PostgreSQL Source Code  git master
pgcheckdir.c
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1 /*-------------------------------------------------------------------------
2  *
3  * pgcheckdir.c
4  *
5  * A simple subroutine to check whether a directory exists and is empty or not.
6  * Useful in both initdb and the backend.
7  *
8  * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group
9  * Portions Copyright (c) 1994, Regents of the University of California
10  *
11  * IDENTIFICATION
12  * src/port/pgcheckdir.c
13  *-------------------------------------------------------------------------
14  */
15 
16 #include "c.h"
17 
18 #include <dirent.h>
19 
20 
21 /*
22  * Test to see if a directory exists and is empty or not.
23  *
24  * Returns:
25  * 0 if nonexistent
26  * 1 if exists and empty
27  * 2 if exists and contains _only_ dot files
28  * 3 if exists and contains a mount point
29  * 4 if exists and not empty
30  * -1 if trouble accessing directory (errno reflects the error)
31  */
32 int
33 pg_check_dir(const char *dir)
34 {
35  int result = 1;
36  DIR *chkdir;
37  struct dirent *file;
38  bool dot_found = false;
39  bool mount_found = false;
40  int readdir_errno;
41 
42  chkdir = opendir(dir);
43  if (chkdir == NULL)
44  return (errno == ENOENT) ? 0 : -1;
45 
46  while (errno = 0, (file = readdir(chkdir)) != NULL)
47  {
48  if (strcmp(".", file->d_name) == 0 ||
49  strcmp("..", file->d_name) == 0)
50  {
51  /* skip this and parent directory */
52  continue;
53  }
54 #ifndef WIN32
55  /* file starts with "." */
56  else if (file->d_name[0] == '.')
57  {
58  dot_found = true;
59  }
60  /* lost+found directory */
61  else if (strcmp("lost+found", file->d_name) == 0)
62  {
63  mount_found = true;
64  }
65 #endif
66  else
67  {
68  result = 4; /* not empty */
69  break;
70  }
71  }
72 
73  if (errno)
74  result = -1; /* some kind of I/O error? */
75 
76  /* Close chkdir and avoid overwriting the readdir errno on success */
77  readdir_errno = errno;
78  if (closedir(chkdir))
79  result = -1; /* error executing closedir */
80  else
81  errno = readdir_errno;
82 
83  /* We report on mount point if we find a lost+found directory */
84  if (result == 1 && mount_found)
85  result = 3;
86 
87  /* We report on dot-files if we _only_ find dot files */
88  if (result == 1 && dot_found)
89  result = 2;
90 
91  return result;
92 }
int closedir(DIR *)
Definition: dirent.c:123
struct dirent * readdir(DIR *)
Definition: dirent.c:78
DIR * opendir(const char *)
Definition: dirent.c:33
int pg_check_dir(const char *dir)
Definition: pgcheckdir.c:33
Definition: dirent.c:26
Definition: dirent.h:10
char d_name[MAX_PATH]
Definition: dirent.h:15