src/loader/loader.c - third_party/mesa - Git at Google

 /*
  * Copyright (C) 2013 Rob Clark <robclark@freedesktop.org>
  * Copyright (C) 2014-2016 Emil Velikov <emil.l.velikov@gmail.com>
  * Copyright (C) 2016 Intel Corporation
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
  * copy of this software and associated documentation files (the "Software"),
  * to deal in the Software without restriction, including without limitation
  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
  * and/or sell copies of the Software, and to permit persons to whom the
  * Software is furnished to do so, subject to the following conditions:
  *
  * The above copyright notice and this permission notice (including the next
  * paragraph) shall be included in all copies or substantial portions of the
  * Software.
  *
  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  * SOFTWARE.
  *
  * Authors:
  *    Rob Clark <robclark@freedesktop.org>
  */

 #include <dlfcn.h>
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <stdarg.h>
 #include <stdio.h>
 #include <stdbool.h>
 #include <string.h>
 #include <unistd.h>
 #include <stdlib.h>
 #include <limits.h>
 #include <sys/param.h>
 #ifdef MAJOR_IN_MKDEV
 #include <sys/mkdev.h>
 #endif
 #ifdef MAJOR_IN_SYSMACROS
 #include <sys/sysmacros.h>
 #endif
 #include <GL/gl.h>
 #include <GL/internal/dri_interface.h>
 #include "loader.h"
 #include "util/os_file.h"
 #include "util/os_misc.h"

 #ifdef HAVE_LIBDRM
 #include <xf86drm.h>
 #define MAX_DRM_DEVICES 64
 #ifdef USE_DRICONF
 #include "util/xmlconfig.h"
 #include "util/driconf.h"
 #endif
 #endif

 #include "util/macros.h"

 #define __IS_LOADER
 #include "pci_id_driver_map.h"

 /* For systems like Hurd */
 #ifndef PATH_MAX
 #define PATH_MAX 4096
 #endif

 static void default_logger(int level, const char *fmt, ...)
 {
    if (level <= _LOADER_WARNING) {
       va_list args;
       va_start(args, fmt);
       vfprintf(stderr, fmt, args);
       va_end(args);
    }
 }

 static loader_logger *log_ = default_logger;

 int
 loader_open_device(const char *device_name)
 {
    int fd;
 #ifdef O_CLOEXEC
    fd = open(device_name, O_RDWR | O_CLOEXEC);
    if (fd == -1 && errno == EINVAL)
 #endif
    {
       fd = open(device_name, O_RDWR);
       if (fd != -1)
          fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) | FD_CLOEXEC);
    }
    if (fd == -1 && errno == EACCES) {
       log_(_LOADER_WARNING, "failed to open %s: %s\n",
            device_name, strerror(errno));
    }
    return fd;
 }

 static char *loader_get_kernel_driver_name(int fd)
 {
 #if HAVE_LIBDRM
    char *driver;
    drmVersionPtr version = drmGetVersion(fd);

    if (!version) {
       log_(_LOADER_WARNING, "failed to get driver name for fd %d\n", fd);
       return NULL;
    }

    driver = strndup(version->name, version->name_len);
    log_(driver ? _LOADER_DEBUG : _LOADER_WARNING, "using driver %s for %d\n",
         driver, fd);

    drmFreeVersion(version);
    return driver;
 #else
    return NULL;
 #endif
 }

 bool
 is_kernel_i915(int fd)
 {
    char *kernel_driver = loader_get_kernel_driver_name(fd);
    bool is_i915 = kernel_driver && strcmp(kernel_driver, "i915") == 0;

    free(kernel_driver);
    return is_i915;
 }

 #if defined(HAVE_LIBDRM)
 int
 loader_open_render_node(const char *name)
 {
    drmDevicePtr devices[MAX_DRM_DEVICES], device;
    int i, num_devices, fd = -1;

    num_devices = drmGetDevices2(0, devices, MAX_DRM_DEVICES);
    if (num_devices <= 0)
       return -ENOENT;

    for (i = 0; i < num_devices; i++) {
       device = devices[i];

       if ((device->available_nodes & (1 << DRM_NODE_RENDER)) &&
           (device->bustype == DRM_BUS_PLATFORM)) {
          drmVersionPtr version;

          fd = loader_open_device(device->nodes[DRM_NODE_RENDER]);
          if (fd < 0)
             continue;

          version = drmGetVersion(fd);
          if (!version) {
             close(fd);
             continue;
          }

          if (strcmp(version->name, name) != 0) {
             drmFreeVersion(version);
             close(fd);
             continue;
          }

          drmFreeVersion(version);
          break;
       }
    }
    drmFreeDevices(devices, num_devices);

    if (i == num_devices)
       return -ENOENT;

    return fd;
 }

 char *
 loader_get_render_node(dev_t device)
 {
    char *render_node = NULL;
    drmDevicePtr dev_ptr;

    if (drmGetDeviceFromDevId(device, 0, &dev_ptr) < 0)
       return NULL;

    if (dev_ptr->available_nodes & (1 << DRM_NODE_RENDER)) {
       render_node = strdup(dev_ptr->nodes[DRM_NODE_RENDER]);
       if (!render_node)
          log_(_LOADER_DEBUG, "MESA-LOADER: failed to allocate memory for render node\n");
    }

    drmFreeDevice(&dev_ptr);

