[PATCH] libdw: Handle all address FORMs for dwarf_highpc, handle errors better.

Mark Wielaard mark@klomp.org
Tue May 22 12:48:00 GMT 2018


dwarf_highpc can use any address FORM, not just DW_FORM_addr. Just try
whether the address can be resolved as address. Always set error when
attribute couldn't be found or resolved. When calculating the base
address for a CU don't try to second guess the error code, just treat
an error the same as the attribute not being there.

Signed-off-by: Mark Wielaard <mark@klomp.org>
---
 libdw/ChangeLog           |  7 +++++++
 libdw/dwarf_getlocation.c | 17 ++++-------------
 libdw/dwarf_highpc.c      | 10 ++++++----
 3 files changed, 17 insertions(+), 17 deletions(-)

diff --git a/libdw/ChangeLog b/libdw/ChangeLog
index e7fd217..3045359 100644
--- a/libdw/ChangeLog
+++ b/libdw/ChangeLog
@@ -1,3 +1,10 @@
+2018-05-22  Mark Wielaard  <mark@klomp.org>
+
+	* dwarf_getlocation.c (__libdw_cu_base_address): Treat errors of
+	getting lowpc or entrypc the same as missing base address (zero).
+	* dwarf_highpc (dwarf_highpc): Handle any address form. Always set
+	error when attribute could not be found.
+
 2018-05-21  Mark Wielaard  <mark@klomp.org>
 
 	* dwarf_begin_elf.c (valid_p): Add a fake_addr_cu to the result.
diff --git a/libdw/dwarf_getlocation.c b/libdw/dwarf_getlocation.c
index 116fa71..ade3e6c 100644
--- a/libdw/dwarf_getlocation.c
+++ b/libdw/dwarf_getlocation.c
@@ -682,19 +682,10 @@ __libdw_cu_base_address (Dwarf_CU *cu)
 							 &attr_mem),
 				     &base) != 0)
 	{
-	  int err = INTUSE(dwarf_errno) ();
-	  if (err != 0)
-	    {
-	      __libdw_seterrno (err);
-	      base = (Dwarf_Addr) -1;
-	    }
-	  else
-	    {
-	      /* The compiler provided no base address when it should
-		 have.  Buggy GCC does this when it used absolute
-		 addresses in the location list and no DW_AT_ranges.  */
-	      base = 0;
-	    }
+	  /* The compiler provided no base address when it should
+	     have.  Buggy GCC does this when it used absolute
+	     addresses in the location list and no DW_AT_ranges.  */
+	   base = 0;
 	}
       cu->base_address = base;
     }
diff --git a/libdw/dwarf_highpc.c b/libdw/dwarf_highpc.c
index 1baffa7..5b2f0fd 100644
--- a/libdw/dwarf_highpc.c
+++ b/libdw/dwarf_highpc.c
@@ -47,10 +47,10 @@ dwarf_highpc (Dwarf_Die *die, Dwarf_Addr *return_addr)
     attr_high = INTUSE(dwarf_attr) (die, DW_AT_high_pc, &attr_high_mem);
 
   if (attr_high == NULL)
-    return -1;
+    goto no_addr;
 
-  if (attr_high->form == DW_FORM_addr)
-    return INTUSE(dwarf_formaddr) (attr_high, return_addr);
+  if (INTUSE(dwarf_formaddr) (attr_high, return_addr) == 0)
+    return 0;
 
   /* DWARF 4 allows high_pc to be a constant offset from low_pc. */
   if (INTUSE(dwarf_lowpc) (die, return_addr) == 0)
@@ -61,8 +61,10 @@ dwarf_highpc (Dwarf_Die *die, Dwarf_Addr *return_addr)
 	  *return_addr += uval;
 	  return 0;
 	}
-      __libdw_seterrno (DWARF_E_NO_ADDR);
     }
+
+no_addr:
+  __libdw_seterrno (DWARF_E_NO_ADDR);
   return -1;
 }
 INTDEF(dwarf_highpc)
-- 
1.8.3.1



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