[PATCH] Xephyr: Prefer using MIT-SHM FD-passing when possible
Alexander Volkov
a.volkov at rusbitech.ru
Tue Jan 30 11:33:30 UTC 2018
This makes the shared memory visible only for the Xephyr
and the X server to which it is connected.
Signed-off-by: Alexander Volkov <a.volkov at rusbitech.ru>
---
hw/kdrive/ephyr/ephyr.h | 1 +
hw/kdrive/ephyr/hostx.c | 165 +++++++++++++++++++++++++++++++++++-------------
2 files changed, 121 insertions(+), 45 deletions(-)
diff --git a/hw/kdrive/ephyr/ephyr.h b/hw/kdrive/ephyr/ephyr.h
index d44dbc17e..604823955 100644
--- a/hw/kdrive/ephyr/ephyr.h
+++ b/hw/kdrive/ephyr/ephyr.h
@@ -79,6 +79,7 @@ typedef struct _ephyrScrPriv {
const char *output; /* Set via -output option */
unsigned char *fb_data; /* only used when host bpp != server bpp */
xcb_shm_segment_info_t shminfo;
+ uint32_t shmsize;
KdScreenInfo *screen;
int mynum; /* Screen number */
diff --git a/hw/kdrive/ephyr/hostx.c b/hw/kdrive/ephyr/hostx.c
index ef8541673..0af32d8d9 100644
--- a/hw/kdrive/ephyr/hostx.c
+++ b/hw/kdrive/ephyr/hostx.c
@@ -41,6 +41,7 @@
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/time.h>
+#include <sys/mman.h>
#include <X11/keysym.h>
#include <xcb/xcb.h>
@@ -75,6 +76,7 @@ struct EphyrHostXVars {
Bool use_sw_cursor;
Bool use_fullscreen;
Bool have_shm;
+ Bool have_shm_fd_passing;
int n_screens;
KdScreenInfo **screens;
@@ -417,6 +419,109 @@ hostx_set_title(char *title)
#pragma does_not_return(exit)
#endif
+static void
+hostx_init_shm(void)
+{
+ /* Try to get share memory ximages for a little bit more speed */
+ if (!hostx_has_extension(&xcb_shm_id) || getenv("XEPHYR_NO_SHM")) {
+ HostX.have_shm = FALSE;
+ } else
+#if (XCB_SHM_MAJOR_VERSION == 1 && XCB_SHM_MINOR_VERSION >= 2) || XCB_SHM_MAJOR_VERSION > 1
+ {
+ xcb_generic_error_t *error = NULL;
+ xcb_shm_query_version_cookie_t cookie;
+ xcb_shm_query_version_reply_t *reply;
+
+ HostX.have_shm = TRUE;
+ HostX.have_shm_fd_passing = FALSE;
+ cookie = xcb_shm_query_version(HostX.conn);
+ reply = xcb_shm_query_version_reply(HostX.conn, cookie, &error);
+ if (reply) {
+ HostX.have_shm_fd_passing =
+ (reply->major_version == 1 && reply->minor_version >= 2) ||
+ reply->major_version > 1;
+ free(reply);
+ }
+ free(error);
+ }
+#else
+ {
+ HostX.have_shm = TRUE;
+ HostX.have_shm_fd_passing = FALSE;
+ }
+#endif
+}
+
+static Bool
+hostx_create_shm_segment(xcb_shm_segment_info_t *shminfo, size_t size)
+{
+ shminfo->shmaddr = NULL;
+
+#if (XCB_SHM_MAJOR_VERSION == 1 && XCB_SHM_MINOR_VERSION >= 2) || XCB_SHM_MAJOR_VERSION > 1
+ if (HostX.have_shm_fd_passing) {
+ xcb_generic_error_t *error = NULL;
+ xcb_shm_create_segment_cookie_t cookie;
+ xcb_shm_create_segment_reply_t *reply;
+
+ shminfo->shmseg = xcb_generate_id(HostX.conn);
+ cookie = xcb_shm_create_segment(HostX.conn, shminfo->shmseg, size, TRUE);
+ reply = xcb_shm_create_segment_reply(HostX.conn, cookie, &error);
+ if (!error && reply && reply->nfd == 1) {
+ int *fds = xcb_shm_create_segment_reply_fds(HostX.conn, reply);
+ if (fds) {
+ shminfo->shmaddr =
+ (uint8_t *)mmap(0, size, PROT_READ|PROT_WRITE, MAP_SHARED, fds[0], 0);
+ close(fds[0]);
+ if (shminfo->shmaddr == MAP_FAILED)
+ shminfo->shmaddr = NULL;
+ }
+ }
+ free(error);
+ free(reply);
+ } else
+#endif
+ {
+ shminfo->shmid = shmget(IPC_PRIVATE, size, IPC_CREAT|0600);
+ if (shminfo->shmid != -1) {
+ shminfo->shmaddr = shmat(shminfo->shmid, 0, 0);
+ if (shminfo->shmaddr == (void *)-1)
+ shminfo->shmaddr = NULL;
+ if (shminfo->shmaddr) {
