TinyX/Xext/shm.c

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

Copyright 1989, 1998  The Open Group

Permission to use, copy, modify, distribute, and sell this software and its
documentation for any purpose is hereby granted without fee, provided that
the above copyright notice appear in all copies and that both that
copyright notice and this permission notice appear in supporting
documentation.

The above copyright notice and this permission notice shall be included in
all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
OPEN GROUP BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

Except as contained in this notice, the name of The Open Group shall not be
used in advertising or otherwise to promote the sale, use or other dealings
in this Software without prior written authorization from The Open Group.

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

/* THIS IS NOT AN X CONSORTIUM STANDARD OR AN X PROJECT TEAM SPECIFICATION */

#define SHM

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

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <unistd.h>
#include <sys/stat.h>
#include <X11/X.h>
#include <X11/Xproto.h>
#include "misc.h"
#include "os.h"
#include "dixstruct.h"
#include "resource.h"
#include "scrnintstr.h"
#include "windowstr.h"
#include "pixmapstr.h"
#include "gcstruct.h"
#include "extnsionst.h"
#include "servermd.h"
#define _XSHM_SERVER_
#include <X11/extensions/shmstr.h>
#include <X11/Xfuncproto.h>


#include "extinit.h"

typedef struct _ShmDesc {
    struct _ShmDesc *next;
    int shmid;
    int refcnt;
    char *addr;
    Bool writable;
    unsigned long size;
} ShmDescRec, *ShmDescPtr;

static void miShmPutImage(XSHM_PUT_IMAGE_ARGS);

static void fbShmPutImage(XSHM_PUT_IMAGE_ARGS);

static PixmapPtr fbShmCreatePixmap(XSHM_CREATE_PIXMAP_ARGS);

static int ShmDetachSegment(pointer /* value */ ,
                            XID /* shmseg */
    );

static void ShmResetProc(ExtensionEntry *       /* extEntry */
    );

static void SShmCompletionEvent(xShmCompletionEvent * /* from */ ,
                                xShmCompletionEvent *   /* to */
    );

static Bool ShmDestroyPixmap(PixmapPtr pPixmap);

static DISPATCH_PROC(ProcShmAttach);

static DISPATCH_PROC(ProcShmCreatePixmap);

static DISPATCH_PROC(ProcShmDetach);

static DISPATCH_PROC(ProcShmDispatch);

static DISPATCH_PROC(ProcShmGetImage);

static DISPATCH_PROC(ProcShmPutImage);

static DISPATCH_PROC(ProcShmQueryVersion);

static DISPATCH_PROC(SProcShmAttach);

static DISPATCH_PROC(SProcShmCreatePixmap);

static DISPATCH_PROC(SProcShmDetach);

static DISPATCH_PROC(SProcShmDispatch);

static DISPATCH_PROC(SProcShmGetImage);

static DISPATCH_PROC(SProcShmPutImage);

static DISPATCH_PROC(SProcShmQueryVersion);

static unsigned char ShmReqCode;

_X_EXPORT int ShmCompletionCode;

_X_EXPORT int BadShmSegCode;

_X_EXPORT RESTYPE ShmSegType;

static ShmDescPtr Shmsegs;

static Bool sharedPixmaps;

static int pixmapFormat;

static int shmPixFormat[MAXSCREENS];

static const ShmFuncs * shmFuncs[MAXSCREENS];

static DestroyPixmapProcPtr destroyPixmap[MAXSCREENS];

static int shmPixmapPrivate;
static const ShmFuncs miFuncs = { NULL, miShmPutImage };
static const ShmFuncs fbFuncs = { fbShmCreatePixmap, fbShmPutImage };

#define VERIFY_SHMSEG(shmseg,shmdesc,client) \
{ \
    shmdesc = (ShmDescPtr)LookupIDByType(shmseg, ShmSegType); \
    if (!shmdesc) \
    { \
	client->errorValue = shmseg; \
	return BadShmSegCode; \
    } \
}

