[svn-r14789] Add handling for external link:

1. src/H5F.c, src/H5system.c: formulate path for mainfile
2. src/H5Lexternal.c: add search for target file
3. configure.in: add H5_HAVE_WINDOW_PATH
4. test/links.c: add tests for external link

7 files changed, 360 insertions, 31 deletions

diff --git a/src/H5F.c b/src/H5F.c
index cb9e3b8..80c28bc 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -978,6 +978,9 @@ done:
  * Programmer:	Robb Matzke
  *		matzke@llnl.gov
  *		Jul 18 1997
+ * Modifications:
+ *		Vailin Choi,  April 2, 2008
+ *		Free f->extpath
  *
  *-------------------------------------------------------------------------
  */
@@ -1068,6 +1071,7 @@ H5F_dest(H5F_t *f, hid_t dxpl_id)
 
     /* Free the non-shared part of the file */
     f->name = H5MM_xfree(f->name);
+    f->extpath = H5MM_xfree(f->extpath);
     f->mtab.child = H5MM_xfree(f->mtab.child);
     f->mtab.nalloc = 0;
     if(H5FO_top_dest(f) < 0)
@@ -1078,6 +1082,8 @@ H5F_dest(H5F_t *f, hid_t dxpl_id)
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5F_dest() */
 
+
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5F_open
@@ -1157,6 +1163,9 @@ H5F_dest(H5F_t *f, hid_t dxpl_id)
  *		Modified H5F_flush call to take one flag instead of
  *		multiple Boolean flags.
  *
+ *		Vailin Choi, 2008-04-02
+ *		To formulate path for later searching of target file for external link
+ *		via H5_build_extpath().
  *-------------------------------------------------------------------------
  */
 H5F_t *
@@ -1353,6 +1362,10 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id, hid_t d
             HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "file close degree doesn't match")
     } /* end if */
 
+    /* formulate the absolute path for later search of target file for external link */
+    if (H5_build_extpath(name, &file->extpath) < 0)
+	HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "unable to build extpath")
+    
     /* Success */
     ret_value = file;
 
