base/nix/mime_util_xdg.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "base/nix/mime_util_xdg.h"
   6
   7 #include <cstdlib>
   8 #include <list>
   9 #include <map>
  10 #include <vector>
  11
  12 #include "base/environment.h"
  13 #include "base/file_util.h"
  14 #include "base/lazy_instance.h"
  15 #include "base/logging.h"
  16 #include "base/memory/scoped_ptr.h"
  17 #include "base/memory/singleton.h"
  18 #include "base/nix/xdg_util.h"
  19 #include "base/strings/string_split.h"
  20 #include "base/strings/string_util.h"
  21 #include "base/synchronization/lock.h"
  22 #include "base/third_party/xdg_mime/xdgmime.h"
  23 #include "base/threading/thread_restrictions.h"
  24 #include "base/time/time.h"
  25
  26 namespace base {
  27 namespace nix {
  28
  29 namespace {
  30
  31 class IconTheme;
  32
  33 // None of the XDG stuff is thread-safe, so serialize all access under
  34 // this lock.
  35 base::LazyInstance<base::Lock>::Leaky
  36     g_mime_util_xdg_lock = LAZY_INSTANCE_INITIALIZER;
  37
  38 class MimeUtilConstants {
  39  public:
  40   typedef std::map<std::string, IconTheme*> IconThemeMap;
  41   typedef std::map<FilePath, base::Time> IconDirMtimeMap;
  42   typedef std::vector<std::string> IconFormats;
  43
  44   // Specified by XDG icon theme specs.
  45   static const int kUpdateIntervalInSeconds = 5;
  46
  47   static const size_t kDefaultThemeNum = 4;
  48
  49   static MimeUtilConstants* GetInstance() {
  50     return Singleton<MimeUtilConstants>::get();
  51   }
  52
  53   // Store icon directories and their mtimes.
  54   IconDirMtimeMap icon_dirs_;
  55
  56   // Store icon formats.
  57   IconFormats icon_formats_;
  58
  59   // Store loaded icon_theme.
  60   IconThemeMap icon_themes_;
  61
  62   // The default theme.
  63   IconTheme* default_themes_[kDefaultThemeNum];
  64
  65   base::TimeTicks last_check_time_;
  66
  67   // The current icon theme, usually set through GTK theme integration.
  68   std::string icon_theme_name_;
  69
  70  private:
  71   MimeUtilConstants() {
  72     icon_formats_.push_back(".png");
  73     icon_formats_.push_back(".svg");
  74     icon_formats_.push_back(".xpm");
  75
  76     for (size_t i = 0; i < kDefaultThemeNum; ++i)
  77       default_themes_[i] = NULL;
  78   }
  79   ~MimeUtilConstants();
  80
  81   friend struct DefaultSingletonTraits<MimeUtilConstants>;
  82
  83   DISALLOW_COPY_AND_ASSIGN(MimeUtilConstants);
  84 };
  85
  86 // IconTheme represents an icon theme as defined by the xdg icon theme spec.
  87 // Example themes on GNOME include 'Human' and 'Mist'.
  88 // Example themes on KDE include 'crystalsvg' and 'kdeclassic'.
  89 class IconTheme {
  90  public:
  91   // A theme consists of multiple sub-directories, like '32x32' and 'scalable'.
  92   class SubDirInfo {
  93    public:
  94     // See spec for details.
  95     enum Type {
  96       Fixed,
  97       Scalable,
  98       Threshold
  99     };
 100     SubDirInfo()
 101         : size(0),
 102           type(Threshold),
 103           max_size(0),
 104           min_size(0),
 105           threshold(2) {
 106     }
 107     size_t size;  // Nominal size of the icons in this directory.
 108     Type type;  // Type of the icon size.
 109     size_t max_size;  // Maximum size that the icons can be scaled to.
 110     size_t min_size;  // Minimum size that the icons can be scaled to.
