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

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

Copyright 1987, 1998  The Open Group

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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
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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/Xproto.h>
#include "misc.h"
#include "dixstruct.h"
#include "extnsionst.h"
#include "gcstruct.h"
#include "scrnintstr.h"
#include "dispatch.h"
#include "privates.h"
#include "registry.h"
#include "xace.h"

#define LAST_ERROR 255

static ExtensionEntry **extensions = (ExtensionEntry **) NULL;

int lastEvent = EXTENSION_EVENT_BASE;
static int lastError = FirstExtensionError;
static unsigned int NumExtensions = 0;

ExtensionEntry *
AddExtension(const char *name, int NumEvents, int NumErrors,
             int (*MainProc) (ClientPtr c1),
             int (*SwappedMainProc) (ClientPtr c2),
             void (*CloseDownProc) (ExtensionEntry * e),
             unsigned short (*MinorOpcodeProc) (ClientPtr c3))
{
    int i;
    ExtensionEntry *ext, **newexts;

    if (!MainProc || !SwappedMainProc || !MinorOpcodeProc)
        return ((ExtensionEntry *) NULL);
    if ((lastEvent + NumEvents > MAXEVENTS) ||
        (unsigned) (lastError + NumErrors > LAST_ERROR)) {
        LogMessage(X_ERROR, "Not enabling extension %s: maximum number of "
                   "events or errors exceeded.\n", name);
        return ((ExtensionEntry *) NULL);
    }

    ext = calloc(sizeof(ExtensionEntry), 1);
    if (!ext)
        return NULL;
    if (!dixAllocatePrivates(&ext->devPrivates, PRIVATE_EXTENSION)) {
        free(ext);
        return NULL;
    }
    ext->name = strdup(name);
    if (!ext->name) {
        dixFreePrivates(ext->devPrivates, PRIVATE_EXTENSION);
        free(ext);
        return ((ExtensionEntry *) NULL);
    }
    i = NumExtensions;
    newexts = reallocarray(extensions, i + 1, sizeof(ExtensionEntry *));
    if (!newexts) {
        free((void *) ext->name);
        dixFreePrivates(ext->devPrivates, PRIVATE_EXTENSION);
        free(ext);
        return ((ExtensionEntry *) NULL);
    }
    NumExtensions++;
    extensions = newexts;
    extensions[i] = ext;
    ext->index = i;
    ext->base = i + EXTENSION_BASE;
    ext->CloseDown = CloseDownProc;
    ext->MinorOpcode = MinorOpcodeProc;
    ProcVector[i + EXTENSION_BASE] = MainProc;
    SwappedProcVector[i + EXTENSION_BASE] = SwappedMainProc;
    if (NumEvents) {
        ext->eventBase = lastEvent;
        ext->eventLast = lastEvent + NumEvents;
        lastEvent += NumEvents;
    }
    else {
        ext->eventBase = 0;
        ext->eventLast = 0;
    }
    if (NumErrors) {
        ext->errorBase = lastError;
        ext->errorLast = lastError + NumErrors;
        lastError += NumErrors;
    }
    else {
        ext->errorBase = 0;
        ext->errorLast = 0;
    }

#ifdef X_REGISTRY_REQUEST
    RegisterExtensionNames(ext);
#endif
    return ext;
}

static int
FindExtension(const char *extname, int len)
{
    int i;

    for (i = 0; i < NumExtensions; i++) {
        if ((strlen(extensions[i]->name) == len) &&
            !strncmp(extname, extensions[i]->name, len))
            break;
    }
    return ((i == NumExtensions) ? -1 : i);
}

/*
 * CheckExtension returns the extensions[] entry for the requested
 * extension name.  Maybe this could just return a Bool instead?
 */
ExtensionEntry *
CheckExtension(const char *extname)
{
    int n;

    n = FindExtension(extname, strlen(extname));
    if (n != -1)
        return extensions[n];
    else
        return NULL;
}

/*
 * Added as part of Xace.
 */
ExtensionEntry *
GetExtensionEntry(int major)
{
    if (major < EXTENSION_BASE)
        return NULL;
    major -= EXTENSION_BASE;
    if (major >= NumExtensions)
        return NULL;
    return extensions[major];
}

unsigned short
StandardMinorOpcode(ClientPtr client)
{
    return ((xReq *) client->requestBuffer)->data;
}

void
CloseDownExtensions(void)
{
    int i;

    for (i = NumExtensions - 1; i >= 0; i--) {
        if (extensions[i]->CloseDown)
            extensions[i]->CloseDown(extensions[i]);
        NumExtensions = i;
        free((void *) extensions[i]->name);
        dixFreePrivates(extensions[i]->devPrivates, PRIVATE_EXTENSION);
        free(extensions[i]);
    }
    free(extensions);
    extensions = (ExtensionEntry **) NULL;
    lastEvent = EXTENSION_EVENT_BASE;
    lastError = FirstExtensionError;
}

static Bool
ExtensionAvailable(ClientPtr client, ExtensionEntry *ext)
{
    if (XaceHook(XACE_EXT_ACCESS, client, ext) != Success)
        return FALSE;
    if (!ext->base)
        return FALSE;
    return TRUE;
}

int
ProcQueryExtension(ClientPtr client)
{
    xQueryExtensionReply reply;
    int i;

    REQUEST(xQueryExtensionReq);

    REQUEST_FIXED_SIZE(xQueryExtensionReq, stuff->nbytes);

    reply = (xQueryExtensionReply) {
        .type = X_Reply,
        .sequenceNumber = client->sequence,
        .length = 0,
        .major_opcode = 0
    };

    if (!NumExtensions)
        reply.present = xFalse;
    else {
        i = FindExtension((char *) &stuff[1], stuff->nbytes);
        if (i < 0 || !ExtensionAvailable(client, extensions[i]))
            reply.present = xFalse;
        else {
            reply.present = xTrue;
            reply.major_opcode = extensions[i]->base;
            reply.first_event = extensions[i]->eventBase;
            reply.first_error = extensions[i]->errorBase;
        }
    }
    WriteReplyToClient(client, sizeof(xQueryExtensionReply), &reply);
    return Success;
}

int
ProcListExtensions(ClientPtr client)
{
    xListExtensionsReply reply;
    char *bufptr, *buffer;
    int total_length = 0;

    REQUEST_SIZE_MATCH(xReq);

    reply = (xListExtensionsReply) {
        .type = X_Reply,
        .nExtensions = 0,
        .sequenceNumber = client->sequence,
        .length = 0
    };
    buffer = NULL;

    if (NumExtensions) {
        int i;

        for (i = 0; i < NumExtensions; i++) {
            /* call callbacks to find out whether to show extension */
            if (!ExtensionAvailable(client, extensions[i]))
                continue;

            total_length += strlen(extensions[i]->name) + 1;
            reply.nExtensions += 1;
        }
        reply.length = bytes_to_int32(total_length);
        buffer = bufptr = malloc(total_length);
        if (!buffer)
            return BadAlloc;
        for (i = 0; i < NumExtensions; i++) {
            int len;

            if (!ExtensionAvailable(client, extensions[i]))
                continue;

            *bufptr++ = len = strlen(extensions[i]->name);
            memmove(bufptr, extensions[i]->name, len);
            bufptr += len;
        }
    }
    WriteReplyToClient(client, sizeof(xListExtensionsReply), &reply);
    if (reply.length)
        WriteToClient(client, total_length, buffer);

    free(buffer);
    return Success;
}