#define VERIFY_SHMPTR(shmseg,offset,needwrite,shmdesc,client) \
{ \
    VERIFY_SHMSEG(shmseg, shmdesc, client); \
    if ((offset & 3) || (offset > shmdesc->size)) \
    { \
	client->errorValue = offset; \
	return BadValue; \
    } \
    if (needwrite && !shmdesc->writable) \
	return BadAccess; \
}

#define VERIFY_SHMSIZE(shmdesc,offset,len,client) \
{ \
    if ((offset + len) > shmdesc->size) \
    { \
	return BadAccess; \
    } \
}

#if defined(__FreeBSD__) || defined(__NetBSD__) || defined(__OpenBSD__) || defined(__CYGWIN__)
#include <sys/signal.h>

static Bool badSysCall = FALSE;

static void
SigSysHandler(signo)
int signo;
{
    badSysCall = TRUE;
}

static Bool
CheckForShmSyscall()
{
    void (*oldHandler) ();

    int shmid = -1;

    /* If no SHM support in the kernel, the bad syscall will generate SIGSYS */
    oldHandler = signal(SIGSYS, SigSysHandler);

    badSysCall = FALSE;
    shmid = shmget(IPC_PRIVATE, 4096, IPC_CREAT);

    if (shmid != -1) {
        /* Successful allocation - clean up */
        shmctl(shmid, IPC_RMID, (struct shmid_ds *) NULL);
    }
    else {
        /* Allocation failed */
        badSysCall = TRUE;
    }
    signal(SIGSYS, oldHandler);
    return (!badSysCall);
}

#define MUST_CHECK_FOR_SHM_SYSCALL

#endif

void
ShmExtensionInit(INITARGS)
{
    ExtensionEntry *extEntry;

    int i;

#ifdef MUST_CHECK_FOR_SHM_SYSCALL
    if (!CheckForShmSyscall()) {
        ErrorF("MIT-SHM extension disabled due to lack of kernel support\n");
        return;
    }
#endif

    sharedPixmaps = xFalse;
    pixmapFormat = 0;
    {
        sharedPixmaps = xTrue;
        pixmapFormat = shmPixFormat[0];
        for (i = 0; i < screenInfo.numScreens; i++) {
            if (!shmFuncs[i])
                shmFuncs[i] = &miFuncs;
            if (!shmFuncs[i]->CreatePixmap)
                sharedPixmaps = xFalse;
            if (shmPixFormat[i] && (shmPixFormat[i] != pixmapFormat)) {
                sharedPixmaps = xFalse;
                pixmapFormat = 0;
            }
        }
        if (!pixmapFormat)
            pixmapFormat = ZPixmap;
        if (sharedPixmaps) {
            for (i = 0; i < screenInfo.numScreens; i++) {
                destroyPixmap[i] = screenInfo.screens[i]->DestroyPixmap;
                screenInfo.screens[i]->DestroyPixmap = ShmDestroyPixmap;
            }
            shmPixmapPrivate = AllocatePixmapPrivateIndex();
            for (i = 0; i < screenInfo.numScreens; i++) {
                if (!AllocatePixmapPrivate(screenInfo.screens[i],
                                           shmPixmapPrivate, 0))
                    return;
            }
        }
    }
    ShmSegType = CreateNewResourceType(ShmDetachSegment);
    if (ShmSegType &&
        (extEntry = AddExtension(SHMNAME, ShmNumberEvents, ShmNumberErrors,
                                 ProcShmDispatch, SProcShmDispatch,
                                 ShmResetProc, StandardMinorOpcode))) {
        ShmReqCode = (unsigned char) extEntry->base;
        ShmCompletionCode = extEntry->eventBase;
        BadShmSegCode = extEntry->errorBase;
        EventSwapVector[ShmCompletionCode] = (EventSwapPtr) SShmCompletionEvent;
    }
}

