Path.cpp revision dce4a407a24b04eebc6a376f8e62b41aaa7b071f 
1//===-- Path.cpp - Implement OS Path Concept ------------------------------===//
2//
3//                     The LLVM Compiler Infrastructure
4//
5// This file is distributed under the University of Illinois Open Source
6// License. See LICENSE.TXT for details.
7//
8//===----------------------------------------------------------------------===//
9//
10//  This file implements the operating system Path API.
11//
12//===----------------------------------------------------------------------===//
13
14#include "llvm/Support/Path.h"
15#include "llvm/Support/Endian.h"
16#include "llvm/Support/ErrorHandling.h"
17#include "llvm/Support/FileSystem.h"
18#include "llvm/Support/Process.h"
19#include <cctype>
20#include <cstdio>
21#include <cstring>
22#include <fcntl.h>
23
24#if !defined(_MSC_VER) && !defined(__MINGW32__)
25#include <unistd.h>
26#else
27#include <io.h>
28#endif
29
30using namespace llvm;
31
32namespace {
33  using llvm::StringRef;
34  using llvm::sys::path::is_separator;
35
36#ifdef LLVM_ON_WIN32
37  const char *separators = "\\/";
38  const char preferred_separator = '\\';
39#else
40  const char  separators = '/';
41  const char preferred_separator = '/';
42#endif
43
44  StringRef find_first_component(StringRef path) {
45    // Look for this first component in the following order.
46    // * empty (in this case we return an empty string)
47    // * either C: or {//,\\}net.
48    // * {/,\}
49    // * {.,..}
50    // * {file,directory}name
51
52    if (path.empty())
53      return path;
54
55#ifdef LLVM_ON_WIN32
56    // C:
57    if (path.size() >= 2 && std::isalpha(static_cast<unsigned char>(path[0])) &&
58        path[1] == ':')
59      return path.substr(0, 2);
60#endif
61
62    // //net
63    if ((path.size() > 2) &&
64        is_separator(path[0]) &&
65        path[0] == path[1] &&
66        !is_separator(path[2])) {
67      // Find the next directory separator.
68      size_t end = path.find_first_of(separators, 2);
69      return path.substr(0, end);
70    }
71
72    // {/,\}
73    if (is_separator(path[0]))
74      return path.substr(0, 1);
75
76    if (path.startswith(".."))
77      return path.substr(0, 2);
78
79    if (path[0] == '.')
80      return path.substr(0, 1);
81
82    // * {file,directory}name
83    size_t end = path.find_first_of(separators);
84    return path.substr(0, end);
85  }
86
87  size_t filename_pos(StringRef str) {
88    if (str.size() == 2 &&
89        is_separator(str[0]) &&
90        str[0] == str[1])
91      return 0;
92
93    if (str.size() > 0 && is_separator(str[str.size() - 1]))
94      return str.size() - 1;
95
96    size_t pos = str.find_last_of(separators, str.size() - 1);
97
98#ifdef LLVM_ON_WIN32
99    if (pos == StringRef::npos)
100      pos = str.find_last_of(':', str.size() - 2);
101#endif
102
103    if (pos == StringRef::npos ||
104        (pos == 1 && is_separator(str[0])))
105      return 0;
106
107    return pos + 1;
108  }
109
110  size_t root_dir_start(StringRef str) {
111    // case "c:/"
112#ifdef LLVM_ON_WIN32
113    if (str.size() > 2 &&
114        str[1] == ':' &&
115        is_separator(str[2]))
116      return 2;
117#endif
118
119    // case "//"
120    if (str.size() == 2 &&
121        is_separator(str[0]) &&
122        str[0] == str[1])
123      return StringRef::npos;
124
125    // case "//net"
126    if (str.size() > 3 &&
127        is_separator(str[0]) &&
128        str[0] == str[1] &&
129        !is_separator(str[2])) {
130      return str.find_first_of(separators, 2);
131    }
132
133    // case "/"
134    if (str.size() > 0 && is_separator(str[0]))
135      return 0;
136
137    return StringRef::npos;
138  }
139
140  size_t parent_path_end(StringRef path) {
141    size_t end_pos = filename_pos(path);
142
143    bool filename_was_sep = path.size() > 0 && is_separator(path[end_pos]);
144
145    // Skip separators except for root dir.