@@ -2140,6 +2153,33 @@ H5F_get_intent(const H5F_t *f)
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5F_get_extpath
+ *
+ * Purpose:	Retrieve the file's 'extpath' flags
+ *		This is used by H5L_extern_traverse() to retrieve the main file's location
+ *		when searching the target file.
+ *
+ * Return:	'extpath' on success/abort on failure (shouldn't fail)
+ * 
+ * Programmer:	Vailin Choi, April 2, 2008
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+char *
+H5F_get_extpath(const H5F_t *f)
+{
+    /* Use FUNC_ENTER_NOAPI_NOINIT_NOFUNC here to avoid performance issues */
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5F_get_extpath)
+
+    HDassert(f);
+
+    FUNC_LEAVE_NOAPI(f->extpath)
+} /* end H5F_get_extpath() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5F_sizeof_addr
  *
  * Purpose:	Quick and dirty routine to retrieve the size of the file's size_t
@@ -3618,4 +3658,3 @@ H5Fget_info(hid_t obj_id, H5F_info_t *finfo)
 done:
     FUNC_LEAVE_API(ret_value)
 } /* end H5Fget_info() */
-
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 3f10e1a..288ef8a 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -142,6 +142,7 @@ typedef struct H5F_mtab_t {
 struct H5F_t {
     unsigned		intent;		/* The flags passed to H5F_open()*/
     char		*name;		/* Name used to open file	*/
+    char               	*extpath;       /* Path for searching target external link file */
     H5F_file_t		*shared;	/* The shared file info		*/
     unsigned		nopen_objs;	/* Number of open object headers*/
     H5FO_t              *obj_count;     /* # of time each object is opened through top file structure */
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 1044b14..27b45f2 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -265,6 +265,7 @@ typedef struct H5F_t H5F_t;
 #define H5F_GC_REF(F)           ((F)->shared->gc_ref)
 #define H5F_USE_LATEST_FORMAT(F) ((F)->shared->latest_format)
 #define H5F_INTENT(F)           ((F)->intent)
+#define H5F_EXTPATH(F)          ((F)->extpath)
 #define H5F_GET_FC_DEGREE(F)    ((F)->shared->fc_degree)
 #define H5F_STORE_MSG_CRT_IDX(F)    ((F)->shared->store_msg_crt_idx)
 #define H5F_GET_FILENO(F,FILENUM) ((FILENUM) = (F)->shared->lf->fileno)
@@ -284,6 +285,7 @@ typedef struct H5F_t H5F_t;
 #define H5F_GC_REF(F)           (H5F_gc_ref(F))
 #define H5F_USE_LATEST_FORMAT(F) (H5F_use_latest_format(F))
 #define H5F_INTENT(F)           (H5F_get_intent(F))
+#define H5F_EXTPATH(F)          (H5F_get_extpath(F))
 #define H5F_GET_FC_DEGREE(F)    (H5F_get_fc_degree(F))
 #define H5F_STORE_MSG_CRT_IDX(F)    (H5F_store_msg_crt_idx(F))
 #define H5F_GET_FILENO(F,FILENUM) (H5F_get_filenum((F), &(FILENUM)))
@@ -417,6 +419,7 @@ H5_DLL herr_t H5F_try_close(H5F_t *f);
 H5_DLL hid_t H5F_get_driver_id(const H5F_t *f);
 H5_DLL hid_t H5F_get_access_plist(H5F_t *f);
 H5_DLL unsigned H5F_get_intent(const H5F_t *f);
+H5_DLL char *H5F_get_extpath(const H5F_t *f);
 H5_DLL herr_t H5F_get_fileno(const H5F_t *f, unsigned long *filenum);
 H5_DLL hid_t H5F_get_id(H5F_t *file);
 H5_DLL unsigned H5F_get_obj_count(const H5F_t *f, unsigned types);
diff --git a/src/H5Lexternal.c b/src/H5Lexternal.c
index 5a8eb33..4e355bb 100644
--- a/src/H5Lexternal.c
+++ b/src/H5Lexternal.c
@@ -76,6 +76,81 @@ H5L_init_extern_interface(void)
 } /* H5L_init_extern_interface() */
 
 
+
+/*--------------------------------------------------------------------------
+ * Function: H5L_getenv_prefix_name --
+ *
+ * Purpose:  Get the first pathname in the list of pathnames stored in ENV_PREFIX,
+ *           which is separated by the environment delimiter.
+ *           ENV_PREFIX is modified to point to the remaining pathnames
+ *           in the list.
+ *
+ * Return:   A pointer to a pathname
+ *
+ * Programmer:	Vailin Choi, April 2, 2008
+ *
+--------------------------------------------------------------------------*/
+static char *
+H5L_getenv_prefix_name(char **env_prefix/*in,out*/)
+{
+    char        *retptr=NULL;
+    char        *strret=NULL;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5L_getenv_prefix_name)
+
+    strret = HDstrchr(*env_prefix, COLON_SEPC);
+    if (strret == NULL) {
+        retptr = *env_prefix;
+        *env_prefix = strret;
+    } else {
+        retptr = *env_prefix;
+        *env_prefix = strret + 1;
+        *strret = '\0';
+    }
+    return(retptr);
+    FUNC_LEAVE_NOAPI(retptr)
+}
+
+
+/*--------------------------------------------------------------------------
+ * Function: H5L_build_name
+ *
+ * Purpose:  Prepend PREFIX to FILE_NAME and store in FULL_NAME
+ *
+ * Return:   Non-negative on success/Negative on failure
+ *
+ * Programmer:	Vailin Choi, April 2, 2008
+ *
+--------------------------------------------------------------------------*/
+static herr_t
+H5L_build_name(char *prefix, char *file_name, char **full_name/*out*/)
+{
+    size_t      prefix_len;             /* length of prefix */
+    size_t      fname_len;              /* Length of external link file name */
+    herr_t      ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5L_build_name)
+
+    prefix_len = HDstrlen(prefix);
+    fname_len = HDstrlen(file_name);
+
+    /* Allocate a buffer to hold the filename + prefix + possibly the delimiter + terminating null byte */
+    if(NULL == (*full_name = H5MM_malloc(prefix_len + fname_len + 2)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "unable to allocate filename buffer")
+
+    /* Copy the prefix into the buffer */
+    HDstrcpy(*full_name, prefix);
+    if (!CHECK_DELIMITER(prefix[prefix_len-1]))
+        HDstrcat(*full_name, DIR_SEPS);
+
+    /* Add the external link's filename to the prefix supplied */
+    HDstrcat(*full_name, file_name);
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5L_build_name() */
+
+
 /*-------------------------------------------------------------------------
  * Function:	H5L_extern_traverse
  *
@@ -92,6 +167,10 @@ H5L_init_extern_interface(void)
  *
  * Programmer:	James Laird
  *              Monday, July 10, 2006
+ * Modifications:
+ *		Vailin Choi, April 2, 2008
+ *		Add handling to search for the target file 
+ *		See description in RM: H5Lcreate_external
  *
  *-------------------------------------------------------------------------
  */
@@ -114,6 +193,11 @@ H5L_extern_traverse(const char UNUSED *link_name, hid_t cur_group,
     hid_t       ext_obj = -1;           /* ID for external link's object */
     hid_t       ret_value;              /* Return value */
 
