libblkid/fileutils.c

/*
 * Copyright (C) 2012 Sami Kerola <kerolasa@iki.fi>
 */

#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <unistd.h>
#include <sys/time.h>
#include <sys/resource.h>

#include "c.h"
#include "fileutils.h"
#include "pathnames.h"
#include "xalloc.h"

#define _PATH_TMP "/tmp"
/* Create open temporary file in safe way.  Please notice that the
 * file permissions are -rw------- by default. */
int xmkstemp(char **tmpname, char *dir)
{
	char *localtmp;
	char *tmpenv;
	mode_t old_mode;
	int fd;

	/* Some use cases must be capable of being moved atomically
	 * with rename(2), which is the reason why dir is here.  */
	if (dir != NULL)
		tmpenv = dir;
	else
		tmpenv = getenv("TMPDIR");

	if (tmpenv)
		xasprintf(&localtmp, "%s/%s.XXXXXX", tmpenv,
			  program_invocation_short_name);
	else
		xasprintf(&localtmp, "%s/%s.XXXXXX", _PATH_TMP,
			  program_invocation_short_name);
	old_mode = umask(077);
	fd = mkstemp(localtmp);
	umask(old_mode);
	if (fd == -1) {
		free(localtmp);
		localtmp = NULL;
	}
	*tmpname = localtmp;
	return fd;
}

/*
 * portable getdtablesize()
 */
int get_fd_tabsize(void)
{
	int m;

#if defined(HAVE_GETDTABLESIZE)
	m = getdtablesize();
#elif defined(HAVE_GETRLIMIT) && defined(RLIMIT_NOFILE)
	struct rlimit rl;

	getrlimit(RLIMIT_NOFILE, &rl);
	m = rl.rlim_cur;
#elif defined(HAVE_SYSCONF) && defined(_SC_OPEN_MAX)
	m = sysconf(_SC_OPEN_MAX);
#else
	m = OPEN_MAX;
#endif
	return m;
}

#ifdef TEST_PROGRAM
int main(void)
{
	FILE *f;
	char *tmpname;
	f = xfmkstemp(&tmpname, NULL);
	unlink(tmpname);
	free(tmpname);
	fclose(f);
	return EXIT_FAILURE;
}
#endif