thumbs.c

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/*
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version 2
 * of the License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
 *
 * The Original Code is Copyright (C) 2007 Blender Foundation
 * All rights reserved.
 */
 
#include <stdio.h>
#include <stdlib.h>
 
#include "MEM_guardedalloc.h"
 
#include "BLI_fileops.h"
#include "BLI_ghash.h"
#include "BLI_hash_md5.h"
#include "BLI_path_util.h"
#include "BLI_string.h"
#include "BLI_system.h"
#include "BLI_threads.h"
#include "BLI_utildefines.h"
#include BLI_SYSTEM_PID_H
 
#include "DNA_space_types.h" /* For FILE_MAX_LIBEXTRA */
 
#include "BLO_readfile.h"
 
#include "IMB_imbuf.h"
#include "IMB_imbuf_types.h"
#include "IMB_metadata.h"
#include "IMB_thumbs.h"
 
#include <ctype.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <time.h>
 
#ifdef WIN32
/* Need to include windows.h so _WIN32_IE is defined. */
#  include <windows.h>
#  ifndef _WIN32_IE
/* Minimal requirements for SHGetSpecialFolderPath on MINGW MSVC has this defined already. */
#    define _WIN32_IE 0x0400
#  endif
/* For SHGetSpecialFolderPath, has to be done before BLI_winstuff
 * because 'near' is disabled through BLI_windstuff */
#  include "BLI_winstuff.h"
#  include "utfconv.h"
#  include <direct.h> /* #chdir */
#  include <shlobj.h>
#endif
 
#if defined(WIN32) || defined(__APPLE__)
/* pass */
#else
#  define USE_FREEDESKTOP
#endif
 
/* '$HOME/.cache/thumbnails' or '$HOME/.thumbnails' */
#ifdef USE_FREEDESKTOP
#  define THUMBNAILS "thumbnails"
#else
#  define THUMBNAILS ".thumbnails"
#endif
 
#define URI_MAX (FILE_MAX * 3 + 8)
 
static bool get_thumb_dir(char *dir, ThumbSize size)
{
  char *s = dir;
  const char *subdir;
#ifdef WIN32
  wchar_t dir_16[MAX_PATH];
  /* yes, applications shouldn't store data there, but so does GIMP :)*/
  SHGetSpecialFolderPathW(0, dir_16, CSIDL_PROFILE, 0);
  conv_utf_16_to_8(dir_16, dir, FILE_MAX);
  s += strlen(dir);
#else
#  if defined(USE_FREEDESKTOP)
  const char *home_cache = BLI_getenv("XDG_CACHE_HOME");
  const char *home = home_cache ? home_cache : BLI_getenv("HOME");
#  else
  const char *home = BLI_getenv("HOME");
#  endif
  if (!home) {
    return 0;
  }
  s += BLI_strncpy_rlen(s, home, FILE_MAX);
 
#  ifdef USE_FREEDESKTOP
  if (!home_cache) {
    s += BLI_strncpy_rlen(s, "/.cache", FILE_MAX - (s - dir));
  }
#  endif
#endif
  switch (size) {
    case THB_NORMAL:
      subdir = "/" THUMBNAILS "/normal/";
      break;
    case THB_LARGE:
      subdir = "/" THUMBNAILS "/large/";
      break;
    case THB_FAIL:
      subdir = "/" THUMBNAILS "/fail/blender/";
      break;
    default:
      return 0; /* unknown size */
  }
 
  s += BLI_strncpy_rlen(s, subdir, FILE_MAX - (s - dir));
  (void)s;
 
  return 1;
}
 
#undef THUMBNAILS
 
/* --- Begin of adapted code from glib. --- */
 
/* -------------------------------------------------------------------- */
typedef enum {
  UNSAFE_ALL = 0x1,        /* Escape all unsafe characters   */
  UNSAFE_ALLOW_PLUS = 0x2, /* Allows '+'  */
  UNSAFE_PATH = 0x8,       /* Allows '/', '&', '=', ':', '@', '+', '$' and ',' */
  UNSAFE_HOST = 0x10,      /* Allows '/' and ':' and '@' */
  UNSAFE_SLASHES = 0x20,   /* Allows all characters except for '/' and '%' */
} UnsafeCharacterSet;
 