146    size_t root_dir_pos = root_dir_start(path.substr(0, end_pos));
147
148    while(end_pos > 0 &&
149          (end_pos - 1) != root_dir_pos &&
150          is_separator(path[end_pos - 1]))
151      --end_pos;
152
153    if (end_pos == 1 && root_dir_pos == 0 && filename_was_sep)
154      return StringRef::npos;
155
156    return end_pos;
157  }
158} // end unnamed namespace
159
160enum FSEntity {
161  FS_Dir,
162  FS_File,
163  FS_Name
164};
165
166// Implemented in Unix/Path.inc and Windows/Path.inc.
167static error_code TempDir(SmallVectorImpl<char> &result);
168
169static error_code createUniqueEntity(const Twine &Model, int &ResultFD,
170                                     SmallVectorImpl<char> &ResultPath,
171                                     bool MakeAbsolute, unsigned Mode,
172                                     FSEntity Type) {
173  SmallString<128> ModelStorage;
174  Model.toVector(ModelStorage);
175
176  if (MakeAbsolute) {
177    // Make model absolute by prepending a temp directory if it's not already.
178    if (!sys::path::is_absolute(Twine(ModelStorage))) {
179      SmallString<128> TDir;
180      if (error_code EC = TempDir(TDir))
181        return EC;
182      sys::path::append(TDir, Twine(ModelStorage));
183      ModelStorage.swap(TDir);
184    }
185  }
186
187  // From here on, DO NOT modify model. It may be needed if the randomly chosen
188  // path already exists.
189  ResultPath = ModelStorage;
190  // Null terminate.
191  ResultPath.push_back(0);
192  ResultPath.pop_back();
193
194retry_random_path:
195  // Replace '%' with random chars.
196  for (unsigned i = 0, e = ModelStorage.size(); i != e; ++i) {
197    if (ModelStorage[i] == '%')
198      ResultPath[i] = "0123456789abcdef"[sys::Process::GetRandomNumber() & 15];
199  }
200
201  // Try to open + create the file.
202  switch (Type) {
203  case FS_File: {
204    if (error_code EC =
205            sys::fs::openFileForWrite(Twine(ResultPath.begin()), ResultFD,
206                                      sys::fs::F_RW | sys::fs::F_Excl, Mode)) {
207      if (EC == errc::file_exists)
208        goto retry_random_path;
209      return EC;
210    }
211
212    return error_code::success();
213  }
214
215  case FS_Name: {
216    bool Exists;
217    error_code EC = sys::fs::exists(ResultPath.begin(), Exists);
218    if (EC)
219      return EC;
220    if (Exists)
221      goto retry_random_path;
222    return error_code::success();
223  }
224
225  case FS_Dir: {
226    if (error_code EC = sys::fs::create_directory(ResultPath.begin(), false)) {
227      if (EC == errc::file_exists)
228        goto retry_random_path;
229      return EC;
230    }
231    return error_code::success();
232  }
233  }
234  llvm_unreachable("Invalid Type");
235}
236
237namespace llvm {
238namespace sys  {
239namespace path {
240
241const_iterator begin(StringRef path) {
242  const_iterator i;
243  i.Path      = path;
244  i.Component = find_first_component(path);
245  i.Position  = 0;
246  return i;
247}
248
249const_iterator end(StringRef path) {
250  const_iterator i;
251  i.Path      = path;
252  i.Position  = path.size();
253  return i;
254}
255
256const_iterator &const_iterator::operator++() {
257  assert(Position < Path.size() && "Tried to increment past end!");
258
259  // Increment Position to past the current component
260  Position += Component.size();
261
262  // Check for end.
263  if (Position == Path.size()) {
264    Component = StringRef();
265    return *this;
266  }
267
268  // Both POSIX and Windows treat paths that begin with exactly two separators
269  // specially.
270  bool was_net = Component.size() > 2 &&
271    is_separator(Component[0]) &&
272    Component[1] == Component[0] &&
273    !is_separator(Component[2]);
274
275  // Handle separators.
276  if (is_separator(Path[Position])) {
277    // Root dir.
278    if (was_net
279#ifdef LLVM_ON_WIN32
280        // c:/
281        || Component.endswith(":")
282#endif
283        ) {
284      Component = Path.substr(Position, 1);
285      return *this;
286    }
287
288    // Skip extra separators.
