src/util/disk_cache_os.c - platform/external/mesa3d - Git at Google

 /*
  * Copyright © 2014 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.
  */

 #ifdef ENABLE_SHADER_CACHE

 #include <assert.h>
 #include <stddef.h>
 #include <stdlib.h>

 #include "zlib.h"

 #ifdef HAVE_ZSTD
 #include "zstd.h"
 #endif

 /* 3 is the recomended level, with 22 as the absolute maximum */
 #define ZSTD_COMPRESSION_LEVEL 3

 /* From the zlib docs:
  *    "If the memory is available, buffers sizes on the order of 128K or 256K
  *    bytes should be used."
  */
 #define BUFSIZE 256 * 1024

 static ssize_t
 write_all(int fd, const void *buf, size_t count);

 /**
  * Compresses cache entry in memory and writes it to disk. Returns the size
  * of the data written to disk.
  */
 static size_t
 deflate_and_write_to_disk(const void *in_data, size_t in_data_size, int dest,
                           const char *filename)
 {
 #ifdef HAVE_ZSTD
    /* from the zstd docs (https://facebook.github.io/zstd/zstd_manual.html):
     * compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
     */
    size_t out_size = ZSTD_compressBound(in_data_size);
    void * out = malloc(out_size);

    size_t ret = ZSTD_compress(out, out_size, in_data, in_data_size,
                               ZSTD_COMPRESSION_LEVEL);
    if (ZSTD_isError(ret)) {
       free(out);
       return 0;
    }
    ssize_t written = write_all(dest, out, ret);
    if (written == -1) {
       free(out);
       return 0;
    }
    free(out);
    return ret;
 #else
    unsigned char *out;

    /* allocate deflate state */
    z_stream strm;
    strm.zalloc = Z_NULL;
    strm.zfree = Z_NULL;
    strm.opaque = Z_NULL;
    strm.next_in = (uint8_t *) in_data;
    strm.avail_in = in_data_size;

    int ret = deflateInit(&strm, Z_BEST_COMPRESSION);
    if (ret != Z_OK)
        return 0;

    /* compress until end of in_data */
    size_t compressed_size = 0;
    int flush;

    out = malloc(BUFSIZE * sizeof(unsigned char));
    if (out == NULL)
       return 0;

    do {
       int remaining = in_data_size - BUFSIZE;
       flush = remaining > 0 ? Z_NO_FLUSH : Z_FINISH;
       in_data_size -= BUFSIZE;

       /* Run deflate() on input until the output buffer is not full (which
        * means there is no more data to deflate).
        */
       do {
          strm.avail_out = BUFSIZE;
          strm.next_out = out;

          ret = deflate(&strm, flush);    /* no bad return value */
          assert(ret != Z_STREAM_ERROR);  /* state not clobbered */

          size_t have = BUFSIZE - strm.avail_out;
          compressed_size += have;

          ssize_t written = write_all(dest, out, have);
          if (written == -1) {
             (void)deflateEnd(&strm);
             free(out);
             return 0;
          }
       } while (strm.avail_out == 0);

       /* all input should be used */
       assert(strm.avail_in == 0);

    } while (flush != Z_FINISH);

    /* stream should be complete */
    assert(ret == Z_STREAM_END);

    /* clean up and return */
    (void)deflateEnd(&strm);
    free(out);
    return compressed_size;
 # endif
 }

 #if DETECT_OS_WINDOWS
 /* TODO: implement disk cache support on windows */

 #else

 #include <dirent.h>
 #include <errno.h>
 #include <inttypes.h>
 #include <pwd.h>
 #include <stdio.h>
 #include <string.h>
 #include <sys/file.h>
 #include <sys/mman.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <unistd.h>

 #include "util/debug.h"
 #include "util/disk_cache.h"
 #include "util/disk_cache_os.h"
 #include "util/ralloc.h"
 #include "util/rand_xor.h"

 /* Create a directory named 'path' if it does not already exist.
  *
  * Returns: 0 if path already exists as a directory or if created.
  *         -1 in all other cases.
  */
 static int
 mkdir_if_needed(const char *path)
 {
    struct stat sb;

    /* If the path exists already, then our work is done if it's a
     * directory, but it's an error if it is not.
     */
    if (stat(path, &sb) == 0) {
       if (S_ISDIR(sb.st_mode)) {
          return 0;
       } else {
          fprintf(stderr, "Cannot use %s for shader cache (not a directory)"
                          "---disabling.\n", path);
          return -1;
       }
    }

    int ret = mkdir(path, 0755);
    if (ret == 0 || (ret == -1 && errno == EEXIST))
      return 0;

    fprintf(stderr, "Failed to create %s for shader cache (%s)---disabling.\n",
            path, strerror(errno));

    return -1;
 }

 /* Concatenate an existing path and a new name to form a new path.  If the new
  * path does not exist as a directory, create it then return the resulting
  * name of the new path (ralloc'ed off of 'ctx').
  *
  * Returns NULL on any error, such as:
  *
  *      <path> does not exist or is not a directory
  *      <path>/<name> exists but is not a directory
  *      <path>/<name> cannot be created as a directory
  */
 static char *
 concatenate_and_mkdir(void *ctx, const char *path, const char *name)
 {
    char *new_path;
    struct stat sb;

    if (stat(path, &sb) != 0 || ! S_ISDIR(sb.st_mode))
       return NULL;

    new_path = ralloc_asprintf(ctx, "%s/%s", path, name);

    if (mkdir_if_needed(new_path) == 0)
       return new_path;
    else
       return NULL;
 }

