From b9883d55d8af0c0c7ccc8f7e1f3ee11894b70e93 Mon Sep 17 00:00:00 2001
From: Rui Ueyama <ruiu@google.com>
Date: Tue, 8 Mar 2016 04:06:27 +0000
Subject: [PATCH] ELF: Add /lib and /usr/lib as default search paths.

GNU ld and gold have these paths as default search paths.
If you don't want these directories, pass -nostdlib.

llvm-svn: 262910
---
 lld/ELF/Config.h               |  1 +
 lld/ELF/Driver.cpp             | 12 +++++++++---
 lld/ELF/LinkerScript.cpp       |  4 +++-
 lld/ELF/Options.td             |  3 +++
 lld/test/ELF/Inputs/nostdlib.s |  3 +++
 lld/test/ELF/nostdlib.s        | 16 ++++++++++++++++
 6 files changed, 35 insertions(+), 4 deletions(-)
 create mode 100644 lld/test/ELF/Inputs/nostdlib.s
 create mode 100644 lld/test/ELF/nostdlib.s

diff --git a/lld/ELF/Config.h b/lld/ELF/Config.h
index 847fb81559b3..465fea2303d7 100644
--- a/lld/ELF/Config.h
+++ b/lld/ELF/Config.h
@@ -67,6 +67,7 @@ struct Configuration {
   bool Mips64EL = false;
   bool NoInhibitExec;
   bool NoUndefined;
+  bool Nostdlib;
   bool PrintGcSections;
   bool Relocatable;
   bool Shared;
diff --git a/lld/ELF/Driver.cpp b/lld/ELF/Driver.cpp
index e476d5d91140..78ce191d68c0 100644
--- a/lld/ELF/Driver.cpp
+++ b/lld/ELF/Driver.cpp
@@ -207,9 +207,6 @@ void LinkerDriver::main(ArrayRef<const char *> ArgsArr) {
 
 // Initializes Config members by the command line options.
 void LinkerDriver::readConfigs(opt::InputArgList &Args) {
-  for (auto *Arg : Args.filtered(OPT_L))
-    Config->SearchPaths.push_back(Arg->getValue());
-
   std::vector<StringRef> RPaths;
   for (auto *Arg : Args.filtered(OPT_rpath))
     RPaths.push_back(Arg->getValue());
@@ -237,6 +234,7 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
   Config->ICF = Args.hasArg(OPT_icf);
   Config->NoInhibitExec = Args.hasArg(OPT_noinhibit_exec);
   Config->NoUndefined = Args.hasArg(OPT_no_undefined);
+  Config->Nostdlib = Args.hasArg(OPT_nostdlib);
   Config->PrintGcSections = Args.hasArg(OPT_print_gc_sections);
   Config->Relocatable = Args.hasArg(OPT_relocatable);
   Config->Shared = Args.hasArg(OPT_shared);
@@ -279,6 +277,14 @@ void LinkerDriver::readConfigs(opt::InputArgList &Args) {
 
   for (auto *Arg : Args.filtered(OPT_undefined))
     Config->Undefined.push_back(Arg->getValue());
+
+  if (!Config->Nostdlib) {
+    Config->SearchPaths.push_back("=/lib");
+    Config->SearchPaths.push_back("=/usr/lib");
+  }
+
+  for (auto *Arg : Args.filtered(OPT_L))
+    Config->SearchPaths.push_back(Arg->getValue());
 }
 
 void LinkerDriver::createFiles(opt::InputArgList &Args) {
diff --git a/lld/ELF/LinkerScript.cpp b/lld/ELF/LinkerScript.cpp
index b4580b5fe7c6..f9ab4dbf1ca9 100644
--- a/lld/ELF/LinkerScript.cpp
+++ b/lld/ELF/LinkerScript.cpp
@@ -396,7 +396,9 @@ void ScriptParser::readOutputFormat() {
 
 void ScriptParser::readSearchDir() {
   expect("(");
-  Config->SearchPaths.push_back(next());
+  StringRef Path = next();
+  if (!Config->Nostdlib)
+    Config->SearchPaths.push_back(Path);
   expect(")");
 }
 
diff --git a/lld/ELF/Options.td b/lld/ELF/Options.td
index 99a208080a16..46a81f0f0349 100644
--- a/lld/ELF/Options.td
+++ b/lld/ELF/Options.td
@@ -91,6 +91,9 @@ def noinhibit_exec : Flag<["--"], "noinhibit-exec">,
 def no_undefined : Flag<["--"], "no-undefined">,
   HelpText<"Report unresolved symbols even if the linker is creating a shared library">;
 
+def nostdlib: Flag<["-", "--"], "nostdlib">,
+  HelpText<"Only search directories specified on the command line">;
+
 def o : JoinedOrSeparate<["-"], "o">, MetaVarName<"<path>">,
   HelpText<"Path to file to write output">;
 
diff --git a/lld/test/ELF/Inputs/nostdlib.s b/lld/test/ELF/Inputs/nostdlib.s
new file mode 100644
index 000000000000..db41c9ccd41c
--- /dev/null
+++ b/lld/test/ELF/Inputs/nostdlib.s
@@ -0,0 +1,3 @@
+.globl foo
+foo:
+  ret
diff --git a/lld/test/ELF/nostdlib.s b/lld/test/ELF/nostdlib.s
new file mode 100644
index 000000000000..f2c45dad0b9b
--- /dev/null
+++ b/lld/test/ELF/nostdlib.s
@@ -0,0 +1,16 @@
+# REQUIRES: x86
+
+# RUN: mkdir -p %t.dir/lib
+# RUN: mkdir -p %t.dir/usr/lib
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %s -o %t1.o
+# RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux %p/Inputs/nostdlib.s -o %t2.o
+# RUN: ld.lld -shared -o %t.dir/lib/libfoo.so %t2.o
+# RUN: ld.lld -shared -o %t.dir/usr/lib/libbar.so %t2.o
+# RUN: ld.lld --sysroot=%t.dir -o %t %t1.o -lfoo
+# RUN: ld.lld --sysroot=%t.dir -o %t %t1.o -lbar
+# RUN: not ld.lld --sysroot=%t.dir -nostdlib -o %t %t1.o -lfoo
+# RUN: not ld.lld --sysroot=%t.dir -nostdlib -o %t %t1.o -lbar
+
+.globl _start
+_start:
+  ret