#include "tclInt.h"
#ifdef _WIN32
#   include "tclWinInt.h"
#endif
#include "tclFileSystem.h"

#ifdef TCL_TEMPLOAD_NO_UNLINK
#ifndef NO_FSTATFS
#include <sys/statfs.h>
#endif
#endif

/*
 * struct FilesystemRecord --
 *
 * A filesystem record is used to keep track of each filesystem currently
 * registered with the core, in a linked list.
 */

 *
 * Side effects:
 *	New code suddenly appears in memory. This may later be unloaded by
 *	calling TclFS_UnloadFile.
 *
 *----------------------------------------------------------------------
 */

/*
 * Workaround for issue with modern HPUX which do allow the unlink (no ETXTBSY
 * error) yet somehow trash some internal data structures which prevents the
 * second and further shared libraries from getting properly loaded. Only the
 * first is ok. We try to get around the issue by not unlinking,
 * i.e. emulating the behaviour of the older HPUX which denied removal.
 *
 * Doing the unlink is also an issue within docker containers, whose AUFS
 * bungles this as well, see
 *     https://github.com/dotcloud/docker/issues/1911
 *
 * For these situations the change below makes the execution of the unlink
 * semi-controllable at runtime.
 *
 *     An AUFS filesystem (if it can be detected) will force avoidance of
 *     unlink. The env variable TCL_TEMPLOAD_NO_UNLINK allows detection of a
 *     users general request (unlink and not.
 *
 * By default the unlink is done (if not in AUFS). However if the variable is
 * present and set to true (any integer > 0) then the unlink is skipped.
 */

int
TclSkipUnlink (Tcl_Obj* shlibFile)
{
    /* Order of testing:
     * 1. On hpux we generally want to skip unlink in general
     *
     * Outside of hpux then:
     * 2. For a general user request   (TCL_TEMPLOAD_NO_UNLINK present, non-empty, => int)
     * 3. For general AUFS environment (statfs, if available).
     *
     * Ad 2: This variable can disable/override the AUFS detection, i.e. for
     * testing if a newer AUFS does not have the bug any more.
     * 
     * Ad 3: This is conditionally compiled in. Condition currently must be set manually.
     *       This part needs proper tests in the configure(.in).
     */

#ifdef hpux
    return 1;
#else
    char* skipstr;

    skipstr = getenv ("TCL_TEMPLOAD_NO_UNLINK");
    if (skipstr && (skipstr[0] != '\0')) {
	return atoi(skipstr);
    }

#ifdef TCL_TEMPLOAD_NO_UNLINK
#ifndef NO_FSTATFS
    {
	struct statfs fs;
	/* Have fstatfs. May not have the AUFS super magic ... Indeed our build
	 * box is too old to have it directly in the headers. Define taken from
	 *     http://mooon.googlecode.com/svn/trunk/linux_include/linux/aufs_type.h
	 *     http://aufs.sourceforge.net/
	 * Better reference will be gladly taken.
	 */
#ifndef AUFS_SUPER_MAGIC
#define AUFS_SUPER_MAGIC ('a' << 24 | 'u' << 16 | 'f' << 8 | 's')
#endif /* AUFS_SUPER_MAGIC */
	if ((statfs(Tcl_GetString (shlibFile), &fs) == 0) &&
	    (fs.f_type == AUFS_SUPER_MAGIC)) {
	    return 1;
	}
    }
#endif /* ... NO_FSTATFS */
#endif /* ... TCL_TEMPLOAD_NO_UNLINK */

    /* Fallback: !hpux, no EV override, no AUFS (detection, nor detected):
     * Don't skip */
    return 0;
#endif /* hpux */
}

int
Tcl_LoadFile(
    Tcl_Interp *interp,		/* Used for error reporting. */
    Tcl_Obj *pathPtr,		/* Name of the file containing the desired
				 * code. */
    const char *const symbols[],/* Names of functions to look up in the file's

    }

    /*
     * Try to delete the file immediately - this is possible in some OSes, and
     * avoids any worries about leaving the copy laying around on exit.
     */

    if (
	!TclSkipUnlink (copyToPtr) &&
	(Tcl_FSDeleteFile(copyToPtr) == TCL_OK)) {
	Tcl_DecrRefCount(copyToPtr);

	/*
	 * We tell our caller about the real shared library which was loaded.
	 * Note that this does mean that the package list maintained by 'load'
	 * will store the original (vfs) path alongside the temporary load
	 * handle and unload proc ptr.