[PATCH 3/8] ELF unexec: Merge Alpha and MIPS COFF debug handling

[Alan Modra]

        * unexelf.c (unexec): Merge Alpha and MIPS COFF debug handling.
        Don't find .mdebug section index, find the section in the loop.
        Allow for unlikely possibility that .mdebug is located at sh_offset
        before bss segment, by calculating move from difference in
        sh_offset rather than just assuming new_data2_size.  Simplify
        cbLineOffset handling.

diff --git a/src/unexelf.c b/src/unexelf.c
index d6c6648..0065491 100644
--- a/src/unexelf.c
+++ b/src/unexelf.c
@@ -660,9 +660,6 @@ unexec (const char *new_name, const char *old_name)
   ptrdiff_t n, nn;
   ptrdiff_t old_bss_index, old_sbss_index, old_plt_index;
   ptrdiff_t old_data_index, new_data2_index;
-#if defined _SYSTYPE_SYSV || defined __sgi
-  ptrdiff_t old_mdebug_index;
-#endif
   struct stat stat_buf;
   off_t old_file_size;
 
@@ -706,13 +703,6 @@ unexec (const char *new_name, const char *old_name)
   old_section_names = (char *) old_base
     + OLD_SECTION_H (old_file_h->e_shstrndx).sh_offset;
 
-  /* Find the mdebug section, if any.  */
-
-#if defined _SYSTYPE_SYSV || defined __sgi
-  old_mdebug_index = find_section (".mdebug", old_section_names,
-                                  old_name, old_file_h, old_section_h, 1);
-#endif
-
   /* Find the old .bss section.  Figure out parameters of the new
      data2 and bss sections.  */
 
@@ -1055,51 +1045,31 @@ temacs:
 
       memcpy (new_shdr->sh_offset + new_base, src, new_shdr->sh_size);
 
-#if defined __alpha__ && !defined __OpenBSD__
-      /* Update Alpha COFF symbol table: */
-      if (strcmp (old_section_names + old_shdr->sh_name, ".mdebug") == 0)
-       {
-         pHDRR symhdr = (pHDRR) (new_shdr->sh_offset + new_base);
-
-         symhdr->cbLineOffset += new_data2_size;
-         symhdr->cbDnOffset += new_data2_size;
-         symhdr->cbPdOffset += new_data2_size;
-         symhdr->cbSymOffset += new_data2_size;
-         symhdr->cbOptOffset += new_data2_size;
-         symhdr->cbAuxOffset += new_data2_size;
-         symhdr->cbSsOffset += new_data2_size;
-         symhdr->cbSsExtOffset += new_data2_size;
-         symhdr->cbFdOffset += new_data2_size;
-         symhdr->cbRfdOffset += new_data2_size;
-         symhdr->cbExtOffset += new_data2_size;
-       }
-#endif /* __alpha__ && !__OpenBSD__ */
-
-#if defined (_SYSTYPE_SYSV)
-      if (new_shdr->sh_type == SHT_MIPS_DEBUG
-         && old_mdebug_index != -1)
+#if (defined __alpha__ && !defined __OpenBSD__) || defined _SYSTYPE_SYSV
+      /* Update Alpha and MIPS COFF debug symbol table.  */
+      if (strcmp (old_section_names + new_shdr->sh_name, ".mdebug") == 0
+         && new_shdr->sh_offset - old_shdr->sh_offset != 0
+#if defined _SYSTYPE_SYSV
+         && new_shdr->sh_type == SHT_MIPS_DEBUG
+#endif
+         )
        {
-         ptrdiff_t new_offset = new_shdr->sh_offset;
-         ptrdiff_t old_offset = OLD_SECTION_H (old_mdebug_index).sh_offset;
-         ptrdiff_t diff = new_offset - old_offset;
+         ptrdiff_t diff = new_shdr->sh_offset - old_shdr->sh_offset;
          HDRR *phdr = (HDRR *) (new_shdr->sh_offset + new_base);
 
-         if (diff)
-           {
-             phdr->cbLineOffset += diff;
-             phdr->cbDnOffset   += diff;
-             phdr->cbPdOffset   += diff;
-             phdr->cbSymOffset  += diff;
-             phdr->cbOptOffset  += diff;
-             phdr->cbAuxOffset  += diff;
-             phdr->cbSsOffset   += diff;
-             phdr->cbSsExtOffset += diff;
-             phdr->cbFdOffset   += diff;
-             phdr->cbRfdOffset  += diff;
-             phdr->cbExtOffset  += diff;
-           }
+         phdr->cbLineOffset += diff;
+         phdr->cbDnOffset += diff;
+         phdr->cbPdOffset += diff;
+         phdr->cbSymOffset += diff;
+         phdr->cbOptOffset += diff;
+         phdr->cbAuxOffset += diff;
+         phdr->cbSsOffset += diff;
+         phdr->cbSsExtOffset += diff;
+         phdr->cbFdOffset += diff;
+         phdr->cbRfdOffset += diff;
+         phdr->cbExtOffset += diff;
        }
-#endif /* _SYSTYPE_SYSV */
+#endif /* __alpha__ || _SYSTYPE_SYSV */
 
 #if __sgi
       /* Adjust  the HDRR offsets in .mdebug and copy the
@@ -1110,7 +1080,8 @@ temacs:
         the ld bug that gets the line table in a hole in the
         elf file rather than in the .mdebug section proper.
         David Anderson. address@hidden  Jan 16,1994.  */
-      if (n == old_mdebug_index)
+      if (strcmp (old_section_names + new_shdr->sh_name, ".mdebug") == 0
+         && new_shdr->sh_offset - old_shdr->sh_offset != 0)
        {
 #define MDEBUGADJUST(__ct,__fileaddr)          \
   if (n_phdrr->__ct > 0)                       \
@@ -1120,7 +1091,7 @@ temacs:
 
          HDRR *o_phdrr = (HDRR *) ((byte *) old_base + old_shdr->sh_offset);
          HDRR *n_phdrr = (HDRR *) ((byte *) new_base + new_shdr->sh_offset);
-         unsigned movement = new_data2_size;
+         ptrdiff_t movement = new_shdr->sh_offset - old_shdr->sh_offset;
 
          MDEBUGADJUST (idnMax, cbDnOffset);
          MDEBUGADJUST (ipdMax, cbPdOffset);
@@ -1136,22 +1107,13 @@ temacs:
             requires special handling.  */
          if (n_phdrr->cbLine > 0)
            {
+             n_phdrr->cbLineOffset += movement;
+
              if (o_phdrr->cbLineOffset > (old_shdr->sh_offset
                                           + old_shdr->sh_size))
-               {
-                 /* line data is in a hole in elf. do special copy and adjust
-                    for this ld mistake.
-                    */
-                 n_phdrr->cbLineOffset += movement;
-
-                 memcpy (n_phdrr->cbLineOffset + new_base,
-                         o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine);
-               }
-             else
-               {
-                 /* somehow line data is in .mdebug as it is supposed to be.  
*/
-                 MDEBUGADJUST (cbLine, cbLineOffset);
-               }
+               /* If not covered by section, it hasn't yet been copied.  */
+               memcpy (n_phdrr->cbLineOffset + new_base,
+                       o_phdrr->cbLineOffset + old_base, n_phdrr->cbLine);
            }
        }
 #endif /* __sgi */

-- 
Alan Modra
Australia Development Lab, IBM