 /*ARGSUSED*/ static void
ShmResetProc(extEntry)
ExtensionEntry *extEntry;
{
    int i;

    for (i = 0; i < MAXSCREENS; i++) {
        shmFuncs[i] = (ShmFuncsPtr) NULL;
        shmPixFormat[i] = 0;
    }
}

void
ShmRegisterFuncs(ScreenPtr pScreen, ShmFuncsPtr funcs)
{
    shmFuncs[pScreen->myNum] = funcs;
}

void
ShmSetPixmapFormat(ScreenPtr pScreen, int format)
{
    shmPixFormat[pScreen->myNum] = format;
}

static Bool
ShmDestroyPixmap(PixmapPtr pPixmap)
{
    ScreenPtr pScreen = pPixmap->drawable.pScreen;

    Bool ret;

    if (pPixmap->refcnt == 1) {
        ShmDescPtr shmdesc;

        shmdesc = (ShmDescPtr) pPixmap->devPrivates[shmPixmapPrivate].ptr;
        if (shmdesc)
            ShmDetachSegment((pointer) shmdesc, pPixmap->drawable.id);
    }

    pScreen->DestroyPixmap = destroyPixmap[pScreen->myNum];
    ret = (*pScreen->DestroyPixmap) (pPixmap);
    destroyPixmap[pScreen->myNum] = pScreen->DestroyPixmap;
    pScreen->DestroyPixmap = ShmDestroyPixmap;
    return ret;
}

void
ShmRegisterFbFuncs(pScreen)
ScreenPtr pScreen;
{
    shmFuncs[pScreen->myNum] = &fbFuncs;
}

static int
ProcShmQueryVersion(client)
ClientPtr client;
{
    xShmQueryVersionReply rep;


    REQUEST_SIZE_MATCH(xShmQueryVersionReq);
    memset(&rep, 0, sizeof(xShmQueryVersionReply));
    rep.type = X_Reply;
    rep.length = 0;
    rep.sequenceNumber = client->sequence;
    rep.sharedPixmaps = sharedPixmaps;
    rep.pixmapFormat = pixmapFormat;
    rep.majorVersion = SHM_MAJOR_VERSION;
    rep.minorVersion = SHM_MINOR_VERSION;
    rep.uid = geteuid();
    rep.gid = getegid();
    if (client->swapped) {
        swaps(&rep.sequenceNumber);
        swapl(&rep.length);
        swaps(&rep.majorVersion);
        swaps(&rep.minorVersion);
        swaps(&rep.uid);
        swaps(&rep.gid);
    }
    WriteToClient(client, sizeof(xShmQueryVersionReply), (char *) &rep);
    return (client->noClientException);
}

/*
 * Simulate the access() system call for a shared memory segement,
 * using the credentials from the client if available
 */
static int
shm_access(ClientPtr client, struct ipc_perm *perm, int readonly)
{
    int uid, gid;

    mode_t mask;

    if (LocalClientCred(client, &uid, &gid) != -1) {

        /* User id 0 always gets access */
        if (uid == 0) {
            return 0;
        }
        /* Check the owner */
        if (perm->uid == uid || perm->cuid == uid) {
            mask = S_IRUSR;
            if (!readonly) {
                mask |= S_IWUSR;
            }
            return (perm->mode & mask) == mask ? 0 : -1;
        }
        /* Check the group */
        if (perm->gid == gid || perm->cgid == gid) {
            mask = S_IRGRP;
            if (!readonly) {
                mask |= S_IWGRP;
            }
            return (perm->mode & mask) == mask ? 0 : -1;
        }
    }
    /* Otherwise, check everyone else */
    mask = S_IROTH;
    if (!readonly) {
        mask |= S_IWOTH;
    }
    return (perm->mode & mask) == mask ? 0 : -1;
}

static int
ProcShmAttach(client)
ClientPtr client;
{
    struct shmid_ds buf;

    ShmDescPtr shmdesc;

    REQUEST(xShmAttachReq);

