From 3f48fe3c668a0fc420db97b3d116b5b007909876 Mon Sep 17 00:00:00 2001

From: Olivier Fourdan <ofourdan@redhat.com>

Date: Tue, 7 Jul 2015 18:19:50 +0200

Subject: [PATCH] configurable maximum number of clients

Make the maximum number of clients user configurable, either from the command

line or from xorg.conf

This patch works by using the MAXCLIENTS (raised to 512) as the maximum

allowed number of clients, but allowing the actual limit to be set by the

user to a lower value (keeping the default of 256).

There is a limit size of 29 bits to be used to store both the client ID and

the X resources ID, so by reducing the number of clients allowed to connect to

the X server, the user can increase the number of X resources per client or

vice-versa.

Parts of this patch are based on a similar patch from Adam Jackson

<ajax@redhat.com>

This now requires at least xproto 7.0.28

Signed-off-by: Adam Jackson <ajax@redhat.com>

Signed-off-by: Olivier Fourdan <ofourdan@redhat.com>

Reviewed-by: Adam Jackson <ajax@redhat.com>

Signed-off-by: Keith Packard <keithp@keithp.com>

---

 dix/colormap.c                 |   28 ++++++++++++++--------------

 dix/dispatch.c                 |    4 ++--

 dix/main.c                     |    2 +-

 dix/resource.c                 |   33 ++++++++++++++++++++++++++++-----

 hw/dmx/glxProxy/glxext.c       |    2 +-

 hw/xfree86/common/xf86Config.c |   16 ++++++++++++++++

 hw/xfree86/man/xorg.conf.man   |    4 ++++

 include/misc.h                 |    3 ++-

 include/opaque.h               |    1 +

 include/resource.h             |   15 ++-------------

 man/Xserver.man                |    5 +++++

 os/connection.c                |    6 +++---

 os/osdep.h                     |    8 ++++----

 os/osinit.c                    |    3 +++

 os/utils.c                     |   14 ++++++++++++++

 15 files changed, 100 insertions(+), 44 deletions(-)

diff --git a/dix/colormap.c b/dix/colormap.c

index 4d408d5..ac1a615 100644

--- a/dix/colormap.c

+++ b/dix/colormap.c

@@ -249,7 +249,7 @@ CreateColormap(Colormap mid, ScreenPtr pScreen, VisualPtr pVisual,

     size = pVisual->ColormapEntries;

     sizebytes = (size * sizeof(Entry)) +

-        (MAXCLIENTS * sizeof(Pixel *)) + (MAXCLIENTS * sizeof(int));

+        (LimitClients * sizeof(Pixel *)) + (LimitClients * sizeof(int));

     if ((class | DynamicClass) == DirectColor)

         sizebytes *= 3;

     sizebytes += sizeof(ColormapRec);

@@ -274,7 +274,7 @@ CreateColormap(Colormap mid, ScreenPtr pScreen, VisualPtr pVisual,

     sizebytes = size * sizeof(Entry);

     pmap->clientPixelsRed = (Pixel **) ((char *) pmap->red + sizebytes);

     pmap->numPixelsRed = (int *) ((char *) pmap->clientPixelsRed +

-                                  (MAXCLIENTS * sizeof(Pixel *)));

+                                  (LimitClients * sizeof(Pixel *)));

     pmap->mid = mid;

     pmap->flags = 0;            /* start out with all flags clear */

     if (mid == pScreen->defColormap)

@@ -286,8 +286,8 @@ CreateColormap(Colormap mid, ScreenPtr pScreen, VisualPtr pVisual,

         size = NUMRED(pVisual);

     pmap->freeRed = size;

     memset((char *) pmap->red, 0, (int) sizebytes);

-    memset((char *) pmap->numPixelsRed, 0, MAXCLIENTS * sizeof(int));

-    for (pptr = &pmap->clientPixelsRed[MAXCLIENTS];

+    memset((char *) pmap->numPixelsRed, 0, LimitClients * sizeof(int));

+    for (pptr = &pmap->clientPixelsRed[LimitClients];

          --pptr >= pmap->clientPixelsRed;)

         *pptr = (Pixel *) NULL;

     if (alloc == AllocAll) {

@@ -310,26 +310,26 @@ CreateColormap(Colormap mid, ScreenPtr pScreen, VisualPtr pVisual,

     if ((class | DynamicClass) == DirectColor) {

         pmap->freeGreen = NUMGREEN(pVisual);

         pmap->green = (EntryPtr) ((char *) pmap->numPixelsRed +

-                                  (MAXCLIENTS * sizeof(int)));