 /* Given a directory path and predicate function, find the entry with
  * the oldest access time in that directory for which the predicate
  * returns true.
  *
  * Returns: A malloc'ed string for the path to the chosen file, (or
  * NULL on any error). The caller should free the string when
  * finished.
  */
 static char *
 choose_lru_file_matching(const char *dir_path,
                          bool (*predicate)(const char *dir_path,
                                            const struct stat *,
                                            const char *, const size_t))
 {
    DIR *dir;
    struct dirent *entry;
    char *filename;
    char *lru_name = NULL;
    time_t lru_atime = 0;

    dir = opendir(dir_path);
    if (dir == NULL)
       return NULL;

    while (1) {
       entry = readdir(dir);
       if (entry == NULL)
          break;

       struct stat sb;
       if (fstatat(dirfd(dir), entry->d_name, &sb, 0) == 0) {
          if (!lru_atime || (sb.st_atime < lru_atime)) {
             size_t len = strlen(entry->d_name);

             if (!predicate(dir_path, &sb, entry->d_name, len))
                continue;

             char *tmp = realloc(lru_name, len + 1);
             if (tmp) {
                lru_name = tmp;
                memcpy(lru_name, entry->d_name, len + 1);
                lru_atime = sb.st_atime;
             }
          }
       }
    }

    if (lru_name == NULL) {
       closedir(dir);
       return NULL;
    }

    if (asprintf(&filename, "%s/%s", dir_path, lru_name) < 0)
       filename = NULL;

    free(lru_name);
    closedir(dir);

    return filename;
 }

 /* Is entry a regular file, and not having a name with a trailing
  * ".tmp"
  */
 static bool
 is_regular_non_tmp_file(const char *path, const struct stat *sb,
                         const char *d_name, const size_t len)
 {
    if (!S_ISREG(sb->st_mode))
       return false;

    if (len >= 4 && strcmp(&d_name[len-4], ".tmp") == 0)
       return false;

    return true;
 }

 /* Returns the size of the deleted file, (or 0 on any error). */
 static size_t
 unlink_lru_file_from_directory(const char *path)
 {
    struct stat sb;
    char *filename;

    filename = choose_lru_file_matching(path, is_regular_non_tmp_file);
    if (filename == NULL)
       return 0;

    if (stat(filename, &sb) == -1) {
       free (filename);
       return 0;
    }

    unlink(filename);
    free (filename);

    return sb.st_blocks * 512;
 }

 /* Is entry a directory with a two-character name, (and not the
  * special name of ".."). We also return false if the dir is empty.
  */
 static bool
 is_two_character_sub_directory(const char *path, const struct stat *sb,
                                const char *d_name, const size_t len)
 {
    if (!S_ISDIR(sb->st_mode))
       return false;

    if (len != 2)
       return false;

    if (strcmp(d_name, "..") == 0)
       return false;

    char *subdir;
    if (asprintf(&subdir, "%s/%s", path, d_name) == -1)
       return false;
    DIR *dir = opendir(subdir);
    free(subdir);

    if (dir == NULL)
      return false;

    unsigned subdir_entries = 0;
    struct dirent *d;
    while ((d = readdir(dir)) != NULL) {
       if(++subdir_entries > 2)
          break;
    }
    closedir(dir);

    /* If dir only contains '.' and '..' it must be empty */
    if (subdir_entries <= 2)
       return false;

    return true;
 }

 /* Create the directory that will be needed for the cache file for \key.
  *
  * Obviously, the implementation here must closely match
  * _get_cache_file above.
 */
 static void
 make_cache_file_directory(struct disk_cache *cache, const cache_key key)
 {
    char *dir;
    char buf[41];

    _mesa_sha1_format(buf, key);
    if (asprintf(&dir, "%s/%c%c", cache->path, buf[0], buf[1]) == -1)
       return;

    mkdir_if_needed(dir);
    free(dir);
 }

 static ssize_t
 write_all(int fd, const void *buf, size_t count)
 {
    const char *out = buf;
    ssize_t written;
    size_t done;

    for (done = 0; done < count; done += written) {
       written = write(fd, out + done, count - done);
       if (written == -1)
          return -1;
    }
    return done;
 }

 /* Evict least recently used cache item */
 void
 disk_cache_evict_lru_item(struct disk_cache *cache)
 {
    char *dir_path;

