Programming with POSIX® Threads

33 while (crew->work_count == 0) {

34  status = pthread_cond_wait (&crew->go, &crew->mutex);

35  if (status != 0)

36  err_abort (status, "Wait for go");

37 }

38

39 status = pthread_mutex_unlock (&crew->mutex);

40 if (status != 0)

41  err_abort (status, "Unlock mutex");

42

43 DPRINTF (("Crew %d starting\n", mine->index));

44

45 /*

46 * Now, as long as there's work, keep doing it.

47 */

48 while (1) {

49 /*

50 * Wait while there is nothing to do, and

51 * the hope of something coming along later. If

52 * crew->first is NULL, there's no work. But if

53 * crew->work_count goes to zero, we're done.

54 */

55  status = pthread_mutex_lock (&crew->mutex);

56  if (status != 0)

57  err_abort (status, "Lock crew mutex");

58

59  DPRINTF (("Crew %d top: first is %#lx, count is %d\n",

60  mine->index, crew->first, crew->work_count));

61  while (crew->first == NULL) {

62  status = pthread_cond_wait (&crew->go, &crew->mutex);

63  if (status != 0)

64  err_abort (status, "Wait for work");

65  }

66

67  DPRINTF (("Crew %d woke: %#lx, %d\n",

68  mine->index, crew->first, crew->work_count));

69

70 /*

71 * Remove and process a work item.

72 */

73  work = crew->first;

74  crew->first = work->next;

75  if (crew->first == NULL)

76  crew->last = NULL;

77

78  DPRINTF (("Crew %d took %#lx, leaves first %#lx, last %#lx\n",

79  mine->index, work, crew->first, crew->last));

80

81  status = pthread_mutex_unlock (&crew->mutex);

82  if (status != 0)

83  err_abort (status, "Unlock mutex");

84

85 /*

86 * We have a work item. Process it, which may involve

87 * queuing new work items.

88 */

89  status = lstat (work->path, &filestat);

90

91  if (S_ISLNK (filestat.st_mode))

92  printf (

93  "Thread %d: %s is a link, skipping.\n",

94  mine->index,

95  work->path);

96  else if (S_ISDIR (filestat.st_mode)) {

97  DIR *directory;

98  struct dirent *result;

99

100 /*

101 * If the file is a directory, search it and place

102 * all files onto the queue as new work items.

103 */

104  directory = opendir (work->path);

105  if (directory == NULL) {

106  fprintf (

107  stderr, "Unable to open directory %s: %d (%s)\n",

108  work->path,

109  errno, strerror (errno));

110  continue;

111  }

112

113  while (1) {

114  status = readdir_r (directory, entry, &result);

115  if (status != 0) {

116  fprintf (

117  stderr,

118  "Unable to read directory %s: %d (%s)\n",

119  work->path,

120  status, strerror (status));

121  break;

122  }

123  if (result == NULL)

124  break; /* End of directory */

125

126 /*

127 * Ignore "." and entries.

128 */