+                                  (LimitClients * sizeof(int)));

         pmap->clientPixelsGreen = (Pixel **) ((char *) pmap->green + sizebytes);

         pmap->numPixelsGreen = (int *) ((char *) pmap->clientPixelsGreen +

-                                        (MAXCLIENTS * sizeof(Pixel *)));

+                                        (LimitClients * sizeof(Pixel *)));

         pmap->freeBlue = NUMBLUE(pVisual);

         pmap->blue = (EntryPtr) ((char *) pmap->numPixelsGreen +

-                                 (MAXCLIENTS * sizeof(int)));

+                                 (LimitClients * sizeof(int)));

         pmap->clientPixelsBlue = (Pixel **) ((char *) pmap->blue + sizebytes);

         pmap->numPixelsBlue = (int *) ((char *) pmap->clientPixelsBlue +

-                                       (MAXCLIENTS * sizeof(Pixel *)));

+                                       (LimitClients * sizeof(Pixel *)));

         memset((char *) pmap->green, 0, (int) sizebytes);

         memset((char *) pmap->blue, 0, (int) sizebytes);

         memmove((char *) pmap->clientPixelsGreen,

-                (char *) pmap->clientPixelsRed, MAXCLIENTS * sizeof(Pixel *));

+                (char *) pmap->clientPixelsRed, LimitClients * sizeof(Pixel *));

         memmove((char *) pmap->clientPixelsBlue,

-                (char *) pmap->clientPixelsRed, MAXCLIENTS * sizeof(Pixel *));

-        memset((char *) pmap->numPixelsGreen, 0, MAXCLIENTS * sizeof(int));

-        memset((char *) pmap->numPixelsBlue, 0, MAXCLIENTS * sizeof(int));

+                (char *) pmap->clientPixelsRed, LimitClients * sizeof(Pixel *));

+        memset((char *) pmap->numPixelsGreen, 0, LimitClients * sizeof(int));

+        memset((char *) pmap->numPixelsBlue, 0, LimitClients * sizeof(int));

         /* If every cell is allocated, mark its refcnt */

         if (alloc == AllocAll) {

@@ -413,7 +413,7 @@ FreeColormap(void *value, XID mid)

     (*pmap->pScreen->DestroyColormap) (pmap);

     if (pmap->clientPixelsRed) {

-        for (i = 0; i < MAXCLIENTS; i++)

+        for (i = 0; i < LimitClients; i++)

             free(pmap->clientPixelsRed[i]);

     }

@@ -431,7 +431,7 @@ FreeColormap(void *value, XID mid)

         }

     }

     if ((pmap->class | DynamicClass) == DirectColor) {

-        for (i = 0; i < MAXCLIENTS; i++) {

+        for (i = 0; i < LimitClients; i++) {

             free(pmap->clientPixelsGreen[i]);

             free(pmap->clientPixelsBlue[i]);

         }

diff --git a/dix/dispatch.c b/dix/dispatch.c

index 17fa75e..bb4a110 100644

--- a/dix/dispatch.c

+++ b/dix/dispatch.c

@@ -3483,7 +3483,7 @@ NextAvailableClient(void *ospriv)

     xReq data;

     i = nextFreeClientID;

-    if (i == MAXCLIENTS)

+    if (i == LimitClients)

         return (ClientPtr) NULL;

     clients[i] = client =

         dixAllocateObjectWithPrivates(ClientRec, PRIVATE_CLIENT);

@@ -3503,7 +3503,7 @@ NextAvailableClient(void *ospriv)

     }

     if (i == currentMaxClients)

         currentMaxClients++;

-    while ((nextFreeClientID < MAXCLIENTS) && clients[nextFreeClientID])

+    while ((nextFreeClientID < LimitClients) && clients[nextFreeClientID])

         nextFreeClientID++;

     /* Enable client ID tracking. This must be done before

diff --git a/dix/main.c b/dix/main.c

index 7c6ac94..287a335 100644

--- a/dix/main.c

+++ b/dix/main.c

@@ -163,7 +163,7 @@ dix_main(int argc, char *argv[], char *envp[])

         OsInit();

         if (serverGeneration == 1) {

             CreateWellKnownSockets();

-            for (i = 1; i < MAXCLIENTS; i++)

+            for (i = 1; i < LimitClients; i++)

                 clients[i] = NullClient;

             serverClient = calloc(sizeof(ClientRec), 1);

             if (!serverClient)

diff --git a/dix/resource.c b/dix/resource.c

index 964f0b3..b33d959 100644

--- a/dix/resource.c

+++ b/dix/resource.c

@@ -600,6 +600,29 @@ CreateNewResourceClass(void)

 static ClientResourceRec clientTable[MAXCLIENTS];