+    char        *tempname=NULL, *ptr=NULL, *extpath=NULL;
+    char        *env_prefix=NULL, *tmp_env_prefix=NULL;
+    char        *out_prefix_name=NULL, *pp=NULL;
+
+
     FUNC_ENTER_NOAPI(H5L_extern_traverse, FAIL)
 
     /* Sanity checks */
@@ -135,28 +219,6 @@ H5L_extern_traverse(const char UNUSED *link_name, hid_t cur_group,
     if(NULL == (plist = H5P_object_verify(lapl_id, H5P_LINK_ACCESS)))
         HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID")
 
-    /* Get the current prefix */
-    if(H5P_get(plist, H5L_ACS_ELINK_PREFIX_NAME, &my_prefix) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get external link prefix")
-
-    /* Check for prefix being set, if so, prepend it to the filename */
-    if(my_prefix) {
-        size_t prefix_len = HDstrlen(my_prefix);
-
-        /* Allocate a buffer to hold the filename plus prefix */
-        if(NULL == (full_name = H5MM_malloc(prefix_len + fname_len + 1)))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "unable to allocate filename buffer")
-
-        /* Copy the prefix into the buffer */
-        HDstrcpy(full_name, my_prefix);
-
-        /* Add the external link's filename to the prefix supplied */
-        HDstrcat(full_name, (const char *)p);
-
-        /* Point to name w/prefix */
-        file_name = full_name;
-    } /* end if */
-
     /* Get the location for the group holding the external link */
     if(H5G_loc(cur_group, &loc) < 0)
         HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't get object location")
@@ -183,10 +245,92 @@ H5L_extern_traverse(const char UNUSED *link_name, hid_t cur_group,
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set file close degree")
     } /* end if */
 
