gdbmmodule.c

/* DBM module using dictionary interface */
/* Author: Anthony Baxter, after dbmmodule.c */
/* Doc strings: Mitch Chapman */


#include"Python.h"

#include<sys/types.h>
#include<sys/stat.h>
#include<fcntl.h>
#include"gdbm.h"

#if defined(WIN32) && !defined(__CYGWIN__)
#include"gdbmerrno.h"
externconstchar*gdbm_strerror(gdbm_error);
#endif

PyDoc_STRVAR(gdbmmodule__doc__,
"This module provides an interface to the GNU DBM (GDBM) library.\n\
\n\
This module is quite similar to the dbm module, but uses GDBM instead to\n\
provide some additional functionality. Please note that the file formats\n\
created by GDBM and dbm are incompatible. \n\
\n\
GDBM objects behave like mappings (dictionaries), except that keys and\n\
values are always strings. Printing a GDBM object doesn't print the\n\
keys and values, and the items() and values() methods are not\n\
supported.");

typedefstruct {
PyObject_HEAD
intdi_size; /* -1 means recompute */
GDBM_FILEdi_dbm;
} dbmobject;

staticPyTypeObjectDbmtype;

#defineis_dbmobject(v) (Py_TYPE(v) == &Dbmtype)
#definecheck_dbmobject_open(v) if ((v)->di_dbm == NULL) \
 { PyErr_SetString(DbmError, "GDBM object has already been closed"); \
 return NULL; }



staticPyObject*DbmError;

PyDoc_STRVAR(gdbm_object__doc__,
"This object represents a GDBM database.\n\
GDBM objects behave like mappings (dictionaries), except that keys and\n\
values are always strings. Printing a GDBM object doesn't print the\n\
keys and values, and the items() and values() methods are not\n\
supported.\n\
\n\
GDBM objects also support additional operations such as firstkey,\n\
nextkey, reorganize, and sync.");

staticPyObject*
newdbmobject(char*file, intflags, intmode)
{
dbmobject*dp;

dp=PyObject_New(dbmobject, &Dbmtype);
if (dp==NULL)
returnNULL;
dp->di_size=-1;
errno=0;
if ((dp->di_dbm=gdbm_open(file, 0, flags, mode, NULL)) ==0) {
if (errno!=0)
PyErr_SetFromErrno(DbmError);
else
PyErr_SetString(DbmError, gdbm_strerror(gdbm_errno));
Py_DECREF(dp);
returnNULL;
 }
return (PyObject*)dp;
}

/* Methods */

staticvoid
dbm_dealloc(register dbmobject*dp)
{
if (dp->di_dbm)
gdbm_close(dp->di_dbm);
PyObject_Del(dp);
}

staticPy_ssize_t
dbm_length(dbmobject*dp)
{
if (dp->di_dbm==NULL) {
PyErr_SetString(DbmError, "GDBM object has already been closed"); 
return-1; 
 }
if (dp->di_size<0) {
datumkey,okey;
intsize;
okey.dsize=0;
okey.dptr=NULL;

size=0;
for (key=gdbm_firstkey(dp->di_dbm); key.dptr;
key=gdbm_nextkey(dp->di_dbm,okey)) {
size++;
if(okey.dsize) free(okey.dptr);
okey=key;
 }
dp->di_size=size;
 }
returndp->di_size;
}

staticPyObject*
dbm_subscript(dbmobject*dp, register PyObject*key)
{
PyObject*v;
datumdrec, krec;

if (!PyArg_Parse(key, "s#", &krec.dptr, &krec.dsize) )
returnNULL;

if (dp->di_dbm==NULL) {
PyErr_SetString(DbmError,
"GDBM object has already been closed");
returnNULL;
 }
drec=gdbm_fetch(dp->di_dbm, krec);
if (drec.dptr==0) {
PyErr_SetString(PyExc_KeyError,
PyString_AS_STRING((PyStringObject*)key));
returnNULL;
 }
v=PyString_FromStringAndSize(drec.dptr, drec.dsize);
free(drec.dptr);
returnv;
}

staticint
dbm_ass_sub(dbmobject*dp, PyObject*v, PyObject*w)
{
datumkrec, drec;