    REQUEST_SIZE_MATCH(xShmAttachReq);
    LEGAL_NEW_RESOURCE(stuff->shmseg, client);
    if ((stuff->readOnly != xTrue) && (stuff->readOnly != xFalse)) {
        client->errorValue = stuff->readOnly;
        return (BadValue);
    }
    for (shmdesc = Shmsegs;
         shmdesc && (shmdesc->shmid != stuff->shmid); shmdesc = shmdesc->next);
    if (shmdesc) {
        if (!stuff->readOnly && !shmdesc->writable)
            return BadAccess;
        shmdesc->refcnt++;
    }
    else {
        shmdesc = malloc(sizeof(ShmDescRec));
        if (!shmdesc)
            return BadAlloc;
        shmdesc->addr = shmat(stuff->shmid, 0,
                              stuff->readOnly ? SHM_RDONLY : 0);
        if ((shmdesc->addr == ((char *) -1)) ||
            shmctl(stuff->shmid, IPC_STAT, &buf)) {
            free(shmdesc);
            return BadAccess;
        }

        /* The attach was performed with root privs. We must
         * do manual checking of access rights for the credentials
         * of the client */

        if (shm_access(client, &(buf.shm_perm), stuff->readOnly) == -1) {
            shmdt(shmdesc->addr);
            free(shmdesc);
            return BadAccess;
        }

        shmdesc->shmid = stuff->shmid;
        shmdesc->refcnt = 1;
        shmdesc->writable = !stuff->readOnly;
        shmdesc->size = buf.shm_segsz;
        shmdesc->next = Shmsegs;
        Shmsegs = shmdesc;
    }
    if (!AddResource(stuff->shmseg, ShmSegType, (pointer) shmdesc))
        return BadAlloc;
    return (client->noClientException);
}

 /*ARGSUSED*/ static int
ShmDetachSegment(value, shmseg)
pointer value;                  /* must conform to DeleteType */

XID shmseg;
{
    ShmDescPtr shmdesc = (ShmDescPtr) value;

    ShmDescPtr *prev;

    if (--shmdesc->refcnt)
        return TRUE;
    shmdt(shmdesc->addr);
    for (prev = &Shmsegs; *prev != shmdesc; prev = &(*prev)->next);
    *prev = shmdesc->next;
    free(shmdesc);
    return Success;
}

static int
ProcShmDetach(client)
ClientPtr client;
{
    ShmDescPtr shmdesc;

    REQUEST(xShmDetachReq);

    REQUEST_SIZE_MATCH(xShmDetachReq);
    VERIFY_SHMSEG(stuff->shmseg, shmdesc, client);
    FreeResource(stuff->shmseg, RT_NONE);
    return (client->noClientException);
}

static void
miShmPutImage(dst, pGC, depth, format, w, h, sx, sy, sw, sh, dx, dy, data)
DrawablePtr dst;

GCPtr pGC;

int depth, w, h, sx, sy, sw, sh, dx, dy;

unsigned int format;

char *data;
{
    PixmapPtr pmap;

    GCPtr putGC;

    putGC = GetScratchGC(depth, dst->pScreen);
    if (!putGC)
        return;
    pmap = (*dst->pScreen->CreatePixmap) (dst->pScreen, sw, sh, depth);
    if (!pmap) {
        FreeScratchGC(putGC);
        return;
    }
    ValidateGC((DrawablePtr) pmap, putGC);
    (*putGC->ops->PutImage) ((DrawablePtr) pmap, putGC, depth, -sx, -sy, w, h,
                             0, (format == XYPixmap) ? XYPixmap : ZPixmap,
                             data);
    FreeScratchGC(putGC);
    if (format == XYBitmap)
        (void) (*pGC->ops->CopyPlane) ((DrawablePtr) pmap, dst, pGC, 0, 0, sw,
                                       sh, dx, dy, 1L);
    else
        (void) (*pGC->ops->CopyArea) ((DrawablePtr) pmap, dst, pGC, 0, 0, sw,
                                      sh, dx, dy);
    (*pmap->drawable.pScreen->DestroyPixmap) (pmap);
}

static void
fbShmPutImage(dst, pGC, depth, format, w, h, sx, sy, sw, sh, dx, dy, data)
DrawablePtr dst;