+static unsigned int

+ilog2(int val)

+{

+    int bits;

+

+    if (val <= 0)

+	return 0;

+    for (bits = 0; val != 0; bits++)

+	val >>= 1;

+    return bits - 1;

+}

+

+/*****************

+ * ResourceClientBits

+ *    Returns the client bit offset in the client + resources ID field

+ *****************/

+

+unsigned int

+ResourceClientBits(void)

+{

+    return (ilog2(LimitClients));

+}

+

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

  * InitClientResources

  *    When a new client is created, call this to allocate space

@@ -883,7 +906,7 @@ FreeResource(XID id, RESTYPE skipDeleteFuncType)

     int *eltptr;

     int elements;

-    if (((cid = CLIENT_ID(id)) < MAXCLIENTS) && clientTable[cid].buckets) {

+    if (((cid = CLIENT_ID(id)) < LimitClients) && clientTable[cid].buckets) {

         head = &clientTable[cid].resources[HashResourceID(id, clientTable[cid].hashsize)];

         eltptr = &clientTable[cid].elements;

@@ -917,7 +940,7 @@ FreeResourceByType(XID id, RESTYPE type, Bool skipFree)

     ResourcePtr res;

     ResourcePtr *prev, *head;

-    if (((cid = CLIENT_ID(id)) < MAXCLIENTS) && clientTable[cid].buckets) {

+    if (((cid = CLIENT_ID(id)) < LimitClients) && clientTable[cid].buckets) {

         head = &clientTable[cid].resources[HashResourceID(id, clientTable[cid].hashsize)];

         prev = head;

@@ -952,7 +975,7 @@ ChangeResourceValue(XID id, RESTYPE rtype, void *value)

     int cid;

     ResourcePtr res;

-    if (((cid = CLIENT_ID(id)) < MAXCLIENTS) && clientTable[cid].buckets) {

+    if (((cid = CLIENT_ID(id)) < LimitClients) && clientTable[cid].buckets) {

         res = clientTable[cid].resources[HashResourceID(id, clientTable[cid].hashsize)];

         for (; res; res = res->next)

@@ -1190,7 +1213,7 @@ dixLookupResourceByType(void **result, XID id, RESTYPE rtype,

     if ((rtype & TypeMask) > lastResourceType)

         return BadImplementation;

-    if ((cid < MAXCLIENTS) && clientTable[cid].buckets) {

+    if ((cid < LimitClients) && clientTable[cid].buckets) {

         res = clientTable[cid].resources[HashResourceID(id, clientTable[cid].hashsize)];

         for (; res; res = res->next)

@@ -1223,7 +1246,7 @@ dixLookupResourceByClass(void **result, XID id, RESTYPE rclass,

     *result = NULL;

-    if ((cid < MAXCLIENTS) && clientTable[cid].buckets) {

+    if ((cid < LimitClients) && clientTable[cid].buckets) {

         res = clientTable[cid].resources[HashResourceID(id, clientTable[cid].hashsize)];

         for (; res; res = res->next)

diff --git a/hw/dmx/glxProxy/glxext.c b/hw/dmx/glxProxy/glxext.c

index 3c5a14b..c858272 100644

--- a/hw/dmx/glxProxy/glxext.c

+++ b/hw/dmx/glxProxy/glxext.c

@@ -347,7 +347,7 @@ GlxExtensionInit(void)

     /*

      ** Initialize table of client state.  There is never a client 0.

      */

-    for (i = 1; i <= MAXCLIENTS; i++) {

+    for (i = 1; i <= LimitClients; i++) {

         __glXClients[i] = 0;

     }

diff --git a/hw/xfree86/common/xf86Config.c b/hw/xfree86/common/xf86Config.c

index d42572f..5f7d13b 100644

--- a/hw/xfree86/common/xf86Config.c

+++ b/hw/xfree86/common/xf86Config.c

@@ -697,6 +697,7 @@ typedef enum {

     FLAG_DRI2,

     FLAG_USE_SIGIO,

     FLAG_AUTO_ADD_GPU,

+    FLAG_MAX_CLIENTS,

 } FlagValues;

 /**

@@ -756,6 +757,8 @@ static OptionInfoRec FlagOptions[] = {

      {0}, FALSE},

     {FLAG_AUTO_ADD_GPU, "AutoAddGPU", OPTV_BOOLEAN,

      {0}, FALSE},

+    {FLAG_MAX_CLIENTS, "MaxClients", OPTV_INTEGER,

+     {0}, FALSE },

     {-1, NULL, OPTV_NONE,

      {0}, FALSE},

 };