/* Don't lose comment alignment. */
/* clang-format off */
static const unsigned char acceptable[96] = {
    /* A table of the ASCII chars from space (32) to DEL (127) */
    /*      !    "    #    $    %    &    '    (    )    *    +    ,    -    .    / */
    0x00,0x3F,0x20,0x20,0x28,0x00,0x2C,0x3F,0x3F,0x3F,0x3F,0x2A,0x28,0x3F,0x3F,0x1C,
    /* 0    1    2    3    4    5    6    7    8    9    :    ;    <    =    >    ? */
    0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x38,0x20,0x20,0x2C,0x20,0x20,
    /* @    A    B    C    D    E    F    G    H    I    J    K    L    M    N    O */
    0x38,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,
    /* P    Q    R    S    T    U    V    W    X    Y    Z    [    \    ]    ^    _ */
    0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x20,0x20,0x20,0x20,0x3F,
    /* `    a    b    c    d    e    f    g    h    i    j    k    l    m    n    o */
    0x20,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,
    /* p    q    r    s    t    u    v    w    x    y    z    {    |    }    ~  DEL */
    0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x3F,0x20,0x20,0x20,0x3F,0x20,
};
/* clang-format on */
 
static const char hex[17] = "0123456789abcdef";
 
/* Note: This escape function works on file: URIs, but if you want to
 * escape something else, please read RFC-2396 */
static void escape_uri_string(const char *string,
                              char *escaped_string,
                              int escaped_string_size,
                              UnsafeCharacterSet mask)
{
#define ACCEPTABLE(a) ((a) >= 32 && (a) < 128 && (acceptable[(a)-32] & use_mask))
 
  const char *p;
  char *q;
  int c;
  UnsafeCharacterSet use_mask;
  use_mask = mask;
 
  BLI_assert(escaped_string_size > 0);
 
  /* space for \0 */
  escaped_string_size -= 1;
 
  for (q = escaped_string, p = string; (*p != '\0') && escaped_string_size; p++) {
    c = (unsigned char)*p;
 
    if (!ACCEPTABLE(c)) {
      if (escaped_string_size < 3) {
        break;
      }
 
      *q++ = '%'; /* means hex coming */
      *q++ = hex[c >> 4];
      *q++ = hex[c & 15];
      escaped_string_size -= 3;
    }
    else {
      *q++ = *p;
      escaped_string_size -= 1;
    }
  }
 
  *q = '\0';
}
 
/* --- End of adapted code from glib. --- */
 
static bool thumbhash_from_path(const char *UNUSED(path), ThumbSource source, char *r_hash)
{
  switch (source) {
    case THB_SOURCE_FONT:
      return IMB_thumb_load_font_get_hash(r_hash);
    default:
      r_hash[0] = '\0';
      return false;
  }
}
 
static bool uri_from_filename(const char *path, char *uri)
{
  char orig_uri[URI_MAX];
  const char *dirstart = path;
 
#ifdef WIN32
  {
    char vol[3];
 
    BLI_strncpy(orig_uri, "file:///", FILE_MAX);
    if (strlen(path) < 2 && path[1] != ':') {
      /* not a correct absolute path */
      return 0;
    }
    /* on windows, using always uppercase drive/volume letter in uri */
    vol[0] = (unsigned char)toupper(path[0]);
    vol[1] = ':';
    vol[2] = '\0';
    strcat(orig_uri, vol);
    dirstart += 2;
  }
  strcat(orig_uri, dirstart);
  BLI_str_replace_char(orig_uri, '\\', '/');
#else
  BLI_snprintf(orig_uri, URI_MAX, "file://%s", dirstart);
#endif
 
  escape_uri_string(orig_uri, uri, URI_MAX, UNSAFE_PATH);
 
  return 1;
}
 
static bool thumbpathname_from_uri(
    const char *uri, char *r_path, const int path_len, char *r_name, int name_len, ThumbSize size)
{
  char name_buff[40];
 
  if (r_path && !r_name) {
    r_name = name_buff;
    name_len = sizeof(name_buff);
  }
 