    return render_node;
 }

 #ifdef USE_DRICONF
 static const driOptionDescription __driConfigOptionsLoader[] = {
     DRI_CONF_SECTION_INITIALIZATION
         DRI_CONF_DEVICE_ID_PATH_TAG()
         DRI_CONF_DRI_DRIVER()
     DRI_CONF_SECTION_END
 };

 static char *loader_get_dri_config_driver(int fd)
 {
    driOptionCache defaultInitOptions;
    driOptionCache userInitOptions;
    char *dri_driver = NULL;
    char *kernel_driver = loader_get_kernel_driver_name(fd);

    driParseOptionInfo(&defaultInitOptions, __driConfigOptionsLoader,
                       ARRAY_SIZE(__driConfigOptionsLoader));
    driParseConfigFiles(&userInitOptions, &defaultInitOptions, 0,
                        "loader", kernel_driver, NULL, NULL, 0, NULL, 0);
    if (driCheckOption(&userInitOptions, "dri_driver", DRI_STRING)) {
       char *opt = driQueryOptionstr(&userInitOptions, "dri_driver");
       /* not an empty string */
       if (*opt)
          dri_driver = strdup(opt);
    }
    driDestroyOptionCache(&userInitOptions);
    driDestroyOptionInfo(&defaultInitOptions);

    free(kernel_driver);
    return dri_driver;
 }

 static char *loader_get_dri_config_device_id(void)
 {
    driOptionCache defaultInitOptions;
    driOptionCache userInitOptions;
    char *prime = NULL;

    driParseOptionInfo(&defaultInitOptions, __driConfigOptionsLoader,
                       ARRAY_SIZE(__driConfigOptionsLoader));
    driParseConfigFiles(&userInitOptions, &defaultInitOptions, 0,
                        "loader", NULL, NULL, NULL, 0, NULL, 0);
    if (driCheckOption(&userInitOptions, "device_id", DRI_STRING)) {
       char *opt = driQueryOptionstr(&userInitOptions, "device_id");
       if (*opt)
          prime = strdup(opt);
    }
    driDestroyOptionCache(&userInitOptions);
    driDestroyOptionInfo(&defaultInitOptions);

    return prime;
 }
 #endif

 static char *drm_construct_id_path_tag(drmDevicePtr device)
 {
    char *tag = NULL;

    if (device->bustype == DRM_BUS_PCI) {
       if (asprintf(&tag, "pci-%04x_%02x_%02x_%1u",
                    device->businfo.pci->domain,
                    device->businfo.pci->bus,
                    device->businfo.pci->dev,
                    device->businfo.pci->func) < 0) {
          return NULL;
       }
    } else if (device->bustype == DRM_BUS_PLATFORM ||
               device->bustype == DRM_BUS_HOST1X) {
       char *fullname, *name, *address;

       if (device->bustype == DRM_BUS_PLATFORM)
          fullname = device->businfo.platform->fullname;
       else
          fullname = device->businfo.host1x->fullname;

       name = strrchr(fullname, '/');
       if (!name)
          name = strdup(fullname);
       else
          name = strdup(name + 1);

       address = strchr(name, '@');
       if (address) {
          *address++ = '\0';

          if (asprintf(&tag, "platform-%s_%s", address, name) < 0)
             tag = NULL;
       } else {
          if (asprintf(&tag, "platform-%s", name) < 0)
             tag = NULL;
       }

       free(name);
    }
    return tag;
 }

 static bool drm_device_matches_tag(drmDevicePtr device, const char *prime_tag)
 {
    char *tag = drm_construct_id_path_tag(device);
    int ret;

    if (tag == NULL)
       return false;

    ret = strcmp(tag, prime_tag);

    free(tag);
    return ret == 0;
 }

 static char *drm_get_id_path_tag_for_fd(int fd)
 {
    drmDevicePtr device;
    char *tag;

    if (drmGetDevice2(fd, 0, &device) != 0)
        return NULL;

    tag = drm_construct_id_path_tag(device);
    drmFreeDevice(&device);
    return tag;
 }

 int loader_get_user_preferred_fd(int default_fd, bool *different_device)
 {
    const char *dri_prime = getenv("DRI_PRIME");
    char *default_tag, *prime = NULL;
    drmDevicePtr devices[MAX_DRM_DEVICES];
    int i, num_devices, fd = -1;
    bool prime_is_vid_did;
    uint16_t vendor_id, device_id;

    if (dri_prime)
       prime = strdup(dri_prime);
 #ifdef USE_DRICONF
    else
       prime = loader_get_dri_config_device_id();
 #endif

    if (prime == NULL) {
       *different_device = false;
       return default_fd;
    } else {
       prime_is_vid_did = sscanf(prime, "%hx:%hx", &vendor_id, &device_id) == 2;
    }

    default_tag = drm_get_id_path_tag_for_fd(default_fd);
    if (default_tag == NULL)
       goto err;

    num_devices = drmGetDevices2(0, devices, MAX_DRM_DEVICES);
    if (num_devices <= 0)
       goto err;

    for (i = 0; i < num_devices; i++) {
       if (!(devices[i]->available_nodes & 1 << DRM_NODE_RENDER))
          continue;