GCPtr pGC;

int depth, w, h, sx, sy, sw, sh, dx, dy;

unsigned int format;

char *data;
{
    if ((format == ZPixmap) || (depth == 1)) {
        PixmapPtr pPixmap;

        pPixmap = GetScratchPixmapHeader(dst->pScreen, w, h, depth,
                                         BitsPerPixel(depth), PixmapBytePad(w,
                                                                            depth),
                                         (pointer) data);
        if (!pPixmap)
            return;
        if (format == XYBitmap)
            (void) (*pGC->ops->CopyPlane) ((DrawablePtr) pPixmap, dst, pGC,
                                           sx, sy, sw, sh, dx, dy, 1L);
        else
            (void) (*pGC->ops->CopyArea) ((DrawablePtr) pPixmap, dst, pGC,
                                          sx, sy, sw, sh, dx, dy);
        FreeScratchPixmapHeader(pPixmap);
    }
    else
        miShmPutImage(dst, pGC, depth, format, w, h, sx, sy, sw, sh, dx, dy,
                      data);
}


static int
ProcShmPutImage(client)
ClientPtr client;
{
    GCPtr pGC;

    DrawablePtr pDraw;

    long length;

    ShmDescPtr shmdesc;

    REQUEST(xShmPutImageReq);

    REQUEST_SIZE_MATCH(xShmPutImageReq);
    VALIDATE_DRAWABLE_AND_GC(stuff->drawable, pDraw, pGC, client);
    VERIFY_SHMPTR(stuff->shmseg, stuff->offset, FALSE, shmdesc, client);
    if ((stuff->sendEvent != xTrue) && (stuff->sendEvent != xFalse))
        return BadValue;
    if (stuff->format == XYBitmap) {
        if (stuff->depth != 1)
            return BadMatch;
        length = PixmapBytePad(stuff->totalWidth, 1);
    }
    else if (stuff->format == XYPixmap) {
        if (pDraw->depth != stuff->depth)
            return BadMatch;
        length = PixmapBytePad(stuff->totalWidth, 1);
        length *= stuff->depth;
    }
    else if (stuff->format == ZPixmap) {
        if (pDraw->depth != stuff->depth)
            return BadMatch;
        length = PixmapBytePad(stuff->totalWidth, stuff->depth);
    }
    else {
        client->errorValue = stuff->format;
        return BadValue;
    }

    VERIFY_SHMSIZE(shmdesc, stuff->offset, length * stuff->totalHeight, client);
    if (stuff->srcX > stuff->totalWidth) {
        client->errorValue = stuff->srcX;
        return BadValue;
    }
    if (stuff->srcY > stuff->totalHeight) {
        client->errorValue = stuff->srcY;
        return BadValue;
    }
    if ((stuff->srcX + stuff->srcWidth) > stuff->totalWidth) {
        client->errorValue = stuff->srcWidth;
        return BadValue;
    }
    if ((stuff->srcY + stuff->srcHeight) > stuff->totalHeight) {
        client->errorValue = stuff->srcHeight;
        return BadValue;
    }

    if ((((stuff->format == ZPixmap) && (stuff->srcX == 0)) ||
         ((stuff->format != ZPixmap) &&
          (stuff->srcX < screenInfo.bitmapScanlinePad) &&
          ((stuff->format == XYBitmap) ||
           ((stuff->srcY == 0) &&
            (stuff->srcHeight == stuff->totalHeight))))) &&
        ((stuff->srcX + stuff->srcWidth) == stuff->totalWidth))
        (*pGC->ops->PutImage) (pDraw, pGC, stuff->depth,
                               stuff->dstX, stuff->dstY,
                               stuff->totalWidth, stuff->srcHeight,
                               stuff->srcX, stuff->format,
                               shmdesc->addr + stuff->offset +
                               (stuff->srcY * length));
    else
        (*shmFuncs[pDraw->pScreen->myNum]->PutImage) (pDraw, pGC, stuff->depth,
                                                      stuff->format,
                                                      stuff->totalWidth,
                                                      stuff->totalHeight,
                                                      stuff->srcX, stuff->srcY,
                                                      stuff->srcWidth,
                                                      stuff->srcHeight,
                                                      stuff->dstX, stuff->dstY,
                                                      shmdesc->addr +
                                                      stuff->offset);