  if (r_name) {
    char hexdigest[33];
    unsigned char digest[16];
    BLI_hash_md5_buffer(uri, strlen(uri), digest);
    hexdigest[0] = '\0';
    BLI_snprintf(r_name, name_len, "%s.png", BLI_hash_md5_to_hexdigest(digest, hexdigest));
    //      printf("%s: '%s' --> '%s'\n", __func__, uri, r_name);
  }
 
  if (r_path) {
    char tmppath[FILE_MAX];
 
    if (get_thumb_dir(tmppath, size)) {
      BLI_snprintf(r_path, path_len, "%s%s", tmppath, r_name);
      //          printf("%s: '%s' --> '%s'\n", __func__, uri, r_path);
      return true;
    }
  }
  return false;
}
 
static void thumbname_from_uri(const char *uri, char *thumb, const int thumb_len)
{
  thumbpathname_from_uri(uri, NULL, 0, thumb, thumb_len, THB_FAIL);
}
 
static bool thumbpath_from_uri(const char *uri, char *path, const int path_len, ThumbSize size)
{
  return thumbpathname_from_uri(uri, path, path_len, NULL, 0, size);
}
 
void IMB_thumb_makedirs(void)
{
  char tpath[FILE_MAX];
#if 0 /* UNUSED */
  if (get_thumb_dir(tpath, THB_NORMAL)) {
    BLI_dir_create_recursive(tpath);
  }
#endif
  if (get_thumb_dir(tpath, THB_LARGE)) {
    BLI_dir_create_recursive(tpath);
  }
  if (get_thumb_dir(tpath, THB_FAIL)) {
    BLI_dir_create_recursive(tpath);
  }
}
 
/* create thumbnail for file and returns new imbuf for thumbnail */
static ImBuf *thumb_create_ex(const char *file_path,
                              const char *uri,
                              const char *thumb,
                              const bool use_hash,
                              const char *hash,
                              const char *blen_group,
                              const char *blen_id,
                              ThumbSize size,
                              ThumbSource source,
                              ImBuf *img)
{
  char desc[URI_MAX + 22];
  char tpath[FILE_MAX];
  char tdir[FILE_MAX];
  char temp[FILE_MAX];
  char mtime[40] = "0";  /* in case we can't stat the file */
  char cwidth[40] = "0"; /* in case images have no data */
  char cheight[40] = "0";
  short tsize = 128;
  short ex, ey;
  float scaledx, scaledy;
  BLI_stat_t info;
 
  switch (size) {
    case THB_NORMAL:
      tsize = PREVIEW_RENDER_DEFAULT_HEIGHT;
      break;
    case THB_LARGE:
      tsize = PREVIEW_RENDER_DEFAULT_HEIGHT * 2;
      break;
    case THB_FAIL:
      tsize = 1;
      break;
    default:
      return NULL; /* unknown size */
  }
 
  /* exception, skip images over 100mb */
  if (source == THB_SOURCE_IMAGE) {
    const size_t file_size = BLI_file_size(file_path);
    if (file_size != -1 && file_size > THUMB_SIZE_MAX) {
      // printf("file too big: %d, skipping %s\n", (int)size, file_path);
      return NULL;
    }
  }
 
  if (get_thumb_dir(tdir, size)) {
    BLI_snprintf(tpath, FILE_MAX, "%s%s", tdir, thumb);
    //      thumb[8] = '\0'; /* shorten for tempname, not needed anymore */
    BLI_snprintf(temp, FILE_MAX, "%sblender_%d_%s.png", tdir, abs(getpid()), thumb);
    if (BLI_path_ncmp(file_path, tdir, sizeof(tdir)) == 0) {
      return NULL;
    }
    if (size == THB_FAIL) {
      img = IMB_allocImBuf(1, 1, 32, IB_rect | IB_metadata);
      if (!img) {
        return NULL;
      }
    }
    else {
      if (ELEM(source, THB_SOURCE_IMAGE, THB_SOURCE_BLEND, THB_SOURCE_FONT)) {
        /* only load if we didn't give an image */
        if (img == NULL) {
          switch (source) {
            case THB_SOURCE_IMAGE:
              img = IMB_loadiffname(file_path, IB_rect | IB_metadata, NULL);
              break;
            case THB_SOURCE_BLEND:
              img = IMB_thumb_load_blend(file_path, blen_group, blen_id);
              break;
            case THB_SOURCE_FONT:
              img = IMB_thumb_load_font(file_path, tsize, tsize);
              break;
            default:
              BLI_assert_unreachable(); /* This should never happen */
          }
        }
 
