postgresql/src/port/dirmod.c

/*-------------------------------------------------------------------------
 *
 * dirmod.c
 *	  rename/unlink()
 *
 * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
 * Portions Copyright (c) 1994, Regents of the University of California
 *
 *	These are replacement versions of unlink and rename that work on
 *	Win32 (NT, Win2k, XP).	replace() doesn't work on Win95/98/Me.
 *
 * IDENTIFICATION
 *	  $PostgreSQL: pgsql/src/port/dirmod.c,v 1.13 2004/08/01 06:19:26 momjian Exp $
 *
 *-------------------------------------------------------------------------
 */

#ifndef FRONTEND
#include "postgres.h"
#else
#include "postgres_fe.h"
#endif

#include <unistd.h>
#include <dirent.h>
#include <sys/stat.h>

#define _(x) gettext((x))

#ifndef TEST_VERSION

#if defined(WIN32) || defined(__CYGWIN__)


#include "miscadmin.h"

#undef rename
#undef unlink

int
pgrename(const char *from, const char *to)
{
	int			loops = 0;

#ifdef WIN32
	while (!MoveFileEx(from, to, MOVEFILE_REPLACE_EXISTING))
#endif
#ifdef __CYGWIN__
	while (rename(from, to) < 0)
#endif
	{
#ifdef WIN32
		if (GetLastError() != ERROR_ACCESS_DENIED)
#endif
#ifdef __CYGWIN__
		if (errno != EACCES)
#endif
			/* set errno? */
			return -1;
		pg_usleep(100000);				/* us */
		if (loops == 30)
#ifndef FRONTEND
			elog(LOG, "could not rename \"%s\" to \"%s\", continuing to try",
				 from, to);
#else
			fprintf(stderr, "could not rename \"%s\" to \"%s\", continuing to try\n",
					from, to);
#endif
		loops++;
	}

	if (loops > 30)
#ifndef FRONTEND
		elog(LOG, "completed rename of \"%s\" to \"%s\"", from, to);
#else
		fprintf(stderr, "completed rename of \"%s\" to \"%s\"\n", from, to);
#endif
	return 0;
}


int
pgunlink(const char *path)
{
	int			loops = 0;

	while (unlink(path))
	{
		if (errno != EACCES)
			/* set errno? */
			return -1;
		pg_usleep(100000);		/* us */
		if (loops == 30)
#ifndef FRONTEND
			elog(LOG, "could not unlink \"%s\", continuing to try",
				 path);
#else
			fprintf(stderr, "could not unlink \"%s\", continuing to try\n",
					path);
#endif
		loops++;
	}

	if (loops > 30)
#ifndef FRONTEND
		elog(LOG, "completed unlink of \"%s\"", path);
#else
		fprintf(stderr, "completed unlink of \"%s\"\n", path);
#endif
	return 0;
}

#endif

#if defined(WIN32) || defined(__CYGWIN__)
#define rmt_unlink(path) pgunlink(path)
#else
#define rmt_unlink(path) unlink(path)
#endif

#ifdef FRONTEND

static void *
xmalloc(size_t size)
{
    void       *result;

    result = malloc(size);
    if (!result)
    {
        fprintf(stderr, _("out of memory\n"));
        exit(1);
    }
    return result;
}

static char *
xstrdup(const char *s)
{
    char       *result;

    result = strdup(s);
    if (!result)
    {
        fprintf(stderr, _("out of memory\n"));
        exit(1);
    }
    return result;
}

#define xfree(n) free(n)

#else

/* on the backend, use palloc and friends */

#define xmalloc(n)	palloc(n)
#define xstrdup(n)	pstrdup(n)
#define xfree(n)	pfree(n)

