Add .gnu_debugdata support.

Update the unwind_info tool to dump all of the sections.

Bug: 23762183

Test: Passes new unit tests.
Change-Id: I8b223bc208a1a2ef06ed333e6d96943c8f273681
diff --git a/libunwindstack/tests/GenGnuDebugdata.cpp b/libunwindstack/tests/GenGnuDebugdata.cpp
new file mode 100644
index 0000000..2644582
--- /dev/null
+++ b/libunwindstack/tests/GenGnuDebugdata.cpp
@@ -0,0 +1,112 @@
+/*
+ * 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 <stdint.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include <string>
+
+#if !defined(EM_AARCH64)
+#define EM_AARCH64 183
+#endif
+
+template <typename Ehdr>
+void InitEhdr(Ehdr* ehdr, uint32_t elf_class, uint32_t machine) {
+  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;
+  ehdr->e_version = EV_CURRENT;
+  ehdr->e_ehsize = sizeof(Ehdr);
+}
+
+template <typename Ehdr, typename Shdr>
+void GenElf(Ehdr* ehdr, int fd) {
+  uint64_t offset = sizeof(Ehdr);
+  ehdr->e_shoff = offset;
+  ehdr->e_shnum = 3;
+  ehdr->e_shentsize = sizeof(Shdr);
+  ehdr->e_shstrndx = 2;
+  TEMP_FAILURE_RETRY(write(fd, ehdr, sizeof(Ehdr)));
+
+  Shdr shdr;
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_name = 0;
+  shdr.sh_type = SHT_NULL;
+  TEMP_FAILURE_RETRY(write(fd, &shdr, sizeof(Shdr)));
+  offset += ehdr->e_shentsize;
+
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_type = SHT_PROGBITS;
+  shdr.sh_name = 11;
+  shdr.sh_addr = 0x5000;
+  shdr.sh_offset = 0x5000;
+  shdr.sh_entsize = 0x100;
+  shdr.sh_size = 0x800;
+  TEMP_FAILURE_RETRY(write(fd, &shdr, sizeof(Shdr)));
+  offset += ehdr->e_shentsize;
+
+  memset(&shdr, 0, sizeof(shdr));
+  shdr.sh_type = SHT_STRTAB;
+  shdr.sh_name = 1;
+  shdr.sh_offset = 0x200;
+  shdr.sh_size = 24;
+  TEMP_FAILURE_RETRY(write(fd, &shdr, sizeof(Shdr)));
+
+  // Write out the name entries information.
+  lseek(fd, 0x200, SEEK_SET);
+  std::string name;
+  TEMP_FAILURE_RETRY(write(fd, name.data(), name.size() + 1));
+  name = ".shstrtab";
+  TEMP_FAILURE_RETRY(write(fd, name.data(), name.size() + 1));
+  name = ".debug_frame";
+  TEMP_FAILURE_RETRY(write(fd, name.data(), name.size() + 1));
+}
+
+int main() {
+  int elf32_fd = TEMP_FAILURE_RETRY(open("elf32", O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0644));
+  if (elf32_fd == -1) {
+    printf("Failed to create elf32: %s\n", strerror(errno));
+    return 1;
+  }
+
+  int elf64_fd = TEMP_FAILURE_RETRY(open("elf64", O_RDWR | O_CREAT | O_TRUNC | O_CLOEXEC, 0644));
+  if (elf64_fd == -1) {
+    printf("Failed to create elf64: %s\n", strerror(errno));
+    return 1;
+  }
+
+  Elf32_Ehdr ehdr32;
+  InitEhdr<Elf32_Ehdr>(&ehdr32, ELFCLASS32, EM_ARM);
+  GenElf<Elf32_Ehdr, Elf32_Shdr>(&ehdr32, elf32_fd);
+  close(elf32_fd);
+
+  Elf64_Ehdr ehdr64;
+  InitEhdr<Elf64_Ehdr>(&ehdr64, ELFCLASS64, EM_AARCH64);
+  GenElf<Elf64_Ehdr, Elf64_Shdr>(&ehdr64, elf64_fd);
+  close(elf64_fd);
+}