-    /* Open the external file */
-    /* (extra work with file intent to mask off inappropriate flags) */
-    if(NULL == (ext_file = H5F_open(file_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY), H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id)))
-	HGOTO_ERROR(H5E_LINK, H5E_CANTOPENFILE, FAIL, "unable to open external file")
+    /*
+     * Start searching for the target file
+     */
+    if ((tempname=H5MM_strdup(file_name)) == NULL)
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+    /* target file_name is an absolute pathname: see RM for detailed description */
+    if (CHECK_ABSOLUTE(file_name) || CHECK_ABS_PATH(file_name)) {
+        if(NULL == (ext_file = H5F_open(file_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                                H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id))) {
+            H5E_clear_stack(NULL);
+            /* get last component of file_name */
+	    GET_LAST_DELIMITER(file_name, ptr)
+	    HDassert(ptr);
+	    HDstrcpy(tempname, ++ptr);
+        }
+    } else if (CHECK_ABS_DRIVE(file_name)) {
+        if(NULL == (ext_file = H5F_open(file_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                                H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id))) {
+            H5E_clear_stack(NULL);
+	    /* strip "<drive-letter>:" */
+	    HDstrcpy(tempname, &file_name[2]);
+	}
+    }
+    
+    /* try searching from paths set in the environment variable */
+    if ((ext_file == NULL) && (env_prefix=HDgetenv("HDF5_EXT_PREFIX"))) {
+
+        tmp_env_prefix = H5MM_strdup(env_prefix);
+	pp = tmp_env_prefix;
+
+        while ((tmp_env_prefix) && (*tmp_env_prefix)) {
+            out_prefix_name = H5L_getenv_prefix_name(&tmp_env_prefix/*in,out*/);
+            if ((out_prefix_name) && (*out_prefix_name)) {
+
+                if (H5L_build_name(out_prefix_name, tempname, &full_name/*out*/) < 0)
+                    HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't prepend prefix to filename")
+
+                ext_file = H5F_open(full_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                            H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id);
+                if (full_name)
+                    H5MM_xfree(full_name);
+                if (ext_file != NULL)
+                    break;
+                H5E_clear_stack(NULL);
+            }
+        } /* end while */
+        if (pp)
+            H5MM_xfree(pp);
+    }
+    
+    /* try searching from property list */
+    if (ext_file == NULL) {
+        if(H5P_get(plist, H5L_ACS_ELINK_PREFIX_NAME, &my_prefix) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get external link prefix")
+        if (my_prefix) {
+            if (H5L_build_name(my_prefix, tempname, &full_name/*out*/) < 0)
+                HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't prepend prefix to filename")
+            if ((ext_file=H5F_open(full_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                        H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id)) == NULL)
+                H5E_clear_stack(NULL);
+            if (full_name)
+                H5MM_xfree(full_name);
+        }
+    }
+
+    /* try searching from main file's "extpath":see description in H5F_open() & H5_build_extpath() */
+    if ((ext_file == NULL) && (extpath=H5F_EXTPATH(loc.oloc->file))) {
+        if (H5L_build_name(extpath, tempname, &full_name/*out*/) < 0)
+            HGOTO_ERROR(H5E_LINK, H5E_CANTGET, FAIL, "can't prepend prefix to filename")
+        if ((ext_file = H5F_open(full_name, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                    H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id)) == NULL)
+            H5E_clear_stack(NULL);
+        if (full_name)
+            H5MM_xfree(full_name);
+    }
+
+    /* try the relative file_name stored in tempname */
+    if (ext_file == NULL) {
+        if ((ext_file=H5F_open(tempname, ((intent & H5F_ACC_RDWR) ? H5F_ACC_RDWR : H5F_ACC_RDONLY),
+                        H5P_FILE_CREATE_DEFAULT, fapl_id, H5AC_dxpl_id)) == NULL)
+            HGOTO_ERROR(H5E_LINK, H5E_CANTOPENFILE, FAIL, "unable to open external file")
+    }
+
+    if (tempname)
+        H5MM_xfree(tempname);
 
     /* Increment the number of open objects, to hold the file open */
     H5F_incr_nopen_objs(ext_file);
@@ -219,10 +363,6 @@ done:
     if(ext_file && H5F_try_close(ext_file) < 0)
         HDONE_ERROR(H5E_LINK, H5E_CANTCLOSEFILE, FAIL, "problem closing external file")
 