 111     size_t threshold;  // Maximum difference from desired size. 2 by default.
 112   };
 113
 114   explicit IconTheme(const std::string& name);
 115
 116   ~IconTheme() {}
 117
 118   // Returns the path to an icon with the name |icon_name| and a size of |size|
 119   // pixels. If the icon does not exist, but |inherits| is true, then look for
 120   // the icon in the parent theme.
 121   FilePath GetIconPath(const std::string& icon_name, int size, bool inherits);
 122
 123   // Load a theme with the name |theme_name| into memory. Returns null if theme
 124   // is invalid.
 125   static IconTheme* LoadTheme(const std::string& theme_name);
 126
 127  private:
 128   // Returns the path to an icon with the name |icon_name| in |subdir|.
 129   FilePath GetIconPathUnderSubdir(const std::string& icon_name,
 130                                   const std::string& subdir);
 131
 132   // Whether the theme loaded properly.
 133   bool IsValid() {
 134     return index_theme_loaded_;
 135   }
 136
 137   // Read and parse |file| which is usually named 'index.theme' per theme spec.
 138   bool LoadIndexTheme(const FilePath& file);
 139
 140   // Checks to see if the icons in |info| matches |size| (in pixels). Returns
 141   // 0 if they match, or the size difference in pixels.
 142   size_t MatchesSize(SubDirInfo* info, size_t size);
 143
 144   // Yet another function to read a line.
 145   std::string ReadLine(FILE* fp);
 146
 147   // Set directories to search for icons to the comma-separated list |dirs|.
 148   bool SetDirectories(const std::string& dirs);
 149
 150   bool index_theme_loaded_;  // True if an instance is properly loaded.
 151   // store the scattered directories of this theme.
 152   std::list<FilePath> dirs_;
 153
 154   // store the subdirs of this theme and array index of |info_array_|.
 155   std::map<std::string, int> subdirs_;
 156   scoped_ptr<SubDirInfo[]> info_array_;  // List of sub-directories.
 157   std::string inherits_;  // Name of the theme this one inherits from.
 158 };
 159
 160 IconTheme::IconTheme(const std::string& name)
 161     : index_theme_loaded_(false) {
 162   base::ThreadRestrictions::AssertIOAllowed();
 163   // Iterate on all icon directories to find directories of the specified
 164   // theme and load the first encountered index.theme.
 165   MimeUtilConstants::IconDirMtimeMap::iterator iter;
 166   FilePath theme_path;
 167   MimeUtilConstants::IconDirMtimeMap* icon_dirs =
 168       &MimeUtilConstants::GetInstance()->icon_dirs_;
 169   for (iter = icon_dirs->begin(); iter != icon_dirs->end(); ++iter) {
 170     theme_path = iter->first.Append(name);
 171     if (!DirectoryExists(theme_path))
 172       continue;
 173     FilePath theme_index = theme_path.Append("index.theme");
 174     if (!index_theme_loaded_ && PathExists(theme_index)) {
 175       if (!LoadIndexTheme(theme_index))
 176         return;
 177       index_theme_loaded_ = true;
 178     }
 179     dirs_.push_back(theme_path);
 180   }
 181 }
 182
 183 FilePath IconTheme::GetIconPath(const std::string& icon_name, int size,
 184                                 bool inherits) {
 185   std::map<std::string, int>::iterator subdir_iter;
 186   FilePath icon_path;
 187
 188   for (subdir_iter = subdirs_.begin();
 189        subdir_iter != subdirs_.end();
 190        ++subdir_iter) {
 191     SubDirInfo* info = &info_array_[subdir_iter->second];
 192     if (MatchesSize(info, size) == 0) {
 193       icon_path = GetIconPathUnderSubdir(icon_name, subdir_iter->first);
 194       if (!icon_path.empty())
 195         return icon_path;
 196     }
 197   }
 198   // Now looking for the mostly matched.