        if (img != NULL) {
          if (BLI_stat(file_path, &info) != -1) {
            BLI_snprintf(mtime, sizeof(mtime), "%ld", (long int)info.st_mtime);
          }
          BLI_snprintf(cwidth, sizeof(cwidth), "%d", img->x);
          BLI_snprintf(cheight, sizeof(cheight), "%d", img->y);
        }
      }
      else if (THB_SOURCE_MOVIE == source) {
        struct anim *anim = NULL;
        anim = IMB_open_anim(file_path, IB_rect | IB_metadata, 0, NULL);
        if (anim != NULL) {
          img = IMB_anim_absolute(anim, 0, IMB_TC_NONE, IMB_PROXY_NONE);
          if (img == NULL) {
            printf("not an anim; %s\n", file_path);
          }
          else {
            IMB_freeImBuf(img);
            img = IMB_anim_previewframe(anim);
          }
          IMB_free_anim(anim);
        }
        if (BLI_stat(file_path, &info) != -1) {
          BLI_snprintf(mtime, sizeof(mtime), "%ld", (long int)info.st_mtime);
        }
      }
      if (!img) {
        return NULL;
      }
 
      if (img->x > img->y) {
        scaledx = (float)tsize;
        scaledy = ((float)img->y / (float)img->x) * tsize;
      }
      else {
        scaledy = (float)tsize;
        scaledx = ((float)img->x / (float)img->y) * tsize;
      }
      /* Scaling down must never assign zero width/height, see: T89868. */
      ex = MAX2(1, (short)scaledx);
      ey = MAX2(1, (short)scaledy);
 
      /* save some time by only scaling byte buf */
      if (img->rect_float) {
        if (img->rect == NULL) {
          IMB_rect_from_float(img);
        }
 
        imb_freerectfloatImBuf(img);
      }
 
      IMB_scaleImBuf(img, ex, ey);
    }
    BLI_snprintf(desc, sizeof(desc), "Thumbnail for %s", uri);
    IMB_metadata_ensure(&img->metadata);
    IMB_metadata_set_field(img->metadata, "Software", "Blender");
    IMB_metadata_set_field(img->metadata, "Thumb::URI", uri);
    IMB_metadata_set_field(img->metadata, "Description", desc);
    IMB_metadata_set_field(img->metadata, "Thumb::MTime", mtime);
    if (use_hash) {
      IMB_metadata_set_field(img->metadata, "X-Blender::Hash", hash);
    }
    if (ELEM(source, THB_SOURCE_IMAGE, THB_SOURCE_BLEND, THB_SOURCE_FONT)) {
      IMB_metadata_set_field(img->metadata, "Thumb::Image::Width", cwidth);
      IMB_metadata_set_field(img->metadata, "Thumb::Image::Height", cheight);
    }
    img->ftype = IMB_FTYPE_PNG;
    img->planes = 32;
 
    /* If we generated from a 16bit PNG e.g., we have a float rect, not a byte one - fix this. */
    IMB_rect_from_float(img);
    imb_freerectfloatImBuf(img);
 
    if (IMB_saveiff(img, temp, IB_rect | IB_metadata)) {
#ifndef WIN32
      chmod(temp, S_IRUSR | S_IWUSR);
#endif
      // printf("%s saving thumb: '%s'\n", __func__, tpath);
 
      BLI_rename(temp, tpath);
    }
  }
  return img;
}
 
static ImBuf *thumb_create_or_fail(const char *file_path,
                                   const char *uri,
                                   const char *thumb,
                                   const bool use_hash,
                                   const char *hash,
                                   const char *blen_group,
                                   const char *blen_id,
                                   ThumbSize size,
                                   ThumbSource source)
{
  ImBuf *img = thumb_create_ex(
      file_path, uri, thumb, use_hash, hash, blen_group, blen_id, size, source, NULL);
 
  if (!img) {
    /* thumb creation failed, write fail thumb */
    img = thumb_create_ex(
        file_path, uri, thumb, use_hash, hash, blen_group, blen_id, THB_FAIL, source, NULL);
    if (img) {
      /* we don't need failed thumb anymore */
      IMB_freeImBuf(img);
      img = NULL;
    }
  }
 