       /* three formats of DRI_PRIME are supported:
        * "1": choose any other card than the card used by default.
        * id_path_tag: (for example "pci-0000_02_00_0") choose the card
        * with this id_path_tag.
        * vendor_id:device_id
        */
       if (!strcmp(prime,"1")) {
          if (drm_device_matches_tag(devices[i], default_tag))
             continue;
       } else {
          if (prime_is_vid_did && devices[i]->bustype == DRM_BUS_PCI &&
              devices[i]->deviceinfo.pci->vendor_id == vendor_id &&
              devices[i]->deviceinfo.pci->device_id == device_id) {
             /* Update prime for the "different_device"
              * determination below. */
             free(prime);
             prime = drm_construct_id_path_tag(devices[i]);
          } else {
             if (!drm_device_matches_tag(devices[i], prime))
                continue;
          }
       }

       fd = loader_open_device(devices[i]->nodes[DRM_NODE_RENDER]);
       break;
    }
    drmFreeDevices(devices, num_devices);

    if (i == num_devices)
       goto err;

    if (fd < 0)
       goto err;

    close(default_fd);

    *different_device = !!strcmp(default_tag, prime);

    free(default_tag);
    free(prime);
    return fd;

  err:
    *different_device = false;

    free(default_tag);
    free(prime);
    return default_fd;
 }
 #else
 int
 loader_open_render_node(const char *name)
 {
    return -1;
 }

 char *
 loader_get_render_node(dev_t device)
 {
    return NULL;
 }

 int loader_get_user_preferred_fd(int default_fd, bool *different_device)
 {
    *different_device = false;
    return default_fd;
 }
 #endif

 #if defined(HAVE_LIBDRM)

 static bool
 drm_get_pci_id_for_fd(int fd, int *vendor_id, int *chip_id)
 {
    drmDevicePtr device;

    if (drmGetDevice2(fd, 0, &device) != 0) {
       log_(_LOADER_WARNING, "MESA-LOADER: failed to retrieve device information\n");
       return false;
    }

    if (device->bustype != DRM_BUS_PCI) {
       drmFreeDevice(&device);
       log_(_LOADER_DEBUG, "MESA-LOADER: device is not located on the PCI bus\n");
       return false;
    }

    *vendor_id = device->deviceinfo.pci->vendor_id;
    *chip_id = device->deviceinfo.pci->device_id;
    drmFreeDevice(&device);
    return true;
 }
 #endif

 #ifdef __linux__
 static int loader_get_linux_pci_field(int maj, int min, const char *field)
 {
    char path[PATH_MAX + 1];
    snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device/%s", maj, min, field);

    char *field_str = os_read_file(path, NULL);
    if (!field_str) {
       /* Probably non-PCI device. */
       return 0;
    }

    int value = (int)strtoll(field_str, NULL, 16);
    free(field_str);

    return value;
 }

 static bool
 loader_get_linux_pci_id_for_fd(int fd, int *vendor_id, int *chip_id)
 {
    struct stat sbuf;
    if (fstat(fd, &sbuf) != 0) {
       log_(_LOADER_DEBUG, "MESA-LOADER: failed to fstat fd\n");
       return false;
    }

    int maj = major(sbuf.st_rdev);
    int min = minor(sbuf.st_rdev);

    *vendor_id = loader_get_linux_pci_field(maj, min, "vendor");
    *chip_id = loader_get_linux_pci_field(maj, min, "device");

    return *vendor_id && *chip_id;
 }
 #endif /* __linux__ */

 bool
 loader_get_pci_id_for_fd(int fd, int *vendor_id, int *chip_id)
 {
 #ifdef __linux__
    /* Implementation without causing full enumeration of DRM devices. */
    if (loader_get_linux_pci_id_for_fd(fd, vendor_id, chip_id))
       return true;
 #endif

 #if HAVE_LIBDRM
    return drm_get_pci_id_for_fd(fd, vendor_id, chip_id);
 #endif
    return false;
 }

 char *
 loader_get_device_name_for_fd(int fd)
 {
    char *result = NULL;

 #if HAVE_LIBDRM
    result = drmGetDeviceNameFromFd2(fd);
 #endif

    return result;
 }

 static char *
 loader_get_pci_driver(int fd)
 {
    int vendor_id, chip_id, i, j;
    char *driver = NULL;

    if (!loader_get_pci_id_for_fd(fd, &vendor_id, &chip_id))
       return NULL;

    for (i = 0; i < ARRAY_SIZE(driver_map); i++) {
       if (vendor_id != driver_map[i].vendor_id)
          continue;

       if (driver_map[i].predicate && !driver_map[i].predicate(fd))
          continue;

       if (driver_map[i].num_chips_ids == -1) {
          driver = strdup(driver_map[i].driver);
          goto out;
       }

       for (j = 0; j < driver_map[i].num_chips_ids; j++)
          if (driver_map[i].chip_ids[j] == chip_id) {
             driver = strdup(driver_map[i].driver);
             goto out;
          }
    }

 out:
    log_(driver ? _LOADER_DEBUG : _LOADER_WARNING,
          "pci id for fd %d: %04x:%04x, driver %s\n",
          fd, vendor_id, chip_id, driver);
    return driver;
 }

 char *
 loader_get_driver_for_fd(int fd)
 {
    char *driver;

    /* Allow an environment variable to force choosing a different driver
     * binary.  If that driver binary can't survive on this FD, that's the
     * user's problem, but this allows vc4 simulator to run on an i965 host,
     * and may be useful for some touch testing of i915 on an i965 host.
     */
    if (geteuid() == getuid()) {
       const char *override = os_get_option("MESA_LOADER_DRIVER_OVERRIDE");
       if (override)
          return strdup(override);
    }