 199   size_t min_delta_seen = 9999;
 200
 201   for (subdir_iter = subdirs_.begin();
 202        subdir_iter != subdirs_.end();
 203        ++subdir_iter) {
 204     SubDirInfo* info = &info_array_[subdir_iter->second];
 205     size_t delta = MatchesSize(info, size);
 206     if (delta < min_delta_seen) {
 207       FilePath path = GetIconPathUnderSubdir(icon_name, subdir_iter->first);
 208       if (!path.empty()) {
 209         min_delta_seen = delta;
 210         icon_path = path;
 211       }
 212     }
 213   }
 214
 215   if (!icon_path.empty() || !inherits || inherits_ == "")
 216     return icon_path;
 217
 218   IconTheme* theme = LoadTheme(inherits_);
 219   // Inheriting from itself means the theme is buggy but we shouldn't crash.
 220   if (theme && theme != this)
 221     return theme->GetIconPath(icon_name, size, inherits);
 222   else
 223     return FilePath();
 224 }
 225
 226 IconTheme* IconTheme::LoadTheme(const std::string& theme_name) {
 227   scoped_ptr<IconTheme> theme;
 228   MimeUtilConstants::IconThemeMap* icon_themes =
 229       &MimeUtilConstants::GetInstance()->icon_themes_;
 230   if (icon_themes->find(theme_name) != icon_themes->end()) {
 231     theme.reset((*icon_themes)[theme_name]);
 232   } else {
 233     theme.reset(new IconTheme(theme_name));
 234     if (!theme->IsValid())
 235       theme.reset();
 236     (*icon_themes)[theme_name] = theme.get();
 237   }
 238   return theme.release();
 239 }
 240
 241 FilePath IconTheme::GetIconPathUnderSubdir(const std::string& icon_name,
 242                                            const std::string& subdir) {
 243   FilePath icon_path;
 244   std::list<FilePath>::iterator dir_iter;
 245   MimeUtilConstants::IconFormats* icon_formats =
 246       &MimeUtilConstants::GetInstance()->icon_formats_;
 247   for (dir_iter = dirs_.begin(); dir_iter != dirs_.end(); ++dir_iter) {
 248     for (size_t i = 0; i < icon_formats->size(); ++i) {
 249       icon_path = dir_iter->Append(subdir);
 250       icon_path = icon_path.Append(icon_name + (*icon_formats)[i]);
 251       if (PathExists(icon_path))
 252         return icon_path;
 253     }
 254   }
 255   return FilePath();
 256 }
 257
 258 bool IconTheme::LoadIndexTheme(const FilePath& file) {
 259   FILE* fp = file_util::OpenFile(file, "r");
 260   SubDirInfo* current_info = NULL;
 261   if (!fp)
 262     return false;
 263
 264   // Read entries.
 265   while (!feof(fp) && !ferror(fp)) {
 266     std::string buf = ReadLine(fp);
 267     if (buf == "")
 268       break;
 269
 270     std::string entry;
 271     TrimWhitespaceASCII(buf, TRIM_ALL, &entry);
 272     if (entry.length() == 0 || entry[0] == '#') {
 273       // Blank line or Comment.