    if (stuff->sendEvent) {
        xShmCompletionEvent ev;

        ev.type = ShmCompletionCode;
        ev.drawable = stuff->drawable;
        ev.minorEvent = X_ShmPutImage;
        ev.majorEvent = ShmReqCode;
        ev.shmseg = stuff->shmseg;
        ev.offset = stuff->offset;
        WriteEventsToClient(client, 1, (xEvent *) &ev);
    }

    return (client->noClientException);
}

static int
ProcShmGetImage(client)
ClientPtr client;
{
    DrawablePtr pDraw;

    long lenPer = 0, length;

    Mask plane = 0;

    xShmGetImageReply xgi;

    ShmDescPtr shmdesc;

    REQUEST(xShmGetImageReq);

    REQUEST_SIZE_MATCH(xShmGetImageReq);
    if ((stuff->format != XYPixmap) && (stuff->format != ZPixmap)) {
        client->errorValue = stuff->format;
        return (BadValue);
    }
    VERIFY_DRAWABLE(pDraw, stuff->drawable, client);
    VERIFY_SHMPTR(stuff->shmseg, stuff->offset, TRUE, shmdesc, client);
    if (pDraw->type == DRAWABLE_WINDOW) {
        if (                    /* check for being viewable */
               !((WindowPtr) pDraw)->realized ||
               /* check for being on screen */
               pDraw->x + stuff->x < 0 ||
               pDraw->x + stuff->x + (int) stuff->width > pDraw->pScreen->width
               || pDraw->y + stuff->y < 0 ||
               pDraw->y + stuff->y + (int) stuff->height >
               pDraw->pScreen->height ||
               /* check for being inside of border */
               stuff->x < -wBorderWidth((WindowPtr) pDraw) ||
               stuff->x + (int) stuff->width >
               wBorderWidth((WindowPtr) pDraw) + (int) pDraw->width ||
               stuff->y < -wBorderWidth((WindowPtr) pDraw) ||
               stuff->y + (int) stuff->height >
               wBorderWidth((WindowPtr) pDraw) + (int) pDraw->height)
            return (BadMatch);
        xgi.visual = wVisual(((WindowPtr) pDraw));
    }
    else {
        if (stuff->x < 0 ||
            stuff->x + (int) stuff->width > pDraw->width ||
            stuff->y < 0 || stuff->y + (int) stuff->height > pDraw->height)
            return (BadMatch);
        xgi.visual = None;
    }
    xgi.type = X_Reply;
    xgi.length = 0;
    xgi.sequenceNumber = client->sequence;
    xgi.depth = pDraw->depth;
    if (stuff->format == ZPixmap) {
        length = PixmapBytePad(stuff->width, pDraw->depth) * stuff->height;
    }
    else {
        lenPer = PixmapBytePad(stuff->width, 1) * stuff->height;
        plane = ((Mask) 1) << (pDraw->depth - 1);
        /* only planes asked for */
        length = lenPer * Ones(stuff->planeMask & (plane | (plane - 1)));
    }