if (!PyArg_Parse(v, "s#", &krec.dptr, &krec.dsize) ) {
PyErr_SetString(PyExc_TypeError,
"gdbm mappings have string indices only");
return-1;
 }
if (dp->di_dbm==NULL) {
PyErr_SetString(DbmError,
"GDBM object has already been closed"); 
return-1; 
 }
dp->di_size=-1;
if (w==NULL) {
if (gdbm_delete(dp->di_dbm, krec) <0) {
PyErr_SetString(PyExc_KeyError,
PyString_AS_STRING((PyStringObject*)v));
return-1;
 }
 }
else {
if (!PyArg_Parse(w, "s#", &drec.dptr, &drec.dsize)) {
PyErr_SetString(PyExc_TypeError,
"gdbm mappings have string elements only");
return-1;
 }
errno=0;
if (gdbm_store(dp->di_dbm, krec, drec, GDBM_REPLACE) <0) {
if (errno!=0)
PyErr_SetFromErrno(DbmError);
else
PyErr_SetString(DbmError,
gdbm_strerror(gdbm_errno));
return-1;
 }
 }
return0;
}

staticint
dbm_contains(register dbmobject*dp, PyObject*arg)
{
datumkey;

if ((dp)->di_dbm==NULL) {
PyErr_SetString(DbmError,
"GDBM object has already been closed");
return-1;
 }
if (!PyString_Check(arg)) {
PyErr_Format(PyExc_TypeError,
"gdbm key must be string, not %.100s",
arg->ob_type->tp_name);
return-1;
 }
key.dptr=PyString_AS_STRING(arg);
key.dsize=PyString_GET_SIZE(arg);
returngdbm_exists(dp->di_dbm, key);
}

staticPySequenceMethodsdbm_as_sequence= {
 (lenfunc)dbm_length, /*_length*/
0, /*sq_concat*/
0, /*sq_repeat*/
0, /*sq_item*/
0, /*sq_slice*/
0, /*sq_ass_item*/
0, /*sq_ass_slice*/
 (objobjproc)dbm_contains, /*sq_contains*/
0, /*sq_inplace_concat*/
0/*sq_inplace_repeat*/
};

staticPyMappingMethodsdbm_as_mapping= {
 (lenfunc)dbm_length, /*mp_length*/
 (binaryfunc)dbm_subscript, /*mp_subscript*/
 (objobjargproc)dbm_ass_sub, /*mp_ass_subscript*/
};

PyDoc_STRVAR(dbm_close__doc__,
"close() -> None\n\
Closes the database.");

staticPyObject*
dbm_close(register dbmobject*dp, PyObject*unused)
{
if (dp->di_dbm)
gdbm_close(dp->di_dbm);
dp->di_dbm=NULL;
Py_INCREF(Py_None);
returnPy_None;
}

PyDoc_STRVAR(dbm_keys__doc__,
"keys() -> list_of_keys\n\
Get a list of all keys in the database.");

staticPyObject*
dbm_keys(register dbmobject*dp, PyObject*unused)
{
 register PyObject*v, *item;
datumkey, nextkey;
interr;

if (dp==NULL|| !is_dbmobject(dp)) {
PyErr_BadInternalCall();
returnNULL;
 }
check_dbmobject_open(dp);

v=PyList_New(0);
if (v==NULL)
returnNULL;

key=gdbm_firstkey(dp->di_dbm);
while (key.dptr) {
item=PyString_FromStringAndSize(key.dptr, key.dsize);
if (item==NULL) {
free(key.dptr);
Py_DECREF(v);
returnNULL;
 }
err=PyList_Append(v, item);
Py_DECREF(item);
if (err!=0) {
free(key.dptr);
Py_DECREF(v);
returnNULL;
 }
nextkey=gdbm_nextkey(dp->di_dbm, key);
free(key.dptr);
key=nextkey;
 }
returnv;
}

PyDoc_STRVAR(dbm_has_key__doc__,
"has_key(key) -> boolean\n\
Find out whether or not the database contains a given key.");

staticPyObject*
dbm_has_key(register dbmobject*dp, PyObject*args)
{
datumkey;

if (!PyArg_ParseTuple(args, "s#:has_key", &key.dptr, &key.dsize))
returnNULL;
check_dbmobject_open(dp);
returnPyInt_FromLong((long) gdbm_exists(dp->di_dbm, key));
}