 #if defined(HAVE_LIBDRM) && defined(USE_DRICONF)
    driver = loader_get_dri_config_driver(fd);
    if (driver)
       return driver;
 #endif

    driver = loader_get_pci_driver(fd);
    if (!driver)
       driver = loader_get_kernel_driver_name(fd);

    return driver;
 }

 void
 loader_set_logger(loader_logger *logger)
 {
    log_ = logger;
 }

 char *
 loader_get_extensions_name(const char *driver_name)
 {
    char *name = NULL;

    if (asprintf(&name, "%s_%s", __DRI_DRIVER_GET_EXTENSIONS, driver_name) < 0)
       return NULL;

    const size_t len = strlen(name);
    for (size_t i = 0; i < len; i++) {
       if (name[i] == '-')
          name[i] = '_';
    }

    return name;
 }

 /**
  * Opens a driver or backend using its name, returning the library handle.
  *
  * \param driverName - a name like "i965", "radeon", "nouveau", etc.
  * \param lib_suffix - a suffix to append to the driver name to generate the
  * full library name.
  * \param search_path_vars - NULL-terminated list of env vars that can be used
  * \param default_search_path - a colon-separted list of directories used if
  * search_path_vars is NULL or none of the vars are set in the environment.
  * \param warn_on_fail - Log a warning if the driver is not found.
  */
 void *
 loader_open_driver_lib(const char *driver_name,
                        const char *lib_suffix,
                        const char **search_path_vars,
                        const char *default_search_path,
                        bool warn_on_fail)
 {
    char path[PATH_MAX];
    const char *search_paths, *next, *end;

    search_paths = NULL;
    if (geteuid() == getuid() && search_path_vars) {
       for (int i = 0; search_path_vars[i] != NULL; i++) {
          search_paths = getenv(search_path_vars[i]);
          if (search_paths)
             break;
       }
    }
    if (search_paths == NULL)
       search_paths = default_search_path;

    void *driver = NULL;
    const char *dl_error = NULL;
    end = search_paths + strlen(search_paths);
    for (const char *p = search_paths; p < end; p = next + 1) {
       int len;
       next = strchr(p, ':');
       if (next == NULL)
          next = end;

       len = next - p;
       snprintf(path, sizeof(path), "%.*s/tls/%s%s.so", len,
                p, driver_name, lib_suffix);
       driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
       if (driver == NULL) {
          snprintf(path, sizeof(path), "%.*s/%s%s.so", len,
                   p, driver_name, lib_suffix);
          driver = dlopen(path, RTLD_NOW | RTLD_GLOBAL);
          if (driver == NULL) {
             dl_error = dlerror();
             log_(_LOADER_DEBUG, "MESA-LOADER: failed to open %s: %s\n",
                  path, dl_error);
          }
       }
       /* not need continue to loop all paths once the driver is found */
       if (driver != NULL)
          break;
    }

    if (driver == NULL) {
       if (warn_on_fail) {
          log_(_LOADER_WARNING,
               "MESA-LOADER: failed to open %s: %s (search paths %s, suffix %s)\n",
               driver_name, dl_error, search_paths, lib_suffix);
       }
       return NULL;
    }

    log_(_LOADER_DEBUG, "MESA-LOADER: dlopen(%s)\n", path);

    return driver;
 }

 /**
  * Opens a DRI driver using its driver name, returning the __DRIextension
  * entrypoints.
  *
  * \param driverName - a name like "i965", "radeon", "nouveau", etc.
  * \param out_driver - Address where the dlopen() return value will be stored.
  * \param search_path_vars - NULL-terminated list of env vars that can be used
  * to override the DEFAULT_DRIVER_DIR search path.
  */
 const struct __DRIextensionRec **
 loader_open_driver(const char *driver_name,
                    void **out_driver_handle,
                    const char **search_path_vars)
 {
    char *get_extensions_name;
    const struct __DRIextensionRec **extensions = NULL;
    const struct __DRIextensionRec **(*get_extensions)(void);
    void *driver = loader_open_driver_lib(driver_name, "_dri", search_path_vars,
                                          DEFAULT_DRIVER_DIR, true);

    if (!driver)
       goto failed;

    get_extensions_name = loader_get_extensions_name(driver_name);
    if (get_extensions_name) {
       get_extensions = dlsym(driver, get_extensions_name);
       if (get_extensions) {
          extensions = get_extensions();
       } else {
          log_(_LOADER_DEBUG, "MESA-LOADER: driver does not expose %s(): %s\n",
               get_extensions_name, dlerror());
       }
       free(get_extensions_name);
    }

    if (!extensions)
       extensions = dlsym(driver, __DRI_DRIVER_EXTENSIONS);
    if (extensions == NULL) {
       log_(_LOADER_WARNING,
            "MESA-LOADER: driver exports no extensions (%s)\n", dlerror());
       dlclose(driver);
       driver = NULL;
    }

 failed:
    *out_driver_handle = driver;
    return extensions;
 }
	/*
	* Copyright (C) 2013 Rob Clark <robclark@freedesktop.org>
	* Copyright (C) 2014-2016 Emil Velikov <emil.l.velikov@gmail.com>
	* Copyright (C) 2016 Intel Corporation
	*
	* Permission is hereby granted, free of charge, to any person obtaining a
	* copy of this software and associated documentation files (the "Software"),
	* to deal in the Software without restriction, including without limitation
	* the rights to use, copy, modify, merge, publish, distribute, sublicense,
	* and/or sell copies of the Software, and to permit persons to whom the
	* Software is furnished to do so, subject to the following conditions:
	*
	* The above copyright notice and this permission notice (including the next
	* paragraph) shall be included in all copies or substantial portions of the
	* Software.
	*
	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
	* IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
	* THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
	* LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
	* OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
	* SOFTWARE.
	*
	* Authors:
	* Rob Clark <robclark@freedesktop.org>
	*/