289    while (Position != Path.size() &&
290           is_separator(Path[Position])) {
291      ++Position;
292    }
293
294    // Treat trailing '/' as a '.'.
295    if (Position == Path.size()) {
296      --Position;
297      Component = ".";
298      return *this;
299    }
300  }
301
302  // Find next component.
303  size_t end_pos = Path.find_first_of(separators, Position);
304  Component = Path.slice(Position, end_pos);
305
306  return *this;
307}
308
309const_iterator &const_iterator::operator--() {
310  // If we're at the end and the previous char was a '/', return '.' unless
311  // we are the root path.
312  size_t root_dir_pos = root_dir_start(Path);
313  if (Position == Path.size() &&
314      Path.size() > root_dir_pos + 1 &&
315      is_separator(Path[Position - 1])) {
316    --Position;
317    Component = ".";
318    return *this;
319  }
320
321  // Skip separators unless it's the root directory.
322  size_t end_pos = Position;
323
324  while(end_pos > 0 &&
325        (end_pos - 1) != root_dir_pos &&
326        is_separator(Path[end_pos - 1]))
327    --end_pos;
328
329  // Find next separator.
330  size_t start_pos = filename_pos(Path.substr(0, end_pos));
331  Component = Path.slice(start_pos, end_pos);
332  Position = start_pos;
333  return *this;
334}
335
336bool const_iterator::operator==(const const_iterator &RHS) const {
337  return Path.begin() == RHS.Path.begin() &&
338         Position == RHS.Position;
339}
340
341bool const_iterator::operator!=(const const_iterator &RHS) const {
342  return !(*this == RHS);
343}
344
345ptrdiff_t const_iterator::operator-(const const_iterator &RHS) const {
346  return Position - RHS.Position;
347}
348
349const StringRef root_path(StringRef path) {
350  const_iterator b = begin(path),
351                 pos = b,
352                 e = end(path);
353  if (b != e) {
354    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
355    bool has_drive =
356#ifdef LLVM_ON_WIN32
357      b->endswith(":");
358#else
359      false;
360#endif
361
362    if (has_net || has_drive) {
363      if ((++pos != e) && is_separator((*pos)[0])) {
364        // {C:/,//net/}, so get the first two components.
365        return path.substr(0, b->size() + pos->size());
366      } else {
367        // just {C:,//net}, return the first component.
368        return *b;
369      }
370    }
371
372    // POSIX style root directory.
373    if (is_separator((*b)[0])) {
374      return *b;
375    }
376  }
377
378  return StringRef();
379}
380
381const StringRef root_name(StringRef path) {
382  const_iterator b = begin(path),
383                 e = end(path);
384  if (b != e) {
385    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
386    bool has_drive =
387#ifdef LLVM_ON_WIN32
388      b->endswith(":");
389#else
390      false;
391#endif
392
393    if (has_net || has_drive) {
394      // just {C:,//net}, return the first component.
395      return *b;
396    }
397  }
398
399  // No path or no name.
400  return StringRef();
401}
402
403const StringRef root_directory(StringRef path) {
404  const_iterator b = begin(path),
405                 pos = b,
406                 e = end(path);
407  if (b != e) {
408    bool has_net = b->size() > 2 && is_separator((*b)[0]) && (*b)[1] == (*b)[0];
409    bool has_drive =
410#ifdef LLVM_ON_WIN32
411      b->endswith(":");
412#else
413      false;
414#endif
415
416    if ((has_net || has_drive) &&
417        // {C:,//net}, skip to the next component.
418        (++pos != e) && is_separator((*pos)[0])) {
419      return *pos;
420    }
421
422    // POSIX style root directory.
423    if (!has_net && is_separator((*b)[0])) {
424      return *b;
425    }
426  }
427
428  // No path or no root.