  return img;
}
 
ImBuf *IMB_thumb_create(const char *path, ThumbSize size, ThumbSource source, ImBuf *img)
{
  char uri[URI_MAX] = "";
  char thumb_name[40];
 
  if (!uri_from_filename(path, uri)) {
    return NULL;
  }
  thumbname_from_uri(uri, thumb_name, sizeof(thumb_name));
 
  return thumb_create_ex(
      path, uri, thumb_name, false, THUMB_DEFAULT_HASH, NULL, NULL, size, source, img);
}
 
/* read thumbnail for file and returns new imbuf for thumbnail */
ImBuf *IMB_thumb_read(const char *path, ThumbSize size)
{
  char thumb[FILE_MAX];
  char uri[URI_MAX];
  ImBuf *img = NULL;
 
  if (!uri_from_filename(path, uri)) {
    return NULL;
  }
  if (thumbpath_from_uri(uri, thumb, sizeof(thumb), size)) {
    img = IMB_loadiffname(thumb, IB_rect | IB_metadata, NULL);
  }
 
  return img;
}
 
/* delete all thumbs for the file */
void IMB_thumb_delete(const char *path, ThumbSize size)
{
  char thumb[FILE_MAX];
  char uri[URI_MAX];
 
  if (!uri_from_filename(path, uri)) {
    return;
  }
  if (thumbpath_from_uri(uri, thumb, sizeof(thumb), size)) {
    if (BLI_path_ncmp(path, thumb, sizeof(thumb)) == 0) {
      return;
    }
    if (BLI_exists(thumb)) {
      BLI_delete(thumb, false, false);
    }
  }
}
 
/* create the thumb if necessary and manage failed and old thumbs */
ImBuf *IMB_thumb_manage(const char *org_path, ThumbSize size, ThumbSource source)
{
  char thumb_path[FILE_MAX];
  char thumb_name[40];
  char uri[URI_MAX];
  char path_buff[FILE_MAX_LIBEXTRA];
  const char *file_path;
  const char *path;
  BLI_stat_t st;
  ImBuf *img = NULL;
  char *blen_group = NULL, *blen_id = NULL;
 
  path = file_path = org_path;
  if (source == THB_SOURCE_BLEND) {
    if (BLO_library_path_explode(path, path_buff, &blen_group, &blen_id)) {
      if (blen_group) {
        if (!blen_id) {
          /* No preview for blen groups */
          return NULL;
        }
        file_path = path_buff; /* path needs to be a valid file! */
      }
    }
  }
 
  if (BLI_stat(file_path, &st) == -1) {
    return NULL;
  }
  if (!uri_from_filename(path, uri)) {
    return NULL;
  }
  if (thumbpath_from_uri(uri, thumb_path, sizeof(thumb_path), THB_FAIL)) {
    /* failure thumb exists, don't try recreating */
    if (BLI_exists(thumb_path)) {
      /* clear out of date fail case (note for blen IDs we use blender file itself here) */
      if (BLI_file_older(thumb_path, file_path)) {
        BLI_delete(thumb_path, false, false);
      }
      else {
        return NULL;
      }
    }
  }
 
  if (thumbpathname_from_uri(
          uri, thumb_path, sizeof(thumb_path), thumb_name, sizeof(thumb_name), size)) {
    if (BLI_path_ncmp(path, thumb_path, sizeof(thumb_path)) == 0) {
      img = IMB_loadiffname(path, IB_rect, NULL);
    }
    else {
      img = IMB_loadiffname(thumb_path, IB_rect | IB_metadata, NULL);
      if (img) {
        bool regenerate = false;
 
        char mtime[40];
        char thumb_hash[33];
        char thumb_hash_curr[33];
 
        const bool use_hash = thumbhash_from_path(file_path, source, thumb_hash);
 
        if (IMB_metadata_get_field(img->metadata, "Thumb::MTime", mtime, sizeof(mtime))) {
          regenerate = (st.st_mtime != atol(mtime));
        }
        else {
          /* illegal thumb, regenerate it! */
          regenerate = true;
        }
 
