[PATCH 07/17] ctf-reader: Fix analyzing single kernel binaries

[dodji@redhat.com]

From: Dodji Seketeli <dodji@redhat.com>

Analyzing a single kernel binary has been broken for a long time, it
seems.  For the record, I mean this:

    $ abidw --ctf vmlinux > vmlinux.ctf.abi

Doesn't work.

This patch fixes ctf::reader::slurp_elf_info to make it not crash on
binaries that have no CTF sections because there is a .ctfa file in
the same directory.

Also, it fixes ctf::reader::read_corpus to support loading the CTF
archive for individual kernel binaries and not just for entire trees
(corpus groups).  In the case of individual kernel binaries, the
archive can be built from the CTF sections of the binary.

	* src/abg-ctf-reader.cc (reader::slurp_elf_info): Do not crash on
	a kernel binary that has no CTF section because the CTF
	information is in a .ctfa file in the same directory.
	(reader::read_corpus): Support loading a CTF archive for a single
	kernel binary.  Also, support loading the CTF archive from the CTF
	sections in the binary itself not necessarily from a .ctfa file in
	the same directory.

Signed-off-by: Dodji Seketeli <dodji@redhat.com>
---
 src/abg-ctf-reader.cc | 51 ++++++++++++++++++++++++-------------------
 1 file changed, 28 insertions(+), 23 deletions(-)

diff --git a/src/abg-ctf-reader.cc b/src/abg-ctf-reader.cc
index c93608ca..fd5a8a58 100644
--- a/src/abg-ctf-reader.cc
+++ b/src/abg-ctf-reader.cc
@@ -383,15 +383,6 @@ public:
     elf::reader::read_corpus(status);
 
     corpus_sptr corp = corpus();
-    if ((corp->get_origin() & corpus::LINUX_KERNEL_BINARY_ORIGIN)
-	&& corpus_group())
-      {
-	// Not finding any debug info so far is expected if we are
-	// building a kABI.
-        status &= static_cast<abigail::fe_iface::status>
-                    (~STATUS_DEBUG_INFO_NOT_FOUND);
-	return;
-      }
 
     if ((status & STATUS_NO_SYMBOLS_FOUND)
 	|| !(status & STATUS_OK))
@@ -415,17 +406,29 @@ public:
       }
 
     const Elf_Scn* ctf_scn = find_ctf_section();
-    fill_ctf_section(ctf_scn, &ctf_sect);
+    if (ctf_scn)
+      fill_ctf_section(ctf_scn, &ctf_sect);
 
     const Elf_Scn* symtab_scn =
       elf_helpers::find_section_by_name(elf_handle(), symtab_name);
-    fill_ctf_section(symtab_scn, &symtab_sect);
+    if (symtab_scn)
+      fill_ctf_section(symtab_scn, &symtab_sect);
 
     const Elf_Scn* strtab_scn =
       elf_helpers::find_section_by_name(elf_handle(), strtab_name);
-    fill_ctf_section(strtab_scn, &strtab_sect);
+    if (strtab_scn)
+      fill_ctf_section(strtab_scn, &strtab_sect);
 
-    status |= fe_iface::STATUS_OK;
+    if (ctf_scn && symtab_scn && strtab_scn)
+      status |= fe_iface::STATUS_OK;
+    else if (corp->get_origin() & corpus::LINUX_KERNEL_BINARY_ORIGIN)
+      {
+	// Not finding any debug info so far is expected if we are
+	// building a kABI.
+        status &= static_cast<abigail::fe_iface::status>
+                    (~STATUS_DEBUG_INFO_NOT_FOUND);
+	return;
+      }
   }
 
   /// Process a CTF archive and create libabigail IR for the types,
@@ -690,8 +693,7 @@ public:
       t.start();
 
     int errp;
-    if ((corp->get_origin() & corpus::LINUX_KERNEL_BINARY_ORIGIN)
-	&& corpus_group())
+    if (corp->get_origin() & corpus::LINUX_KERNEL_BINARY_ORIGIN)
       {
 	if (ctfa == nullptr)
 	  {
@@ -700,14 +702,17 @@ public:
 	      ctfa = ctf_arc_open(ctfa_filename.c_str(), &errp);
 	  }
       }
-    else
-      /* Build the ctfa from the contents of the relevant ELF sections,
-	 and process the CTF archive in the read context, if any.
-	 Information about the types, variables, functions, etc contained
-	 in the archive are added to the given corpus.  */
-      if (ctfa == nullptr)
-	ctfa = ctf_arc_bufopen(&ctf_sect, &symtab_sect,
-			       &strtab_sect, &errp);
+
+    /* Build the ctfa from the contents of the relevant ELF sections,
+       and process the CTF archive in the read context, if any.
+       Information about the types, variables, functions, etc contained
+       in the archive are added to the given corpus.  */
+    if (ctfa == nullptr
+	&& ctf_sect.cts_data
+	&& symtab_sect.cts_data
+	&& strtab_sect.cts_data)
+      ctfa = ctf_arc_bufopen(&ctf_sect, &symtab_sect,
+			     &strtab_sect, &errp);
 
     if (do_log())
       {
-- 
2.43.5