PyDoc_STRVAR(dbm_firstkey__doc__,
"firstkey() -> key\n\
It's possible to loop over every key in the database using this method\n\
and the nextkey() method. The traversal is ordered by GDBM's internal\n\
hash values, and won't be sorted by the key values. This method\n\
returns the starting key.");

staticPyObject*
dbm_firstkey(register dbmobject*dp, PyObject*unused)
{
 register PyObject*v;
datumkey;

check_dbmobject_open(dp);
key=gdbm_firstkey(dp->di_dbm);
if (key.dptr) {
v=PyString_FromStringAndSize(key.dptr, key.dsize);
free(key.dptr);
returnv;
 }
else {
Py_INCREF(Py_None);
returnPy_None;
 }
}

PyDoc_STRVAR(dbm_nextkey__doc__,
"nextkey(key) -> next_key\n\
Returns the key that follows key in the traversal.\n\
The following code prints every key in the database db, without having\n\
to create a list in memory that contains them all:\n\
\n\
 k = db.firstkey()\n\
 while k != None:\n\
 print k\n\
 k = db.nextkey(k)");

staticPyObject*
dbm_nextkey(register dbmobject*dp, PyObject*args)
{
 register PyObject*v;
datumkey, nextkey;

if (!PyArg_ParseTuple(args, "s#:nextkey", &key.dptr, &key.dsize))
returnNULL;
check_dbmobject_open(dp);
nextkey=gdbm_nextkey(dp->di_dbm, key);
if (nextkey.dptr) {
v=PyString_FromStringAndSize(nextkey.dptr, nextkey.dsize);
free(nextkey.dptr);
returnv;
 }
else {
Py_INCREF(Py_None);
returnPy_None;
 }
}

PyDoc_STRVAR(dbm_reorganize__doc__,
"reorganize() -> None\n\
If you have carried out a lot of deletions and would like to shrink\n\
the space used by the GDBM file, this routine will reorganize the\n\
database. GDBM will not shorten the length of a database file except\n\
by using this reorganization; otherwise, deleted file space will be\n\
kept and reused as new (key,value) pairs are added.");

staticPyObject*
dbm_reorganize(register dbmobject*dp, PyObject*unused)
{
check_dbmobject_open(dp);
errno=0;
if (gdbm_reorganize(dp->di_dbm) <0) {
if (errno!=0)
PyErr_SetFromErrno(DbmError);
else
PyErr_SetString(DbmError, gdbm_strerror(gdbm_errno));
returnNULL;
 }
Py_INCREF(Py_None);
returnPy_None;
}

PyDoc_STRVAR(dbm_sync__doc__,
"sync() -> None\n\
When the database has been opened in fast mode, this method forces\n\
any unwritten data to be written to the disk.");

staticPyObject*
dbm_sync(register dbmobject*dp, PyObject*unused)
{
check_dbmobject_open(dp);
gdbm_sync(dp->di_dbm);
Py_INCREF(Py_None);
returnPy_None;
}

staticPyMethodDefdbm_methods[] = {
 {"close", (PyCFunction)dbm_close, METH_NOARGS, dbm_close__doc__},
 {"keys", (PyCFunction)dbm_keys, METH_NOARGS, dbm_keys__doc__},
 {"has_key", (PyCFunction)dbm_has_key, METH_VARARGS, dbm_has_key__doc__},
 {"firstkey", (PyCFunction)dbm_firstkey,METH_NOARGS, dbm_firstkey__doc__},
 {"nextkey", (PyCFunction)dbm_nextkey, METH_VARARGS, dbm_nextkey__doc__},
 {"reorganize",(PyCFunction)dbm_reorganize,METH_NOARGS, dbm_reorganize__doc__},
 {"sync", (PyCFunction)dbm_sync, METH_NOARGS, dbm_sync__doc__},
 {NULL, NULL} /* sentinel */
};

staticPyObject*
dbm_getattr(dbmobject*dp, char*name)
{
returnPy_FindMethod(dbm_methods, (PyObject*)dp, name);
}

staticPyTypeObjectDbmtype= {
PyVarObject_HEAD_INIT(0, 0)
"gdbm.gdbm",
sizeof(dbmobject),
0,
 (destructor)dbm_dealloc, /*tp_dealloc*/
0, /*tp_print*/
 (getattrfunc)dbm_getattr, /*tp_getattr*/
0, /*tp_setattr*/
0, /*tp_compare*/
0, /*tp_repr*/
0, /*tp_as_number*/
&dbm_as_sequence, /*tp_as_sequence*/
&dbm_as_mapping, /*tp_as_mapping*/
0, /*tp_hash*/
0, /*tp_call*/
0, /*tp_str*/
0, /*tp_getattro*/
0, /*tp_setattro*/
0, /*tp_as_buffer*/
Py_TPFLAGS_DEFAULT, /*tp_xxx4*/
gdbm_object__doc__, /*tp_doc*/
};