429  return StringRef();
430}
431
432const StringRef relative_path(StringRef path) {
433  StringRef root = root_path(path);
434  return path.substr(root.size());
435}
436
437void append(SmallVectorImpl<char> &path, const Twine &a,
438                                         const Twine &b,
439                                         const Twine &c,
440                                         const Twine &d) {
441  SmallString<32> a_storage;
442  SmallString<32> b_storage;
443  SmallString<32> c_storage;
444  SmallString<32> d_storage;
445
446  SmallVector<StringRef, 4> components;
447  if (!a.isTriviallyEmpty()) components.push_back(a.toStringRef(a_storage));
448  if (!b.isTriviallyEmpty()) components.push_back(b.toStringRef(b_storage));
449  if (!c.isTriviallyEmpty()) components.push_back(c.toStringRef(c_storage));
450  if (!d.isTriviallyEmpty()) components.push_back(d.toStringRef(d_storage));
451
452  for (SmallVectorImpl<StringRef>::const_iterator i = components.begin(),
453                                                  e = components.end();
454                                                  i != e; ++i) {
455    bool path_has_sep = !path.empty() && is_separator(path[path.size() - 1]);
456    bool component_has_sep = !i->empty() && is_separator((*i)[0]);
457    bool is_root_name = has_root_name(*i);
458
459    if (path_has_sep) {
460      // Strip separators from beginning of component.
461      size_t loc = i->find_first_not_of(separators);
462      StringRef c = i->substr(loc);
463
464      // Append it.
465      path.append(c.begin(), c.end());
466      continue;
467    }
468
469    if (!component_has_sep && !(path.empty() || is_root_name)) {
470      // Add a separator.
471      path.push_back(preferred_separator);
472    }
473
474    path.append(i->begin(), i->end());
475  }
476}
477
478void append(SmallVectorImpl<char> &path,
479            const_iterator begin, const_iterator end) {
480  for (; begin != end; ++begin)
481    path::append(path, *begin);
482}
483
484const StringRef parent_path(StringRef path) {
485  size_t end_pos = parent_path_end(path);
486  if (end_pos == StringRef::npos)
487    return StringRef();
488  else
489    return path.substr(0, end_pos);
490}
491
492void remove_filename(SmallVectorImpl<char> &path) {
493  size_t end_pos = parent_path_end(StringRef(path.begin(), path.size()));
494  if (end_pos != StringRef::npos)
495    path.set_size(end_pos);
496}
497
498void replace_extension(SmallVectorImpl<char> &path, const Twine &extension) {
499  StringRef p(path.begin(), path.size());
500  SmallString<32> ext_storage;
501  StringRef ext = extension.toStringRef(ext_storage);
502
503  // Erase existing extension.
504  size_t pos = p.find_last_of('.');
505  if (pos != StringRef::npos && pos >= filename_pos(p))
506    path.set_size(pos);
507
508  // Append '.' if needed.
509  if (ext.size() > 0 && ext[0] != '.')
510    path.push_back('.');
511
512  // Append extension.
513  path.append(ext.begin(), ext.end());
514}
515
516void native(const Twine &path, SmallVectorImpl<char> &result) {
517  assert((!path.isSingleStringRef() ||
518          path.getSingleStringRef().data() != result.data()) &&
519         "path and result are not allowed to overlap!");
520  // Clear result.
521  result.clear();
522  path.toVector(result);
523  native(result);
524}
525
526void native(SmallVectorImpl<char> &path) {
527#ifdef LLVM_ON_WIN32
528  std::replace(path.begin(), path.end(), '/', '\\');
529#endif
530}
531
532const StringRef filename(StringRef path) {
533  return *(--end(path));
534}
535
536const StringRef stem(StringRef path) {
537  StringRef fname = filename(path);
538  size_t pos = fname.find_last_of('.');
539  if (pos == StringRef::npos)
540    return fname;
541  else
542    if ((fname.size() == 1 && fname == ".") ||
543        (fname.size() == 2 && fname == ".."))
544      return fname;
545    else
546      return fname.substr(0, pos);
547}
548
549const StringRef extension(StringRef path) {
550  StringRef fname = filename(path);
551  size_t pos = fname.find_last_of('.');
552  if (pos == StringRef::npos)
553    return StringRef();
554  else
555    if ((fname.size() == 1 && fname == ".") ||
556        (fname.size() == 2 && fname == ".."))
557      return StringRef();
558    else
559      return fname.substr(pos);
560}
561
562bool is_separator(char value) {
563  switch(value) {
564#ifdef LLVM_ON_WIN32
565    case '\\': // fall through
566#endif
567    case '/': return true;
568    default: return false;
569  }
570}
571
572static const char preferred_separator_string[] = { preferred_separator, '\0' };
573
574const StringRef get_separator() {
575  return preferred_separator_string;
576}
577
578void system_temp_directory(bool erasedOnReboot, SmallVectorImpl<char> &result) {
579  result.clear();
580
581#if defined(_CS_DARWIN_USER_TEMP_DIR) && defined(_CS_DARWIN_USER_CACHE_DIR)
582  // On Darwin, use DARWIN_USER_TEMP_DIR or DARWIN_USER_CACHE_DIR.
