Fork of the Android NDK crazy linker.

third_party/android_crazy_linker/src/src/crazy_linker_elf_view.cpp

Index: third_party/android_crazy_linker/src/src/crazy_linker_elf_view.cpp
diff --git a/third_party/android_crazy_linker/src/src/crazy_linker_elf_view.cpp b/third_party/android_crazy_linker/src/src/crazy_linker_elf_view.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..65ec2818533860d0ab2d8f605ef070f99ba96722
--- /dev/null
+++ b/third_party/android_crazy_linker/src/src/crazy_linker_elf_view.cpp
@@ -0,0 +1,121 @@
+#include "crazy_linker_elf_view.h"
+
+#include <errno.h>
+
+#include "crazy_linker_debug.h"
+#include "crazy_linker_error.h"
+#include "linker_phdr.h"
+
+namespace crazy {
+
+bool ElfView::InitUnmapped(size_t load_address,
+                           const ELF::Phdr* phdr,
+                           size_t phdr_count,
+                           Error* error) {
+  // Compute load size and bias.
+  size_t min_vaddr = 0;
+  load_size_ = phdr_table_get_load_size(phdr, phdr_count, &min_vaddr, NULL);
+  if (load_size_ == 0) {
+    *error = "Invalid program header table";
+    return false;
+  }
+  load_address_ = (load_address ? load_address : min_vaddr);
+  load_bias_ = load_address - min_vaddr;
+
+  // Extract the dynamic table information.
+  phdr_table_get_dynamic_section(phdr,
+                                 phdr_count,
+                                 load_address,
+                                 &dynamic_,
+                                 &dynamic_count_,
+                                 &dynamic_flags_);
+  if (!dynamic_) {
+    *error = "No PT_DYNAMIC section!";
+    return false;
+  }
+
+  // Compute the program header table address relative to load_address.
+  // This is different from |phdr|..|phdr + phdr_count| which can actually
+  // be at a different location.
+  const ELF::Phdr* phdr0 = NULL;
+
+  // First, if there is a PT_PHDR, use it directly.
+  for (size_t n = 0; n < phdr_count; ++n) {
+    const ELF::Phdr* entry = &phdr[n];
+    if (entry->p_type == PT_PHDR) {
+      phdr0 = entry;
+      break;
+    }
+  }
+
+  // Otherwise, check the first loadable segment. If its file offset
+  // is 0, it starts with the ELF header, and we can trivially find the
+  // loaded program header from it.
+  if (!phdr0) {
+    for (size_t n = 0; n < phdr_count; ++n) {
+      const ELF::Phdr* entry = &phdr[n];
+      if (entry->p_type == PT_LOAD) {
+        if (entry->p_offset == 0) {
+          ELF::Addr elf_addr = load_bias_ + entry->p_vaddr;
+          const ELF::Ehdr* ehdr = reinterpret_cast<const ELF::Ehdr*>(elf_addr);
+          ELF::Addr offset = ehdr->e_phoff;
+          phdr0 = reinterpret_cast<const ELF::Phdr*>(elf_addr + offset);
+        }
+        break;
+      }
+    }
+  }
+
+  // Check that the program header table is indeed in a loadable segment,
+  // this helps catching malformed ELF binaries.
+  if (phdr0) {
+    ELF::Addr phdr0_addr = reinterpret_cast<ELF::Addr>(phdr0);
+    ELF::Addr phdr0_limit = phdr0_addr + sizeof(ELF::Phdr) * phdr_count;
+    bool found = false;
+    for (size_t n = 0; n < phdr_count; ++n) {
+      size_t seg_start = load_bias_ + phdr[n].p_vaddr;
+      size_t seg_end = seg_start + phdr[n].p_filesz;
+
+      if (seg_start <= phdr0_addr && phdr0_limit <= seg_end) {
+        found = true;
+        break;
+      }
+    }
+
+    if (!found)
+      phdr0 = NULL;
+  }
+
+  if (!phdr0) {
+    *error = "Malformed ELF binary";
+    return false;
+  }
+
+  phdr_ = phdr0;
+  phdr_count_ = phdr_count;
+
+  LOG("%s: New ELF view [load_address:%p, load_size:%p, load_bias:%p, phdr:%p, "
+      "phdr_count:%d, dynamic:%p, dynamic_count:%d, dynamic_flags:%d",
+      __FUNCTION__,
+      load_address_,
+      load_size_,
+      load_bias_,
+      phdr_,
+      phdr_count_,
+      dynamic_,
+      dynamic_count_,
+      dynamic_flags_);
+  return true;
+}
+
+bool ElfView::ProtectRelroSection(Error* error) {
+  LOG("%s: Enabling GNU RELRO protection\n", __FUNCTION__);
+
+  if (phdr_table_protect_gnu_relro(phdr_, phdr_count_, load_bias_) < 0) {
+    error->Format("Can't enable GNU RELRO protection: %s", strerror(errno));
+    return false;
+  }
+  return true;
+}
+
+}  // namespace crazy