[svn-r19798] Purpose:

Add additional error checking to catch erroneous user input.

Description:

    Attempting to retrieve a links's name by index in the case
    where the link is external and the file that the object is
    located in doesn't exist was causing a segmentation fault
    (in production) and an assertion failure (in debug).

    The segfault wasn't occuring until the metadata accumulator
    attempted a write, so I've added error checking higher in
    the pipeline in H5O_protect (where there was previously just
    an assert) to catch this. I've also added additional asserts
    in the H5F layer where there were none.

    Additionally, I added another case to the links.c test to
    test that this fails gracefully instead of segfaulting or 
    asserting out.

Tested:

    h5committest and gandalf (mac os x)

release_docs/RELEASE.txt

@@ -249,6 +249,10 @@ Bug Fixes since HDF5-1.8.0 release
 
     Library
     -------
+      - Retrieving a link's name by index in the case where the link is
+            external and the file that the link refers to doesn't exist will 
+            now fail gracefully rather than cause a segmentation fault. 
+            (MAM - 2010/11/17)
       - Modified library to always cache symbol table information.  Libraries
             version 1.6.3 have a bug which causes them to require this
             information for some operations. (NAF - 2010/09/21 - 1864)

src/H5Fio.c

@@ -102,6 +102,7 @@ H5F_block_read(const H5F_t *f, H5FD_mem_t type, haddr_t addr, size_t size,
     HDassert(f);
     HDassert(f->shared);
     HDassert(buf);
+    HDassert(H5F_addr_defined(addr));
 
     /* Check for attempting I/O on 'temporary' file address */
     if(H5F_addr_le(f->shared->tmp_addr, (addr + size)))
@@ -146,6 +147,7 @@ HDfprintf(stderr, "%s: write to addr = %a, size = %Zu\n", FUNC, addr, size);
     HDassert(f->shared);
     HDassert(f->intent & H5F_ACC_RDWR);
     HDassert(buf);
+    HDassert(H5F_addr_defined(addr));
 
     /* Check for attempting I/O on 'temporary' file address */
     if(H5F_addr_le(f->shared->tmp_addr, (addr + size)))

src/H5O.c

@@ -1662,7 +1662,10 @@ H5O_protect(const H5O_loc_t *loc, hid_t dxpl_id, H5AC_protect_t prot)
     /* check args */
     HDassert(loc);
     HDassert(loc->file);
-    HDassert(H5F_addr_defined(loc->addr));
+
+    /* Check for valid address */
+    if(!H5F_addr_defined(loc->addr))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, NULL, "address undefined")
 
     /* Check for write access on the file */
     file_intent = H5F_INTENT(loc->file);

test/links.c

@@ -2640,6 +2640,8 @@ external_link_dangling(hid_t fapl, hbool_t new_format)
 {
     hid_t	fid = (-1);     		/* File ID */
     hid_t	gid = (-1);	                /* Group IDs */
+    hid_t   rid = (-1);             /* Root Group ID */
+    hid_t   status = (-1);          /* Status */
     char	filename1[NAME_BUF_SIZE],
     		filename2[NAME_BUF_SIZE];       /* Names of files to externally link across */
 
@@ -2672,6 +2674,9 @@ external_link_dangling(hid_t fapl, hbool_t new_format)
     /* Open first file */
     if((fid=H5Fopen(filename1, H5F_ACC_RDWR, fapl)) < 0) TEST_ERROR
 
+    /* Get root group ID */
+    if((rid=H5Gopen2(fid, "/", H5P_DEFAULT)) < 0) TEST_ERROR;
+
     /* Open object through dangling file external link */
     H5E_BEGIN_TRY {
         gid = H5Gopen2(fid, "no_file", H5P_DEFAULT);
@@ -2692,6 +2697,18 @@ external_link_dangling(hid_t fapl, hbool_t new_format)
 	goto error;
     }
 
+    /* Try to get name of object by index through dangling file external link */
+    H5E_BEGIN_TRY {
+        status = H5Lget_name_by_idx(rid, "no_file", H5_INDEX_NAME, H5_ITER_INC, 0, NULL, 0, H5P_DEFAULT);
+    } H5E_END_TRY;
+    if (status >= 0) {
+        H5_FAILED();
+        puts("    Retreiving name of object by index through dangling file external link should have failed.");
+    } /* end if */
+
+    /* Close root group */
+    if(H5Gclose(rid) < 0) TEST_ERROR
+
     /* Close first file */
     if(H5Fclose(fid) < 0) TEST_ERROR