    VERIFY_SHMSIZE(shmdesc, stuff->offset, length, client);
    xgi.size = length;

    if (length == 0) {
        /* nothing to do */
    }
    else if (stuff->format == ZPixmap) {
        (*pDraw->pScreen->GetImage) (pDraw, stuff->x, stuff->y,
                                     stuff->width, stuff->height,
                                     stuff->format, stuff->planeMask,
                                     shmdesc->addr + stuff->offset);
    }
    else {

        length = stuff->offset;
        for (; plane; plane >>= 1) {
            if (stuff->planeMask & plane) {
                (*pDraw->pScreen->GetImage) (pDraw,
                                             stuff->x, stuff->y,
                                             stuff->width, stuff->height,
                                             stuff->format, plane,
                                             shmdesc->addr + length);
                length += lenPer;
            }
        }
    }

    if (client->swapped) {
        swaps(&xgi.sequenceNumber);
        swapl(&xgi.length);
        swapl(&xgi.visual);
        swapl(&xgi.size);
    }
    WriteToClient(client, sizeof(xShmGetImageReply), (char *) &xgi);

    return (client->noClientException);
}

static PixmapPtr
fbShmCreatePixmap(pScreen, width, height, depth, addr)
ScreenPtr pScreen;

int width;

int height;

int depth;

char *addr;
{
    PixmapPtr pPixmap;

    pPixmap = (*pScreen->CreatePixmap) (pScreen, 0, 0, pScreen->rootDepth);
    if (!pPixmap)
        return NullPixmap;

    if (!(*pScreen->ModifyPixmapHeader) (pPixmap, width, height, depth,
                                         BitsPerPixel(depth),
                                         PixmapBytePad(width, depth),
                                         (pointer) addr)) {
        (*pScreen->DestroyPixmap) (pPixmap);
        return NullPixmap;
    }
    return pPixmap;
}

static int
ProcShmCreatePixmap(client)
ClientPtr client;
{
    PixmapPtr pMap;

    DrawablePtr pDraw;

    DepthPtr pDepth;

    int i;

    ShmDescPtr shmdesc;

    REQUEST(xShmCreatePixmapReq);

    REQUEST_SIZE_MATCH(xShmCreatePixmapReq);
    client->errorValue = stuff->pid;
    if (!sharedPixmaps)
        return BadImplementation;
    LEGAL_NEW_RESOURCE(stuff->pid, client);
    VERIFY_GEOMETRABLE(pDraw, stuff->drawable, client);
    VERIFY_SHMPTR(stuff->shmseg, stuff->offset, TRUE, shmdesc, client);
    if (!stuff->width || !stuff->height) {
        client->errorValue = 0;
        return BadValue;
    }
    if (stuff->depth != 1) {
        pDepth = pDraw->pScreen->allowedDepths;
        for (i = 0; i < pDraw->pScreen->numDepths; i++, pDepth++)
            if (pDepth->depth == stuff->depth)
                goto CreatePmap;
        client->errorValue = stuff->depth;
        return BadValue;
    }
 CreatePmap:
    VERIFY_SHMSIZE(shmdesc, stuff->offset,
                   PixmapBytePad(stuff->width, stuff->depth) * stuff->height,
                   client);
    pMap =
        (*shmFuncs[pDraw->pScreen->myNum]->CreatePixmap) (pDraw->pScreen,
                                                          stuff->width,
                                                          stuff->height,
                                                          stuff->depth,
                                                          shmdesc->addr +
                                                          stuff->offset);
    if (pMap) {
        pMap->devPrivates[shmPixmapPrivate].ptr = (pointer) shmdesc;
        shmdesc->refcnt++;
        pMap->drawable.serialNumber = NEXT_SERIAL_NUMBER;
        pMap->drawable.id = stuff->pid;
        if (AddResource(stuff->pid, RT_PIXMAP, (pointer) pMap)) {
            return (client->noClientException);
        }
    }
    return (BadAlloc);
}

static int
ProcShmDispatch(client)
ClientPtr client;
{
    REQUEST(xReq);
    switch (stuff->data) {
    case X_ShmQueryVersion:
        return ProcShmQueryVersion(client);
    case X_ShmAttach:
        return ProcShmAttach(client);
    case X_ShmDetach:
        return ProcShmDetach(client);
    case X_ShmPutImage:
        return ProcShmPutImage(client);
    case X_ShmGetImage:
        return ProcShmGetImage(client);
    case X_ShmCreatePixmap:
        return ProcShmCreatePixmap(client);
    default:
        return BadRequest;
    }
}

