[yaml2obj][ELF] Add an optional `Size` field to the YAML section declaration.

Now the only method to configure ELF section's content and size is to assign
a hexadecimal string to the `Content` field. Unfortunately this way is
completely useless when you need to declare a really large section.

To solve this problem this patch adds one more optional field `Size`
to the `RawContentSection` structure. When yaml2obj generates an ELF file
it uses the following algorithm:
1. If both `Content` and `Size` fields are missed create an empty section.
2. If only `Content` field is missed take section length from the `Size`
   field and fill the section by zero.
3. If only `Size` field is missed create a section using data from
   the `Content` field.
4. If both `Content` and `Size` fields are provided validate that the `Size`
   value is not less than size of `Content` data. Than take section length
   from the `Size`, fill beginning of the section by `Content` and the rest
   by zero.

Examples
--------
* Create a section 0x10000 bytes long filled by zero
  Name: .data
  Type: SHT_PROGBITS
  Flags: [ SHF_ALLOC ]
  Size: 0x10000

* Create a section 0x10000 bytes long starting from 'CA' 'FE' 'BA' 'BE'
  Name: .data
  Type: SHT_PROGBITS
  Flags: [ SHF_ALLOC ]
  Content: CAFEBABE
  Size: 0x10000

The patch reviewed by Michael Spencer.

git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@208995 91177308-0d34-0410-b5e6-96231b3b80d8

1 files changed, 26 insertions, 0 deletions

diff --git a/test/Object/yaml2obj-elf-section-invalid-size.yaml b/test/Object/yaml2obj-elf-section-invalid-size.yaml
new file mode 100644
index 0000000000..d0cb370072
--- /dev/null
+++ b/test/Object/yaml2obj-elf-section-invalid-size.yaml
@@ -0,0 +1,26 @@
+# RUN: not yaml2obj -format=elf -o %t %s 2>&1 | FileCheck %s
+
+!ELF
+FileHeader:
+  Class: ELFCLASS64
+  Data: ELFDATA2LSB
+  Type: ET_REL
+  Machine: EM_X86_64
+
+Sections:
+  - Name: .text
+    Type: SHT_PROGBITS
+    Flags: [ SHF_ALLOC, SHF_EXECINSTR ]
+    Content: EBFE
+    AddressAlign: 2
+
+  - Name: .data
+    Type: SHT_PROGBITS
+    Flags: [ SHF_ALLOC ]
+    Content: 0000000000000000
+    Size: 2
+
+# CHECK: YAML:17:5: error: Section size must be greater or equal to the content size
+# CHECK-NEXT: - Name: .data
+# CHECK-NEXT:   ^
+# CHECK-NEXT: yaml2obj: Failed to parse YAML file!