+ xcb_generic_error_t *error = NULL;
+ xcb_void_cookie_t cookie;
+
+ shmctl(shminfo->shmid, IPC_RMID, 0);
+
+ shminfo->shmseg = xcb_generate_id(HostX.conn);
+ cookie = xcb_shm_attach_checked(HostX.conn, shminfo->shmseg, shminfo->shmid, TRUE);
+ error = xcb_request_check(HostX.conn, cookie);
+
+ if (error) {
+ free(error);
+ shmdt(shminfo->shmaddr);
+ shminfo->shmaddr = NULL;
+ }
+ }
+ }
+ }
+ return shminfo->shmaddr != NULL;
+}
+
+static void
+hostx_destroy_shm_segment(xcb_shm_segment_info_t *shminfo, size_t size)
+{
+#if (XCB_SHM_MAJOR_VERSION == 1 && XCB_SHM_MINOR_VERSION >= 2) || XCB_SHM_MAJOR_VERSION > 1
+ if (HostX.have_shm_fd_passing) {
+ munmap(shminfo->shmaddr, size);
+ } else
+#endif
+ {
+ shmdt(shminfo->shmaddr);
+ shmctl(shminfo->shmid, IPC_RMID, 0);
+ }
+ shminfo->shmaddr = NULL;
+}
+
int
hostx_init(void)
{
@@ -638,36 +743,18 @@ hostx_init(void)
}
}
- /* Try to get share memory ximages for a little bit more speed */
- if (!hostx_has_extension(&xcb_shm_id) || getenv("XEPHYR_NO_SHM")) {
- fprintf(stderr, "\nXephyr unable to use SHM XImages\n");
- HostX.have_shm = FALSE;
- }
- else {
+ hostx_init_shm();
+ if (HostX.have_shm) {
/* Really really check we have shm - better way ?*/
xcb_shm_segment_info_t shminfo;
- xcb_generic_error_t *e;
- xcb_void_cookie_t cookie;
- xcb_shm_seg_t shmseg;
-
- HostX.have_shm = TRUE;
-
- shminfo.shmid = shmget(IPC_PRIVATE, 1, IPC_CREAT|0777);
- shminfo.shmaddr = shmat(shminfo.shmid,0,0);
-
- shmseg = xcb_generate_id(HostX.conn);
- cookie = xcb_shm_attach_checked(HostX.conn, shmseg, shminfo.shmid,
- TRUE);
- e = xcb_request_check(HostX.conn, cookie);
-
- if (e) {
- fprintf(stderr, "\nXephyr unable to use SHM XImages\n");
+ if (!hostx_create_shm_segment(&shminfo, 1)) {
HostX.have_shm = FALSE;
- free(e);
+ fprintf(stderr, "\nXephyr unable to use SHM XImages\n");
+ } else {
+ hostx_destroy_shm_segment(&shminfo, 1);
}
-
- shmdt(shminfo.shmaddr);
- shmctl(shminfo.shmid, IPC_RMID, 0);
+ } else {
+ fprintf(stderr, "\nXephyr unable to use SHM XImages\n");
}
xcb_flush(HostX.conn);
@@ -814,8 +901,7 @@ hostx_screen_init(KdScreenInfo *screen,
if (HostX.have_shm) {
xcb_shm_detach(HostX.conn, scrpriv->shminfo.shmseg);
xcb_image_destroy(scrpriv->ximg);
- shmdt(scrpriv->shminfo.shmaddr);
- shmctl(scrpriv->shminfo.shmid, IPC_RMID, 0);
+ hostx_destroy_shm_segment(&scrpriv->shminfo, scrpriv->shmsize);
}
else {
free(scrpriv->ximg->data);
@@ -835,27 +921,16 @@ hostx_screen_init(KdScreenInfo *screen,
~0,
NULL);
- scrpriv->shminfo.shmid =
- shmget(IPC_PRIVATE,
- scrpriv->ximg->stride * buffer_height,
- IPC_CREAT | 0777);
- scrpriv->ximg->data = shmat(scrpriv->shminfo.shmid, 0, 0);
- scrpriv->shminfo.shmaddr = scrpriv->ximg->data;
-
- if (scrpriv->ximg->data == (uint8_t *) -1) {
+ scrpriv->shmsize = scrpriv->ximg->stride * buffer_height;
+ if (!hostx_create_shm_segment(&scrpriv->shminfo,
+ scrpriv->shmsize)) {
EPHYR_DBG
("Can't attach SHM Segment, falling back to plain XImages");
HostX.have_shm = FALSE;
- xcb_image_destroy (scrpriv->ximg);
- shmctl(scrpriv->shminfo.shmid, IPC_RMID, 0);
- }
- else {
+ xcb_image_destroy(scrpriv->ximg);
+ } else {
EPHYR_DBG("SHM segment attached %p", scrpriv->shminfo.shmaddr);
- scrpriv->shminfo.shmseg = xcb_generate_id(HostX.conn);
- xcb_shm_attach(HostX.conn,
- scrpriv->shminfo.shmseg,
- scrpriv->shminfo.shmid,
- FALSE);
+ scrpriv->ximg->data = scrpriv->shminfo.shmaddr;
shm_success = TRUE;
}
}
--
2.11.0
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