[llvm/Object] - Make ELFObjectFile::getRelocatedSection return Expected<section_iterator>

It returns just a section_iterator currently and have a report_fatal_error call inside.
This change adds a way to return errors and handle them on caller sides.

The patch also changes/improves current users and adds test cases.

Differential revision: https://reviews.llvm.org/D69167

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@375408 91177308-0d34-0410-b5e6-96231b3b80d8

test/tools/llvm-cxxdump/broken-reloc-sec.test

@@ -0,0 +1,20 @@
+## Check we report an error when trying to dump an object
+## which has a relocation section that has a broken sh_info
+## field, which is larger than the number of sections.
+
+# RUN: yaml2obj %s -o %t
+# RUN: not llvm-cxxdump %t 2>&1 | FileCheck %s
+# CHECK: error: reading file: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.foo
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-dwarfdump/elf-broken-reloc-target.yaml

@@ -0,0 +1,20 @@
+## Check we report an error if the relocated section identified by the
+## sh_info field of a relocation section is invalid.
+
+# RUN: yaml2obj %s -o %t
+# RUN: llvm-dwarfdump %t 2>&1 | FileCheck %s -DFILE=%t --check-prefix=ERR
+
+# ERR: error: failed to get relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.debug_info
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-objdump/X86/elf-disassemble-relocs.test

@@ -1,8 +1,8 @@
 ## Show that --disassemble + --reloc prints relocations inline and does not dump
 ## the relocation sections.
 
-# RUN: yaml2obj %s -o %t.o
-# RUN: llvm-objdump %t.o -d -r | FileCheck %s --implicit-check-not="RELOCATION RECORDS"
+# RUN: yaml2obj %s --docnum=1 -o %t1.o
+# RUN: llvm-objdump %t1.o -d -r | FileCheck %s --implicit-check-not="RELOCATION RECORDS"
 
 # CHECK:      0: e8 00 00 00 00                callq   0 <.text+0x5>
 # CHECK-NEXT:          0000000000000001:  R_X86_64_PC32        foo-4
@@ -40,3 +40,24 @@ Sections:
 Symbols:
   - Name: foo
   - Name: bar
+
+## Check we report an error if the relocated section identified by the
+## sh_info field of a relocation section is invalid.
+
+# RUN: yaml2obj %s --docnum=2 -o %t2.o
+# RUN: not llvm-objdump %t2.o --disassemble --reloc 2>&1 | FileCheck %s -DFILE=%t2.o --check-prefix=ERR
+
+# ERR: error: '[[FILE]]': section (1): failed to get a relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS64
+  Data:    ELFDATA2LSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+- Name: .rela.debug_info
+  Type: SHT_RELA
+  Link: 0
+  Info: 0xFF
+  Relocations: []

test/tools/llvm-objdump/relocations-elf.test

@@ -74,8 +74,8 @@ Symbols:
 ## Check we report an error if the relocated section identified by the
 ## sh_info field of a relocation section is invalid.
 # RUN: yaml2obj --docnum=2 %s > %t2
-# RUN: not llvm-objdump --reloc %t2 2>&1 | FileCheck %s --check-prefix=ERR
-# ERR: LLVM ERROR: Invalid data was encountered while parsing the file
+# RUN: not llvm-objdump --reloc %t2 2>&1 | FileCheck %s -DFILE=%t2 --check-prefix=ERR
+# ERR: error: '[[FILE]]': section (1): unable to get a relocation target: invalid section index: 255
 
 --- !ELF
 FileHeader:
@@ -86,7 +86,7 @@ FileHeader:
 Sections:
 - Name: .rela.foo
   Type: SHT_RELA
-  Info: 0x255
+  Info: 0xFF
   Relocations:
     - Offset: 0x1
       Type: R_X86_64_NONE

test/tools/llvm-readobj/stack-sizes.test

@@ -641,3 +641,26 @@ Sections:
     Relocations:
       - Offset: 0
         Type:   R_X86_64_64
+
+## Check we report an error when dumping stack sizes if the relocated section
+## identified by the sh_info field is invalid. Here sh_info value is larger than
+## the number of sections.
+
+# RUN: yaml2obj --docnum=13 %s > %t18
+# RUN: not llvm-readelf --stack-sizes %t18 2>&1 | FileCheck %s -DFILE=%t18 --check-prefix=INVALID-TARGET
+# RUN: not llvm-readobj --stack-sizes %t18 2>&1 | FileCheck %s -DFILE=%t18 --check-prefix=INVALID-TARGET
+
+# INVALID-TARGET: error: '[[FILE]]': .rela.stack_sizes: failed to get a relocated section: invalid section index: 255
+
+--- !ELF
+FileHeader:
+  Class:   ELFCLASS32
+  Data:    ELFDATA2MSB
+  Type:    ET_REL
+  Machine: EM_X86_64
+Sections:
+  - Name: .rela.stack_sizes
+    Type: SHT_RELA
+    Link: 0
+    Info: 0xFF
+    Relocations: []