static void
SShmCompletionEvent(from, to)
xShmCompletionEvent *from, *to;
{
    to->type = from->type;
    cpswaps(from->sequenceNumber, to->sequenceNumber);
    cpswapl(from->drawable, to->drawable);
    cpswaps(from->minorEvent, to->minorEvent);
    to->majorEvent = from->majorEvent;
    cpswapl(from->shmseg, to->shmseg);
    cpswapl(from->offset, to->offset);
}

static int
SProcShmQueryVersion(client)
ClientPtr client;
{

    REQUEST(xShmQueryVersionReq);

    swaps(&stuff->length);
    return ProcShmQueryVersion(client);
}

static int
SProcShmAttach(client)
ClientPtr client;
{

    REQUEST(xShmAttachReq);
    swaps(&stuff->length);
    REQUEST_SIZE_MATCH(xShmAttachReq);
    swapl(&stuff->shmseg);
    swapl(&stuff->shmid);
    return ProcShmAttach(client);
}

static int
SProcShmDetach(client)
ClientPtr client;
{

    REQUEST(xShmDetachReq);
    swaps(&stuff->length);
    REQUEST_SIZE_MATCH(xShmDetachReq);
    swapl(&stuff->shmseg);
    return ProcShmDetach(client);
}

static int
SProcShmPutImage(client)
ClientPtr client;
{

    REQUEST(xShmPutImageReq);
    swaps(&stuff->length);
    REQUEST_SIZE_MATCH(xShmPutImageReq);
    swapl(&stuff->drawable);
    swapl(&stuff->gc);
    swaps(&stuff->totalWidth);
    swaps(&stuff->totalHeight);
    swaps(&stuff->srcX);
    swaps(&stuff->srcY);
    swaps(&stuff->srcWidth);
    swaps(&stuff->srcHeight);
    swaps(&stuff->dstX);
    swaps(&stuff->dstY);
    swapl(&stuff->shmseg);
    swapl(&stuff->offset);
    return ProcShmPutImage(client);
}

static int
SProcShmGetImage(client)
ClientPtr client;
{

    REQUEST(xShmGetImageReq);
    swaps(&stuff->length);
    REQUEST_SIZE_MATCH(xShmGetImageReq);
    swapl(&stuff->drawable);
    swaps(&stuff->x);
    swaps(&stuff->y);
    swaps(&stuff->width);
    swaps(&stuff->height);
    swapl(&stuff->planeMask);
    swapl(&stuff->shmseg);
    swapl(&stuff->offset);
    return ProcShmGetImage(client);
}

static int
SProcShmCreatePixmap(client)
ClientPtr client;
{

    REQUEST(xShmCreatePixmapReq);
    swaps(&stuff->length);
    REQUEST_SIZE_MATCH(xShmCreatePixmapReq);
    swapl(&stuff->pid);
    swapl(&stuff->drawable);
    swaps(&stuff->width);
    swaps(&stuff->height);
    swapl(&stuff->shmseg);
    swapl(&stuff->offset);
    return ProcShmCreatePixmap(client);
}

static int
SProcShmDispatch(client)
ClientPtr client;
{
    REQUEST(xReq);
    switch (stuff->data) {
    case X_ShmQueryVersion:
        return SProcShmQueryVersion(client);
    case X_ShmAttach:
        return SProcShmAttach(client);
    case X_ShmDetach:
        return SProcShmDetach(client);
    case X_ShmPutImage:
        return SProcShmPutImage(client);
    case X_ShmGetImage:
        return SProcShmGetImage(client);
    case X_ShmCreatePixmap:
        return SProcShmCreatePixmap(client);
    default:
        return BadRequest;
    }
}