[PATCH 08/10] Add support for MIT-SHM AttachFd request
Keith Packard
keithp at keithp.com
Thu Oct 31 23:43:40 CET 2013
This passes a file descriptor from the client to the server, which is
then mmap'd
Signed-off-by: Keith Packard <keithp at keithp.com>
---
Xext/shm.c | 159 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
Xext/shmint.h | 1 +
include/os.h | 2 +
os/io.c | 8 +++
4 files changed, 167 insertions(+), 3 deletions(-)
diff --git a/Xext/shm.c b/Xext/shm.c
index f6995cc..1a70260 100644
--- a/Xext/shm.c
+++ b/Xext/shm.c
@@ -53,6 +53,7 @@ in this Software without prior written authorization from The Open Group.
#include "xace.h"
#include <X11/extensions/shmproto.h>
#include <X11/Xfuncproto.h>
+#include <sys/mman.h>
#include "protocol-versions.h"
/* Needed for Solaris cross-zone shared memory extension */
@@ -382,8 +383,10 @@ ProcShmAttach(ClientPtr client)
client->errorValue = stuff->readOnly;
return BadValue;
}
- for (shmdesc = Shmsegs;
- shmdesc && (shmdesc->shmid != stuff->shmid); shmdesc = shmdesc->next);
+ for (shmdesc = Shmsegs; shmdesc; shmdesc = shmdesc->next) {
+ if (!shmdesc->is_fd && shmdesc->shmid == stuff->shmid)
+ break;
+ }
if (shmdesc) {
if (!stuff->readOnly && !shmdesc->writable)
return BadAccess;
@@ -393,6 +396,7 @@ ProcShmAttach(ClientPtr client)
shmdesc = malloc(sizeof(ShmDescRec));
if (!shmdesc)
return BadAlloc;
+ shmdesc->is_fd = FALSE;
shmdesc->addr = shmat(stuff->shmid, 0,
stuff->readOnly ? SHM_RDONLY : 0);
if ((shmdesc->addr == ((char *) -1)) || SHMSTAT(stuff->shmid, &buf)) {
@@ -431,7 +435,10 @@ ShmDetachSegment(pointer value, /* must conform to DeleteType */
if (--shmdesc->refcnt)
return TRUE;
- shmdt(shmdesc->addr);
+ if (shmdesc->is_fd)
+ munmap(shmdesc->addr, shmdesc->size);
+ else
+ shmdt(shmdesc->addr);
for (prev = &Shmsegs; *prev != shmdesc; prev = &(*prev)->next);
*prev = shmdesc->next;
free(shmdesc);
@@ -1088,6 +1095,122 @@ ProcShmCreatePixmap(ClientPtr client)
}
static int
+ProcShmAttachFd(ClientPtr client)
+{
+ int fd;
+ ShmDescPtr shmdesc;
+ REQUEST(xShmAttachFdReq);
+ struct stat statb;
+
+ SetReqFds(client, 1);
+ REQUEST_SIZE_MATCH(xShmAttachFdReq);
+ LEGAL_NEW_RESOURCE(stuff->shmseg, client);
+ if ((stuff->readOnly != xTrue) && (stuff->readOnly != xFalse)) {
+ client->errorValue = stuff->readOnly;
+ return BadValue;
+ }
+ fd = ReadFdFromClient(client);
+ if (fd < 0)
+ return BadMatch;
+
+ if (fstat(fd, &statb) < 0 || statb.st_size == 0) {
+ close(fd);
+ return BadMatch;
+ }
+
+ shmdesc = malloc(sizeof(ShmDescRec));
+ if (!shmdesc) {
+ close(fd);
+ return BadAlloc;
+ }
+ shmdesc->is_fd = TRUE;
+ shmdesc->addr = mmap(NULL, statb.st_size,
+ stuff->readOnly ? PROT_READ : PROT_READ|PROT_WRITE,
+ MAP_SHARED,
+ fd, 0);
+
+ close(fd);
+ if ((shmdesc->addr == ((char *) -1))) {
+ free(shmdesc);
+ return BadAccess;
+ }
+
+ shmdesc->refcnt = 1;
+ shmdesc->writable = !stuff->readOnly;
+ shmdesc->size = statb.st_size;
+ shmdesc->next = Shmsegs;
+ Shmsegs = shmdesc;
+
+ if (!AddResource(stuff->shmseg, ShmSegType, (pointer) shmdesc))
+ return BadAlloc;
+ return Success;
+}
+
+static int
+ProcShmCreateSegment(ClientPtr client)
+{
+ int fd;
+ ShmDescPtr shmdesc;
+ REQUEST(xShmCreateSegmentReq);
+ xShmCreateSegmentReply rep = {
+ .type = X_Reply,
+ .nfd = 1,
+ .sequenceNumber = client->sequence,
+ .length = 0,
+ };
+ char template[] = "/tmp/shm-XXXXXX";
+
+ REQUEST_SIZE_MATCH(xShmCreateSegmentReq);
+ if ((stuff->readOnly != xTrue) && (stuff->readOnly != xFalse)) {
+ client->errorValue = stuff->readOnly;
+ return BadValue;