    /* With a reasonably-sized, full cache, (and with keys generated
     * from a cryptographic hash), we can choose two random hex digits
     * and reasonably expect the directory to exist with a file in it.
     * Provides pseudo-LRU eviction to reduce checking all cache files.
     */
    uint64_t rand64 = rand_xorshift128plus(cache->seed_xorshift128plus);
    if (asprintf(&dir_path, "%s/%02" PRIx64 , cache->path, rand64 & 0xff) < 0)
       return;

    size_t size = unlink_lru_file_from_directory(dir_path);

    free(dir_path);

    if (size) {
       p_atomic_add(cache->size, - (uint64_t)size);
       return;
    }

    /* In the case where the random choice of directory didn't find
     * something, we choose the least recently accessed from the
     * existing directories.
     *
     * Really, the only reason this code exists is to allow the unit
     * tests to work, (which use an artificially-small cache to be able
     * to force a single cached item to be evicted).
     */
    dir_path = choose_lru_file_matching(cache->path,
                                        is_two_character_sub_directory);
    if (dir_path == NULL)
       return;

    size = unlink_lru_file_from_directory(dir_path);

    free(dir_path);

    if (size)
       p_atomic_add(cache->size, - (uint64_t)size);
 }

 void
 disk_cache_write_item_to_disk(struct disk_cache_put_job *dc_job,
                               struct cache_entry_file_data *cf_data,
                               char *filename)
 {
    int fd = -1, fd_final = -1;

    /* Write to a temporary file to allow for an atomic rename to the
     * final destination filename, (to prevent any readers from seeing
     * a partially written file).
     */
    char *filename_tmp = NULL;
    if (asprintf(&filename_tmp, "%s.tmp", filename) == -1)
       goto done;

    fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);

    /* Make the two-character subdirectory within the cache as needed. */
    if (fd == -1) {
       if (errno != ENOENT)
          goto done;

       make_cache_file_directory(dc_job->cache, dc_job->key);

       fd = open(filename_tmp, O_WRONLY | O_CLOEXEC | O_CREAT, 0644);
       if (fd == -1)
          goto done;
    }

    /* With the temporary file open, we take an exclusive flock on
     * it. If the flock fails, then another process still has the file
     * open with the flock held. So just let that file be responsible
     * for writing the file.
     */
 #ifdef HAVE_FLOCK
    int err = flock(fd, LOCK_EX | LOCK_NB);
 #else
    struct flock lock = {
       .l_start = 0,
       .l_len = 0, /* entire file */
       .l_type = F_WRLCK,
       .l_whence = SEEK_SET
    };
    int err = fcntl(fd, F_SETLK, &lock);
 #endif
    if (err == -1)
       goto done;

    /* Now that we have the lock on the open temporary file, we can
     * check to see if the destination file already exists. If so,
     * another process won the race between when we saw that the file
     * didn't exist and now. In this case, we don't do anything more,
     * (to ensure the size accounting of the cache doesn't get off).
     */
    fd_final = open(filename, O_RDONLY | O_CLOEXEC);
    if (fd_final != -1) {
       unlink(filename_tmp);
       goto done;
    }

    /* OK, we're now on the hook to write out a file that we know is
     * not in the cache, and is also not being written out to the cache
     * by some other process.
     */

    /* Write the driver_keys_blob, this can be used find information about the
     * mesa version that produced the entry or deal with hash collisions,
     * should that ever become a real problem.
     */
    int ret = write_all(fd, dc_job->cache->driver_keys_blob,
                        dc_job->cache->driver_keys_blob_size);
    if (ret == -1) {
       unlink(filename_tmp);
       goto done;
    }

    /* Write the cache item metadata. This data can be used to deal with
     * hash collisions, as well as providing useful information to 3rd party
     * tools reading the cache files.
     */
    ret = write_all(fd, &dc_job->cache_item_metadata.type,
                    sizeof(uint32_t));
    if (ret == -1) {
       unlink(filename_tmp);
       goto done;
    }

    if (dc_job->cache_item_metadata.type == CACHE_ITEM_TYPE_GLSL) {
       ret = write_all(fd, &dc_job->cache_item_metadata.num_keys,
                       sizeof(uint32_t));
       if (ret == -1) {
          unlink(filename_tmp);
          goto done;
       }

       ret = write_all(fd, dc_job->cache_item_metadata.keys[0],
                       dc_job->cache_item_metadata.num_keys *
                       sizeof(cache_key));
       if (ret == -1) {
          unlink(filename_tmp);
          goto done;
       }
    }

    size_t cf_data_size = sizeof(*cf_data);
    ret = write_all(fd, cf_data, cf_data_size);
    if (ret == -1) {
       unlink(filename_tmp);
       goto done;
    }

