[PATCH] D57987: lld: unquote possibly quoted `EXTERN("symbol")` entry in linker script

[Lucian Adrian Grijincu via Phabricator via llvm-commits]

luciang created this revision.
luciang added a reviewer: ruiu.
Herald added subscribers: llvm-commits, arichardson, emaste.
Herald added a reviewer: espindola.
Herald added a project: LLVM.

`gold` accepts quoted strings:

name=gold/yyscript.y
  252┊ file_cmd:
  253┊           EXTERN '(' extern_name_list ')'
  
  312┊ /* A list of external undefined symbols.  We put the lexer into
  313┊    expression mode so that commas separate names; this is what the GNU
  314┊    linker does.  */
  315┊
  316┊ extern_name_list:
  317┊             { script_push_lex_into_expression_mode(closure); }
  318┊           extern_name_list_body
  319┊             { script_pop_lex_mode(closure); }
  320┊         ;
  321┊
  322┊ extern_name_list_body:
  323┊           string
  324┊             { script_add_extern(closure, $1.value, $1.length); }
  325┊         | extern_name_list_body string
  326┊             { script_add_extern(closure, $2.value, $2.length); }
  327┊         | extern_name_list_body ',' string
  328┊             { script_add_extern(closure, $3.value, $3.length); }
  329┊         ;
  330┊
  
  1123┊ /* A string can be either a STRING or a QUOTED_STRING.  Almost all the
  1124┊    time we don't care, and we use this rule.  */
  1125┊ string:
  1126┊           STRING
  1127┊             { $$ = $1; }
  1128┊         | QUOTED_STRING
  1129┊             { $$ = $1; }
  1130┊         ;

`binutils` requires quoted strings for some kinds of symbols, e.g.:

- it accepts quoted symbols with `@` in name:

  $ echo 'EXTERN("__libc_start_main@@GLIBC_2.2.5")' > a.script
  $ g++ a.script
  /usr/lib/gcc/x86_64-redhat-linux/4.8.5/../../../../lib64/crt1.o: In function `_start':
  (.text+0x20): undefined reference to `main'
  collect2: error: ld returned 1 exit status

- but rejects them if unquoted:

  $ echo 'EXTERN(__libc_start_main@@GLIBC_2.2.5)' > a.script
  $ g++ a.script
  a.script: file not recognized: File format not recognized
  collect2: error: ld returned 1 exit status

To maintain compatibility with existing linker scripts support quoted strings in `lld` as well.


Repository:
  rG LLVM Github Monorepo

https://reviews.llvm.org/D57987

Files:
  lld/ELF/ScriptParser.cpp
  lld/test/ELF/linkerscript/linkerscript.s


Index: lld/test/ELF/linkerscript/linkerscript.s
===================================================================
--- lld/test/ELF/linkerscript/linkerscript.s
+++ lld/test/ELF/linkerscript/linkerscript.s
@@ -3,7 +3,7 @@
 # RUN: llvm-mc -filetype=obj -triple=x86_64-unknown-linux \
 # RUN:   %p/Inputs/libsearch-st.s -o %t2.o
 
-# RUN: echo "EXTERN( undef undef2 )" > %t.script
+# RUN: echo "EXTERN( undef undef2 \"undef3\" \"undef4@@other\")" > %t.script
 # RUN: ld.lld %t -o %t2 %t.script
 # RUN: llvm-readobj %t2 > /dev/null
 
Index: lld/ELF/ScriptParser.cpp
===================================================================
--- lld/ELF/ScriptParser.cpp
+++ lld/ELF/ScriptParser.cpp
@@ -329,7 +329,7 @@
 void ScriptParser::readExtern() {
   expect("(");
   while (!errorCount() && !consume(")"))
-    Config->Undefined.push_back(next());
+    Config->Undefined.push_back(unquote(next()));
 }
 
 void ScriptParser::readGroup() {


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