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authorJordan Justen <jordan.l.justen@intel.com>2013-12-06 02:21:17 -0800
committerIan Romanick <ian.d.romanick@intel.com>2013-12-09 17:28:20 -0800
commitfdede182756e01690df62cece8a022c437274201 (patch)
treec6156146cc11602320931d7994ab11e5b972509f /src/mesa
parent4cbd4246315314cbd6e9c93013f93363a1a376cb (diff)
dri megadriver_stub: add compatibility for older DRI loaders
To help the transition period when DRI loaders are being updated to support the newer __driDriverExtensions_foo mechanism, we populate __driDriverExtensions with the extensions returned by __driDriverExtensions_foo during a library contructor function. We find the driver foo's name by using the dladdr function which gives the path of the dynamic library's name that was being loaded. Signed-off-by: Jordan Justen <jordan.l.justen@intel.com> Reviewed-by: Matt Turner <mattst88@gmail.com> Reviewed-by: Kenneth Graunke <kenneth@whitecape.org> Reviewed-by: Keith Packard <keithp@keithp.com> Cc: "10.0" <mesa-stable@lists.freedesktop.org> (cherry picked from commit 4859d492b25cba61f43bb883d878d6388be742be)
Diffstat (limited to 'src/mesa')
-rw-r--r--src/mesa/drivers/dri/common/megadriver_stub.c126
1 files changed, 126 insertions, 0 deletions
diff --git a/src/mesa/drivers/dri/common/megadriver_stub.c b/src/mesa/drivers/dri/common/megadriver_stub.c
index 6bf5d73279a..a8217703daf 100644
--- a/src/mesa/drivers/dri/common/megadriver_stub.c
+++ b/src/mesa/drivers/dri/common/megadriver_stub.c
@@ -23,6 +23,132 @@
#include <stdio.h>
#include "dri_util.h"
+#include <dlfcn.h>
+#include "main/macros.h"
+
+/* We need GNU extensions to dlfcn.h in order to provide backward
+ * compatibility for the older DRI driver loader mechanism. (dladdr,
+ * Dl_info, and RTLD_DEFAULT are only defined when _GNU_SOURCE is
+ * defined.)
+ */
+#ifdef _GNU_SOURCE
+
+#define MEGADRIVER_STUB_MAX_EXTENSIONS 10
+#define LIB_PATH_SUFFIX "_dri.so"
+#define LIB_PATH_SUFFIX_LENGTH (sizeof(LIB_PATH_SUFFIX)-1)
+
+/* This is the table of extensions that the loader will dlsym() for.
+ *
+ * Initially it is empty for the megadriver stub, but the library
+ * constructor may initialize it based on the name of the library that
+ * is being loaded.
+ */
+PUBLIC const __DRIextension *
+__driDriverExtensions[MEGADRIVER_STUB_MAX_EXTENSIONS] = {
+ NULL
+};
+
+/**
+ * This is a constructor function for the megadriver dynamic library.
+ *
+ * When the driver is dlopen'ed, this function will run. It will
+ * search for the name of the foo_dri.so file that was opened using
+ * the dladdr function.
+ *
+ * After finding foo's name, it will call __driDriverGetExtensions_foo
+ * and use the return to update __driDriverExtensions to enable
+ * compatibility with older DRI driver loaders.
+ */
+__attribute__((constructor)) static void
+megadriver_stub_init(void)
+{
+ Dl_info info;
+ char *driver_name;
+ size_t name_len;
+ char *get_extensions_name;
+ const __DRIextension **(*get_extensions)(void);
+ const __DRIextension **extensions;
+ int i;
+
+ /* Call dladdr on __driDriverExtensions. We are really
+ * interested in the returned info.dli_fname so we can
+ * figure out the path name of the library being loaded.
+ */
+ i = dladdr((void*) __driDriverExtensions, &info);
+ if (i == 0)
+ return;
+
+ /* Search for the last '/' character in the path. */
+ driver_name = strrchr(info.dli_fname, '/');
+ if (driver_name != NULL) {
+ /* Skip '/' character */
+ driver_name++;
+ } else {
+ /* Try using the start of the path */
+ driver_name = (char*) info.dli_fname;
+ }
+
+ /* Make sure the path ends with _dri.so */
+ name_len = strlen(driver_name);
+ i = name_len - LIB_PATH_SUFFIX_LENGTH;
+ if (i < 0 || strcmp(driver_name + i, LIB_PATH_SUFFIX) != 0)
+ return;
+
+ /* Duplicate the string so we can modify it.
+ * So far we've been using info.dli_fname.
+ */
+ driver_name = strdup(driver_name);
+ if (!driver_name)
+ return;
+
+ /* The path ends with _dri.so. Chop this part of the
+ * string off. Then we'll have the driver's final name.
+ */
+ driver_name[i] = '\0';
+
+ i = asprintf(&get_extensions_name, "%s_%s",
+ __DRI_DRIVER_GET_EXTENSIONS, driver_name);
+ free(driver_name);
+ if (i == -1)
+ return;
+
+ /* dlsym to get the driver's get extensions function. We
+ * don't have the dlopen handle, so we have to use
+ * RTLD_DEFAULT. It seems unlikely that the symbol will
+ * be found in another library, but this isn't optimal.
+ */
+ get_extensions = dlsym(RTLD_DEFAULT, get_extensions_name);
+ free(get_extensions_name);
+ if (!get_extensions)
+ return;
+
+ /* Use the newer DRI loader entrypoint to find extensions.
+ * We will then expose these extensions via the older
+ * __driDriverExtensions symbol.
+ */
+ extensions = get_extensions();
+
+ /* Copy the extensions into the __driDriverExtensions array
+ * we declared.
+ */
+ for (i = 0; i < ARRAY_SIZE(__driDriverExtensions); i++) {
+ __driDriverExtensions[i] = extensions[i];
+ if (extensions[i] == NULL)
+ break;
+ }
+
+ /* If the driver had more extensions than we reserved, then
+ * bail out.
+ */
+ if (i == ARRAY_SIZE(__driDriverExtensions)) {
+ __driDriverExtensions[0] = NULL;
+ fprintf(stderr, "Megadriver stub did not reserve enough extension "
+ "slots.\n");
+ return;
+ }
+}
+
+#endif /* _GNU_SOURCE */
static const
__DRIconfig **stub_error_init_screen(__DRIscreen *psp)