    /* Now, finally, write out the contents to the temporary file, then
     * rename them atomically to the destination filename, and also
     * perform an atomic increment of the total cache size.
     */
    size_t file_size = deflate_and_write_to_disk(dc_job->data, dc_job->size,
                                                 fd, filename_tmp);
    if (file_size == 0) {
       unlink(filename_tmp);
       goto done;
    }
    ret = rename(filename_tmp, filename);
    if (ret == -1) {
       unlink(filename_tmp);
       goto done;
    }

    struct stat sb;
    if (stat(filename, &sb) == -1) {
       /* Something went wrong remove the file */
       unlink(filename);
       goto done;
    }

    p_atomic_add(dc_job->cache->size, sb.st_blocks * 512);

  done:
    if (fd_final != -1)
       close(fd_final);
    /* This close finally releases the flock, (now that the final file
     * has been renamed into place and the size has been added).
     */
    if (fd != -1)
       close(fd);
    free(filename_tmp);
 }

 /* Determine path for cache based on the first defined name as follows:
  *
  *   $MESA_GLSL_CACHE_DIR
  *   $XDG_CACHE_HOME/mesa_shader_cache
  *   <pwd.pw_dir>/.cache/mesa_shader_cache
  */
 char *
 disk_cache_generate_cache_dir(void *mem_ctx)
 {
    char *path = getenv("MESA_GLSL_CACHE_DIR");
    if (path) {
       if (mkdir_if_needed(path) == -1)
          return NULL;

       path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
       if (!path)
          return NULL;
    }

    if (path == NULL) {
       char *xdg_cache_home = getenv("XDG_CACHE_HOME");

       if (xdg_cache_home) {
          if (mkdir_if_needed(xdg_cache_home) == -1)
             return NULL;

          path = concatenate_and_mkdir(mem_ctx, xdg_cache_home, CACHE_DIR_NAME);
          if (!path)
             return NULL;
       }
    }

    if (!path) {
       char *buf;
       size_t buf_size;
       struct passwd pwd, *result;

       buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
       if (buf_size == -1)
          buf_size = 512;

       /* Loop until buf_size is large enough to query the directory */
       while (1) {
          buf = ralloc_size(mem_ctx, buf_size);

          getpwuid_r(getuid(), &pwd, buf, buf_size, &result);
          if (result)
             break;

          if (errno == ERANGE) {
             ralloc_free(buf);
             buf = NULL;
             buf_size *= 2;
          } else {
             return NULL;
          }
       }

       path = concatenate_and_mkdir(mem_ctx, pwd.pw_dir, ".cache");
       if (!path)
          return NULL;

       path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
       if (!path)
          return NULL;
    }

    return path;
 }

 bool
 disk_cache_enabled()
 {
    /* If running as a users other than the real user disable cache */
    if (geteuid() != getuid())
       return false;

    /* At user request, disable shader cache entirely. */
    if (env_var_as_boolean("MESA_GLSL_CACHE_DISABLE", false))
       return false;

    return true;
 }

 bool
 disk_cache_mmap_cache_index(void *mem_ctx, struct disk_cache *cache,
                             char *path)
 {
    int fd = -1;
    bool mapped = false;

    cache->path = ralloc_strdup(cache, path);
    if (cache->path == NULL)
       goto path_fail;

    path = ralloc_asprintf(mem_ctx, "%s/index", cache->path);
    if (path == NULL)
       goto path_fail;

    fd = open(path, O_RDWR | O_CREAT | O_CLOEXEC, 0644);
    if (fd == -1)
       goto path_fail;

    struct stat sb;
    if (fstat(fd, &sb) == -1)
       goto path_fail;

    /* Force the index file to be the expected size. */
    size_t size = sizeof(*cache->size) + CACHE_INDEX_MAX_KEYS * CACHE_KEY_SIZE;
    if (sb.st_size != size) {
       if (ftruncate(fd, size) == -1)
          goto path_fail;
    }

    /* We map this shared so that other processes see updates that we
     * make.
     *
     * Note: We do use atomic addition to ensure that multiple
     * processes don't scramble the cache size recorded in the
     * index. But we don't use any locking to prevent multiple
     * processes from updating the same entry simultaneously. The idea
     * is that if either result lands entirely in the index, then
     * that's equivalent to a well-ordered write followed by an
     * eviction and a write. On the other hand, if the simultaneous
     * writes result in a corrupt entry, that's not really any
     * different than both entries being evicted, (since within the
     * guarantees of the cryptographic hash, a corrupt entry is
     * unlikely to ever match a real cache key).
     */
    cache->index_mmap = mmap(NULL, size, PROT_READ | PROT_WRITE,
                             MAP_SHARED, fd, 0);
    if (cache->index_mmap == MAP_FAILED)
       goto path_fail;
    cache->index_mmap_size = size;

    cache->size = (uint64_t *) cache->index_mmap;
    cache->stored_keys = cache->index_mmap + sizeof(uint64_t);
    mapped = true;

 path_fail:
    if (fd != -1)
       close(fd);

    return mapped;
 }

 void
 disk_cache_destroy_mmap(struct disk_cache *cache)
 {
    munmap(cache->index_mmap, cache->index_mmap_size);
 }
 #endif

