cpython/Modules/dbhashmodule.c

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/* Berkeley DB hash interface.
   Author: Michael McLay
   Hacked: Guido van Rossum

   XXX To do:
   - provide interface to the B-tree and record libraries too
   - provide a way to access the various hash functions
   - support more open flags
 */

#include "allobjects.h"
#include "modsupport.h"

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <db.h>
/* Please don't include internal header files of the Berkeley db package
   (it messes up the info required in the Setup file) */

typedef struct {
    OB_HEAD
    DB *di_dbhash;
    int di_size;	/* -1 means recompute */
} dbhashobject;

staticforward typeobject Dbhashtype;

#define is_dbhashobject(v) ((v)->ob_type == &Dbhashtype)

static object *DbhashError;

static object *
newdbhashobject(file, flags, mode,
		bsize, ffactor, nelem, cachesize, hash, lorder)
    char *file;
    int flags;
    int mode;
    int bsize;
    int ffactor;
    int nelem;
    int cachesize;
    int hash; /* XXX ignored */
    int lorder;
{
    dbhashobject *dp;
    HASHINFO info;

    if ((dp = NEWOBJ(dbhashobject, &Dbhashtype)) == NULL)
	return NULL;

    info.bsize = bsize;
    info.ffactor = ffactor;
    info.nelem = nelem;
    info.cachesize = cachesize;
    info.hash = NULL; /* XXX should derive from hash argument */
    info.lorder = lorder;

    if ((dp->di_dbhash = dbopen(file, flags, mode, DB_HASH, &info)) == NULL) {
	err_errno(DbhashError);
	DECREF(dp);
	return NULL;
    }

    dp->di_size = -1;

    return (object *)dp;
}

static void
dbhash_dealloc(dp)
    dbhashobject *dp;
{
    if (dp->di_dbhash != NULL) {
	if ((dp->di_dbhash->close)(dp->di_dbhash) != 0)
	    fprintf(stderr,
		    "Python dbhash: close errno %s in dealloc\n", errno);
    }
    DEL(dp);
}

static int
dbhash_length(dp)
    dbhashobject *dp;
{
    if (dp->di_size < 0) {
	DBT krec, drec;
	int status;
	int size = 0;
	for (status = (dp->di_dbhash->seq)(dp->di_dbhash, &krec, &drec,R_FIRST);
	     status == 0;
	     status = (dp->di_dbhash->seq)(dp->di_dbhash, &krec, &drec, R_NEXT))
	    size++;
	if (status < 0) {
	    err_errno(DbhashError);
	    return -1;
	}
	dp->di_size = size;
    }
    return dp->di_size;
}

static object *
dbhash_subscript(dp, key)
    dbhashobject *dp;
    object *key;
{
    int status;
    object *v;
    DBT krec, drec;
    char *data;
    int size;

    if (!getargs(key, "s#", &data, &size))
	return NULL;
    krec.data = data;
    krec.size = size;

    status = (dp->di_dbhash->get)(dp->di_dbhash, &krec, &drec, 0);
    if (status != 0) {
	if (status < 0)
	    err_errno(DbhashError);
	else
	    err_setval(KeyError, key);
	return NULL;
    }

    return newsizedstringobject((char *)drec.data, (int)drec.size);
}

static int
dbhash_ass_sub(dp, key, value)
    dbhashobject *dp;
    object *key, *value;
{
    int status;
    DBT krec, drec;
    char *data;
    int size;

    if (!getargs(key, "s#", &data, &size)) {
	err_setstr(TypeError, "dbhash key type must be string");
	return -1;
    }
    krec.data = data;
    krec.size = size;
    dp->di_size = -1;
    if (value == NULL) {
	status = (dp->di_dbhash->del)(dp->di_dbhash, &krec, 0);
    }
    else {
	if (!getargs(value, "s#", &data, &size)) {
	    err_setstr(TypeError, "dbhash value type must be string");
	    return -1;
	}
	drec.data = data;
	drec.size = size;
	status = (dp->di_dbhash->put)(dp->di_dbhash, &krec, &drec, 0);
    }
    if (status != 0) {
	if (status < 0)
	    err_errno(DbhashError);
	else
	    err_setval(KeyError, key);
	return -1;
    }
    return 0;
}

static mapping_methods dbhash_as_mapping = {
    (inquiry)dbhash_length,		/*mp_length*/
    (binaryfunc)dbhash_subscript,	/*mp_subscript*/
    (objobjargproc)dbhash_ass_sub,	/*mp_ass_subscript*/
};

static object *
dbhash_close(dp, args)
    dbhashobject *dp;
    object *args;
{
    if (!getnoarg(args))
	return NULL;
    if (dp->di_dbhash != NULL) {
	if ((dp->di_dbhash->close)(dp->di_dbhash) != 0) {
		dp->di_dbhash = NULL;
	    err_errno(DbhashError);
	    return NULL;
	}
    }
    dp->di_dbhash = NULL;
    INCREF(None);
    return None;
}