-    /* Free full_name if it's been allocated */
-    if(full_name)
-        H5MM_xfree(full_name);
-
     /* Close object if it's open and something failed */
     if(ret_value < 0 && ext_obj >= 0 && H5I_dec_ref(ext_obj) < 0)
         HDONE_ERROR(H5E_ATOM, H5E_CANTRELEASE, FAIL, "unable to close atom for external object")
diff --git a/src/H5config.h.in b/src/H5config.h.in
index 5c767ef..77a3b23 100644
--- a/src/H5config.h.in
+++ b/src/H5config.h.in
@@ -368,6 +368,9 @@
 /* Define to 1 if you have the `waitpid' function. */
 #undef HAVE_WAITPID
 
+/* Define if your system has window style path name. */
+#undef HAVE_WINDOW_PATH
+
 /* Define to 1 if you have the <winsock.h> header file. */
 #undef HAVE_WINSOCK_H
 
diff --git a/src/H5private.h b/src/H5private.h
index 11f3037..734290d 100644
--- a/src/H5private.h
+++ b/src/H5private.h
@@ -638,9 +638,19 @@ H5_DLL int HDfprintf (FILE *stream, const char *fmt, ...);
 #define HDfwrite(M,Z,N,F)	fwrite(M,Z,N,F)
 #define HDgetc(F)		getc(F)
 #define HDgetchar()		getchar()
+#ifdef _WIN32
+#define HDgetcwd(S,Z)		_getcwd(S,Z)
+#define HDgetdcwd(D,S,Z)	_getdcwd(D,S,Z)
+#define HDgetdrive()		_getdrive()
+#else
 #define HDgetcwd(S,Z)		getcwd(S,Z)
+#define HDgetdcwd(D,S,Z)	getcwd(S,Z)
+#define HDgetdrive()		0
+#endif
 #define HDgetegid()		getegid()
 #define HDgetenv(S)		getenv(S)
+#define HDsetenv(S,V,O)		setenv(S,V,O)
+#define HDunsetenv(S)		unsetenv(S)
 #define HDgeteuid()		geteuid()
 #define HDgetgid()		getgid()
 #define HDgetgrgid(G)		getgrgid(G)
@@ -911,6 +921,43 @@ extern char *strdup(const char *s);
 
 #endif /* _WIN32 */
 
+#ifdef H5_HAVE_WINDOW_PATH
+
+/* directory delimiter for Windows: slash and backslash are acceptable on Windows */
+#define	DIR_SLASH_SEPC 		'/'
+#define	DIR_SEPC 		'\\'
+#define	DIR_SEPS 		"\\"
+#define CHECK_DELIMITER(SS)     ((SS == DIR_SEPC)||(SS == DIR_SLASH_SEPC))
+#define CHECK_ABSOLUTE(NAME)    (((isalpha(NAME[0])) && (NAME[1] == ':') && CHECK_DELIMITER(NAME[2]))
+#define CHECK_ABS_DRIVE(NAME)   ((isalpha(NAME[0])) && (NAME[1] == ':'))
+#define CHECK_ABS_PATH(NAME)    (CHECK_DELIMITER(NAME[0]))
+
+#define GET_LAST_DELIMITER(NAME, ptr) {                 \
+    char        *slash, *backslash;                     \
+    slash = strrchr(NAME, DIR_SLASH_SEPC);              \
+    backslash = strrchr(NAME, DIR_SEPC);                \
+    if (backslash > slash)                              \
+        (ptr = backslash);                              \
+    else                                                \
+        (ptr = slash);                                  \
+}
+
+
+#else
+
+#define		DIR_SEPC	'/'
+#define		DIR_SEPS	"/"
+#define         CHECK_DELIMITER(SS)             (SS == DIR_SEPC)
+#define         CHECK_ABSOLUTE(NAME)            (CHECK_DELIMITER(*NAME))
+#define 	CHECK_ABS_DRIVE(NAME)   	(0)
+#define 	CHECK_ABS_PATH(NAME)    	(0)
+#define         GET_LAST_DELIMITER(NAME, ptr)   ptr = strrchr(NAME, DIR_SEPC);
+
+#endif
+
+#define 	COLON_SEPC	':'
+H5_DLL herr_t 	H5_build_extpath(const char *, char **/*out*/);
+
 