	#include <dlfcn.h>
	#include <errno.h>
	#include <fcntl.h>
	#include <sys/stat.h>
	#include <stdarg.h>
	#include <stdio.h>
	#include <stdbool.h>
	#include <string.h>
	#include <unistd.h>
	#include <stdlib.h>
	#include <limits.h>
	#include <sys/param.h>
	#ifdef MAJOR_IN_MKDEV
	#include <sys/mkdev.h>
	#endif
	#ifdef MAJOR_IN_SYSMACROS
	#include <sys/sysmacros.h>
	#endif
	#include <GL/gl.h>
	#include <GL/internal/dri_interface.h>
	#include "loader.h"
	#include "util/os_file.h"
	#include "util/os_misc.h"

	#ifdef HAVE_LIBDRM
	#include <xf86drm.h>
	#define MAX_DRM_DEVICES 64
	#ifdef USE_DRICONF
	#include "util/xmlconfig.h"
	#include "util/driconf.h"
	#endif
	#endif

	#include "util/macros.h"

	#define __IS_LOADER
	#include "pci_id_driver_map.h"

	/* For systems like Hurd */
	#ifndef PATH_MAX
	#define PATH_MAX 4096
	#endif

	static void default_logger(int level, const char *fmt, ...)
	{
	if (level <= _LOADER_WARNING) {
	va_list args;
	va_start(args, fmt);
	vfprintf(stderr, fmt, args);
	va_end(args);
	}
	}

	static loader_logger *log_ = default_logger;

	int
	loader_open_device(const char *device_name)
	{
	int fd;
	#ifdef O_CLOEXEC
	fd = open(device_name, O_RDWR \| O_CLOEXEC);
	if (fd == -1 && errno == EINVAL)
	#endif
	{
	fd = open(device_name, O_RDWR);
	if (fd != -1)
	fcntl(fd, F_SETFD, fcntl(fd, F_GETFD) \| FD_CLOEXEC);
	}
	if (fd == -1 && errno == EACCES) {
	log_(_LOADER_WARNING, "failed to open %s: %s\n",
	device_name, strerror(errno));
	}
	return fd;
	}

	static char *loader_get_kernel_driver_name(int fd)
	{
	#if HAVE_LIBDRM
	char *driver;
	drmVersionPtr version = drmGetVersion(fd);

	if (!version) {
	log_(_LOADER_WARNING, "failed to get driver name for fd %d\n", fd);
	return NULL;
	}

	driver = strndup(version->name, version->name_len);
	log_(driver ? _LOADER_DEBUG : _LOADER_WARNING, "using driver %s for %d\n",
	driver, fd);

	drmFreeVersion(version);
	return driver;
	#else
	return NULL;
	#endif
	}

	bool
	is_kernel_i915(int fd)
	{
	char *kernel_driver = loader_get_kernel_driver_name(fd);
	bool is_i915 = kernel_driver && strcmp(kernel_driver, "i915") == 0;

	free(kernel_driver);
	return is_i915;
	}

	#if defined(HAVE_LIBDRM)
	int
	loader_open_render_node(const char *name)
	{
	drmDevicePtr devices[MAX_DRM_DEVICES], device;
	int i, num_devices, fd = -1;

	num_devices = drmGetDevices2(0, devices, MAX_DRM_DEVICES);
	if (num_devices <= 0)
	return -ENOENT;

	for (i = 0; i < num_devices; i++) {
	device = devices[i];

	if ((device->available_nodes & (1 << DRM_NODE_RENDER)) &&
	(device->bustype == DRM_BUS_PLATFORM)) {
	drmVersionPtr version;

	fd = loader_open_device(device->nodes[DRM_NODE_RENDER]);
	if (fd < 0)
	continue;

	version = drmGetVersion(fd);
	if (!version) {
	close(fd);
	continue;
	}

	if (strcmp(version->name, name) != 0) {
	drmFreeVersion(version);
	close(fd);
	continue;
	}

	drmFreeVersion(version);
	break;
	}
	}
	drmFreeDevices(devices, num_devices);

	if (i == num_devices)
	return -ENOENT;

	return fd;
	}

	char *
	loader_get_render_node(dev_t device)
	{
	char *render_node = NULL;
	drmDevicePtr dev_ptr;

	if (drmGetDeviceFromDevId(device, 0, &dev_ptr) < 0)
	return NULL;

	if (dev_ptr->available_nodes & (1 << DRM_NODE_RENDER)) {
	render_node = strdup(dev_ptr->nodes[DRM_NODE_RENDER]);
	if (!render_node)
	log_(_LOADER_DEBUG, "MESA-LOADER: failed to allocate memory for render node\n");
	}