+ }
+ fd = mkstemp(template);
+ if (fd < 0)
+ return BadAlloc;
+ unlink(template);
+ if (ftruncate(fd, stuff->size) < 0) {
+ close(fd);
+ return BadAlloc;
+ }
+ shmdesc = malloc(sizeof(ShmDescRec));
+ if (!shmdesc) {
+ close(fd);
+ return BadAlloc;
+ }
+ shmdesc->is_fd = TRUE;
+ shmdesc->addr = mmap(NULL, stuff->size,
+ stuff->readOnly ? PROT_READ : PROT_READ|PROT_WRITE,
+ MAP_SHARED,
+ fd, 0);
+
+ if ((shmdesc->addr == ((char *) -1))) {
+ close(fd);
+ free(shmdesc);
+ return BadAccess;
+ }
+
+ shmdesc->refcnt = 1;
+ shmdesc->writable = !stuff->readOnly;
+ shmdesc->size = stuff->size;
+ shmdesc->next = Shmsegs;
+ Shmsegs = shmdesc;
+
+ if (!AddResource(stuff->shmseg, ShmSegType, (pointer) shmdesc)) {
+ close(fd);
+ return BadAlloc;
+ }
+
+ if (WriteFdToClient(client, fd, TRUE) < 0) {
+ FreeResource(stuff->shmseg, RT_NONE);
+ close(fd);
+ return BadAlloc;
+ }
+ WriteToClient(client, sizeof (xShmCreateSegmentReply), &rep);
+ return Success;
+}
+
+static int
ProcShmDispatch(ClientPtr client)
{
REQUEST(xReq);
@@ -1116,6 +1239,10 @@ ProcShmDispatch(ClientPtr client)
return ProcPanoramiXShmCreatePixmap(client);
#endif
return ProcShmCreatePixmap(client);
+ case X_ShmAttachFd:
+ return ProcShmAttachFd(client);
+ case X_ShmCreateSegment:
+ return ProcShmCreateSegment(client);
default:
return BadRequest;
}
@@ -1217,6 +1344,28 @@ SProcShmCreatePixmap(ClientPtr client)
}
static int
+SProcShmAttachFd(ClientPtr client)
+{
+ REQUEST(xShmAttachFdReq);
+ SetReqFds(client, 1);
+ swaps(&stuff->length);
+ REQUEST_SIZE_MATCH(xShmAttachFdReq);
+ swapl(&stuff->shmseg);
+ return ProcShmAttachFd(client);
+}
+
+static int
+SProcShmCreateSegment(ClientPtr client)
+{
+ REQUEST(xShmCreateSegmentReq);
+ swaps(&stuff->length);
+ REQUEST_SIZE_MATCH(xShmCreateSegmentReq);
+ swapl(&stuff->shmseg);
+ swapl(&stuff->size);
+ return ProcShmCreateSegment(client);
+}
+
+static int
SProcShmDispatch(ClientPtr client)
{
REQUEST(xReq);
@@ -1233,6 +1382,10 @@ SProcShmDispatch(ClientPtr client)
return SProcShmGetImage(client);
case X_ShmCreatePixmap:
return SProcShmCreatePixmap(client);
+ case X_ShmAttachFd:
+ return SProcShmAttachFd(client);
+ case X_ShmCreateSegment:
+ return SProcShmCreateSegment(client);
default:
return BadRequest;
}
diff --git a/Xext/shmint.h b/Xext/shmint.h
index 9002ce5..db35fbb 100644
--- a/Xext/shmint.h
+++ b/Xext/shmint.h
@@ -61,6 +61,7 @@ typedef struct _ShmDesc {
int shmid;
int refcnt;
char *addr;
+ Bool is_fd;
Bool writable;
unsigned long size;
} ShmDescRec, *ShmDescPtr;
diff --git a/include/os.h b/include/os.h
index b654a0d..11b2198 100644
--- a/include/os.h
+++ b/include/os.h
@@ -100,6 +100,8 @@ extern _X_EXPORT int ReadRequestFromClient(ClientPtr /*client */ );
extern _X_EXPORT int ReadFdFromClient(ClientPtr client);
+extern _X_EXPORT int WriteFdToClient(ClientPtr client, int fd, Bool do_close);
+
extern _X_EXPORT Bool InsertFakeRequest(ClientPtr /*client */ ,
char * /*data */ ,
int /*count */ );
diff --git a/os/io.c b/os/io.c
index 83df6e9..a20faa5 100644
--- a/os/io.c
+++ b/os/io.c
@@ -506,6 +506,14 @@ ReadFdFromClient(ClientPtr client)
return fd;
}
+int
+WriteFdToClient(ClientPtr client, int fd, Bool do_close)
+{
+ OsCommPtr oc = (OsCommPtr) client->osPrivate;
+
+ return _XSERVTransSendFd(oc->trans_conn, fd, do_close);
+}
+
/*****************************************************************
* InsertFakeRequest
* Splice a consed up (possibly partial) request in as the next request.
--
1.8.4.rc3
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