583  // macros defined in <unistd.h> on darwin >= 9
584  int ConfName = erasedOnReboot? _CS_DARWIN_USER_TEMP_DIR
585                               : _CS_DARWIN_USER_CACHE_DIR;
586  size_t ConfLen = confstr(ConfName, nullptr, 0);
587  if (ConfLen > 0) {
588    do {
589      result.resize(ConfLen);
590      ConfLen = confstr(ConfName, result.data(), result.size());
591    } while (ConfLen > 0 && ConfLen != result.size());
592
593    if (ConfLen > 0) {
594      assert(result.back() == 0);
595      result.pop_back();
596      return;
597    }
598
599    result.clear();
600  }
601#endif
602
603  // Check whether the temporary directory is specified by an environment
604  // variable.
605  const char *EnvironmentVariable;
606#ifdef LLVM_ON_WIN32
607  EnvironmentVariable = "TEMP";
608#else
609  EnvironmentVariable = "TMPDIR";
610#endif
611  if (char *RequestedDir = getenv(EnvironmentVariable)) {
612    result.append(RequestedDir, RequestedDir + strlen(RequestedDir));
613    return;
614  }
615
616  // Fall back to a system default.
617  const char *DefaultResult;
618#ifdef LLVM_ON_WIN32
619  (void)erasedOnReboot;
620  DefaultResult = "C:\\TEMP";
621#else
622  if (erasedOnReboot)
623    DefaultResult = "/tmp";
624  else
625    DefaultResult = "/var/tmp";
626#endif
627  result.append(DefaultResult, DefaultResult + strlen(DefaultResult));
628}
629
630bool has_root_name(const Twine &path) {
631  SmallString<128> path_storage;
632  StringRef p = path.toStringRef(path_storage);
633
634  return !root_name(p).empty();
635}
636
637bool has_root_directory(const Twine &path) {
638  SmallString<128> path_storage;
639  StringRef p = path.toStringRef(path_storage);
640
641  return !root_directory(p).empty();
642}
643
644bool has_root_path(const Twine &path) {
645  SmallString<128> path_storage;
646  StringRef p = path.toStringRef(path_storage);
647
648  return !root_path(p).empty();
649}
650
651bool has_relative_path(const Twine &path) {
652  SmallString<128> path_storage;
653  StringRef p = path.toStringRef(path_storage);
654
655  return !relative_path(p).empty();
656}
657
658bool has_filename(const Twine &path) {
659  SmallString<128> path_storage;
660  StringRef p = path.toStringRef(path_storage);
661
662  return !filename(p).empty();
663}
664
665bool has_parent_path(const Twine &path) {
666  SmallString<128> path_storage;
667  StringRef p = path.toStringRef(path_storage);
668
669  return !parent_path(p).empty();
670}
671
672bool has_stem(const Twine &path) {
673  SmallString<128> path_storage;
674  StringRef p = path.toStringRef(path_storage);
675
676  return !stem(p).empty();
677}
678
679bool has_extension(const Twine &path) {
680  SmallString<128> path_storage;
681  StringRef p = path.toStringRef(path_storage);
682
683  return !extension(p).empty();
684}
685
686bool is_absolute(const Twine &path) {
687  SmallString<128> path_storage;
688  StringRef p = path.toStringRef(path_storage);
689
690  bool rootDir = has_root_directory(p),
691#ifdef LLVM_ON_WIN32
692       rootName = has_root_name(p);
693#else
694       rootName = true;
695#endif
696
697  return rootDir && rootName;
698}
699
700bool is_relative(const Twine &path) {
701  return !is_absolute(path);
702}
703
704} // end namespace path
705
706namespace fs {
707
708error_code getUniqueID(const Twine Path, UniqueID &Result) {
709  file_status Status;
710  error_code EC = status(Path, Status);
711  if (EC)
712    return EC;
713  Result = Status.getUniqueID();
714  return error_code::success();
715}
716
717error_code createUniqueFile(const Twine &Model, int &ResultFd,
718                            SmallVectorImpl<char> &ResultPath, unsigned Mode) {
719  return createUniqueEntity(Model, ResultFd, ResultPath, false, Mode, FS_File);
720}
721
722error_code createUniqueFile(const Twine &Model,
723                            SmallVectorImpl<char> &ResultPath) {
724  int Dummy;
725  return createUniqueEntity(Model, Dummy, ResultPath, false, 0, FS_Name);
726}
727
728static error_code createTemporaryFile(const Twine &Model, int &ResultFD,
729                                      llvm::SmallVectorImpl<char> &ResultPath,
730                                      FSEntity Type) {
731  SmallString<128> Storage;
732  StringRef P = Model.toNullTerminatedStringRef(Storage);
733  assert(P.find_first_of(separators) == StringRef::npos &&
734         "Model must be a simple filename.");
735  // Use P.begin() so that createUniqueEntity doesn't need to recreate Storage.