	drmFreeDevice(&dev_ptr);

	return render_node;
	}

	#ifdef USE_DRICONF
	static const driOptionDescription __driConfigOptionsLoader[] = {
	DRI_CONF_SECTION_INITIALIZATION
	DRI_CONF_DEVICE_ID_PATH_TAG()
	DRI_CONF_DRI_DRIVER()
	DRI_CONF_SECTION_END
	};

	static char *loader_get_dri_config_driver(int fd)
	{
	driOptionCache defaultInitOptions;
	driOptionCache userInitOptions;
	char *dri_driver = NULL;
	char *kernel_driver = loader_get_kernel_driver_name(fd);

	driParseOptionInfo(&defaultInitOptions, __driConfigOptionsLoader,
	ARRAY_SIZE(__driConfigOptionsLoader));
	driParseConfigFiles(&userInitOptions, &defaultInitOptions, 0,
	"loader", kernel_driver, NULL, NULL, 0, NULL, 0);
	if (driCheckOption(&userInitOptions, "dri_driver", DRI_STRING)) {
	char *opt = driQueryOptionstr(&userInitOptions, "dri_driver");
	/* not an empty string */
	if (*opt)
	dri_driver = strdup(opt);
	}
	driDestroyOptionCache(&userInitOptions);
	driDestroyOptionInfo(&defaultInitOptions);

	free(kernel_driver);
	return dri_driver;
	}

	static char *loader_get_dri_config_device_id(void)
	{
	driOptionCache defaultInitOptions;
	driOptionCache userInitOptions;
	char *prime = NULL;

	driParseOptionInfo(&defaultInitOptions, __driConfigOptionsLoader,
	ARRAY_SIZE(__driConfigOptionsLoader));
	driParseConfigFiles(&userInitOptions, &defaultInitOptions, 0,
	"loader", NULL, NULL, NULL, 0, NULL, 0);
	if (driCheckOption(&userInitOptions, "device_id", DRI_STRING)) {
	char *opt = driQueryOptionstr(&userInitOptions, "device_id");
	if (*opt)
	prime = strdup(opt);
	}
	driDestroyOptionCache(&userInitOptions);
	driDestroyOptionInfo(&defaultInitOptions);

	return prime;
	}
	#endif

	static char *drm_construct_id_path_tag(drmDevicePtr device)
	{
	char *tag = NULL;

	if (device->bustype == DRM_BUS_PCI) {
	if (asprintf(&tag, "pci-%04x_%02x_%02x_%1u",
	device->businfo.pci->domain,
	device->businfo.pci->bus,
	device->businfo.pci->dev,
	device->businfo.pci->func) < 0) {
	return NULL;
	}
	} else if (device->bustype == DRM_BUS_PLATFORM \|\|
	device->bustype == DRM_BUS_HOST1X) {
	char fullname, name, *address;

	if (device->bustype == DRM_BUS_PLATFORM)
	fullname = device->businfo.platform->fullname;
	else
	fullname = device->businfo.host1x->fullname;

	name = strrchr(fullname, '/');
	if (!name)
	name = strdup(fullname);
	else
	name = strdup(name + 1);

	address = strchr(name, '@');
	if (address) {
	*address++ = '\0';

	if (asprintf(&tag, "platform-%s_%s", address, name) < 0)
	tag = NULL;
	} else {
	if (asprintf(&tag, "platform-%s", name) < 0)
	tag = NULL;
	}

	free(name);
	}
	return tag;
	}

	static bool drm_device_matches_tag(drmDevicePtr device, const char *prime_tag)
	{
	char *tag = drm_construct_id_path_tag(device);
	int ret;

	if (tag == NULL)
	return false;

	ret = strcmp(tag, prime_tag);

	free(tag);
	return ret == 0;
	}

	static char *drm_get_id_path_tag_for_fd(int fd)
	{
	drmDevicePtr device;
	char *tag;

	if (drmGetDevice2(fd, 0, &device) != 0)
	return NULL;

	tag = drm_construct_id_path_tag(device);
	drmFreeDevice(&device);
	return tag;
	}

	int loader_get_user_preferred_fd(int default_fd, bool *different_device)
	{
	const char *dri_prime = getenv("DRI_PRIME");
	char default_tag, prime = NULL;
	drmDevicePtr devices[MAX_DRM_DEVICES];
	int i, num_devices, fd = -1;
	bool prime_is_vid_did;
	uint16_t vendor_id, device_id;

	if (dri_prime)
	prime = strdup(dri_prime);
	#ifdef USE_DRICONF
	else
	prime = loader_get_dri_config_device_id();
	#endif

	if (prime == NULL) {
	*different_device = false;
	return default_fd;
	} else {
	prime_is_vid_did = sscanf(prime, "%hx:%hx", &vendor_id, &device_id) == 2;
	}

	default_tag = drm_get_id_path_tag_for_fd(default_fd);
	if (default_tag == NULL)
	goto err;

	num_devices = drmGetDevices2(0, devices, MAX_DRM_DEVICES);
	if (num_devices <= 0)
	goto err;

	for (i = 0; i < num_devices; i++) {
	if (!(devices[i]->available_nodes & 1 << DRM_NODE_RENDER))
	continue;

