Minidumps never contain MD_LINUX_DSO_DEBUG info when breakpad is in a shared library

A=Mike Hommey <mh@glandium.org>
R=ted at http://breakpad.appspot.com/422002/

git-svn-id: http://google-breakpad.googlecode.com/svn/trunk@1044 4c0a9323-5329-0410-9bdc-e9ce6186880e

1 files changed, 23 insertions, 45 deletions

diff --git a/src/client/linux/minidump_writer/linux_dumper.cc b/src/client/linux/minidump_writer/linux_dumper.cc
index 6e2bbc8b..2124224e 100644
--- a/src/client/linux/minidump_writer/linux_dumper.cc
+++ b/src/client/linux/minidump_writer/linux_dumper.cc
@@ -66,20 +66,24 @@ inline static bool IsMappedFileOpenUnsafe(
 
 namespace google_breakpad {
 
+// All interesting auvx entry types are below AT_SYSINFO_EHDR
+#define AT_MAX AT_SYSINFO_EHDR
+
 LinuxDumper::LinuxDumper(pid_t pid)
     : pid_(pid),
       crash_address_(0),
       crash_signal_(0),
       crash_thread_(0),
       threads_(&allocator_, 8),
-      mappings_(&allocator_) {
+      mappings_(&allocator_),
+      auxv_(&allocator_, AT_MAX + 1) {
 }
 
 LinuxDumper::~LinuxDumper() {
 }
 
 bool LinuxDumper::Init() {
-  return EnumerateThreads() && EnumerateMappings();
+  return ReadAuxv() && EnumerateThreads() && EnumerateMappings();
 }
 
 bool
@@ -131,58 +135,30 @@ LinuxDumper::ElfFileIdentifierForMapping(const MappingInfo& mapping,
   return success;
 }
 
-void*
-LinuxDumper::FindBeginningOfLinuxGateSharedLibrary(pid_t pid) const {
+bool LinuxDumper::ReadAuxv() {
   char auxv_path[NAME_MAX];
-  if (!BuildProcPath(auxv_path, pid, "auxv"))
-    return NULL;
-
-  // Find the AT_SYSINFO_EHDR entry for linux-gate.so
-  // See http://www.trilithium.com/johan/2005/08/linux-gate/ for more
-  // information.
-  int fd = sys_open(auxv_path, O_RDONLY, 0);
-  if (fd < 0) {
-    return NULL;
-  }
-
-  elf_aux_entry one_aux_entry;
-  while (sys_read(fd,
-                  &one_aux_entry,
-                  sizeof(elf_aux_entry)) == sizeof(elf_aux_entry) &&
-         one_aux_entry.a_type != AT_NULL) {
-    if (one_aux_entry.a_type == AT_SYSINFO_EHDR) {
-      sys_close(fd);
-      return reinterpret_cast<void*>(one_aux_entry.a_un.a_val);
-    }
+  if (!BuildProcPath(auxv_path, pid_, "auxv")) {
+    return false;
   }
-  sys_close(fd);
-  return NULL;
-}
-
-void*
-LinuxDumper::FindEntryPoint(pid_t pid) const {
-  char auxv_path[NAME_MAX];
-  if (!BuildProcPath(auxv_path, pid, "auxv"))
-    return NULL;
 
   int fd = sys_open(auxv_path, O_RDONLY, 0);
   if (fd < 0) {
-    return NULL;
+    return false;
   }
 
-  // Find the AT_ENTRY entry
   elf_aux_entry one_aux_entry;
+  bool res = false;
   while (sys_read(fd,
                   &one_aux_entry,
                   sizeof(elf_aux_entry)) == sizeof(elf_aux_entry) &&
          one_aux_entry.a_type != AT_NULL) {
-    if (one_aux_entry.a_type == AT_ENTRY) {
-      sys_close(fd);
-      return reinterpret_cast<void*>(one_aux_entry.a_un.a_val);
+    if (one_aux_entry.a_type <= AT_MAX) {
+      auxv_[one_aux_entry.a_type] = one_aux_entry.a_un.a_val;
+      res = true;
     }
   }
   sys_close(fd);
-  return NULL;
+  return res;
 }
 
 bool LinuxDumper::EnumerateMappings() {
@@ -192,15 +168,17 @@ bool LinuxDumper::EnumerateMappings() {
 
   // linux_gate_loc is the beginning of the kernel's mapping of
   // linux-gate.so in the process.  It doesn't actually show up in the
-  // maps list as a filename, so we use the aux vector to find it's
-  // load location and special case it's entry when creating the list
-  // of mappings.
-  const void* linux_gate_loc;
-  linux_gate_loc = FindBeginningOfLinuxGateSharedLibrary(pid_);
+  // maps list as a filename, but it can be found using the AT_SYSINFO_EHDR
+  // aux vector entry, which gives the information necessary to special
+  // case its entry when creating the list of mappings.
+  // See http://www.trilithium.com/johan/2005/08/linux-gate/ for more
+  // information.
+  const void* linux_gate_loc =
+      reinterpret_cast<void *>(auxv_[AT_SYSINFO_EHDR]);
   // Although the initial executable is usually the first mapping, it's not
   // guaranteed (see http://crosbug.com/25355); therefore, try to use the
   // actual entry point to find the mapping.
-  const void* entry_point_loc = FindEntryPoint(pid_);
+  const void* entry_point_loc = reinterpret_cast<void *>(auxv_[AT_ENTRY]);
 
   const int fd = sys_open(maps_path, O_RDONLY, 0);
   if (fd < 0)