736  return createUniqueEntity(P.begin(), ResultFD, ResultPath,
737                            true, owner_read | owner_write, Type);
738}
739
740static error_code
741createTemporaryFile(const Twine &Prefix, StringRef Suffix, int &ResultFD,
742                    llvm::SmallVectorImpl<char> &ResultPath,
743                    FSEntity Type) {
744  const char *Middle = Suffix.empty() ? "-%%%%%%" : "-%%%%%%.";
745  return createTemporaryFile(Prefix + Middle + Suffix, ResultFD, ResultPath,
746                             Type);
747}
748
749
750error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
751                               int &ResultFD,
752                               SmallVectorImpl<char> &ResultPath) {
753  return createTemporaryFile(Prefix, Suffix, ResultFD, ResultPath, FS_File);
754}
755
756error_code createTemporaryFile(const Twine &Prefix, StringRef Suffix,
757                               SmallVectorImpl<char> &ResultPath) {
758  int Dummy;
759  return createTemporaryFile(Prefix, Suffix, Dummy, ResultPath, FS_Name);
760}
761
762
763// This is a mkdtemp with a different pattern. We use createUniqueEntity mostly
764// for consistency. We should try using mkdtemp.
765error_code createUniqueDirectory(const Twine &Prefix,
766                                 SmallVectorImpl<char> &ResultPath) {
767  int Dummy;
768  return createUniqueEntity(Prefix + "-%%%%%%", Dummy, ResultPath,
769                            true, 0, FS_Dir);
770}
771
772error_code make_absolute(SmallVectorImpl<char> &path) {
773  StringRef p(path.data(), path.size());
774
775  bool rootDirectory = path::has_root_directory(p),
776#ifdef LLVM_ON_WIN32
777       rootName = path::has_root_name(p);
778#else
779       rootName = true;
780#endif
781
782  // Already absolute.
783  if (rootName && rootDirectory)
784    return error_code::success();
785
786  // All of the following conditions will need the current directory.
787  SmallString<128> current_dir;
788  if (error_code ec = current_path(current_dir)) return ec;
789
790  // Relative path. Prepend the current directory.
791  if (!rootName && !rootDirectory) {
792    // Append path to the current directory.
793    path::append(current_dir, p);
794    // Set path to the result.
795    path.swap(current_dir);
796    return error_code::success();
797  }
798
799  if (!rootName && rootDirectory) {
800    StringRef cdrn = path::root_name(current_dir);
801    SmallString<128> curDirRootName(cdrn.begin(), cdrn.end());
802    path::append(curDirRootName, p);
803    // Set path to the result.
804    path.swap(curDirRootName);
805    return error_code::success();
806  }
807
808  if (rootName && !rootDirectory) {
809    StringRef pRootName      = path::root_name(p);
810    StringRef bRootDirectory = path::root_directory(current_dir);
811    StringRef bRelativePath  = path::relative_path(current_dir);
812    StringRef pRelativePath  = path::relative_path(p);
813
814    SmallString<128> res;
815    path::append(res, pRootName, bRootDirectory, bRelativePath, pRelativePath);
816    path.swap(res);
817    return error_code::success();
818  }
819
820  llvm_unreachable("All rootName and rootDirectory combinations should have "
821                   "occurred above!");
822}
823
824error_code create_directories(const Twine &Path, bool IgnoreExisting) {
825  SmallString<128> PathStorage;
826  StringRef P = Path.toStringRef(PathStorage);
827
828  // Be optimistic and try to create the directory
829  error_code EC = create_directory(P, IgnoreExisting);
830  // If we succeeded, or had any error other than the parent not existing, just
831  // return it.
