1 files changed, 64 insertions, 0 deletions
diff --git a/src/H5FDint.c b/src/H5FDint.c
index 2d1fc09..9f02a25 100644
--- a/src/H5FDint.c
+++ b/src/H5FDint.c
@@ -103,6 +103,70 @@ H5FD_int_init_interface(void)
 
 
 /*-------------------------------------------------------------------------
+ * Function:    H5FD_locate_signature
+ *
+ * Purpose:     Finds the HDF5 superblock signature in a file.  The
+ *              signature can appear at address 0, or any power of two
+ *              beginning with 512.
+ *
+ * Return:      Success:        SUCCEED
+ *              Failure:        FAIL
+ *
+ * Programmer:  Robb Matzke
+ *              Friday, November  7, 1997
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5FD_locate_signature(H5FD_t *file, const H5P_genplist_t *dxpl, haddr_t *sig_addr)
+{
+    haddr_t         addr, eoa;
+    uint8_t         buf[H5F_SIGNATURE_LEN];
+    unsigned        n, maxpow;
+    herr_t          ret_value = SUCCEED; /* Return value */
+
+    FUNC_ENTER_NOAPI_NOINIT
+
+    /* Find the least N such that 2^N is larger than the file size */
+    if(HADDR_UNDEF == (addr = H5FD_get_eof(file)) || HADDR_UNDEF == (eoa = H5FD_get_eoa(file, H5FD_MEM_SUPER)))
+        HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to obtain EOF/EOA value")
+    for(maxpow = 0; addr; maxpow++)
+        addr >>= 1;
+    maxpow = MAX(maxpow, 9);
+
+    /*
+     * Search for the file signature at format address zero followed by
+     * powers of two larger than 9.
+     */
+    for(n = 8; n < maxpow; n++) {
+        addr = (8 == n) ? 0 : (haddr_t)1 << n;
+        if(H5FD_set_eoa(file, H5FD_MEM_SUPER, addr + H5F_SIGNATURE_LEN) < 0)
+            HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to set EOA value for file signature")
+        if(H5FD_read(file, dxpl, H5FD_MEM_SUPER, addr, (size_t)H5F_SIGNATURE_LEN, buf) < 0)
+            HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to read file signature")
+        if(!HDmemcmp(buf, H5F_SIGNATURE, (size_t)H5F_SIGNATURE_LEN))
+            break;
+    } /* end for */
+
+    /*
+     * If the signature was not found then reset the EOA value and return
+     * HADDR_UNDEF.
+     */
+    if(n >= maxpow) {
+        if(H5FD_set_eoa(file, H5FD_MEM_SUPER, eoa) < 0)
+            HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to reset EOA value")
+        *sig_addr = HADDR_UNDEF;
+    } /* end if */
+    else
+        /* Set return value */
+        *sig_addr = addr;
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5FD_locate_signature() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5FD_read
  *
  * Purpose:	Private version of H5FDread()