xref: /xsrc/external/mit/xorg-server/dist/dix/atom.c

/***********************************************************

Copyright 1987, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
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in this Software without prior written authorization from The Open Group.

Copyright 1987 by Digital Equipment Corporation, Maynard, Massachusetts.

                        All Rights Reserved

Permission to use, copy, modify, and distribute this software and its
documentation for any purpose and without fee is hereby granted,
provided that the above copyright notice appear in all copies and that
both that copyright notice and this permission notice appear in
supporting documentation, and that the name of Digital not be
used in advertising or publicity pertaining to distribution of the
software without specific, written prior permission.

DIGITAL DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
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******************************************************************/

#ifdef HAVE_DIX_CONFIG_H
#include <dix-config.h>
#endif

#include <X11/X.h>
#include <X11/Xatom.h>
#include <stdio.h>
#include <string.h>
#include "misc.h"
#include "resource.h"
#include "dix.h"

#define InitialTableSize 256

typedef struct _Node {
    struct _Node *left, *right;
    Atom a;
    unsigned int fingerPrint;
    const char *string;
} NodeRec, *NodePtr;

static Atom lastAtom = None;
static NodePtr atomRoot = NULL;
static unsigned long tableLength;
static NodePtr *nodeTable;

Atom
MakeAtom(const char *string, unsigned len, Bool makeit)
{
    NodePtr *np;
    unsigned i;
    int comp;
    unsigned int fp = 0;

    np = &atomRoot;
    for (i = 0; i < (len + 1) / 2; i++) {
        fp = fp * 27 + string[i];
        fp = fp * 27 + string[len - 1 - i];
    }
    while (*np != NULL) {
        if (fp < (*np)->fingerPrint)
            np = &((*np)->left);
        else if (fp > (*np)->fingerPrint)
            np = &((*np)->right);
        else {                  /* now start testing the strings */
            comp = strncmp(string, (*np)->string, (int) len);
            if ((comp < 0) || ((comp == 0) && (len < strlen((*np)->string))))
                np = &((*np)->left);
            else if (comp > 0)
                np = &((*np)->right);
            else
                return (*np)->a;
        }
    }
    if (makeit) {
        NodePtr nd;

        nd = malloc(sizeof(NodeRec));
        if (!nd)
            return BAD_RESOURCE;
        if (lastAtom < XA_LAST_PREDEFINED) {
            nd->string = string;
        }
        else {
            nd->string = strndup(string, len);
            if (!nd->string) {
                free(nd);
                return BAD_RESOURCE;
            }
        }
        if ((lastAtom + 1) >= tableLength) {
            NodePtr *table;

            table = reallocarray(nodeTable, tableLength, 2 * sizeof(NodePtr));
            if (!table) {
                if (nd->string != string) {
                    /* nd->string has been strdup'ed */
                    free((char *) nd->string);
                }
                free(nd);
                return BAD_RESOURCE;
            }
            tableLength <<= 1;
            nodeTable = table;
        }
        *np = nd;
        nd->left = nd->right = NULL;
        nd->fingerPrint = fp;
        nd->a = ++lastAtom;
        nodeTable[lastAtom] = nd;
        return nd->a;
    }
    else
        return None;
}

Bool
ValidAtom(Atom atom)
{
    return (atom != None) && (atom <= lastAtom);
}

const char *
NameForAtom(Atom atom)
{
    NodePtr node;

    if (atom > lastAtom)
        return 0;
    if ((node = nodeTable[atom]) == NULL)
        return 0;
    return node->string;
}

void
AtomError(void)
{
    FatalError("initializing atoms");
}

static void
FreeAtom(NodePtr patom)
{
    if (patom->left)
        FreeAtom(patom->left);
    if (patom->right)
        FreeAtom(patom->right);
    if (patom->a > XA_LAST_PREDEFINED) {
        /*
         * All strings above XA_LAST_PREDEFINED are strdup'ed, so it's safe to
         * cast here
         */
        free((char *) patom->string);
    }
    free(patom);
}

void
FreeAllAtoms(void)
{
    if (atomRoot == NULL)
        return;
    FreeAtom(atomRoot);
    atomRoot = NULL;
    free(nodeTable);
    nodeTable = NULL;
    lastAtom = None;
}

void
InitAtoms(void)
{
    FreeAllAtoms();
    tableLength = InitialTableSize;
    nodeTable = xallocarray(InitialTableSize, sizeof(NodePtr));
    if (!nodeTable)
        AtomError();
    nodeTable[None] = NULL;
    MakePredeclaredAtoms();
    if (lastAtom != XA_LAST_PREDEFINED)
        AtomError();
}