832  if (EC != errc::no_such_file_or_directory)
833    return EC;
834
835  // We failed because of a no_such_file_or_directory, try to create the
836  // parent.
837  StringRef Parent = path::parent_path(P);
838  if (Parent.empty())
839    return EC;
840
841  if ((EC = create_directories(Parent)))
842      return EC;
843
844  return create_directory(P, IgnoreExisting);
845}
846
847bool exists(file_status status) {
848  return status_known(status) && status.type() != file_type::file_not_found;
849}
850
851bool status_known(file_status s) {
852  return s.type() != file_type::status_error;
853}
854
855bool is_directory(file_status status) {
856  return status.type() == file_type::directory_file;
857}
858
859error_code is_directory(const Twine &path, bool &result) {
860  file_status st;
861  if (error_code ec = status(path, st))
862    return ec;
863  result = is_directory(st);
864  return error_code::success();
865}
866
867bool is_regular_file(file_status status) {
868  return status.type() == file_type::regular_file;
869}
870
871error_code is_regular_file(const Twine &path, bool &result) {
872  file_status st;
873  if (error_code ec = status(path, st))
874    return ec;
875  result = is_regular_file(st);
876  return error_code::success();
877}
878
879bool is_other(file_status status) {
880  return exists(status) &&
881         !is_regular_file(status) &&
882         !is_directory(status);
883}
884
885void directory_entry::replace_filename(const Twine &filename, file_status st) {
886  SmallString<128> path(Path.begin(), Path.end());
887  path::remove_filename(path);
888  path::append(path, filename);
889  Path = path.str();
890  Status = st;
891}
892
893error_code has_magic(const Twine &path, const Twine &magic, bool &result) {
894  SmallString<32>  MagicStorage;
895  StringRef Magic = magic.toStringRef(MagicStorage);
896  SmallString<32> Buffer;
897
898  if (error_code ec = get_magic(path, Magic.size(), Buffer)) {
899    if (ec == errc::value_too_large) {
900      // Magic.size() > file_size(Path).
901      result = false;
902      return error_code::success();
903    }
904    return ec;
905  }
906
907  result = Magic == Buffer;
908  return error_code::success();
909}
910
911/// @brief Identify the magic in magic.
912  file_magic identify_magic(StringRef Magic) {
913  if (Magic.size() < 4)
914    return file_magic::unknown;
915  switch ((unsigned char)Magic[0]) {
916    case 0x00: {
917      // COFF short import library file
918      if (Magic[1] == (char)0x00 && Magic[2] == (char)0xff &&
919          Magic[3] == (char)0xff)
920        return file_magic::coff_import_library;
921      // Windows resource file
922      const char Expected[] = { 0, 0, 0, 0, '\x20', 0, 0, 0, '\xff' };
923      if (Magic.size() >= sizeof(Expected) &&
924          memcmp(Magic.data(), Expected, sizeof(Expected)) == 0)
925        return file_magic::windows_resource;
926      // 0x0000 = COFF unknown machine type
927      if (Magic[1] == 0)
928        return file_magic::coff_object;
929      break;
930    }
931    case 0xDE:  // 0x0B17C0DE = BC wraper
932      if (Magic[1] == (char)0xC0 && Magic[2] == (char)0x17 &&
933          Magic[3] == (char)0x0B)
934        return file_magic::bitcode;
935      break;
936    case 'B':
937      if (Magic[1] == 'C' && Magic[2] == (char)0xC0 && Magic[3] == (char)0xDE)
938        return file_magic::bitcode;
939      break;
940    case '!':
941      if (Magic.size() >= 8)
942        if (memcmp(Magic.data(),"!<arch>\n",8) == 0)
943          return file_magic::archive;
944      break;
945
946    case '\177':
947      if (Magic.size() >= 18 && Magic[1] == 'E' && Magic[2] == 'L' &&
948          Magic[3] == 'F') {
949        bool Data2MSB = Magic[5] == 2;
950        unsigned high = Data2MSB ? 16 : 17;
951        unsigned low  = Data2MSB ? 17 : 16;
952        if (Magic[high] == 0)
953          switch (Magic[low]) {
954            default: break;
955            case 1: return file_magic::elf_relocatable;
956            case 2: return file_magic::elf_executable;
957            case 3: return file_magic::elf_shared_object;
958            case 4: return file_magic::elf_core;
959          }
960      }
961      break;
962
963    case 0xCA:
964      if (Magic[1] == char(0xFE) && Magic[2] == char(0xBA) &&
965          Magic[3] == char(0xBE)) {
966        // This is complicated by an overlap with Java class files.