 #endif /* ENABLE_SHADER_CACHE */
	/*
	* Copyright © 2014 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.
	*/

	#ifdef ENABLE_SHADER_CACHE

	#include <assert.h>
	#include <stddef.h>
	#include <stdlib.h>

	#include "zlib.h"

	#ifdef HAVE_ZSTD
	#include "zstd.h"
	#endif

	/* 3 is the recomended level, with 22 as the absolute maximum */
	#define ZSTD_COMPRESSION_LEVEL 3

	/* From the zlib docs:
	* "If the memory is available, buffers sizes on the order of 128K or 256K
	* bytes should be used."
	*/
	#define BUFSIZE 256 * 1024

	static ssize_t
	write_all(int fd, const void *buf, size_t count);

	/**
	* Compresses cache entry in memory and writes it to disk. Returns the size
	* of the data written to disk.
	*/
	static size_t
	deflate_and_write_to_disk(const void *in_data, size_t in_data_size, int dest,
	const char *filename)
	{
	#ifdef HAVE_ZSTD
	/* from the zstd docs (https://facebook.github.io/zstd/zstd_manual.html):
	* compression runs faster if `dstCapacity` >= `ZSTD_compressBound(srcSize)`.
	*/
	size_t out_size = ZSTD_compressBound(in_data_size);
	void * out = malloc(out_size);

	size_t ret = ZSTD_compress(out, out_size, in_data, in_data_size,
	ZSTD_COMPRESSION_LEVEL);
	if (ZSTD_isError(ret)) {
	free(out);
	return 0;
	}
	ssize_t written = write_all(dest, out, ret);
	if (written == -1) {
	free(out);
	return 0;
	}
	free(out);
	return ret;
	#else
	unsigned char *out;

	/* allocate deflate state */
	z_stream strm;
	strm.zalloc = Z_NULL;
	strm.zfree = Z_NULL;
	strm.opaque = Z_NULL;
	strm.next_in = (uint8_t *) in_data;
	strm.avail_in = in_data_size;

	int ret = deflateInit(&strm, Z_BEST_COMPRESSION);
	if (ret != Z_OK)
	return 0;

	/* compress until end of in_data */
	size_t compressed_size = 0;
	int flush;

	out = malloc(BUFSIZE * sizeof(unsigned char));
	if (out == NULL)
	return 0;

	do {
	int remaining = in_data_size - BUFSIZE;
	flush = remaining > 0 ? Z_NO_FLUSH : Z_FINISH;
	in_data_size -= BUFSIZE;

	/* Run deflate() on input until the output buffer is not full (which
	* means there is no more data to deflate).
	*/
	do {
	strm.avail_out = BUFSIZE;
	strm.next_out = out;

	ret = deflate(&strm, flush); /* no bad return value */
	assert(ret != Z_STREAM_ERROR); /* state not clobbered */

	size_t have = BUFSIZE - strm.avail_out;
	compressed_size += have;

	ssize_t written = write_all(dest, out, have);
	if (written == -1) {
	(void)deflateEnd(&strm);
	free(out);
	return 0;
	}
	} while (strm.avail_out == 0);

	/* all input should be used */
	assert(strm.avail_in == 0);

	} while (flush != Z_FINISH);

	/* stream should be complete */
	assert(ret == Z_STREAM_END);

	/* clean up and return */
	(void)deflateEnd(&strm);
	free(out);
	return compressed_size;
	# endif
	}

	#if DETECT_OS_WINDOWS
	/* TODO: implement disk cache support on windows */

	#else

	#include <dirent.h>
	#include <errno.h>
	#include <inttypes.h>
	#include <pwd.h>
	#include <stdio.h>
	#include <string.h>
	#include <sys/file.h>
	#include <sys/mman.h>
	#include <sys/types.h>
	#include <sys/stat.h>
	#include <unistd.h>

	#include "util/debug.h"
	#include "util/disk_cache.h"
	#include "util/disk_cache_os.h"
	#include "util/ralloc.h"
	#include "util/rand_xor.h"

	/* Create a directory named 'path' if it does not already exist.
	*
	* Returns: 0 if path already exists as a directory or if created.
	* -1 in all other cases.
	*/
	static int
	mkdir_if_needed(const char *path)
	{
	struct stat sb;

