[ELF] Respect --sysroot for INCLUDE

If an included script is under the sysroot directory, when it opens an
absolute path file (`INPUT` or `GROUP`), add sysroot before the absolute
path. When the included script ends, the `isUnderSysroot` state is
restored.

Author: MaskRay

lld/ELF/ScriptLexer.cpp

@@ -27,15 +27,32 @@
 //===----------------------------------------------------------------------===//
 
 #include "ScriptLexer.h"
+#include "Config.h"
 #include "lld/Common/ErrorHandler.h"
 #include "llvm/ADT/Twine.h"
 #include "llvm/Support/ErrorHandling.h"
+#include "llvm/Support/FileSystem.h"
+#include "llvm/Support/Path.h"
 #include <algorithm>
 
 using namespace llvm;
 using namespace lld;
 using namespace lld::elf;
 
+ScriptLexer::Buffer::Buffer(MemoryBufferRef mb)
+    : s(mb.getBuffer()), filename(mb.getBufferIdentifier()),
+      begin(mb.getBufferStart()) {
+  if (config->sysroot == "")
+    return;
+  StringRef path = filename;
+  for (; !path.empty(); path = sys::path::parent_path(path)) {
+    if (!sys::fs::equivalent(config->sysroot, path))
+      continue;
+    isUnderSysroot = true;
+    return;
+  }
+}
+
 ScriptLexer::ScriptLexer(MemoryBufferRef mb) : curBuf(mb), mbs(1, mb) {
   activeFilenames.insert(mb.getBufferIdentifier());
 }

lld/ELF/ScriptLexer.h

@@ -25,10 +25,12 @@ class ScriptLexer {
     StringRef s, filename;
     const char *begin = nullptr;
     size_t lineNumber = 1;
+    // True if the script is opened as an absolute path under the --sysroot
+    // directory.
+    bool isUnderSysroot = false;
+
     Buffer() = default;
-    Buffer(MemoryBufferRef mb)
-        : s(mb.getBuffer()), filename(mb.getBufferIdentifier()),
-          begin(mb.getBufferStart()) {}
+    Buffer(MemoryBufferRef mb);
   };
   // The current buffer and parent buffers due to INCLUDE.
   Buffer curBuf;

lld/ELF/ScriptParser.cpp

@@ -48,16 +48,6 @@ namespace {
 class ScriptParser final : ScriptLexer {
 public:
   ScriptParser(MemoryBufferRef mb) : ScriptLexer(mb) {
-    // Initialize IsUnderSysroot
-    if (config->sysroot == "")
-      return;
-    StringRef path = mb.getBufferIdentifier();
-    for (; !path.empty(); path = sys::path::parent_path(path)) {
-      if (!sys::fs::equivalent(config->sysroot, path))
-        continue;
-      isUnderSysroot = true;
-      return;
-    }
   }
 
   void readLinkerScript();
@@ -135,9 +125,6 @@ class ScriptParser final : ScriptLexer {
   std::pair<SmallVector<SymbolVersion, 0>, SmallVector<SymbolVersion, 0>>
   readSymbols();
 
-  // True if a script being read is in the --sysroot directory.
-  bool isUnderSysroot = false;
-
   // If we are currently parsing a PROVIDE|PROVIDE_HIDDEN command,
   // then this member is set to the PROVIDE symbol name.
   std::optional<llvm::StringRef> activeProvideSym;
@@ -319,7 +306,7 @@ void ScriptParser::readNoCrossRefs(bool to) {
 }
 
 void ScriptParser::addFile(StringRef s) {
-  if (isUnderSysroot && s.starts_with("/")) {
+  if (curBuf.isUnderSysroot && s.starts_with("/")) {
     SmallString<128> pathData;
     StringRef path = (config->sysroot + s).toStringRef(pathData);
     if (sys::fs::exists(path))

lld/test/ELF/linkerscript/group.s

@@ -24,7 +24,8 @@
 # RUN: echo 'GROUP(AS_NEEDED("a.o"))INPUT(/libb.a)' > %t.dir/3a.t
 # RUN: ld.lld 3.t --sysroot=%t.dir
 # RUN: llvm-nm a.out | FileCheck %s
-# RUN: not ld.lld 3i.t --sysroot=%t.dir 2>&1 | FileCheck %s --check-prefix=CANNOT_OPEN -DFILE=/libb.a
+# RUN: ld.lld 3i.t --sysroot=%t.dir
+# RUN: llvm-nm a.out | FileCheck %s
 
 # RUN: echo 'GROUP("%t.dir/4a.t")INPUT(/libb.a)' > 4.t
 # RUN: echo 'GROUP(AS_NEEDED("a.o"))' > %t.dir/4a.t