Allow invoking the linker on an executable.

The executable can be inside a zip file using the same syntax used for
shared objects: path.zip!/libentry.so.

The linker currently requires an absolute path. This restriction could be
loosened, but it didn't seem important? If it allowed non-absolute paths,
we'd need to decide how to handle:
 - foo/bar      (relative to CWD?)
 - foo          (search PATH / LD_LIBRARY_PATH, or also relative to CWD?)
 - foo.zip!/bar (normalize_path() requires an absolute path)

The linker adjusts the argc/argv passed to main() and to constructor
functions to hide the initial linker argument, but doesn't adjust the auxv
vector or files like /proc/self/{exe,cmdline,auxv,stat}. Those files will
report that the kernel loaded the linker as an executable.

I think the linker_logger.cpp change guarding against (g_argv == NULL)
isn't actually necessary, but it seemed like a good idea given that I'm
delaying initialization of g_argv until after C++ constructors have run.

Bug: http://b/112050209
Test: bionic unit tests
Change-Id: I846faf98b16fd34218946f6167e8b451897debe5

1 files changed, 2 insertions, 2 deletions

diff --git a/linker/linker_logger.cpp b/linker/linker_logger.cpp
index 4c6603b6a..d0e507218 100644
--- a/linker/linker_logger.cpp
+++ b/linker/linker_logger.cpp
@@ -106,8 +106,8 @@ void LinkerLogger::ResetState() {
   static CachedProperty debug_ld_all("debug.ld.all");
   flags_ |= ParseProperty(debug_ld_all.Get());
 
-  // Ignore processes started without argv (http://b/33276926).
-  if (g_argv[0] == nullptr) {
+  // Safeguard against a NULL g_argv. Ignore processes started without argv (http://b/33276926).
+  if (g_argv == nullptr || g_argv[0] == nullptr) {
     return;
   }