 274       continue;
 275     } else if (entry[0] == '[' && info_array_.get()) {
 276       current_info = NULL;
 277       std::string subdir = entry.substr(1, entry.length() - 2);
 278       if (subdirs_.find(subdir) != subdirs_.end())
 279         current_info = &info_array_[subdirs_[subdir]];
 280     }
 281
 282     std::string key, value;
 283     std::vector<std::string> r;
 284     base::SplitStringDontTrim(entry, '=', &r);
 285     if (r.size() < 2)
 286       continue;
 287
 288     TrimWhitespaceASCII(r[0], TRIM_ALL, &key);
 289     for (size_t i = 1; i < r.size(); i++)
 290       value.append(r[i]);
 291     TrimWhitespaceASCII(value, TRIM_ALL, &value);
 292
 293     if (current_info) {
 294       if (key == "Size") {
 295         current_info->size = atoi(value.c_str());
 296       } else if (key == "Type") {
 297         if (value == "Fixed")
 298           current_info->type = SubDirInfo::Fixed;
 299         else if (value == "Scalable")
 300           current_info->type = SubDirInfo::Scalable;
 301         else if (value == "Threshold")
 302           current_info->type = SubDirInfo::Threshold;
 303       } else if (key == "MaxSize") {
 304         current_info->max_size = atoi(value.c_str());
 305       } else if (key == "MinSize") {
 306         current_info->min_size = atoi(value.c_str());
 307       } else if (key == "Threshold") {
 308         current_info->threshold = atoi(value.c_str());
 309       }
 310     } else {
 311       if (key.compare("Directories") == 0 && !info_array_.get()) {
 312         if (!SetDirectories(value)) break;
 313       } else if (key.compare("Inherits") == 0) {
 314         if (value != "hicolor")
 315           inherits_ = value;
 316       }
 317     }
 318   }
 319
 320   file_util::CloseFile(fp);
 321   return info_array_.get() != NULL;
 322 }
 323
 324 size_t IconTheme::MatchesSize(SubDirInfo* info, size_t size) {
 325   if (info->type == SubDirInfo::Fixed) {
 326     if (size > info->size)
 327       return size - info->size;
 328     else
 329       return info->size - size;
 330   } else if (info->type == SubDirInfo::Scalable) {
 331     if (size < info->min_size)
 332       return info->min_size - size;
 333     if (size > info->max_size)
 334       return size - info->max_size;
 335     return 0;
 336   } else {
 337     if (size + info->threshold < info->size)
 338       return info->size - size - info->threshold;
 339     if (size > info->size + info->threshold)
 340       return size - info->size - info->threshold;
 341     return 0;
 342   }
 343 }
 344
 345 std::string IconTheme::ReadLine(FILE* fp) {
 346   if (!fp)
 347     return std::string();
 348
 349   std::string result;
 350   const size_t kBufferSize = 100;
 351   char buffer[kBufferSize];
 352   while ((fgets(buffer, kBufferSize - 1, fp)) != NULL) {
 353     result += buffer;
 354     size_t len = result.length();
 355     if (len == 0)
 356       break;
 357     char end = result[len - 1];
 358     if (end == '\n' || end == '\0')
 359       break;
 360   }
 361
 362   return result;
 363 }
 364
 365 bool IconTheme::SetDirectories(const std::string& dirs) {
 366   int num = 0;
 367   std::string::size_type pos = 0, epos;
 368   std::string dir;
 369   while ((epos = dirs.find(',', pos)) != std::string::npos) {
 370     TrimWhitespaceASCII(dirs.substr(pos, epos - pos), TRIM_ALL, &dir);
 371     if (dir.length() == 0) {
 372       DLOG(WARNING) << "Invalid index.theme: blank subdir";
 373       return false;
 374     }
 375     subdirs_[dir] = num++;
 376     pos = epos + 1;
 377   }
 378   TrimWhitespaceASCII(dirs.substr(pos), TRIM_ALL, &dir);
 379   if (dir.length() == 0) {
 380     DLOG(WARNING) << "Invalid index.theme: blank subdir";
 381     return false;
 382   }
 383   subdirs_[dir] = num++;
 384   info_array_.reset(new SubDirInfo[num]);
 385   return true;
 386 }
 387
 388 bool CheckDirExistsAndGetMtime(const FilePath& dir,
 389                                base::Time* last_modified) {
 390   if (!DirectoryExists(dir))
 391     return false;
 392   base::PlatformFileInfo file_info;
 393   if (!file_util::GetFileInfo(dir, &file_info))
 394     return false;
 395   *last_modified = file_info.last_modified;
 396   return true;
 397 }
 398
 399 // Make sure |dir| exists and add it to the list of icon directories.