	/* If the path exists already, then our work is done if it's a
	* directory, but it's an error if it is not.
	*/
	if (stat(path, &sb) == 0) {
	if (S_ISDIR(sb.st_mode)) {
	return 0;
	} else {
	fprintf(stderr, "Cannot use %s for shader cache (not a directory)"
	"---disabling.\n", path);
	return -1;
	}
	}

	int ret = mkdir(path, 0755);
	if (ret == 0 \|\| (ret == -1 && errno == EEXIST))
	return 0;

	fprintf(stderr, "Failed to create %s for shader cache (%s)---disabling.\n",
	path, strerror(errno));

	return -1;
	}

	/* Concatenate an existing path and a new name to form a new path. If the new
	* path does not exist as a directory, create it then return the resulting
	* name of the new path (ralloc'ed off of 'ctx').
	*
	* Returns NULL on any error, such as:
	*
	* <path> does not exist or is not a directory
	* <path>/<name> exists but is not a directory
	* <path>/<name> cannot be created as a directory
	*/
	static char *
	concatenate_and_mkdir(void ctx, const char path, const char *name)
	{
	char *new_path;
	struct stat sb;

	if (stat(path, &sb) != 0 \|\| ! S_ISDIR(sb.st_mode))
	return NULL;

	new_path = ralloc_asprintf(ctx, "%s/%s", path, name);

	if (mkdir_if_needed(new_path) == 0)
	return new_path;
	else
	return NULL;
	}

	/* Given a directory path and predicate function, find the entry with
	* the oldest access time in that directory for which the predicate
	* returns true.
	*
	* Returns: A malloc'ed string for the path to the chosen file, (or
	* NULL on any error). The caller should free the string when
	* finished.
	*/
	static char *
	choose_lru_file_matching(const char *dir_path,
	bool (predicate)(const char dir_path,
	const struct stat *,
	const char *, const size_t))
	{
	DIR *dir;
	struct dirent *entry;
	char *filename;
	char *lru_name = NULL;
	time_t lru_atime = 0;

	dir = opendir(dir_path);
	if (dir == NULL)
	return NULL;

	while (1) {
	entry = readdir(dir);
	if (entry == NULL)
	break;

	struct stat sb;
	if (fstatat(dirfd(dir), entry->d_name, &sb, 0) == 0) {
	if (!lru_atime \|\| (sb.st_atime < lru_atime)) {
	size_t len = strlen(entry->d_name);

	if (!predicate(dir_path, &sb, entry->d_name, len))
	continue;

	char *tmp = realloc(lru_name, len + 1);
	if (tmp) {
	lru_name = tmp;
	memcpy(lru_name, entry->d_name, len + 1);
	lru_atime = sb.st_atime;
	}
	}
	}
	}

	if (lru_name == NULL) {
	closedir(dir);
	return NULL;
	}

	if (asprintf(&filename, "%s/%s", dir_path, lru_name) < 0)
	filename = NULL;

	free(lru_name);
	closedir(dir);

	return filename;
	}

	/* Is entry a regular file, and not having a name with a trailing
	* ".tmp"
	*/
	static bool
	is_regular_non_tmp_file(const char path, const struct stat sb,
	const char *d_name, const size_t len)
	{
	if (!S_ISREG(sb->st_mode))
	return false;

	if (len >= 4 && strcmp(&d_name[len-4], ".tmp") == 0)
	return false;

	return true;
	}

	/* Returns the size of the deleted file, (or 0 on any error). */
	static size_t
	unlink_lru_file_from_directory(const char *path)
	{
	struct stat sb;
	char *filename;

	filename = choose_lru_file_matching(path, is_regular_non_tmp_file);
	if (filename == NULL)
	return 0;

	if (stat(filename, &sb) == -1) {
	free (filename);
	return 0;
	}

	unlink(filename);
	free (filename);

	return sb.st_blocks * 512;
	}

	/* Is entry a directory with a two-character name, (and not the
	* special name of ".."). We also return false if the dir is empty.
	*/
	static bool
	is_two_character_sub_directory(const char path, const struct stat sb,
	const char *d_name, const size_t len)
	{
	if (!S_ISDIR(sb->st_mode))
	return false;

	if (len != 2)
	return false;

	if (strcmp(d_name, "..") == 0)
	return false;

	char *subdir;
	if (asprintf(&subdir, "%s/%s", path, d_name) == -1)
	return false;
	DIR *dir = opendir(subdir);
	free(subdir);

	if (dir == NULL)
	return false;

	unsigned subdir_entries = 0;
	struct dirent *d;
	while ((d = readdir(dir)) != NULL) {
	if(++subdir_entries > 2)
	break;
	}
	closedir(dir);

	/* If dir only contains '.' and '..' it must be empty */
	if (subdir_entries <= 2)
	return false;

	return true;
	}

	/* Create the directory that will be needed for the cache file for \key.
	*
	* Obviously, the implementation here must closely match
	* _get_cache_file above.
	*/
	static void
	make_cache_file_directory(struct disk_cache *cache, const cache_key key)
	{
	char *dir;
	char buf[41];

	_mesa_sha1_format(buf, key);
	if (asprintf(&dir, "%s/%c%c", cache->path, buf[0], buf[1]) == -1)
	return;

	mkdir_if_needed(dir);
	free(dir);
	}

	static ssize_t
	write_all(int fd, const void *buf, size_t count)
	{
	const char *out = buf;
	ssize_t written;
	size_t done;

	for (done = 0; done < count; done += written) {
	written = write(fd, out + done, count - done);
	if (written == -1)
	return -1;
	}
	return done;
	}

	/* Evict least recently used cache item */
	void
	disk_cache_evict_lru_item(struct disk_cache *cache)
	{
	char *dir_path;

