diff options
| -rw-r--r-- | src/mesa/drivers/dri/common/megadriver_stub.c | 126 |
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) |