%
% (c) The GRASP/AQUA Project, Glasgow University, 1995
%
\subsection[renameFile.lc]{renameFile Runtime Support}

\begin{code}

#include "rtsdefs.h"
#include "stgio.h"

#ifdef HAVE_SYS_TYPES_H
#include <sys/types.h>
#endif

#ifdef HAVE_SYS_STAT_H
#include <sys/stat.h>
#endif

#ifdef HAVE_FCNTL_H
#include <fcntl.h>
#endif

StgInt
renameFile(opath, npath)
StgByteArray opath;
StgByteArray npath;
{
    struct stat sb;
    int fd;
    int created = 0;

    /* Check for a non-directory source */
    while (stat(opath, &sb) != 0) {
	if (errno != EINTR) {
	    cvtErrno();
	    stdErrno();
	    return -1;
	}
    }
    if (S_ISDIR(sb.st_mode)) {
	ghc_errtype = ERR_INAPPROPRIATETYPE;
	ghc_errstr = "file is a directory";
	return -1;
    }

    /* Ensure a non-directory destination */

    /* First try to open without creating */
    while ((fd = open(npath, O_RDONLY | O_NOCTTY, 0)) < 0) {
	if (errno == ENOENT) {
	    /* Now try to create it */
	    while ((fd = open(npath, O_RDONLY | O_NOCTTY | O_CREAT | O_EXCL, 0)) < 0) {
		if (errno == EEXIST) {
		    /* Race detected; go back and open without creating it */
		    break;
		} else if (errno != EINTR) {
		    cvtErrno();
		    switch (ghc_errno) {
		    default:
			stdErrno();
			break;
		    case GHC_ENOENT:
		    case GHC_ENOTDIR:
			ghc_errtype = ERR_NOSUCHTHING;
			ghc_errstr = "no path to file";
			break;
		    case GHC_EINVAL:
			ghc_errtype = ERR_PERMISSIONDENIED;
			ghc_errstr = "unsupported owner or group";
			break;
		    }
		    return -1;
		}
	    }
	    if (fd >= 0) {
		created = 1;
		break;
	    }
	} else if (errno != EINTR) {
	    cvtErrno();
	    switch (ghc_errno) {
	    default:
		stdErrno();
		break;
	    case GHC_ENOTDIR:
		ghc_errtype = ERR_NOSUCHTHING;
		ghc_errstr = "no path to file";
		break;
	    case GHC_EINVAL:
		ghc_errtype = ERR_PERMISSIONDENIED;
		ghc_errstr = "unsupported owner or group";
		break;
	    }
	    return -1;
	}
    }

    /* Make sure that we aren't looking at a directory */

    while (fstat(fd, &sb) < 0) {
	/* highly unlikely */
	if (errno != EINTR) {
	    cvtErrno();
	    if (created)
		(void) unlink(npath);
	    (void) close(fd);
	    return -1;
	}
    }
    if (S_ISDIR(sb.st_mode)) {
	ghc_errtype = ERR_INAPPROPRIATETYPE;
	ghc_errstr = "destination is a directory";
	/* We can't have created it in this case. */
	(void) close(fd);
	return -1;
    }

    while(rename(opath, npath) != 0) {
	if (errno != EINTR) {
	    cvtErrno();
	    stdErrno();
	    if (created)
		(void) unlink(npath);
	    (void) close(fd);
	    return -1;
	}
    }

    close(fd);    
    return 0;
}
\end{code}