	/* three formats of DRI_PRIME are supported:
	* "1": choose any other card than the card used by default.
	* id_path_tag: (for example "pci-0000_02_00_0") choose the card
	* with this id_path_tag.
	* vendor_id:device_id
	*/
	if (!strcmp(prime,"1")) {
	if (drm_device_matches_tag(devices[i], default_tag))
	continue;
	} else {
	if (prime_is_vid_did && devices[i]->bustype == DRM_BUS_PCI &&
	devices[i]->deviceinfo.pci->vendor_id == vendor_id &&
	devices[i]->deviceinfo.pci->device_id == device_id) {
	/* Update prime for the "different_device"
	* determination below. */
	free(prime);
	prime = drm_construct_id_path_tag(devices[i]);
	} else {
	if (!drm_device_matches_tag(devices[i], prime))
	continue;
	}
	}

	fd = loader_open_device(devices[i]->nodes[DRM_NODE_RENDER]);
	break;
	}
	drmFreeDevices(devices, num_devices);

	if (i == num_devices)
	goto err;

	if (fd < 0)
	goto err;

	close(default_fd);

	*different_device = !!strcmp(default_tag, prime);

	free(default_tag);
	free(prime);
	return fd;

	err:
	*different_device = false;

	free(default_tag);
	free(prime);
	return default_fd;
	}
	#else
	int
	loader_open_render_node(const char *name)
	{
	return -1;
	}

	char *
	loader_get_render_node(dev_t device)
	{
	return NULL;
	}

	int loader_get_user_preferred_fd(int default_fd, bool *different_device)
	{
	*different_device = false;
	return default_fd;
	}
	#endif

	#if defined(HAVE_LIBDRM)

	static bool
	drm_get_pci_id_for_fd(int fd, int vendor_id, int chip_id)
	{
	drmDevicePtr device;

	if (drmGetDevice2(fd, 0, &device) != 0) {
	log_(_LOADER_WARNING, "MESA-LOADER: failed to retrieve device information\n");
	return false;
	}

	if (device->bustype != DRM_BUS_PCI) {
	drmFreeDevice(&device);
	log_(_LOADER_DEBUG, "MESA-LOADER: device is not located on the PCI bus\n");
	return false;
	}

	*vendor_id = device->deviceinfo.pci->vendor_id;
	*chip_id = device->deviceinfo.pci->device_id;
	drmFreeDevice(&device);
	return true;
	}
	#endif

	#ifdef __linux__
	static int loader_get_linux_pci_field(int maj, int min, const char *field)
	{
	char path[PATH_MAX + 1];
	snprintf(path, sizeof(path), "/sys/dev/char/%d:%d/device/%s", maj, min, field);

	char *field_str = os_read_file(path, NULL);
	if (!field_str) {
	/* Probably non-PCI device. */
	return 0;
	}

	int value = (int)strtoll(field_str, NULL, 16);
	free(field_str);

	return value;
	}

	static bool
	loader_get_linux_pci_id_for_fd(int fd, int vendor_id, int chip_id)
	{
	struct stat sbuf;
	if (fstat(fd, &sbuf) != 0) {
	log_(_LOADER_DEBUG, "MESA-LOADER: failed to fstat fd\n");
	return false;
	}

	int maj = major(sbuf.st_rdev);
	int min = minor(sbuf.st_rdev);

	*vendor_id = loader_get_linux_pci_field(maj, min, "vendor");
	*chip_id = loader_get_linux_pci_field(maj, min, "device");

	return vendor_id && chip_id;
	}
	#endif /* __linux__ */

	bool
	loader_get_pci_id_for_fd(int fd, int vendor_id, int chip_id)
	{
	#ifdef __linux__
	/* Implementation without causing full enumeration of DRM devices. */
	if (loader_get_linux_pci_id_for_fd(fd, vendor_id, chip_id))
	return true;
	#endif

	#if HAVE_LIBDRM
	return drm_get_pci_id_for_fd(fd, vendor_id, chip_id);
	#endif
	return false;
	}

	char *
	loader_get_device_name_for_fd(int fd)
	{
	char *result = NULL;

	#if HAVE_LIBDRM
	result = drmGetDeviceNameFromFd2(fd);
	#endif

	return result;
	}

	static char *
	loader_get_pci_driver(int fd)
	{
	int vendor_id, chip_id, i, j;
	char *driver = NULL;

	if (!loader_get_pci_id_for_fd(fd, &vendor_id, &chip_id))
	return NULL;

	for (i = 0; i < ARRAY_SIZE(driver_map); i++) {
	if (vendor_id != driver_map[i].vendor_id)
	continue;

	if (driver_map[i].predicate && !driver_map[i].predicate(fd))
	continue;

	if (driver_map[i].num_chips_ids == -1) {
	driver = strdup(driver_map[i].driver);
	goto out;
	}

	for (j = 0; j < driver_map[i].num_chips_ids; j++)
	if (driver_map[i].chip_ids[j] == chip_id) {
	driver = strdup(driver_map[i].driver);
	goto out;
	}
	}

	out:
	log_(driver ? _LOADER_DEBUG : _LOADER_WARNING,
	"pci id for fd %d: %04x:%04x, driver %s\n",
	fd, vendor_id, chip_id, driver);
	return driver;
	}

	char *
	loader_get_driver_for_fd(int fd)
	{
	char *driver;