	/* With a reasonably-sized, full cache, (and with keys generated
	* from a cryptographic hash), we can choose two random hex digits
	* and reasonably expect the directory to exist with a file in it.
	* Provides pseudo-LRU eviction to reduce checking all cache files.
	*/
	uint64_t rand64 = rand_xorshift128plus(cache->seed_xorshift128plus);
	if (asprintf(&dir_path, "%s/%02" PRIx64 , cache->path, rand64 & 0xff) < 0)
	return;

	size_t size = unlink_lru_file_from_directory(dir_path);

	free(dir_path);

	if (size) {
	p_atomic_add(cache->size, - (uint64_t)size);
	return;
	}

	/* In the case where the random choice of directory didn't find
	* something, we choose the least recently accessed from the
	* existing directories.
	*
	* Really, the only reason this code exists is to allow the unit
	* tests to work, (which use an artificially-small cache to be able
	* to force a single cached item to be evicted).
	*/
	dir_path = choose_lru_file_matching(cache->path,
	is_two_character_sub_directory);
	if (dir_path == NULL)
	return;

	size = unlink_lru_file_from_directory(dir_path);

	free(dir_path);

	if (size)
	p_atomic_add(cache->size, - (uint64_t)size);
	}

	void
	disk_cache_write_item_to_disk(struct disk_cache_put_job *dc_job,
	struct cache_entry_file_data *cf_data,
	char *filename)
	{
	int fd = -1, fd_final = -1;

	/* Write to a temporary file to allow for an atomic rename to the
	* final destination filename, (to prevent any readers from seeing
	* a partially written file).
	*/
	char *filename_tmp = NULL;
	if (asprintf(&filename_tmp, "%s.tmp", filename) == -1)
	goto done;

	fd = open(filename_tmp, O_WRONLY \| O_CLOEXEC \| O_CREAT, 0644);

	/* Make the two-character subdirectory within the cache as needed. */
	if (fd == -1) {
	if (errno != ENOENT)
	goto done;

	make_cache_file_directory(dc_job->cache, dc_job->key);

	fd = open(filename_tmp, O_WRONLY \| O_CLOEXEC \| O_CREAT, 0644);
	if (fd == -1)
	goto done;
	}

	/* With the temporary file open, we take an exclusive flock on
	* it. If the flock fails, then another process still has the file
	* open with the flock held. So just let that file be responsible
	* for writing the file.
	*/
	#ifdef HAVE_FLOCK
	int err = flock(fd, LOCK_EX \| LOCK_NB);
	#else
	struct flock lock = {
	.l_start = 0,
	.l_len = 0, /* entire file */
	.l_type = F_WRLCK,
	.l_whence = SEEK_SET
	};
	int err = fcntl(fd, F_SETLK, &lock);
	#endif
	if (err == -1)
	goto done;

	/* Now that we have the lock on the open temporary file, we can
	* check to see if the destination file already exists. If so,
	* another process won the race between when we saw that the file
	* didn't exist and now. In this case, we don't do anything more,
	* (to ensure the size accounting of the cache doesn't get off).
	*/
	fd_final = open(filename, O_RDONLY \| O_CLOEXEC);
	if (fd_final != -1) {
	unlink(filename_tmp);
	goto done;
	}

	/* OK, we're now on the hook to write out a file that we know is
	* not in the cache, and is also not being written out to the cache
	* by some other process.
	*/

	/* Write the driver_keys_blob, this can be used find information about the
	* mesa version that produced the entry or deal with hash collisions,
	* should that ever become a real problem.
	*/
	int ret = write_all(fd, dc_job->cache->driver_keys_blob,
	dc_job->cache->driver_keys_blob_size);
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}

	/* Write the cache item metadata. This data can be used to deal with
	* hash collisions, as well as providing useful information to 3rd party
	* tools reading the cache files.
	*/
	ret = write_all(fd, &dc_job->cache_item_metadata.type,
	sizeof(uint32_t));
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}

	if (dc_job->cache_item_metadata.type == CACHE_ITEM_TYPE_GLSL) {
	ret = write_all(fd, &dc_job->cache_item_metadata.num_keys,
	sizeof(uint32_t));
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}

	ret = write_all(fd, dc_job->cache_item_metadata.keys[0],
	dc_job->cache_item_metadata.num_keys *
	sizeof(cache_key));
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}
	}

	size_t cf_data_size = sizeof(*cf_data);
	ret = write_all(fd, cf_data, cf_data_size);
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}