#endif

/*
 * deallocate memory used for filenames
 */

static void
rmt_cleanup(char ** filenames)
{
	char ** fn;

	for (fn = filenames; *fn; fn++)
		xfree(*fn);

	xfree(filenames);
}



/*
 * delete a directory tree recursively
 * assumes path points to a valid directory
 * deletes everything under path
 * if rmtopdir is true deletes the directory too
 *
 */

bool
rmtree(char *path, bool rmtopdir)
{
	char		filepath[MAXPGPATH];
	DIR		   *dir;
	struct dirent *file;
	char	  **filenames;
	char	  **filename;
	int			numnames = 0;
	struct stat statbuf;

	/*
	 * we copy all the names out of the directory before we start
	 * modifying it.
	 */

	dir = opendir(path);
	if (dir == NULL)
		return false;

	while ((file = readdir(dir)) != NULL)
	{
		if (strcmp(file->d_name, ".") != 0 && strcmp(file->d_name, "..") != 0)
			numnames++;
	}

	rewinddir(dir);

	filenames = xmalloc((numnames + 2) * sizeof(char *));
	numnames = 0;

	while ((file = readdir(dir)) != NULL)
	{
		if (strcmp(file->d_name, ".") != 0 && strcmp(file->d_name, "..") != 0)
			filenames[numnames++] = xstrdup(file->d_name);
	}

	filenames[numnames] = NULL;

	closedir(dir);

	/* now we have the names we can start removing things */

	for (filename = filenames; *filename; filename++)
	{
		snprintf(filepath, MAXPGPATH, "%s/%s", path, *filename);

		if (stat(filepath, &statbuf) != 0)
		{
			rmt_cleanup(filenames);
			return false;
		}

		if (S_ISDIR(statbuf.st_mode))
		{
			/* call ourselves recursively for a directory */
			if (!rmtree(filepath, true))
			{
				rmt_cleanup(filenames);
				return false;
			}
		}
		else
		{
			if (rmt_unlink(filepath) != 0)
			{
				rmt_cleanup(filenames);
				return false;
			}
		}
	}

	if (rmtopdir)
	{
		if (rmdir(path) != 0)
		{
			rmt_cleanup(filenames);
			return false;
		}
	}

	rmt_cleanup(filenames);
	return true;
}


#else


/*
 *	Illustrates problem with Win32 rename() and unlink()
 *	under concurrent access.
 *
 *	Run with arg '1', then less than 5 seconds later, run with
 *	 arg '2' (rename) or '3'(unlink) to see the problem.
 */

#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <windows.h>

#define halt(str) \
do { \
	fputs(str, stderr); \
	exit(1); \
} while (0)

int
main(int argc, char *argv[])
{
	FILE	   *fd;

	if (argc != 2)
		halt("Arg must be '1' (test), '2' (rename), or '3' (unlink)\n"
			 "Run '1' first, then less than 5 seconds later, run\n"
			 "'2' to test rename, or '3' to test unlink.\n");

	if (atoi(argv[1]) == 1)
	{
		if ((fd = fopen("/rtest.txt", "w")) == NULL)
			halt("Can not create file\n");
		fclose(fd);
		if ((fd = fopen("/rtest.txt", "r")) == NULL)
			halt("Can not open file\n");
		Sleep(5000);
	}
	else if (atoi(argv[1]) == 2)
	{
		unlink("/rtest.new");
		if ((fd = fopen("/rtest.new", "w")) == NULL)
			halt("Can not create file\n");
		fclose(fd);
		while (!MoveFileEx("/rtest.new", "/rtest.txt", MOVEFILE_REPLACE_EXISTING))
		{
			if (GetLastError() != ERROR_ACCESS_DENIED)
				halt("Unknown failure\n");
			else
				fprintf(stderr, "move failed\n");
			Sleep(500);
		}
		halt("move successful\n");
	}
	else if (atoi(argv[1]) == 3)
	{
		while (unlink("/rtest.txt"))
		{
			if (errno != EACCES)
				halt("Unknown failure\n");
			else
				fprintf(stderr, "unlink failed\n");
			Sleep(500);
		}
		halt("unlink successful\n");
	}
	else
		halt("invalid arg\n");

	return 0;
}

#endif