@@ -1046,6 +1049,19 @@ configServerFlags(XF86ConfFlagsPtr flagsconf, XF86OptionPtr layoutopts)

         xf86Info.dri2From = X_CONFIG;

     }

 #endif

+

+    from = X_DEFAULT;

+    if (LimitClients != LIMITCLIENTS)

+	from = X_CMDLINE;

+    i = -1;

+    if (xf86GetOptValInteger(FlagOptions, FLAG_MAX_CLIENTS, &i)) {

+	if (i != 64 && i != 128 && i != 256 && i != 512)

+		ErrorF("MaxClients must be one of 64, 128, 256 or 512\n");

+	from = X_CONFIG;

+	LimitClients = i;

+    }

+    xf86Msg(from, "Max clients allowed: %i, resource mask: 0x%x\n",

+	    LimitClients, RESOURCE_ID_MASK);

 }

 Bool

diff --git a/hw/xfree86/man/xorg.conf.man b/hw/xfree86/man/xorg.conf.man

index d26c3cc..9157fc9 100644

--- a/hw/xfree86/man/xorg.conf.man

+++ b/hw/xfree86/man/xorg.conf.man

@@ -621,6 +621,10 @@ It is only enabled for screens that have the

 .B \*qDPMS\*q

 option set (see the MONITOR section below).

 .TP 7

+.BI "Option \*qMaxClients\*q  \*q" integer \*q

+Set the maximum number of clients allowed to connect to the X server.

+Acceptable values are 64, 128, 256 or 512.

+.TP 7

 .BI "Option \*qPixmap\*q  \*q" bpp \*q

 This sets the pixmap format to use for depth 24.

 Allowed values for

diff --git a/include/misc.h b/include/misc.h

index 9b1c03a..56e138c 100644

--- a/include/misc.h

+++ b/include/misc.h

@@ -86,7 +86,8 @@ OF THIS SOFTWARE.

 #ifndef MAXGPUSCREENS

 #define MAXGPUSCREENS	16

 #endif

-#define MAXCLIENTS	256

+#define MAXCLIENTS	512

+#define LIMITCLIENTS	256     /* Must be a power of 2 and <= MAXCLIENTS */

 #define MAXEXTENSIONS   128

 #define MAXFORMATS	8

 #define MAXDEVICES	40      /* input devices */

diff --git a/include/opaque.h b/include/opaque.h

index a2c54aa..0ba0d64 100644

--- a/include/opaque.h

+++ b/include/opaque.h

@@ -36,6 +36,7 @@ from The Open Group.

 extern _X_EXPORT const char *defaultTextFont;

 extern _X_EXPORT const char *defaultCursorFont;

 extern _X_EXPORT int MaxClients;

+extern _X_EXPORT int LimitClients;

 extern _X_EXPORT volatile char isItTimeToYield;

 extern _X_EXPORT volatile char dispatchException;

diff --git a/include/resource.h b/include/resource.h

index 772f363..597f7b6 100644

--- a/include/resource.h

+++ b/include/resource.h

@@ -85,21 +85,10 @@ typedef uint32_t RESTYPE;

 #define RT_LASTPREDEF	((RESTYPE)9)

 #define RT_NONE		((RESTYPE)0)

+extern unsigned int ResourceClientBits(void);

 /* bits and fields within a resource id */

 #define RESOURCE_AND_CLIENT_COUNT   29  /* 29 bits for XIDs */

-#if MAXCLIENTS == 64

-#define RESOURCE_CLIENT_BITS	6

-#endif

-#if MAXCLIENTS == 128

-#define RESOURCE_CLIENT_BITS	7

-#endif

-#if MAXCLIENTS == 256

-#define RESOURCE_CLIENT_BITS	8

-#endif

-#if MAXCLIENTS == 512

-#define RESOURCE_CLIENT_BITS	9

-#endif

-/* client field offset */

+#define RESOURCE_CLIENT_BITS        ResourceClientBits() /* client field offset */

 #define CLIENTOFFSET	    (RESOURCE_AND_CLIENT_COUNT - RESOURCE_CLIENT_BITS)

 /* resource field */

 #define RESOURCE_ID_MASK	((1 << CLIENTOFFSET) - 1)

diff --git a/man/Xserver.man b/man/Xserver.man

index bc4c7fc..d927913 100644

--- a/man/Xserver.man

+++ b/man/Xserver.man

@@ -320,6 +320,11 @@ sets the stack space limit of the server to the specified number of kilobytes.