967        // See the Mach-O section in /usr/share/file/magic for details.
968        if (Magic.size() >= 8 && Magic[7] < 43)
969          return file_magic::macho_universal_binary;
970      }
971      break;
972
973      // The two magic numbers for mach-o are:
974      // 0xfeedface - 32-bit mach-o
975      // 0xfeedfacf - 64-bit mach-o
976    case 0xFE:
977    case 0xCE:
978    case 0xCF: {
979      uint16_t type = 0;
980      if (Magic[0] == char(0xFE) && Magic[1] == char(0xED) &&
981          Magic[2] == char(0xFA) &&
982          (Magic[3] == char(0xCE) || Magic[3] == char(0xCF))) {
983        /* Native endian */
984        if (Magic.size() >= 16) type = Magic[14] << 8 | Magic[15];
985      } else if ((Magic[0] == char(0xCE) || Magic[0] == char(0xCF)) &&
986                 Magic[1] == char(0xFA) && Magic[2] == char(0xED) &&
987                 Magic[3] == char(0xFE)) {
988        /* Reverse endian */
989        if (Magic.size() >= 14) type = Magic[13] << 8 | Magic[12];
990      }
991      switch (type) {
992        default: break;
993        case 1: return file_magic::macho_object;
994        case 2: return file_magic::macho_executable;
995        case 3: return file_magic::macho_fixed_virtual_memory_shared_lib;
996        case 4: return file_magic::macho_core;
997        case 5: return file_magic::macho_preload_executable;
998        case 6: return file_magic::macho_dynamically_linked_shared_lib;
999        case 7: return file_magic::macho_dynamic_linker;
1000        case 8: return file_magic::macho_bundle;
1001        case 9: return file_magic::macho_dynamic_linker;
1002        case 10: return file_magic::macho_dsym_companion;
1003      }
1004      break;
1005    }
1006    case 0xF0: // PowerPC Windows
1007    case 0x83: // Alpha 32-bit
1008    case 0x84: // Alpha 64-bit
1009    case 0x66: // MPS R4000 Windows
1010    case 0x50: // mc68K
1011    case 0x4c: // 80386 Windows
1012    case 0xc4: // ARMNT Windows
1013      if (Magic[1] == 0x01)
1014        return file_magic::coff_object;
1015
1016    case 0x90: // PA-RISC Windows
1017    case 0x68: // mc68K Windows
1018      if (Magic[1] == 0x02)
1019        return file_magic::coff_object;
1020      break;
1021
1022    case 0x4d: // Possible MS-DOS stub on Windows PE file
1023      if (Magic[1] == 0x5a) {
1024        uint32_t off =
1025          *reinterpret_cast<const support::ulittle32_t*>(Magic.data() + 0x3c);
1026        // PE/COFF file, either EXE or DLL.
1027        if (off < Magic.size() && memcmp(Magic.data() + off, "PE\0\0",4) == 0)
1028          return file_magic::pecoff_executable;
1029      }
1030      break;
1031
1032    case 0x64: // x86-64 Windows.
1033      if (Magic[1] == char(0x86))
1034        return file_magic::coff_object;
1035      break;
1036
1037    default:
1038      break;
1039  }
1040  return file_magic::unknown;
1041}
1042
1043error_code identify_magic(const Twine &path, file_magic &result) {
1044  SmallString<32> Magic;
1045  error_code ec = get_magic(path, Magic.capacity(), Magic);
1046  if (ec && ec != errc::value_too_large)
1047    return ec;
1048
1049  result = identify_magic(Magic);
1050  return error_code::success();
1051}
1052
1053error_code directory_entry::status(file_status &result) const {
1054  return fs::status(Path, result);
1055}
1056
1057} // end namespace fs
1058} // end namespace sys
1059} // end namespace llvm
1060
1061// Include the truly platform-specific parts.
1062#if defined(LLVM_ON_UNIX)
1063#include "Unix/Path.inc"
1064#endif
1065#if defined(LLVM_ON_WIN32)
1066#include "Windows/Path.inc"
1067#endif
1068