 /*
  * These macros check whether debugging has been requested for a certain
diff --git a/src/H5system.c b/src/H5system.c
index 5eae11d..d65103a 100644
--- a/src/H5system.c
+++ b/src/H5system.c
@@ -35,6 +35,8 @@
 #include "H5private.h"		/* Generic Functions			*/
 #include "H5Fprivate.h"		/* File access				*/
 #include "H5MMprivate.h"	/* Memory management			*/
+#include "H5Eprivate.h"
+
 
 
 /****************/
@@ -578,4 +580,98 @@ HDremove_all(const char *fname)
 }
 #endif
 
+
+/*
+ *
+ * Function: H5_build_extpath
+ *
+ * Purpose:  To build the path for later searching of target file for external link.
+ *   	     This path can be either:
+ *                      1. The absolute path of NAME
+ *                      or
+ *                      2. The current working directory + relative path of NAME
+ *
+ * Return:	Success:        0
+ *		Failure:	-1
+ *
+ * Programmer:	Vailin Choi
+ *		April 2, 2008
+ */
+#define MAX_PATH_LEN     1024
+
+herr_t
+H5_build_extpath(const char *name, char **extpath/*out*/)
+{
+    char        *full_path=NULL, *ptr=NULL;
+    char        *retcwd=NULL, *cwdpath=NULL, *new_name=NULL;
+    int         drive;
+    size_t      cwdlen, path_len;
+    herr_t      ret_value = SUCCEED;    /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT(H5_build_extpath)
+
+    *extpath = NULL;
+
+    /* 
+     * Unix: name[0] is a "/"
+     * Windows: name[0-2] is "<drive letter>:\" or "<drive-letter>:/"
+     */
+    if (CHECK_ABSOLUTE(name)) {
+        if ((full_path=H5MM_strdup(name)) == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+    } else { /* relative pathname */
+        if ((cwdpath=H5MM_malloc(MAX_PATH_LEN)) == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+        if ((new_name=H5MM_strdup(name)) == NULL)
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+	/* 
+	 * Windows: name[0-1] is "<drive-letter>:"
+	 * 	Get current working directory on the drive specified in NAME 
+	 * Unix: does not apply
+	 */
+        if (CHECK_ABS_DRIVE(name)) {
+            drive = name[0] - 'A' + 1;
+            retcwd = HDgetdcwd(drive, cwdpath, MAX_PATH_LEN);
+            HDstrcpy(new_name, &name[2]);
+	/* 
+	 * Windows: name[0] is a '/' or '\' 
+	 *	Get current drive
+	 * Unix: does not apply
+	 */
+        } else if (CHECK_ABS_PATH(name) && (drive=HDgetdrive())) {
+            sprintf(cwdpath, "%c:%c", (drive+'A'-1), name[0]);
+            retcwd = cwdpath;
+            HDstrcpy(new_name, &name[1]);
+        } else /* totally relative for both Unix and Windows: get current working directory  */
+            retcwd = HDgetcwd(cwdpath, MAX_PATH_LEN);
+
+        if (retcwd != NULL) {
+            cwdlen = HDstrlen(cwdpath);
+            HDassert(cwdlen);
+            path_len = cwdlen + HDstrlen(new_name) + 2;
+            if ((full_path=H5MM_malloc(path_len)) == NULL)
+                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
+
+            HDstrcpy(full_path, cwdpath);
+            if (!CHECK_DELIMITER(cwdpath[cwdlen-1]))
+                HDstrcat(full_path, DIR_SEPS);
+            HDstrcat(full_path, new_name);
+        }
+    }
+
+    /* strip out the last component (the file name itself) from the path */
+    if (full_path) {
+        GET_LAST_DELIMITER(full_path, ptr)
+        HDassert(ptr);
+        *++ptr = '\0';
+        *extpath = full_path;
+    }
 
+done:
+    if (cwdpath)
+	H5MM_xfree(cwdpath);
+    if (new_name)
+	H5MM_xfree(new_name);
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* H5_build_extpath() */