Line data    Source code

       1             : /*-------------------------------------------------------------------------
       2             :  *
       3             :  * src/port/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) 1996-2017, PostgreSQL Global Development Group
       9             :  * Portions Copyright (c) 1994, Regents of the University of California
      10             :  *
      11             :  *-------------------------------------------------------------------------
      12             :  */
      13             : 
      14             : #include "c.h"
      15             : 
      16             : #include <dirent.h>
      17             : 
      18             : 
      19             : /*
      20             :  * Test to see if a directory exists and is empty or not.
      21             :  *
      22             :  * Returns:
      23             :  *      0 if nonexistent
      24             :  *      1 if exists and empty
      25             :  *      2 if exists and contains _only_ dot files
      26             :  *      3 if exists and contains a mount point
      27             :  *      4 if exists and not empty
      28             :  *      -1 if trouble accessing directory (errno reflects the error)
      29             :  */
      30             : int
      31           1 : pg_check_dir(const char *dir)
      32             : {
      33           1 :     int         result = 1;
      34             :     DIR        *chkdir;
      35             :     struct dirent *file;
      36           1 :     bool        dot_found = false;
      37           1 :     bool        mount_found = false;
      38             :     int         readdir_errno;
      39             : 
      40           1 :     chkdir = opendir(dir);
      41           1 :     if (chkdir == NULL)
      42           1 :         return (errno == ENOENT) ? 0 : -1;
      43             : 
      44           0 :     while (errno = 0, (file = readdir(chkdir)) != NULL)
      45             :     {
      46           0 :         if (strcmp(".", file->d_name) == 0 ||
      47           0 :             strcmp("..", file->d_name) == 0)
      48             :         {
      49             :             /* skip this and parent directory */
      50           0 :             continue;
      51             :         }
      52             : #ifndef WIN32
      53             :         /* file starts with "." */
      54           0 :         else if (file->d_name[0] == '.')
      55             :         {
      56           0 :             dot_found = true;
      57             :         }
      58             :         /* lost+found directory */
      59           0 :         else if (strcmp("lost+found", file->d_name) == 0)
      60             :         {
      61           0 :             mount_found = true;
      62             :         }
      63             : #endif
      64             :         else
      65             :         {
      66           0 :             result = 4;         /* not empty */
      67           0 :             break;
      68             :         }
      69             :     }
      70             : 
      71           0 :     if (errno)
      72           0 :         result = -1;            /* some kind of I/O error? */
      73             : 
      74             :     /* Close chkdir and avoid overwriting the readdir errno on success */
      75           0 :     readdir_errno = errno;
      76           0 :     if (closedir(chkdir))
      77           0 :         result = -1;            /* error executing closedir */
      78             :     else
      79           0 :         errno = readdir_errno;
      80             : 
      81             :     /* We report on mount point if we find a lost+found directory */
      82           0 :     if (result == 1 && mount_found)
      83           0 :         result = 3;
      84             : 
      85             :     /* We report on dot-files if we _only_ find dot files */
      86           0 :     if (result == 1 && dot_found)
      87           0 :         result = 2;
      88             : 
      89           0 :     return result;
      90             : }