Init .gnu_debugdata in GetElf().

- Modify the tests to share some code for the generation of the elf data.
- Move the gnu_debugdata files into a separate directory.
- Add tests for GetElf().
- Move the CreateMemory() tests and the GetElf() tests into separate files.

Bug: 23762183

Test: New unit tests pass.
Change-Id: Ie3380296bb49753c2ac8801cfa11f93d6ff7121d
diff --git a/libunwindstack/tests/ElfTestUtils.cpp b/libunwindstack/tests/ElfTestUtils.cpp
new file mode 100644
index 0000000..8755f16
--- /dev/null
+++ b/libunwindstack/tests/ElfTestUtils.cpp
@@ -0,0 +1,129 @@
+/*
+ * Copyright (C) 2016 The Android Open Source Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *      http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+#include <elf.h>
+#include <errno.h>
+#include <fcntl.h>
+#include <signal.h>
+#include <string.h>
+#include <sys/mman.h>
+#include <sys/ptrace.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+#include <vector>
+
+#include <gtest/gtest.h>
+
+#include "ElfTestUtils.h"
+
+template <typename Ehdr>
+void TestInitEhdr(Ehdr* ehdr, uint32_t elf_class, uint32_t machine_type) {
+  memset(ehdr, 0, sizeof(Ehdr));
+  memcpy(&ehdr->e_ident[0], ELFMAG, SELFMAG);
+  ehdr->e_ident[EI_DATA] = ELFDATA2LSB;
+  ehdr->e_ident[EI_VERSION] = EV_CURRENT;
+  ehdr->e_ident[EI_OSABI] = ELFOSABI_SYSV;
+  ehdr->e_ident[EI_CLASS] = elf_class;
+  ehdr->e_type = ET_DYN;
+  ehdr->e_machine = machine_type;
+  ehdr->e_version = EV_CURRENT;
+  ehdr->e_ehsize = sizeof(Ehdr);
+}
+
+template <typename Ehdr, typename Shdr>
+void TestInitGnuDebugdata(uint32_t elf_class, uint32_t machine, bool init_gnu_debugdata,
+                          TestCopyFuncType copy_func) {
+  Ehdr ehdr;
+
+  TestInitEhdr(&ehdr, elf_class, machine);
+
+  uint64_t offset = sizeof(Ehdr);
+  ehdr.e_shoff = offset;
+  ehdr.e_shnum = 3;
+  ehdr.e_shentsize = sizeof(Shdr);
+  ehdr.e_shstrndx = 2;
+  copy_func(0, &ehdr, sizeof(ehdr));
+
+  Shdr shdr;
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_type = SHT_NULL;
+  copy_func(offset, &shdr, sizeof(shdr));
+  offset += ehdr.e_shentsize;
+
+  // Skip this header, it will contain the gnu_debugdata information.
+  uint64_t gnu_offset = offset;
+  offset += ehdr.e_shentsize;
+
+  uint64_t symtab_offset = sizeof(ehdr) + ehdr.e_shnum * ehdr.e_shentsize;
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_name = 1;
+  shdr.sh_type = SHT_STRTAB;
+  shdr.sh_offset = symtab_offset;
+  shdr.sh_size = 0x100;
+  copy_func(offset, &shdr, sizeof(shdr));
+
+  char value = '\0';
+  uint64_t symname_offset = symtab_offset;
+  copy_func(symname_offset, &value, 1);
+  symname_offset++;
+  std::string name(".shstrtab");
+  copy_func(symname_offset, name.c_str(), name.size() + 1);
+  symname_offset += name.size() + 1;
+  name = ".gnu_debugdata";
+  copy_func(symname_offset, name.c_str(), name.size() + 1);
+
+  ssize_t bytes = 0x100;
+  offset = symtab_offset + 0x100;
+  if (init_gnu_debugdata) {
+    // Read in the compressed elf data and copy it in.
+    name = "tests/files/";
+    if (elf_class == ELFCLASS32) {
+      name += "elf32.xz";
+    } else {
+      name += "elf64.xz";
+    }
+    int fd = TEMP_FAILURE_RETRY(open(name.c_str(), O_RDONLY));
+    ASSERT_NE(-1, fd) << "Cannot open " + name;
+    // Assumes the file is less than 1024 bytes.
+    std::vector<uint8_t> buf(1024);
+    bytes = TEMP_FAILURE_RETRY(read(fd, buf.data(), buf.size()));
+    ASSERT_GT(bytes, 0);
+    // Make sure the file isn't too big.
+    ASSERT_NE(static_cast<size_t>(bytes), buf.size())
+        << "File " + name + " is too big, increase buffer size.";
+    close(fd);
+    buf.resize(bytes);
+    copy_func(offset, buf.data(), buf.size());
+  }
+
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_type = SHT_PROGBITS;
+  shdr.sh_name = symname_offset - symtab_offset;
+  shdr.sh_addr = offset;
+  shdr.sh_offset = offset;
+  shdr.sh_size = bytes;
+  copy_func(gnu_offset, &shdr, sizeof(shdr));
+}
+
+template void TestInitEhdr<Elf32_Ehdr>(Elf32_Ehdr*, uint32_t, uint32_t);
+template void TestInitEhdr<Elf64_Ehdr>(Elf64_Ehdr*, uint32_t, uint32_t);
+
+template void TestInitGnuDebugdata<Elf32_Ehdr, Elf32_Shdr>(uint32_t, uint32_t, bool,
+                                                           TestCopyFuncType);
+template void TestInitGnuDebugdata<Elf64_Ehdr, Elf64_Shdr>(uint32_t, uint32_t, bool,
+                                                           TestCopyFuncType);