_keys(register dbmobject *dp, PyObject *args)
 175 {
 176         register PyObject *v, *item;
 177         datum key;
 178         int err;
 179
 180         if (!PyArg_ParseTuple(args, ":keys"))
 181                 return NULL;
 182         check_dbmobject_open(dp);
 183         v = PyList_New(0);
 184         if (v == NULL)
 185                 return NULL;
 186         for (key = dbm_firstkey(dp->di_dbm); key.dptr;
 187              key = dbm_nextkey(dp->di_dbm)) {
 188                 item = PyString_FromStringAndSize(key.dptr, key.dsize);
 189                 if (item == NULL) {
 190                         Py_DECREF(v);
 191                         return NULL;
 192                 }
 193                 err = PyList_Append(v, item);
 194                 Py_DECREF(item);
 195                 if (err != 0) {
 196                         Py_DECREF(v);
 197                         return NULL;
 198                 }
 199         }
 200         return v;
 201 }
 202
 203 static PyObject *
 204 dbm_has_key(register dbmobject *dp, PyObject *args)
 205 {
 206         datum key, val;
 207
 208         if (!PyArg_ParseTuple(args, "s#:has_key", &key.dptr, &key.dsize))
 209                 return NULL;
 210         check_dbmobject_open(dp);
 211         val = dbm_fetch(dp->di_dbm, key);
 212         return PyInt_FromLong(val.dptr != NULL);
 213 }
 214
 215 static PyObject *
 216 dbm_get(register dbmobject *dp, PyObject *args)
 217 {
 218         datum key, val;
 219         PyObject *defvalue = Py_None;
 220
 221         if (!PyArg_ParseTuple(args, "s#|O:get",
 222                               &key.dptr, &key.dsize, &defvalue))
 223                 return NULL;
 224         check_dbmobject_open(dp);
 225         val = dbm_fetch(dp->di_dbm, key);
 226         if (val.dptr != NULL)
 227                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 228         else {
 229                 Py_INCREF(defvalue);
 230                 return defvalue;
 231         }
 232 }
 233
 234 static PyObject *
 235 dbm_setdefault(register dbmobject *dp, PyObject *args)
 236 {
 237         datum key, val;
 238         PyObject *defvalue = NULL;
 239
 240         if (!PyArg_ParseTuple(args, "s#|S:setdefault",
 241                               &key.dptr, &key.dsize, &defvalue))
 242                 return NULL;
 243         check_dbmobject_open(dp);
 244         val = dbm_fetch(dp->di_dbm, key);
 245         if (val.dptr != NULL)
 246                 return PyString_FromStringAndSize(val.dptr, val.dsize);
 247         if (defvalue == NULL) {
 248                 defvalue = PyString_FromStringAndSize(NULL, 0);
 249                 if (defvalue == NULL)
 250                         return NULL;
 251         }
 252         else
 253                 Py_INCREF(defvalue);
 254         val.dptr = PyString_AS_STRING(defvalue);
 255         val.dsize = PyString_GET_SIZE(defvalue);
 256         if (dbm_store(dp->di_dbm, key, val, DBM_INSERT) < 0) {
 257                 dbm_clearerr(dp->di_dbm);
 258                 PyErr_SetString(DbmError, "cannot add item to database");
 259                 return NULL;
 260         }
 261         return defvalue;
 262 }
 263
 264 static PyMethodDef dbm_methods[] = {
 265         {"close",       (PyCFunction)dbm__close,        METH_VARARGS,
 266          "close()\nClose the database."},
 267         {"keys",        (PyCFunction)dbm_keys,          METH_VARARGS,
 268          "keys() -> list\nReturn a list of all keys in the database."},
 269         {"has_key",     (PyCFunction)dbm_has_key,       METH_VARARGS,
 270          "has_key(key} -> boolean\nReturn true iff key is in the database."},
 271         {"get",         (PyCFunction)dbm_get,           METH_VARARGS,
 272          "get(key[, default]) -> value\n"
 273          "Return the value for key if present, otherwise default."},
 274         {"setdefault",  (PyCFunction)dbm_setdefault,    METH_VARARGS,
 275          "setdefault(key[, default]) -> value\n"
 276          "Return the value for key if present, otherwise default.  If key\n"
 277          "is not in the database, it is inserted with default as the value."},
 278         {NULL,          NULL}           /* sentinel */
 279 };
 280
 281 static PyObject *
 282 dbm_getattr(dbmobject *dp, char *name)
 283 {
 284         return Py_FindMethod(dbm_methods, (PyObject *)dp, name);
 285 }
 286
 287 static PyTypeObject Dbmtype = {
 288         PyObject_HEAD_INIT(NULL)
 289         0,
 290         "dbm",
 291         sizeof(dbmobject),
 292         0,
 293         (destructor)dbm_dealloc,  /*tp_dealloc*/
 294         0,                        /*tp_print*/
 295         (getattrfunc)dbm_getattr, /*tp_getattr*/
 296         0,                        /*tp_setattr*/
 297         0,                        /*tp_compare*/
 298         0,                        /*tp_repr*/
 299         0,                        /*tp_as_number*/
 300         0,                        /*tp_as_sequence*/
 301         &dbm_as_mapping,          /*tp_as_mapping*/
 302 };
 303
 304 /* ----------------------------------------------------------------- */
 305
 306 static PyObject *
 307 dbmopen(PyObject *self, PyObject *args)
 308 {
 309         char *name;
 310         char *flags = "r";
 311         int iflags;
 312         int mode = 0666;
 313
 314         if ( !PyArg_ParseTuple(args, "s|si:open", &name, &flags, &mode) )
 315                 return NULL;
 316         if ( strcmp(flags, "r") == 0 )
 317                 iflags = O_RDONLY;
 318         else if ( strcmp(flags, "w") == 0 )
 319                 iflags = O_RDWR;
 320         else if ( strcmp(flags, "rw") == 0 ) /* B/W compat */
 321                 iflags = O_RDWR|O_CREAT;
 322         else if ( strcmp(flags, "c") == 0 )
 323                 iflags = O_RDWR|O_CREAT;
 324         else if ( strcmp(flags, "n") == 0 )
 325                 iflags = O_RDWR|O_CREAT|O_TRUNC;
 326         else {
 327                 PyErr_SetString(DbmError,
 328                                 "arg 2 to open should be 'r', 'w', 'c', or 'n'");
 329                 return NULL;
 330         }
 331         return newdbmobject(name, iflags, mode);
 332 }
 333
 334 static PyMethodDef dbmmodule_methods[] = {
 335         { "open", (PyCFunction)dbmopen, METH_VARARGS,
 336           "open(path[, flag[, mode]]) -> mapping\n"
 337           "Return a database object."},
 338         { 0, 0 },
 339 };
 340
 341 DL_EXPORT(void)
 342 initdbm(void) {
 343         PyObject *m, *d, *s;
 344
 345         Dbmtype.ob_type = &PyType_Type;
 346         m = Py_InitModule("dbm", dbmmodule_methods);
 347         d = PyModule_GetDict(m);
 348         if (DbmError == NULL)
 349                 DbmError = PyErr_NewException("dbm.error", NULL, NULL);
 350         s = PyString_FromString(which_dbm);
 351         if (s != NULL) {
 352                 PyDict_SetItemString(d, "library", s);
 353                 Py_DECREF(s);
 354         }
 355         if (DbmError != NULL)
 356                 PyDict_SetItemString(d, "error", DbmError);
 357 }