[PATCH 2/2] elf-from-memory: Refactor to get rid of nested function

[tbaeder@redhat.com]

From: Timm Bäder <tbaeder@redhat.com>

Try to unify the 32/64 bit code paths and get rid of the nested
handle_segment() this way.

Signed-off-by: Timm Bäder <tbaeder@redhat.com>
---
 libdwfl/elf-from-memory.c | 115 +++++++++++++++++---------------------
 1 file changed, 50 insertions(+), 65 deletions(-)

diff --git a/libdwfl/elf-from-memory.c b/libdwfl/elf-from-memory.c
index 933ab864..a0ef0014 100644
--- a/libdwfl/elf-from-memory.c
+++ b/libdwfl/elf-from-memory.c
@@ -292,80 +292,65 @@ elf_from_remote_memory (GElf_Addr ehdr_vma,
       goto no_memory;
     }
 
-  switch (ehdr.e32.e_ident[EI_CLASS])
+  for (uint_fast16_t i = 0; i < phnum; ++i)
     {
-      /* Reads the given segment.  Returns true if reading fails,
-	 false otherwise.  */
-      inline bool handle_segment (GElf_Addr vaddr, GElf_Off offset,
-				  GElf_Xword filesz)
-	{
-	  GElf_Off start = offset & -pagesize;
-	  GElf_Off end = (offset + filesz + pagesize - 1) & -pagesize;
-	  if (end > (GElf_Off) contents_size)
-	    end = contents_size;
-	  nread = (*read_memory) (arg, buffer + start,
-				  (loadbase + vaddr) & -pagesize,
-				  end - start, end - start);
-	  return nread <= 0;
-	}
+      GElf_Word type = class32 ? (*p32)[i].p_type : (*p64)[i].p_type;
 
-    case ELFCLASS32:
-      for (uint_fast16_t i = 0; i < phnum; ++i)
-	if ((*p32)[i].p_type == PT_LOAD)
-	  if (handle_segment ((*p32)[i].p_vaddr, (*p32)[i].p_offset,
-			      (*p32)[i].p_filesz))
-	    goto read_error;
-
-      /* If the segments visible in memory didn't include the section
-	 headers, then clear them from the file header.  */
-      if (contents_size < shdrs_end)
-	{
-	  ehdr.e32.e_shoff = 0;
-	  ehdr.e32.e_shnum = 0;
-	  ehdr.e32.e_shstrndx = 0;
-	}
+      if (type != PT_LOAD)
+        continue;
+
+      GElf_Addr vaddr = class32 ? (*p32)[i].p_vaddr : (*p64)[i].p_vaddr;
+      GElf_Off offset = class32 ? (*p32)[i].p_offset : (*p64)[i].p_offset;
+      GElf_Xword filesz = class32 ? (*p32)[i].p_filesz : (*p64)[i].p_filesz;
+
+      GElf_Off start = offset & -pagesize;
+      GElf_Off end = (offset + filesz + pagesize - 1) & -pagesize;
+      if (end > (GElf_Off) contents_size)
+        end = contents_size;
+      nread = (*read_memory) (arg, buffer + start,
+                              (loadbase + vaddr) & -pagesize,
+                              end - start, end - start);
+      if (nread <= 0)
+        goto read_error;
+    }
+
+  /* If the segments visible in memory didn't include the section
+     headers, then clear them from the file header.  */
+  if (contents_size < shdrs_end)
+    {
+      if (class32)
+        {
+          ehdr.e32.e_shoff = 0;
+          ehdr.e32.e_shnum = 0;
+          ehdr.e32.e_shstrndx = 0;
+        }
+      else
+        {
+          ehdr.e64.e_shoff = 0;
+          ehdr.e64.e_shnum = 0;
+          ehdr.e64.e_shstrndx = 0;
+        }
+    }
 
-      /* This will normally have been in the first PT_LOAD segment.  But it
-	 conceivably could be missing, and we might have just changed it.  */
-      xlatefrom.d_type = xlateto.d_type = ELF_T_EHDR;
+  /* This will normally have been in the first PT_LOAD segment.  But it
+     conceivably could be missing, and we might have just changed it.  */
+  xlatefrom.d_type = xlateto.d_type = ELF_T_EHDR;
+  xlateto.d_buf = buffer;
+  if (class32)
+    {
       xlatefrom.d_size = xlateto.d_size = sizeof ehdr.e32;
       xlatefrom.d_buf = &ehdr.e32;
-      xlateto.d_buf = buffer;
       if (elf32_xlatetof (&xlateto, &xlatefrom,
-			  ehdr.e32.e_ident[EI_DATA]) == NULL)
-	goto libelf_error;
-      break;
-
-    case ELFCLASS64:
-      for (uint_fast16_t i = 0; i < phnum; ++i)
-	if ((*p64)[i].p_type == PT_LOAD)
-	  if (handle_segment ((*p64)[i].p_vaddr, (*p64)[i].p_offset,
-			      (*p64)[i].p_filesz))
-	    goto read_error;
-
-      /* If the segments visible in memory didn't include the section
-	 headers, then clear them from the file header.  */
-      if (contents_size < shdrs_end)
-	{
-	  ehdr.e64.e_shoff = 0;
-	  ehdr.e64.e_shnum = 0;
-	  ehdr.e64.e_shstrndx = 0;
-	}
-
-      /* This will normally have been in the first PT_LOAD segment.  But it
-	 conceivably could be missing, and we might have just changed it.  */
-      xlatefrom.d_type = xlateto.d_type = ELF_T_EHDR;
+                          ehdr.e32.e_ident[EI_DATA]) == NULL)
+        goto libelf_error;
+    }
+  else
+    {
       xlatefrom.d_size = xlateto.d_size = sizeof ehdr.e64;
       xlatefrom.d_buf = &ehdr.e64;
-      xlateto.d_buf = buffer;
       if (elf64_xlatetof (&xlateto, &xlatefrom,
-			  ehdr.e64.e_ident[EI_DATA]) == NULL)
-	goto libelf_error;
-      break;
-
-    default:
-      abort ();
-      break;
+                          ehdr.e64.e_ident[EI_DATA]) == NULL)
+        goto libelf_error;
     }
 
   free (phdrsp);
-- 
2.26.2