static object *
dbhash_keys(dp, args)
    dbhashobject *dp;
    object *args;
{
    object *list, *item;
    DBT krec, drec;
    int status;
    int err;

    if (!getnoarg(args))
	return NULL;
    list = newlistobject(0);
    if (list == NULL)
	return NULL;
    for (status = (dp->di_dbhash->seq)(dp->di_dbhash, &krec, &drec, R_FIRST);
	 status == 0;
	 status = (dp->di_dbhash->seq)(dp->di_dbhash, &krec, &drec, R_NEXT)) {
	item = newsizedstringobject((char *)krec.data, (int)krec.size);
	if (item == NULL) {
	    DECREF(list);
	    return NULL;
	}
	err = addlistitem(list, item);
	DECREF(item);
	if (err != 0) {
	    DECREF(list);
	    return NULL;
	}
    }
    if (status < 0) {
	err_errno(DbhashError);
	DECREF(list);
	return NULL;
    }
    if (dp->di_size < 0)
	dp->di_size = getlistsize(list); /* We just did the work for this... */
    return list;
}

static object *
dbhash_has_key(dp, args)
    dbhashobject *dp;
    object *args;
{
    DBT krec, drec;
    int status;
    char *data;
    int size;

    if (!getargs(args, "s#", &data, &size))
	return NULL;
    krec.data = data;
    krec.size = size;

    status = (dp->di_dbhash->get)(dp->di_dbhash, &krec, &drec, 0);
    if (status < 0) {
	err_errno(DbhashError);
	return NULL;
    }

    return newintobject(status == 0);
}

static struct methodlist dbhash_methods[] = {
    {"close",		(method)dbhash_close},
    {"keys",		(method)dbhash_keys},
    {"has_key",		(method)dbhash_has_key},
    {NULL,	       	NULL}		/* sentinel */
};

static object *
dbhash_getattr(dp, name)
    object *dp;
    char *name;
{
    return findmethod(dbhash_methods, dp, name);
}

static typeobject Dbhashtype = {
    OB_HEAD_INIT(&Typetype)
    0,
    "dbhash",
    sizeof(dbhashobject),
    0,
    (destructor)dbhash_dealloc, /*tp_dealloc*/
    0,			/*tp_print*/
    (getattrfunc)dbhash_getattr, /*tp_getattr*/
    0,			/*tp_setattr*/
    0,			/*tp_compare*/
    0,			/*tp_repr*/
    0,			/*tp_as_number*/
    0,			/*tp_as_sequence*/
    &dbhash_as_mapping,	/*tp_as_mapping*/
};

static object *
dbhashopen(self, args)
    object *self;
    object *args;
{
    char *file;
    char *flag = NULL;
    int flags = O_RDONLY;
    int mode = 0666;
    int bsize = 0;
    int ffactor = 0;
    int nelem = 0;
    int cachesize = 0;
    int hash = 0; /* XXX currently ignored */
    int lorder = 0;

    if (!newgetargs(args, "s|siiiiiii",
		 &file, &flag, &mode,
		 &bsize, &ffactor, &nelem, &cachesize, &hash, &lorder))
	  return NULL;
    if (flag != NULL) {
	/* XXX need a way to pass O_EXCL, O_EXLOCK, O_NONBLOCK, O_SHLOCK */
	if (flag[0] == 'r')
	    flags = O_RDONLY;
	else if (flag[0] == 'w')
	    flags = O_RDWR;
	else if (flag[0] == 'c')
	    flags = O_RDWR|O_CREAT;
	else if (flag[0] == 'n')
	    flags = O_RDWR|O_CREAT|O_TRUNC;
	else {
	    err_setstr(DbhashError,
		       "Flag should begin with 'r', 'w', 'c' or 'n'");
	    return NULL;
	}
	if (flag[1] == 'l') {
#if defined(O_EXLOCK) && defined(O_SHLOCK)
	    if (flag[0] == 'r')
	        flags |= O_SHLOCK;
	    else
		flags |= O_EXLOCK;
#else
	    err_setstr(DbhashError, "locking not supported on this platform");
	    return NULL;
#endif
	}
    }
    return newdbhashobject(file, flags, mode,
			   bsize, ffactor, nelem, cachesize, hash, lorder);
}

static struct methodlist dbhashmodule_methods[] = {
    {"open",	(method)dbhashopen, 1},
    {0,		0},
};

void
initdbhash() {
    object *m, *d;

    m = initmodule("dbhash", dbhashmodule_methods);
    d = getmoduledict(m);
    DbhashError = newstringobject("dbhash.error");
    if (DbhashError == NULL || dictinsert(d, "error", DbhashError))
	fatal("can't define dbhash.error");
}