Re: [Tinycc-devel] linux/unix shared libraries?

[grischka]

From: "grischka":
> ...
> The problem with the layout from TCC seem to be that the dynamic 
> linker (/lib/ld-linux.so.2) thinks RELSZ is the size of rel.text, 
> and then crashes when it goes over the end of it.

The above from my last email was somewhere near but still wrong. 
TCC is okay to add on the sizes because it has all that sections 
in order.

Instead it looks like if it generates bogus relocations for sections 
with zero size. From objdump -x libmylib.so:

 Idx Name                Size      VMA       LMA       File off  Algn
  11 .debug_line         00000000  00000000  00000000  000004a0  2**0
  12 .rel.debug_line     00000038  00000360  00000360  00000360  2**2

This patch fixes it for me:

diff --git a/tccelf.c b/tccelf.c
index 730643d..e17f2df 100644
--- a/tccelf.c
+++ b/tccelf.c
@@ -1372,7 +1372,9 @@ int tcc_output_file(TCCState *s1, const char *filename)
     if (file_type == TCC_OUTPUT_DLL && 
       s->sh_type == SHT_REL && 
       !(s->sh_flags & SHF_ALLOC)) {
-            prepare_dynamic_rel(s1, s);
+            /* //gr: avoid bogus relocs for empty (debug) sections */
+            if (s1->sections[s->sh_info]->sh_flags & SHF_ALLOC)
+                prepare_dynamic_rel(s1, s);
     } else if (do_debug || 
       file_type == TCC_OUTPUT_OBJ || 
       (s->sh_flags & SHF_ALLOC) ||

--- grischka