egldevice: implement EGL_MESA_device_hashdevice-hash

Use the hash table string hashing function as it's probably fine. The
hash is taken of the string of the vendor and device IDs from the PCI
bus.

Signed-off-by: Jonny Lamb <jonny.lamb@collabora.co.uk>

5 files changed, 171 insertions, 1 deletions

diff --git a/docs/specs/EGL_MESA_device_hash.txt b/docs/specs/EGL_MESA_device_hash.txt
new file mode 100644
index 0000000000..910a33e66e
--- /dev/null
+++ b/docs/specs/EGL_MESA_device_hash.txt
@@ -0,0 +1,95 @@
+Name
+
+    EGL_MESA_device_hash
+
+Name Strings
+
+    EGL_MESA_device_hash
+
+Contributors
+
+    Jonny Lamb <jonny.lamb@collabora.co.uk>
+
+Contact
+
+    Jonny Lamb <jonny.lamb@collabora.co.uk>
+
+Status
+
+    Draft
+
+Version
+
+    Version 1, 2015-07-22
+
+Number
+
+    EGL Extension #XXX
+
+Extension Type
+
+    EGL device extension
+
+Dependencies
+
+    This extension is written against the wording of EGL 1.5 as
+    modified by EGL_EXT_device_query.
+
+    EGL_EXT_device_query is required.
+
+Overview
+
+    The EGLDeviceEXT object is useful for referring to a particular
+    device on the system. However, this handle is only valid for the
+    current process. For referring to devices across different
+    processes on the same system an integer value is required.
+
+    Additionally, when using functions with EGLint argument types, it
+    is currently not possible to refer to EGLDeviceEXT objects. An
+    integer value for said objects is necessary to enable this
+    functionality. The <attrib_list> argument of eglGetPlatformDisplay
+    is an example of a function with an argument of type EGLint.
+
+New Types
+
+    None
+
+New Procedures and Functions
+
+    None
+
+New Tokens
+
+    Accepted as a queried <attribute> in eglQueryDeviceAttribEXT:
+
+        EGL_DEVICE_HASH_MESA               0x31E0
+
+Additions to the EGL 1.5 Specification
+
+    In section 3.2 "Devices", replace the paragraph immediately
+    following the prototype for eglQueryDeviceAttribEXT with the
+    following:
+
+    "On success, EGL_TRUE is returned and the requested attribute
+    value is returned in <value>. Currently the only valid value for
+    <attribute> is EGL_DEVICE_HASH_MESA which returns in <value> an
+    EGLint hash value for the EGLDeviceEXT object given in <device>.
+    This hash value can be used for comparing EGLDeviceEXT objects
+    across different processes on the same system and for when an EGL
+    function argument type is EGLint instead of EGLattrib. With a
+    successful call using EGL_DEVICE_HASH_MESA as <attribute> the
+    returned EGLint is always non-zero.
+
+    The method used to calculate the hash for a EGLDeviceEXT is left
+    up to the implementation. Compatibility between hash values can
+    only be assumed with the same version of the same implementation
+    running on the same system."
+
+Issues
+
+    None
+
+Revision History
+
+    Version 1, 2015-7-22 (Jonny Lamb)
+        - Initial draft
diff --git a/include/EGL/eglmesaext.h b/include/EGL/eglmesaext.h
index 917a2043c7..ea96e97737 100644
--- a/include/EGL/eglmesaext.h
+++ b/include/EGL/eglmesaext.h
@@ -95,6 +95,11 @@ typedef EGLBoolean (EGLAPIENTRYP PFNEGLSWAPBUFFERSREGIONNOK) (EGLDisplay dpy, EG
 #define EGL_NO_CONFIG_MESA			((EGLConfig)0)
 #endif
 
+#ifndef EGL_MESA_device_hash
+#define EGL_MESA_device_hash 1
+#define EGL_DEVICE_HASH_MESA			0x31E0
+#endif
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/src/egl/main/Makefile.am b/src/egl/main/Makefile.am
index 9030d272b5..e2811371de 100644
--- a/src/egl/main/Makefile.am
+++ b/src/egl/main/Makefile.am
@@ -23,6 +23,7 @@ include Makefile.sources
 
