[v7,4/5] gdb: extend the [[N]]::foo syntax for files

Message ID 20260601192251.60958-5-guinevere@redhat.com
State New
Headers
Series Introduce syntax for linker-namespace specific symbols |

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Commit Message

Guinevere Larsen June 1, 2026, 7:22 p.m. UTC
  This commit implements the missing support for [[N]]::'file.c'::var
syntax that was skipped on the previous commit.  This is done with a new
rule, 'block: block COLONCOLON FILENAME', a few changes to
classify_name and adding a value to the parser_state.

classify_name now restricts its search for files to ones available in
the provided linker namespace (if there was one), which is found in the
parser_state.  To explain why the search has to be restricted, imagine
the following scenario: An inferior has 2 linker namespaces. In
namespace 0, there is a library with the file 'foo' loaded; in namespace
1, there is a function 'foo', which is in the stack.  If the user were to
type [[1]]::foo::var, it could be possible that foo is mis-classified as
a filename, then when executing the rule 'block: block COLONCOLON FILENAME'
we search for the file with the filename restriction and error out because
there are no files named that.  Therefore, the safest way to ensure we're
always classifying things correctly is to use the linker namespace in the
classify_name function.  And the reason the linker namespace must be in
the parser_state is because, while running classify_name, we don't have
access to the previous states to see if there was a LINKER_NAMESPACE
token, so adding it to the global state is the only way to pass it
along.

The new rule only exists to make sure that it is only used in the
intended syntax, instead of allowing for something like
function::filename::variable.

This commit also adds a link to the solib_ops relevant
to the expression being parsed, as a way to identify if linker
namespaces are supported; this could be achieved by guarding the search
functions instead, but I think that this is more reliable.

The new rule uses "block" rather than a linker namespace specific token,
because if we allowed that token to also reduce into block, the new rule
would never be triggered as the simple reduction would be preferred. If
we didn't allow the linker namespace to reduce into block, the rest of
the syntaxes for [[N]]::foo would be more involved, so the option in
this commit seemed like the simplest solution.

The rule "block: block COLONCOLON name" also had to be updated because,
if a user tried to search for a file not present in the linker
namespace, GDB would miscategorize it to 'name' instead of 'filename',
and if no function of the same name was found, the error would only say
"No function \"foo\" (...)" which could confuse a user. The new error
says "Nothing named \"foo\" (...)" instead since it is impossible for us
to disambiguate between filename or function name, and both would be
valid in this code path.

The parser_state changes were not used for the previous commit because
the lookup_symbol calls would lead to an even more intrusive change for
no real gain, since the search would be rerun any way. There is an
argument to be made that the results could be different if only
namespace had a type and another had a variable, but a situation where
that significantly changes the result is quite unlikely, I think.
---
 gdb/c-exp.y                                  | 23 ++++++++++--
 gdb/linespec.c                               |  4 +--
 gdb/parse.c                                  |  3 +-
 gdb/parser-defs.h                            | 37 ++++++++++++++++++--
 gdb/rust-parse.c                             |  3 +-
 gdb/symtab.c                                 | 37 +++++++++++++-------
 gdb/symtab.h                                 |  4 ++-
 gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c |  2 ++
 gdb/testsuite/gdb.base/dlmopen-ns-ids.exp    | 21 +++++++++++
 9 files changed, 112 insertions(+), 22 deletions(-)
  

Patch

diff --git a/gdb/c-exp.y b/gdb/c-exp.y
index 8e405e4dc41..f152b1d53f0 100644
--- a/gdb/c-exp.y
+++ b/gdb/c-exp.y
@@ -1064,15 +1064,18 @@  block	:	BLOCKNAME
 				   copy_name ($1.stoken).c_str ());
 			  $$.search_namespace = false;
 			  $$.b_val = $1.sym.symbol->value_block ();
+			  pstate->reset_linker_namespace ();
 			}
 	|	FILENAME
 			{
 			  $$ = $1;
+			  pstate->reset_linker_namespace ();
 			}
 	|	DOUBLESQUAREOPEN INT DOUBLESQUARECLOSE
 			{
 			  $$.search_namespace = true;
 			  $$.namespace_val = $2.val;
+			  pstate->set_linker_namespace ($2.val);
 			}
 	;
 
@@ -1089,12 +1092,26 @@  block	:	block COLONCOLON name
 						 SEARCH_FUNCTION_DOMAIN,
 						 nullptr);
 
-			  if (tem.symbol == nullptr)
+			  if (tem.symbol == nullptr && !$1.search_namespace)
 			    error (_("No function \"%ps\" in specified context."),
 				   styled_string (function_name_style.style (),
 						  copy.c_str ()));
+			  else if (tem.symbol == nullptr && $1.search_namespace)
+			    /* COPY can be a function or a file.  There is no way
+			       to identify which the user intended, so emit a
+			       generic warning instead.  */
+			    error (_("Nothing named \"%s\" in specified context."),
+				   copy.c_str ());
 			  $$.b_val = tem.symbol->value_block ();
 			  $$.search_namespace = false;
+			  pstate->reset_linker_namespace ();
+			}
+	|	block COLONCOLON FILENAME
+			{
+			    if (!$1.search_namespace)
+				error (_("Filename must be the first part of the expression"));
+			    $$ = $3;
+			  pstate->reset_linker_namespace ();
 			}
 	;
 