	/* Now, finally, write out the contents to the temporary file, then
	* rename them atomically to the destination filename, and also
	* perform an atomic increment of the total cache size.
	*/
	size_t file_size = deflate_and_write_to_disk(dc_job->data, dc_job->size,
	fd, filename_tmp);
	if (file_size == 0) {
	unlink(filename_tmp);
	goto done;
	}
	ret = rename(filename_tmp, filename);
	if (ret == -1) {
	unlink(filename_tmp);
	goto done;
	}

	struct stat sb;
	if (stat(filename, &sb) == -1) {
	/* Something went wrong remove the file */
	unlink(filename);
	goto done;
	}

	p_atomic_add(dc_job->cache->size, sb.st_blocks * 512);

	done:
	if (fd_final != -1)
	close(fd_final);
	/* This close finally releases the flock, (now that the final file
	* has been renamed into place and the size has been added).
	*/
	if (fd != -1)
	close(fd);
	free(filename_tmp);
	}

	/* Determine path for cache based on the first defined name as follows:
	*
	* $MESA_GLSL_CACHE_DIR
	* $XDG_CACHE_HOME/mesa_shader_cache
	* <pwd.pw_dir>/.cache/mesa_shader_cache
	*/
	char *
	disk_cache_generate_cache_dir(void *mem_ctx)
	{
	char *path = getenv("MESA_GLSL_CACHE_DIR");
	if (path) {
	if (mkdir_if_needed(path) == -1)
	return NULL;

	path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
	if (!path)
	return NULL;
	}

	if (path == NULL) {
	char *xdg_cache_home = getenv("XDG_CACHE_HOME");

	if (xdg_cache_home) {
	if (mkdir_if_needed(xdg_cache_home) == -1)
	return NULL;

	path = concatenate_and_mkdir(mem_ctx, xdg_cache_home, CACHE_DIR_NAME);
	if (!path)
	return NULL;
	}
	}

	if (!path) {
	char *buf;
	size_t buf_size;
	struct passwd pwd, *result;

	buf_size = sysconf(_SC_GETPW_R_SIZE_MAX);
	if (buf_size == -1)
	buf_size = 512;

	/* Loop until buf_size is large enough to query the directory */
	while (1) {
	buf = ralloc_size(mem_ctx, buf_size);

	getpwuid_r(getuid(), &pwd, buf, buf_size, &result);
	if (result)
	break;

	if (errno == ERANGE) {
	ralloc_free(buf);
	buf = NULL;
	buf_size *= 2;
	} else {
	return NULL;
	}
	}

	path = concatenate_and_mkdir(mem_ctx, pwd.pw_dir, ".cache");
	if (!path)
	return NULL;

	path = concatenate_and_mkdir(mem_ctx, path, CACHE_DIR_NAME);
	if (!path)
	return NULL;
	}

	return path;
	}

	bool
	disk_cache_enabled()
	{
	/* If running as a users other than the real user disable cache */
	if (geteuid() != getuid())
	return false;

	/* At user request, disable shader cache entirely. */
	if (env_var_as_boolean("MESA_GLSL_CACHE_DISABLE", false))
	return false;

	return true;
	}

	bool
	disk_cache_mmap_cache_index(void mem_ctx, struct disk_cache cache,
	char *path)
	{
	int fd = -1;
	bool mapped = false;

	cache->path = ralloc_strdup(cache, path);
	if (cache->path == NULL)
	goto path_fail;

	path = ralloc_asprintf(mem_ctx, "%s/index", cache->path);
	if (path == NULL)
	goto path_fail;

	fd = open(path, O_RDWR \| O_CREAT \| O_CLOEXEC, 0644);
	if (fd == -1)
	goto path_fail;

	struct stat sb;
	if (fstat(fd, &sb) == -1)
	goto path_fail;

	/* Force the index file to be the expected size. */
	size_t size = sizeof(cache->size) + CACHE_INDEX_MAX_KEYS CACHE_KEY_SIZE;
	if (sb.st_size != size) {
	if (ftruncate(fd, size) == -1)
	goto path_fail;
	}

	/* We map this shared so that other processes see updates that we
	* make.
	*
	* Note: We do use atomic addition to ensure that multiple
	* processes don't scramble the cache size recorded in the
	* index. But we don't use any locking to prevent multiple
	* processes from updating the same entry simultaneously. The idea
	* is that if either result lands entirely in the index, then
	* that's equivalent to a well-ordered write followed by an
	* eviction and a write. On the other hand, if the simultaneous
	* writes result in a corrupt entry, that's not really any
	* different than both entries being evicted, (since within the
	* guarantees of the cryptographic hash, a corrupt entry is
	* unlikely to ever match a real cache key).
	*/
	cache->index_mmap = mmap(NULL, size, PROT_READ \| PROT_WRITE,
	MAP_SHARED, fd, 0);
	if (cache->index_mmap == MAP_FAILED)
	goto path_fail;
	cache->index_mmap_size = size;

	cache->size = (uint64_t *) cache->index_mmap;
	cache->stored_keys = cache->index_mmap + sizeof(uint64_t);
	mapped = true;

	path_fail:
	if (fd != -1)
	close(fd);

	return mapped;
	}

	void
	disk_cache_destroy_mmap(struct disk_cache *cache)
	{
	munmap(cache->index_mmap, cache->index_mmap_size);
	}
	#endif

	#endif /* ENABLE_SHADER_CACHE */