libsframe: make flip_header version aware

Future versions of the format may have alternative representation of an
FDE.  As the format evolves, endian flipping will need to be version
aware.

flip_header now takes the SFrame version as argument.  Currently unused,
this argument will be used later when we introduce SFrame V3.

SFrame encoder, at the momemnt, writes the SFrame data in the most recent
format version by default.

libsframe/
        * sframe.c (flip_header): Make version aware.
        (sframe_decode): Adjust usage of flup_header.
        (sframe_encoder_write): Likewise.

diff --git a/libsframe/sframe.c b/libsframe/sframe.c
index 04ff6868591d108fff84e86d475011a856db8444..17f42dbd485b0cd24b592f4ba86956d5126e948d 100644 (file)
--- a/libsframe/sframe.c
+++ b/libsframe/sframe.c
@@ -181,21 +181,37 @@ need_swapping (int endian)
   return 0;
 }
 
-/* Flip the endianness of the SFrame header.  */
+/* Flip the endianness of the SFrame header starting at BUF.
+   VER is the version of the SFrame data in the buffer.
 
-static void
-flip_header (sframe_header *sfheader)
-{
-  swap_thing (sfheader->sfh_preamble.sfp_magic);
-  swap_thing (sfheader->sfh_preamble.sfp_version);
-  swap_thing (sfheader->sfh_preamble.sfp_flags);
-  swap_thing (sfheader->sfh_cfa_fixed_fp_offset);
-  swap_thing (sfheader->sfh_cfa_fixed_ra_offset);
-  swap_thing (sfheader->sfh_num_fdes);
-  swap_thing (sfheader->sfh_num_fres);
-  swap_thing (sfheader->sfh_fre_len);
-  swap_thing (sfheader->sfh_fdeoff);
-  swap_thing (sfheader->sfh_freoff);
+   Returns SFRAME_ERR if any error.  If error code is returned, the flipped
+   header should not be used.  */
+
+static int
+flip_header (char *buf, uint8_t ver ATTRIBUTE_UNUSED)
+{
+  /* SFrame header binary format has remained the same in SFRAME_VERSION_1,
+     SFRAME_VERSION_2.  */
+  sframe_header *sfh = (sframe_header *) buf;
+  swap_thing (sfh->sfh_preamble.sfp_magic);
+  swap_thing (sfh->sfh_preamble.sfp_version);
+  swap_thing (sfh->sfh_preamble.sfp_flags);
+  swap_thing (sfh->sfh_abi_arch);
+  swap_thing (sfh->sfh_cfa_fixed_fp_offset);
+  swap_thing (sfh->sfh_cfa_fixed_ra_offset);
+  swap_thing (sfh->sfh_auxhdr_len);
+  swap_thing (sfh->sfh_num_fdes);
+  swap_thing (sfh->sfh_num_fres);
+  swap_thing (sfh->sfh_fre_len);
+  swap_thing (sfh->sfh_fdeoff);
+  swap_thing (sfh->sfh_freoff);
+
+  /* Alert for missing functionatlity.  Auxiliary header, if present, needs to
+     flipped based on per abi/arch semantics.  */
+  if (sfh->sfh_auxhdr_len)
+    return SFRAME_ERR;
+
+  return 0;
 }
 
 /* Endian flip the SFrame FDE at BUF, given the SFrame version VER.  Update
@@ -991,15 +1007,19 @@ sframe_decode (const char *sf_buf, size_t sf_size, int *errp)
        return sframe_ret_set_errno (errp, SFRAME_ERR_NOMEM);
       memcpy (tempbuf, sf_buf, sf_size);
 
-      /* Flip the header.  */
-      sframe_header *ihp = (sframe_header *) tempbuf;
-      flip_header (ihp);
+      /* Flip the header first.  */
+      if (flip_header (tempbuf, sfp->sfp_version))
+       {
+         sframe_ret_set_errno (errp, SFRAME_ERR_BUF_INVAL);
+         goto decode_fail_free;
+       }
       /* Flip the rest of the SFrame section data buffer.  */
       if (flip_sframe (tempbuf, sf_size, 0))
        {
-         free (tempbuf);
-         return sframe_ret_set_errno (errp, SFRAME_ERR_BUF_INVAL);
+         sframe_ret_set_errno (errp, SFRAME_ERR_BUF_INVAL);
+         goto decode_fail_free;
        }
+
       frame_buf = tempbuf;
       /* This buffer is malloc'd when endian flipping the contents of the input
         buffer are needed.  Keep a reference to it so it can be free'd up
@@ -2023,6 +2043,10 @@ sframe_encoder_write (sframe_encoder_ctx *encoder,
     * sizeof (sframe_func_desc_entry);
   fresz = encoder->sfe_fre_nbytes;
 
+  /* Encoder writes out data in the latest SFrame format version.  */
+  if (sframe_encoder_get_version (encoder) != SFRAME_VERSION)
+    return sframe_ret_set_errno (errp, SFRAME_ERR_VERSION_INVAL);
+
   /* The total size of buffer is the sum of header, SFrame Function Descriptor
      Entries section and the FRE section.  */
   bufsize = hdrsize + fsz + fresz;
@@ -2049,7 +2073,8 @@ sframe_encoder_write (sframe_encoder_ctx *encoder,
     {
       if (flip_sframe (encoder->sfe_data, bufsize, 1))
        return sframe_ret_set_errno (errp, SFRAME_ERR_BUF_INVAL);
-      flip_header ((sframe_header*)encoder->sfe_data);
+      if (flip_header (encoder->sfe_data, SFRAME_VERSION))
+       return sframe_ret_set_errno (errp, SFRAME_ERR_BUF_INVAL);
     }
 
   *encoded_size = bufsize;