	/* Allow an environment variable to force choosing a different driver
	* binary. If that driver binary can't survive on this FD, that's the
	* user's problem, but this allows vc4 simulator to run on an i965 host,
	* and may be useful for some touch testing of i915 on an i965 host.
	*/
	if (geteuid() == getuid()) {
	const char *override = os_get_option("MESA_LOADER_DRIVER_OVERRIDE");
	if (override)
	return strdup(override);
	}

	#if defined(HAVE_LIBDRM) && defined(USE_DRICONF)
	driver = loader_get_dri_config_driver(fd);
	if (driver)
	return driver;
	#endif

	driver = loader_get_pci_driver(fd);
	if (!driver)
	driver = loader_get_kernel_driver_name(fd);

	return driver;
	}

	void
	loader_set_logger(loader_logger *logger)
	{
	log_ = logger;
	}

	char *
	loader_get_extensions_name(const char *driver_name)
	{
	char *name = NULL;

	if (asprintf(&name, "%s_%s", __DRI_DRIVER_GET_EXTENSIONS, driver_name) < 0)
	return NULL;

	const size_t len = strlen(name);
	for (size_t i = 0; i < len; i++) {
	if (name[i] == '-')
	name[i] = '_';
	}

	return name;
	}

	/**
	* Opens a driver or backend using its name, returning the library handle.
	*
	* \param driverName - a name like "i965", "radeon", "nouveau", etc.
	* \param lib_suffix - a suffix to append to the driver name to generate the
	* full library name.
	* \param search_path_vars - NULL-terminated list of env vars that can be used
	* \param default_search_path - a colon-separted list of directories used if
	* search_path_vars is NULL or none of the vars are set in the environment.
	* \param warn_on_fail - Log a warning if the driver is not found.
	*/
	void *
	loader_open_driver_lib(const char *driver_name,
	const char *lib_suffix,
	const char **search_path_vars,
	const char *default_search_path,
	bool warn_on_fail)
	{
	char path[PATH_MAX];
	const char search_paths, next, *end;

	search_paths = NULL;
	if (geteuid() == getuid() && search_path_vars) {
	for (int i = 0; search_path_vars[i] != NULL; i++) {
	search_paths = getenv(search_path_vars[i]);
	if (search_paths)
	break;
	}
	}
	if (search_paths == NULL)
	search_paths = default_search_path;

	void *driver = NULL;
	const char *dl_error = NULL;
	end = search_paths + strlen(search_paths);
	for (const char *p = search_paths; p < end; p = next + 1) {
	int len;
	next = strchr(p, ':');
	if (next == NULL)
	next = end;

	len = next - p;
	snprintf(path, sizeof(path), "%.*s/tls/%s%s.so", len,
	p, driver_name, lib_suffix);
	driver = dlopen(path, RTLD_NOW \| RTLD_GLOBAL);
	if (driver == NULL) {
	snprintf(path, sizeof(path), "%.*s/%s%s.so", len,
	p, driver_name, lib_suffix);
	driver = dlopen(path, RTLD_NOW \| RTLD_GLOBAL);
	if (driver == NULL) {
	dl_error = dlerror();
	log_(_LOADER_DEBUG, "MESA-LOADER: failed to open %s: %s\n",
	path, dl_error);
	}
	}
	/* not need continue to loop all paths once the driver is found */
	if (driver != NULL)
	break;
	}

	if (driver == NULL) {
	if (warn_on_fail) {
	log_(_LOADER_WARNING,
	"MESA-LOADER: failed to open %s: %s (search paths %s, suffix %s)\n",
	driver_name, dl_error, search_paths, lib_suffix);
	}
	return NULL;
	}

	log_(_LOADER_DEBUG, "MESA-LOADER: dlopen(%s)\n", path);

	return driver;
	}

	/**
	* Opens a DRI driver using its driver name, returning the __DRIextension
	* entrypoints.
	*
	* \param driverName - a name like "i965", "radeon", "nouveau", etc.
	* \param out_driver - Address where the dlopen() return value will be stored.
	* \param search_path_vars - NULL-terminated list of env vars that can be used
	* to override the DEFAULT_DRIVER_DIR search path.
	*/
	const struct __DRIextensionRec **
	loader_open_driver(const char *driver_name,
	void **out_driver_handle,
	const char **search_path_vars)
	{
	char *get_extensions_name;
	const struct __DRIextensionRec **extensions = NULL;
	const struct __DRIextensionRec *(get_extensions)(void);
	void *driver = loader_open_driver_lib(driver_name, "_dri", search_path_vars,
	DEFAULT_DRIVER_DIR, true);

	if (!driver)
	goto failed;

	get_extensions_name = loader_get_extensions_name(driver_name);
	if (get_extensions_name) {
	get_extensions = dlsym(driver, get_extensions_name);
	if (get_extensions) {
	extensions = get_extensions();
	} else {
	log_(_LOADER_DEBUG, "MESA-LOADER: driver does not expose %s(): %s\n",
	get_extensions_name, dlerror());
	}
	free(get_extensions_name);
	}

	if (!extensions)
	extensions = dlsym(driver, __DRI_DRIVER_EXTENSIONS);
	if (extensions == NULL) {
	log_(_LOADER_WARNING,
	"MESA-LOADER: driver exports no extensions (%s)\n", dlerror());
	dlclose(driver);
	driver = NULL;
	}

	failed:
	*out_driver_handle = driver;
	return extensions;
	}