 400 void TryAddIconDir(const FilePath& dir) {
 401   base::Time last_modified;
 402   if (!CheckDirExistsAndGetMtime(dir, &last_modified))
 403     return;
 404   MimeUtilConstants::GetInstance()->icon_dirs_[dir] = last_modified;
 405 }
 406
 407 // For a xdg directory |dir|, add the appropriate icon sub-directories.
 408 void AddXDGDataDir(const FilePath& dir) {
 409   if (!DirectoryExists(dir))
 410     return;
 411   TryAddIconDir(dir.Append("icons"));
 412   TryAddIconDir(dir.Append("pixmaps"));
 413 }
 414
 415 // Add all the xdg icon directories.
 416 void InitIconDir() {
 417   FilePath home = file_util::GetHomeDir();
 418   if (!home.empty()) {
 419       FilePath legacy_data_dir(home);
 420       legacy_data_dir = legacy_data_dir.AppendASCII(".icons");
 421       if (DirectoryExists(legacy_data_dir))
 422         TryAddIconDir(legacy_data_dir);
 423   }
 424   const char* env = getenv("XDG_DATA_HOME");
 425   if (env) {
 426     AddXDGDataDir(FilePath(env));
 427   } else if (!home.empty()) {
 428     FilePath local_data_dir(home);
 429     local_data_dir = local_data_dir.AppendASCII(".local");
 430     local_data_dir = local_data_dir.AppendASCII("share");
 431     AddXDGDataDir(local_data_dir);
 432   }
 433
 434   env = getenv("XDG_DATA_DIRS");
 435   if (!env) {
 436     AddXDGDataDir(FilePath("/usr/local/share"));
 437     AddXDGDataDir(FilePath("/usr/share"));
 438   } else {
 439     std::string xdg_data_dirs = env;
 440     std::string::size_type pos = 0, epos;
 441     while ((epos = xdg_data_dirs.find(':', pos)) != std::string::npos) {
 442       AddXDGDataDir(FilePath(xdg_data_dirs.substr(pos, epos - pos)));
 443       pos = epos + 1;
 444     }
 445     AddXDGDataDir(FilePath(xdg_data_dirs.substr(pos)));
 446   }
 447 }
 448
 449 void EnsureUpdated() {
 450   MimeUtilConstants* constants = MimeUtilConstants::GetInstance();
 451   if (constants->last_check_time_.is_null()) {
 452     constants->last_check_time_ = base::TimeTicks::Now();
 453     InitIconDir();
 454     return;
 455   }
 456
 457   // Per xdg theme spec, we should check the icon directories every so often
 458   // for newly added icons.
 459   base::TimeDelta time_since_last_check =
 460       base::TimeTicks::Now() - constants->last_check_time_;
 461   if (time_since_last_check.InSeconds() > constants->kUpdateIntervalInSeconds) {
 462     constants->last_check_time_ += time_since_last_check;
 463
 464     bool rescan_icon_dirs = false;
 465     MimeUtilConstants::IconDirMtimeMap* icon_dirs = &constants->icon_dirs_;
 466     MimeUtilConstants::IconDirMtimeMap::iterator iter;
 467     for (iter = icon_dirs->begin(); iter != icon_dirs->end(); ++iter) {
 468       base::Time last_modified;
 469       if (!CheckDirExistsAndGetMtime(iter->first, &last_modified) ||
 470           last_modified != iter->second) {
 471         rescan_icon_dirs = true;
 472         break;
 473       }
 474     }
 475
 476     if (rescan_icon_dirs) {
 477       constants->icon_dirs_.clear();
 478       constants->icon_themes_.clear();
 479       InitIconDir();
 480     }
 481   }
 482 }
 483
 484 // Find a fallback icon if we cannot find it in the default theme.