 AM_CFLAGS = \
 	-I$(top_srcdir)/include \
+	-I$(top_srcdir)/src \
 	-I$(top_srcdir)/src/gbm/main \
 	$(DEFINES) \
 	$(VISIBILITY_CFLAGS) \
@@ -37,6 +38,7 @@ libEGL_la_SOURCES = \
 	${LIBEGL_C_FILES}
 
 libEGL_la_LIBADD = \
+	$(top_builddir)/src/util/libmesautil.la
 	$(EGL_LIB_DEPS)
 libEGL_la_LDFLAGS = \
 	-no-undefined \
diff --git a/src/egl/main/egldevice.c b/src/egl/main/egldevice.c
index 8a717a6c6a..69121e6812 100644
--- a/src/egl/main/egldevice.c
+++ b/src/egl/main/egldevice.c
@@ -34,6 +34,8 @@
 #include <assert.h>
 #include <string.h>
 
+#include "util/hash_table.h"
+
 #include "eglcurrent.h"
 #include "egldevice.h"
 #include "egldriver.h"
@@ -79,7 +81,7 @@ _eglEnsureDeviceInfo(EGLBoolean get_devices)
 
       /* update this string like in eglglobals.c to add support for a device
        * extension */
-      info->extensions = "";
+      info->extensions = "EGL_MESA_device_hash";
 
 #ifdef HAVE_LIBUDEV
       info->udev = NULL;
@@ -216,6 +218,64 @@ _eglFiniDeviceInfo(void)
    _eglGlobal.DeviceInfo = NULL;
 }
 
+static EGLBoolean
+_eglQueryDeviceHash(_EGLDevice *device,
+                    EGLAttrib *value)
+{
+#ifdef HAVE_LIBUDEV
+   struct udev_device *parent;
+   EGLBoolean ret = EGL_TRUE;
+   const char *subsystem_vendor, *subsystem_device;
+   char *str;
+   int len;
+   UDEV_SYMBOL(struct udev_device *, udev_device_get_parent_with_subsystem_devtype,
+               (struct udev_device *, const char *, const char *));
+   UDEV_SYMBOL(const char *, udev_device_get_sysattr_value,
+               (struct udev_device *, const char *));
+
+   if (dlsym_failed)
+      return EGL_FALSE;
+
+   assert(device->Hash == 0);
+
+   mtx_lock(_eglGlobal.Mutex);
+
+   parent = udev_device_get_parent_with_subsystem_devtype(
+      device->Info, "pci", NULL);
+
+   if (!parent) {
+      ret = EGL_FALSE;
+      goto out;
+   }
+
+   subsystem_vendor = udev_device_get_sysattr_value(parent, "subsystem_vendor");
+   subsystem_device = udev_device_get_sysattr_value(parent, "subsystem_device");
+
+   if (!subsystem_vendor || !subsystem_device) {
+      ret = EGL_FALSE;
+      goto out;
+   }
+
+   len = strlen(subsystem_vendor) + strlen(subsystem_device);
+   str = calloc(len + 1, sizeof(char));
+
+   str = strdup(subsystem_vendor);
+   strcat(str, subsystem_device);
+
+   *value = _mesa_hash_string(str);
+
+   device->Hash = *value;
+
+   free(str);
+
+out:
+   mtx_unlock(_eglGlobal.Mutex);
+   return ret;
+#else
+   return EGL_FALSE;
+#endif
+}
+
 /**
  * Get attribute about specific device
  */
@@ -228,6 +288,13 @@ _eglQueryDeviceAttribEXT(_EGLDevice *device,
       return _eglError(EGL_BAD_PARAMETER, "eglQueryDeviceAttribEXT");
 
    switch (attribute) {
+   case EGL_DEVICE_HASH_MESA:
+      if (device->Hash > 0) {
+         return device->Hash;
+      } else {
+         return _eglQueryDeviceHash(device, value);
+      }
+      break;
    default:
       return _eglError(EGL_BAD_ATTRIBUTE, "eglQueryDeviceAttribEXT");
       break;
diff --git a/src/egl/main/egldevice.h b/src/egl/main/egldevice.h
index 2c7986acb7..fb30bd2050 100644
--- a/src/egl/main/egldevice.h
+++ b/src/egl/main/egldevice.h
@@ -37,6 +37,7 @@ struct _egl_device {
    _EGLDevice *Next;
 
    void *Info;
+   EGLint Hash;
 };