/* ----------------------------------------------------------------- */

PyDoc_STRVAR(dbmopen__doc__,
"open(filename, [flags, [mode]]) -> dbm_object\n\
Open a dbm database and return a dbm object. The filename argument is\n\
the name of the database file.\n\
\n\
The optional flags argument can be 'r' (to open an existing database\n\
for reading only -- default), 'w' (to open an existing database for\n\
reading and writing), 'c' (which creates the database if it doesn't\n\
exist), or 'n' (which always creates a new empty database).\n\
\n\
Some versions of gdbm support additional flags which must be\n\
appended to one of the flags described above. The module constant\n\
'open_flags' is a string of valid additional flags. The 'f' flag\n\
opens the database in fast mode; altered data will not automatically\n\
be written to the disk after every change. This results in faster\n\
writes to the database, but may result in an inconsistent database\n\
if the program crashes while the database is still open. Use the\n\
sync() method to force any unwritten data to be written to the disk.\n\
The 's' flag causes all database operations to be synchronized to\n\
disk. The 'u' flag disables locking of the database file.\n\
\n\
The optional mode argument is the Unix mode of the file, used only\n\
when the database has to be created. It defaults to octal 0666. ");

staticPyObject*
dbmopen(PyObject*self, PyObject*args)
{
char*name;
char*flags="r";
intiflags;
intmode=0666;

if (!PyArg_ParseTuple(args, "s|si:open", &name, &flags, &mode))
returnNULL;
switch (flags[0]) {
case'r':
iflags=GDBM_READER;
break;
case'w':
iflags=GDBM_WRITER;
break;
case'c':
iflags=GDBM_WRCREAT;
break;
case'n':
iflags=GDBM_NEWDB;
break;
default:
PyErr_SetString(DbmError,
"First flag must be one of 'r', 'w', 'c' or 'n'");
returnNULL;
 }
for (flags++; *flags!='\0'; flags++) {
charbuf[40];
switch (*flags) {
#ifdefGDBM_FAST
case'f':
iflags |= GDBM_FAST;
break;
#endif
#ifdefGDBM_SYNC
case's':
iflags |= GDBM_SYNC;
break;
#endif
#ifdefGDBM_NOLOCK
case'u':
iflags |= GDBM_NOLOCK;
break;
#endif
default:
PyOS_snprintf(buf, sizeof(buf), "Flag '%c' is not supported.",
*flags);
PyErr_SetString(DbmError, buf);
returnNULL;
 }
 }

returnnewdbmobject(name, iflags, mode);
}

staticchardbmmodule_open_flags[] ="rwcn"
#ifdefGDBM_FAST
"f"
#endif
#ifdefGDBM_SYNC
"s"
#endif
#ifdefGDBM_NOLOCK
"u"
#endif
 ;

staticPyMethodDefdbmmodule_methods[] = {
 { "open", (PyCFunction)dbmopen, METH_VARARGS, dbmopen__doc__},
 { 0, 0 },
};

PyMODINIT_FUNC
initgdbm(void) {
PyObject*m, *d, *s;

Dbmtype.ob_type=&PyType_Type;
m=Py_InitModule4("gdbm", dbmmodule_methods,
gdbmmodule__doc__, (PyObject*)NULL,
PYTHON_API_VERSION);
if (m==NULL)
return;
d=PyModule_GetDict(m);
DbmError=PyErr_NewException("gdbm.error", NULL, NULL);
if (DbmError!=NULL) {
PyDict_SetItemString(d, "error", DbmError);
s=PyString_FromString(dbmmodule_open_flags);
PyDict_SetItemString(d, "open_flags", s);
Py_DECREF(s);
 }
}