 485 FilePath LookupFallbackIcon(const std::string& icon_name) {
 486   MimeUtilConstants* constants = MimeUtilConstants::GetInstance();
 487   MimeUtilConstants::IconDirMtimeMap::iterator iter;
 488   MimeUtilConstants::IconDirMtimeMap* icon_dirs = &constants->icon_dirs_;
 489   MimeUtilConstants::IconFormats* icon_formats = &constants->icon_formats_;
 490   for (iter = icon_dirs->begin(); iter != icon_dirs->end(); ++iter) {
 491     for (size_t i = 0; i < icon_formats->size(); ++i) {
 492       FilePath icon = iter->first.Append(icon_name + (*icon_formats)[i]);
 493       if (PathExists(icon))
 494         return icon;
 495     }
 496   }
 497   return FilePath();
 498 }
 499
 500 // Initialize the list of default themes.
 501 void InitDefaultThemes() {
 502   IconTheme** default_themes =
 503       MimeUtilConstants::GetInstance()->default_themes_;
 504
 505   scoped_ptr<base::Environment> env(base::Environment::Create());
 506   base::nix::DesktopEnvironment desktop_env =
 507       base::nix::GetDesktopEnvironment(env.get());
 508   if (desktop_env == base::nix::DESKTOP_ENVIRONMENT_KDE3 ||
 509       desktop_env == base::nix::DESKTOP_ENVIRONMENT_KDE4) {
 510     // KDE
 511     std::string kde_default_theme;
 512     std::string kde_fallback_theme;
 513
 514     // TODO(thestig): Figure out how to get the current icon theme on KDE.
 515     // Setting stored in ~/.kde/share/config/kdeglobals under Icons -> Theme.
 516     default_themes[0] = NULL;
 517
 518     // Try some reasonable defaults for KDE.
 519     if (desktop_env == base::nix::DESKTOP_ENVIRONMENT_KDE3) {
 520       // KDE 3
 521       kde_default_theme = "default.kde";
 522       kde_fallback_theme = "crystalsvg";
 523     } else {
 524       // KDE 4
 525       kde_default_theme = "default.kde4";
 526       kde_fallback_theme = "oxygen";
 527     }
 528     default_themes[1] = IconTheme::LoadTheme(kde_default_theme);
 529     default_themes[2] = IconTheme::LoadTheme(kde_fallback_theme);
 530   } else {
 531     // Assume it's Gnome and use GTK to figure out the theme.
 532     default_themes[1] = IconTheme::LoadTheme(
 533         MimeUtilConstants::GetInstance()->icon_theme_name_);
 534     default_themes[2] = IconTheme::LoadTheme("gnome");
 535   }
 536   // hicolor needs to be last per icon theme spec.
 537   default_themes[3] = IconTheme::LoadTheme("hicolor");
 538
 539   for (size_t i = 0; i < MimeUtilConstants::kDefaultThemeNum; i++) {
 540     if (default_themes[i] == NULL)
 541       continue;
 542     // NULL out duplicate pointers.
 543     for (size_t j = i + 1; j < MimeUtilConstants::kDefaultThemeNum; j++) {
 544       if (default_themes[j] == default_themes[i])
 545         default_themes[j] = NULL;
 546     }
 547   }
 548 }
 549
 550 // Try to find an icon with the name |icon_name| that's |size| pixels.
