check_dir.c

/*
 * check_dir.c - Directories management functions
 * Copyright (C) 2ndQuadrant, 2010
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include <sys/stat.h>
#include <sys/types.h>
#include <dirent.h>
#include <errno.h>
#include <stdio.h>
#include <string.h>

#include "postgres_fe.h"
#include "check_dir.h"


static int mkdir_p(char *path, mode_t omode);

/*
 * make sure the directory either doesn't exist or is empty
 * we use this function to check the new data directory and
 * the directories for tablespaces
 *
 * This is the same check initdb does on the new PGDATA dir
 *
 * Returns 0 if nonexistent, 1 if exists and empty, 2 if not empty,
 * or -1 if trouble accessing directory
 */
int
check_dir(char *dir)
{
	DIR        *chkdir;
	struct 		dirent *file;
	int         result = 1;

	errno = 0;

	chkdir = opendir(dir);

	if (!chkdir)
		return (errno == ENOENT) ? 0 : -1;

	while ((file = readdir(chkdir)) != NULL)
	{
		if (strcmp(".", file->d_name) == 0 ||
		        strcmp("..", file->d_name) == 0)
		{
			/* skip this and parent directory */
			continue;
		}
		else
		{
			result = 2;         /* not empty */
			break;
		}
	}

#ifdef WIN32
	/*
	 * This fix is in mingw cvs (runtime/mingwex/dirent.c rev 1.4), but not in
	 * released version
	 */
	if (GetLastError() == ERROR_NO_MORE_FILES)
		errno = 0;
#endif

	closedir(chkdir);

	if (errno != 0)
		return -1;          /* some kind of I/O error? */

	return result;
}


/*
 * Create directory
 */
bool
create_directory(char *dir)
{
	if (mkdir_p(dir, 0700) == 0)
		return true;

	fprintf(stderr, _("Could not create directory \"%s\": %s\n"),
	        dir, strerror(errno));

	return false;
}

bool
set_directory_permissions(char *dir)
{
	return (chmod(dir, 0700) != 0) ? false : true;
}



/* function from initdb.c */
/* source stolen from FreeBSD /src/bin/mkdir/mkdir.c and adapted */

/*
 * this tries to build all the elements of a path to a directory a la mkdir -p
 * we assume the path is in canonical form, i.e. uses / as the separator
 * we also assume it isn't null.
 *
 * note that on failure, the path arg has been modified to show the particular
 * directory level we had problems with.
 */
static int
mkdir_p(char *path, mode_t omode)
{
	struct stat sb;
	mode_t		numask,
	oumask;
	int			first,
	last,
	retval;
	char	   *p;

	p = path;
	oumask = 0;
	retval = 0;

#ifdef WIN32
	/* skip network and drive specifiers for win32 */
	if (strlen(p) >= 2)
	{
		if (p[0] == '/' && p[1] == '/')
		{
			/* network drive */
			p = strstr(p + 2, "/");
			if (p == NULL)
				return 1;
		}
		else if (p[1] == ':' &&
		         ((p[0] >= 'a' && p[0] <= 'z') ||
		          (p[0] >= 'A' && p[0] <= 'Z')))
		{
			/* local drive */
			p += 2;
		}
	}
#endif

	if (p[0] == '/')			/* Skip leading '/'. */
		++p;
	for (first = 1, last = 0; !last; ++p)
	{
		if (p[0] == '\0')
			last = 1;
		else if (p[0] != '/')
			continue;
		*p = '\0';
		if (!last && p[1] == '\0')
			last = 1;
		if (first)
		{
			/*
			 * POSIX 1003.2: For each dir operand that does not name an
			 * existing directory, effects equivalent to those caused by the
			 * following command shall occcur:
			 *
			 * mkdir -p -m $(umask -S),u+wx $(dirname dir) && mkdir [-m mode]
			 * dir
			 *
			 * We change the user's umask and then restore it, instead of
			 * doing chmod's.
			 */
			oumask = umask(0);
			numask = oumask & ~(S_IWUSR | S_IXUSR);
			(void) umask(numask);
			first = 0;
		}
		if (last)
			(void) umask(oumask);

		/* check for pre-existing directory; ok if it's a parent */
		if (stat(path, &sb) == 0)
		{
			if (!S_ISDIR(sb.st_mode))
			{
				if (last)
					errno = EEXIST;
				else
					errno = ENOTDIR;
				retval = 1;
				break;
			}
		}
		else if (mkdir(path, last ? omode : S_IRWXU | S_IRWXG | S_IRWXO) < 0)
		{
			retval = 1;
			break;
		}
		if (!last)
			*p = '/';
	}
	if (!first && !last)
		(void) umask(oumask);
	return retval;
}


bool
is_pg_dir(char *dir)
{
	char	path[8192];
	struct stat sb;

	sprintf(path, "%s/PG_VERSION", dir);

	return (stat(path, &sb) == 0) ? true : false;
}