 A value of zero makes the stack size as large as possible.  The default value

 of \-1 leaves the stack space limit unchanged.

 .TP 8

+.B \-maxclients

+.BR 64 | 128 | 256 | 512

+Set the maximum number of clients allowed to connect to the X server.

+Acceptable values are 64, 128, 256 or 512.

+.TP 8

 .B \-render

 .BR default | mono | gray | color

 sets the color allocation policy that will be used by the render extension.

diff --git a/os/connection.c b/os/connection.c

index 7ff44e1..d198e1f 100644

--- a/os/connection.c

+++ b/os/connection.c

@@ -161,9 +161,9 @@ int *ConnectionTranslation = NULL;

  */

 #undef MAXSOCKS

-#define MAXSOCKS 500

+#define MAXSOCKS 512

 #undef MAXSELECT

-#define MAXSELECT 500

+#define MAXSELECT 512

 struct _ct_node {

     struct _ct_node *next;

@@ -299,7 +299,7 @@ InitConnectionLimits(void)

     if (lastfdesc > MAXCLIENTS) {

         lastfdesc = MAXCLIENTS;

         if (debug_conns)

-            ErrorF("REACHED MAXIMUM CLIENTS LIMIT %d\n", MAXCLIENTS);

+            ErrorF("REACHED MAXIMUM CLIENTS LIMIT %d\n", LimitClients);

     }

     MaxClients = lastfdesc;

diff --git a/os/osdep.h b/os/osdep.h

index 77a5b53..86263a5 100644

--- a/os/osdep.h

+++ b/os/osdep.h

@@ -65,7 +65,7 @@ SOFTWARE.

 #ifndef OPEN_MAX

 #ifdef SVR4

-#define OPEN_MAX 256

+#define OPEN_MAX 512

 #else

 #include <sys/param.h>

 #ifndef OPEN_MAX

@@ -75,7 +75,7 @@ SOFTWARE.

 #if !defined(WIN32)

 #define OPEN_MAX NOFILES_MAX

 #else

-#define OPEN_MAX 256

+#define OPEN_MAX 512

 #endif

 #endif

 #endif

@@ -89,10 +89,10 @@ SOFTWARE.

  * like sysconf(_SC_OPEN_MAX) is not supported.

  */

-#if OPEN_MAX <= 256

+#if OPEN_MAX <= 512

 #define MAXSOCKS (OPEN_MAX - 1)

 #else

-#define MAXSOCKS 256

+#define MAXSOCKS 512

 #endif

 /* MAXSELECT is the number of fds that select() can handle */

diff --git a/os/osinit.c b/os/osinit.c

index 91e3e06..ddd3fce 100644

--- a/os/osinit.c

+++ b/os/osinit.c

@@ -86,6 +86,9 @@ int limitStackSpace = -1;

 int limitNoFile = -1;

 #endif

+/* The actual user defined max number of clients */

+int LimitClients = LIMITCLIENTS;

+

 static OsSigWrapperPtr OsSigWrapper = NULL;

 OsSigWrapperPtr

diff --git a/os/utils.c b/os/utils.c

index 03721fd..b518add 100644

--- a/os/utils.c

+++ b/os/utils.c

@@ -556,6 +556,7 @@ UseMsg(void)

 #ifdef LOCK_SERVER

     ErrorF("-nolock                disable the locking mechanism\n");

 #endif

+    ErrorF("-maxclients n          set maximum number of clients (power of two)\n");

     ErrorF("-nolisten string       don't listen on protocol\n");

     ErrorF("-listen string         listen on protocol\n");

     ErrorF("-noreset               don't reset after last client exists\n");

@@ -860,6 +861,19 @@ ProcessCommandLine(int argc, char *argv[])

                 nolock = TRUE;

         }

 #endif

+	else if ( strcmp( argv[i], "-maxclients") == 0)

+	{

+	    if (++i < argc) {

+		LimitClients = atoi(argv[i]);

+		if (LimitClients != 64 &&

+		    LimitClients != 128 &&

+		    LimitClients != 256 &&

+		    LimitClients != 512) {

+		    FatalError("maxclients must be one of 64, 128, 256 or 512\n");

+		}

+	    } else

+		UseMsg();

+	}

         else if (strcmp(argv[i], "-nolisten") == 0) {

             if (++i < argc) {

                 if (_XSERVTransNoListen(argv[i]))

-- 

1.7.1