update_engine: Migrate build system to gyp.

This change migrates the SConstruct file to the platform2 gyp
infrastructure without changing the way UE is compiled. The
code is still compiled as a single static library shared
between delta_generator, update_engine and update_engine_client.

This patch adds two generic .gypi rules to generate bindings for
DBus glib and public keys using openssl.

update_engine_unittests requires to run the openssl version from the
board and not the one on the host. This changes does that by using
SYSROOT when possible.

delta_generator is built without -pie to avoid a bug on how it
is run from au-generator.zip.

BUG=chromium:393293,chromium:394241
TEST=emerge-link update_engine; sudo emerge update_engine
TEST=cros_workon_make --reconf --test update_engine
TEST=cbuildbot link-release amd64-generic-full x86-generic-full
CQ-DEPEND=CL:Id81c7dca798ac8003252259eed03a12a60054437

Change-Id: Icc5e24ac202e552275cd197ee0b9a4a3d9b4a47c
Reviewed-on: https://chromium-review.googlesource.com/208487
Tested-by: Alex Deymo <deymo@chromium.org>
Reviewed-by: Bertrand Simonnet <bsimonnet@chromium.org>
Commit-Queue: Alex Deymo <deymo@chromium.org>

1 files changed, 21 insertions, 0 deletions

diff --git a/utils.cc b/utils.cc
index f78861ae..1235a6b4 100644
--- a/utils.cc
+++ b/utils.cc
@@ -669,6 +669,27 @@ bool GetFilesystemSizeFromFD(int fd,
   return true;
 }
 
+string GetPathOnBoard(const string& command) {
+  int return_code = 0;
+  string command_path;
+  // TODO(deymo): prepend SYSROOT to each PATH instead of the result.
+  if (!Subprocess::SynchronousExec(
+      {"which", command}, &return_code, &command_path)) {
+    return command;
+  }
+  if (return_code != 0)
+    return command;
+
+  base::TrimWhitespaceASCII(command_path, base::TRIM_ALL, &command_path);
+  const char* env_sysroot = getenv("SYSROOT");
+  if (env_sysroot) {
+    string sysroot_command_path = env_sysroot + command_path;
+    if (utils::FileExists(sysroot_command_path.c_str()))
+      return sysroot_command_path;
+  }
+  return command_path;
+}
+
 // Tries to parse the header of an ELF file to obtain a human-readable
 // description of it on the |output| string.
 static bool GetFileFormatELF(const char* buffer, size_t size, string* output) {