 551 FilePath LookupIconInDefaultTheme(const std::string& icon_name, int size) {
 552   EnsureUpdated();
 553   MimeUtilConstants* constants = MimeUtilConstants::GetInstance();
 554   MimeUtilConstants::IconThemeMap* icon_themes = &constants->icon_themes_;
 555   if (icon_themes->empty())
 556     InitDefaultThemes();
 557
 558   FilePath icon_path;
 559   IconTheme** default_themes = constants->default_themes_;
 560   for (size_t i = 0; i < MimeUtilConstants::kDefaultThemeNum; i++) {
 561     if (default_themes[i]) {
 562       icon_path = default_themes[i]->GetIconPath(icon_name, size, true);
 563       if (!icon_path.empty())
 564         return icon_path;
 565     }
 566   }
 567   return LookupFallbackIcon(icon_name);
 568 }
 569
 570 MimeUtilConstants::~MimeUtilConstants() {
 571   for (size_t i = 0; i < kDefaultThemeNum; i++)
 572     delete default_themes_[i];
 573 }
 574
 575 }  // namespace
 576
 577 std::string GetFileMimeType(const FilePath& filepath) {
 578   if (filepath.empty())
 579     return std::string();
 580   base::ThreadRestrictions::AssertIOAllowed();
 581   base::AutoLock scoped_lock(g_mime_util_xdg_lock.Get());
 582   return xdg_mime_get_mime_type_from_file_name(filepath.value().c_str());
 583 }
 584
 585 std::string GetDataMimeType(const std::string& data) {
 586   base::ThreadRestrictions::AssertIOAllowed();
 587   base::AutoLock scoped_lock(g_mime_util_xdg_lock.Get());
 588   return xdg_mime_get_mime_type_for_data(data.data(), data.length(), NULL);
 589 }
 590
 591 void SetIconThemeName(const std::string& name) {
 592   // If the theme name is already loaded, do nothing. Chrome doesn't respond
 593   // to changes in the system theme, so we never need to set this more than
 594   // once.
 595   if (!MimeUtilConstants::GetInstance()->icon_theme_name_.empty())
 596     return;
 597
 598   MimeUtilConstants::GetInstance()->icon_theme_name_ = name;
 599 }
 600
 601 FilePath GetMimeIcon(const std::string& mime_type, size_t size) {
 602   base::ThreadRestrictions::AssertIOAllowed();
 603   std::vector<std::string> icon_names;
 604   std::string icon_name;
 605   FilePath icon_file;
 606
 607   if (!mime_type.empty()) {
 608     base::AutoLock scoped_lock(g_mime_util_xdg_lock.Get());
 609     const char *icon = xdg_mime_get_icon(mime_type.c_str());
 610     icon_name = std::string(icon ? icon : "");
 611   }
 612
 613   if (icon_name.length())
 614     icon_names.push_back(icon_name);
 615
 616   // For text/plain, try text-plain.
 617   icon_name = mime_type;
 618   for (size_t i = icon_name.find('/', 0); i != std::string::npos;
 619        i = icon_name.find('/', i + 1)) {
 620     icon_name[i] = '-';
 621   }
 622   icon_names.push_back(icon_name);
 623   // Also try gnome-mime-text-plain.
 624   icon_names.push_back("gnome-mime-" + icon_name);
 625
 626   // Try "deb" for "application/x-deb" in KDE 3.
 627   size_t x_substr_pos = mime_type.find("/x-");
 628   if (x_substr_pos != std::string::npos) {
 629     icon_name = mime_type.substr(x_substr_pos + 3);
 630     icon_names.push_back(icon_name);
 631   }
 632
 633   // Try generic name like text-x-generic.
 634   icon_name = mime_type.substr(0, mime_type.find('/')) + "-x-generic";
 635   icon_names.push_back(icon_name);
 636
 637   // Last resort
 638   icon_names.push_back("unknown");
 639
 640   for (size_t i = 0; i < icon_names.size(); i++) {
 641     if (icon_names[i][0] == '/') {
 642       icon_file = FilePath(icon_names[i]);
 643       if (PathExists(icon_file))
 644         return icon_file;
 645     } else {
 646       icon_file = LookupIconInDefaultTheme(icon_names[i], size);
 647       if (!icon_file.empty())
 648         return icon_file;
 649     }
 650   }
 651   return FilePath();
 652 }
 653
 654 }  // namespace nix
 655 }  // namespace base