        if (use_hash && !regenerate) {
          if (IMB_metadata_get_field(
                  img->metadata, "X-Blender::Hash", thumb_hash_curr, sizeof(thumb_hash_curr))) {
            regenerate = !STREQ(thumb_hash, thumb_hash_curr);
          }
          else {
            regenerate = true;
          }
        }
 
        if (regenerate) {
          /* recreate all thumbs */
          IMB_freeImBuf(img);
          img = NULL;
          IMB_thumb_delete(path, THB_NORMAL);
          IMB_thumb_delete(path, THB_LARGE);
          IMB_thumb_delete(path, THB_FAIL);
          img = thumb_create_or_fail(
              file_path, uri, thumb_name, use_hash, thumb_hash, blen_group, blen_id, size, source);
        }
      }
      else {
        char thumb_hash[33];
        const bool use_hash = thumbhash_from_path(file_path, source, thumb_hash);
 
        img = thumb_create_or_fail(
            file_path, uri, thumb_name, use_hash, thumb_hash, blen_group, blen_id, size, source);
      }
    }
  }
 
  /* Our imbuf **must** have a valid rect (i.e. 8-bits/channels)
   * data, we rely on this in draw code.
   * However, in some cases we may end loading 16bits PNGs, which generated float buffers.
   * This should be taken care of in generation step, but add also a safeguard here! */
  if (img) {
    IMB_rect_from_float(img);
    imb_freerectfloatImBuf(img);
  }
 
  return img;
}
 
/* ***** Threading ***** */
/* Thumbnail handling is not really threadsafe in itself.
 * However, as long as we do not operate on the same file, we shall have no collision.
 * So idea is to 'lock' a given source file path.
 */
 
static struct IMBThumbLocks {
  GSet *locked_paths;
  int lock_counter;
  ThreadCondition cond;
} thumb_locks = {0};
 
void IMB_thumb_locks_acquire(void)
{
  BLI_thread_lock(LOCK_IMAGE);
 
  if (thumb_locks.lock_counter == 0) {
    BLI_assert(thumb_locks.locked_paths == NULL);
    thumb_locks.locked_paths = BLI_gset_str_new(__func__);
    BLI_condition_init(&thumb_locks.cond);
  }
  thumb_locks.lock_counter++;
 
  BLI_assert(thumb_locks.locked_paths != NULL);
  BLI_assert(thumb_locks.lock_counter > 0);
  BLI_thread_unlock(LOCK_IMAGE);
}
 
void IMB_thumb_locks_release(void)
{
  BLI_thread_lock(LOCK_IMAGE);
  BLI_assert((thumb_locks.locked_paths != NULL) && (thumb_locks.lock_counter > 0));
 
  thumb_locks.lock_counter--;
  if (thumb_locks.lock_counter == 0) {
    BLI_gset_free(thumb_locks.locked_paths, MEM_freeN);
    thumb_locks.locked_paths = NULL;
    BLI_condition_end(&thumb_locks.cond);
  }
 
  BLI_thread_unlock(LOCK_IMAGE);
}
 
void IMB_thumb_path_lock(const char *path)
{
  void *key = BLI_strdup(path);
 
  BLI_thread_lock(LOCK_IMAGE);
  BLI_assert((thumb_locks.locked_paths != NULL) && (thumb_locks.lock_counter > 0));
 
  if (thumb_locks.locked_paths) {
    while (!BLI_gset_add(thumb_locks.locked_paths, key)) {
      BLI_condition_wait_global_mutex(&thumb_locks.cond, LOCK_IMAGE);
    }
  }
 
  BLI_thread_unlock(LOCK_IMAGE);
}
 
void IMB_thumb_path_unlock(const char *path)
{
  const void *key = path;
 
  BLI_thread_lock(LOCK_IMAGE);
  BLI_assert((thumb_locks.locked_paths != NULL) && (thumb_locks.lock_counter > 0));
 
  if (thumb_locks.locked_paths) {
    if (!BLI_gset_remove(thumb_locks.locked_paths, key, MEM_freeN)) {
      BLI_assert_unreachable();
    }
    BLI_condition_notify_all(&thumb_locks.cond);
  }
 
  BLI_thread_unlock(LOCK_IMAGE);
}