@@ -1131,6 +1148,7 @@  variable:	block COLONCOLON name
 			    pstate->block_tracker->update (sym);
 
 			  pstate->push_new<var_value_operation> (sym);
+			  pstate->reset_linker_namespace ();
 			}
 	;
 
@@ -3207,7 +3225,8 @@  classify_name (struct parser_state *par_state, const struct block *block,
 	  || is_quoted_name)
 	{
 	  /* See if it's a file name. */
-	  if (auto symtab = lookup_symtab (current_program_space, copy.c_str ());
+	  if (auto symtab = lookup_symtab (current_program_space, copy.c_str (),
+					   par_state->get_linker_namespace ());
 	      symtab != nullptr)
 	    {
 	      yylval.bval.b_val
diff --git a/gdb/linespec.c b/gdb/linespec.c
index 5371d8426ae..38a30f04f77 100644
--- a/gdb/linespec.c
+++ b/gdb/linespec.c
@@ -3628,11 +3628,11 @@  collect_symtabs_from_filename (const char *file,
 	  if (pspace->executing_startup)
 	    continue;
 
-	  for_each_symtab (pspace, file, collector);
+	  for_each_symtab (pspace, file, -1, collector);
 	}
     }
   else
-    for_each_symtab (search_pspace, file, collector);
+    for_each_symtab (search_pspace, file, -1, collector);
 
   /* It is tempting to use the unordered_dense 'extract' method here,
      and remove the separate vector -- but it's unclear if ordering
diff --git a/gdb/parse.c b/gdb/parse.c
index fd190d6e15e..2ed52d689a1 100644
--- a/gdb/parse.c
+++ b/gdb/parse.c
@@ -426,7 +426,8 @@  parse_exp_in_context (const char **stringptr, CORE_ADDR pc,
 
   parser_state ps (lang, get_current_arch (), expression_context_block,
 		   expression_context_pc, flags, *stringptr,
-		   completer != nullptr, tracker);
+		   completer != nullptr, tracker,
+		   current_program_space->solib_ops ());
 
   scoped_restore_current_language lang_saver (lang->la_language);
 
diff --git a/gdb/parser-defs.h b/gdb/parser-defs.h
index a424f0c7b6f..299fd2b74af 100644
--- a/gdb/parser-defs.h
+++ b/gdb/parser-defs.h
@@ -26,6 +26,7 @@ 
 #include "expression.h"
 #include "symtab.h"
 #include "expop.h"
+#include "solib.h"
 
 struct block;
 struct language_defn;
@@ -147,7 +148,8 @@  struct parser_state : public expr_builder
 		parser_flags flags,
 		const char *input,
 		bool completion,
-		innermost_block_tracker *tracker)
+		innermost_block_tracker *tracker,
+		const solib_ops *ops)
     : expr_builder (lang, gdbarch),
       expression_context_block (context_block),
       expression_context_pc (context_pc),
@@ -157,7 +159,8 @@  struct parser_state : public expr_builder
       comma_terminates ((flags & PARSER_COMMA_TERMINATES) != 0),
       parse_completion (completion),
       void_context_p ((flags & PARSER_VOID_CONTEXT) != 0),
-      debug ((flags & PARSER_DEBUG) != 0)
+      debug ((flags & PARSER_DEBUG) != 0),
+      m_solib_ops (ops)
   {
   }
 
@@ -267,6 +270,26 @@  struct parser_state : public expr_builder
     push (expr::make_operation<T> (std::move (lhs), std::move (rhs)));
   }
 
+  void set_linker_namespace (LONGEST ns_id)
+  {
+    if (m_solib_ops == nullptr)
+      error (_("Linker namespaces require an active inferior"));
+    if (m_solib_ops->supports_namespaces ())
+      m_linker_namespace = ns_id;
+    else
+      error (_("Linker namespaces are not supported"));
+  }
+
+  void reset_linker_namespace ()
+  {
+    m_linker_namespace = -1;
+  }
+
+  LONGEST get_linker_namespace () const
+  {
+    return m_linker_namespace;
+  }
+
   /* Function called from the various parsers' yyerror functions to throw
      an error.  The error will include a message identifying the location
      of the error within the current expression.  */
@@ -327,6 +350,16 @@  struct parser_state : public expr_builder
 
   /* Stack of operations.  */
   std::vector<expr::operation_up> m_operations;
+
+  /* If the expression is being restricted to a specific namespace, this is
+     where that information is stored for the block lookup.  It should be
+     accessed through setter/getters to ensure that the linker namespace is
+     only set when the gdbarch supports it.  */
+  LONGEST m_linker_namespace = -1;
+
+  /* Used to figure out if an inferior is capable of handling linker
+     namespaces at all.  */
+  const solib_ops *m_solib_ops;
 };
 
 /* A string token, either a char-string or bit-string.  Char-strings are
diff --git a/gdb/rust-parse.c b/gdb/rust-parse.c
index 0c4f2a501ab..728fc88842b 100644
--- a/gdb/rust-parse.c
+++ b/gdb/rust-parse.c
@@ -2305,7 +2305,8 @@  rust_lex_tests (void)
 {
   /* Set up dummy "parser", so that rust_type works.  */
   parser_state ps (language_def (language_rust), current_inferior ()->arch (),
-		   nullptr, 0, 0, nullptr, 0, nullptr);
+		   nullptr, 0, 0, nullptr, 0, nullptr,
+		   current_program_space->solib_ops ());
   rust_parser parser (&ps);
 
   rust_lex_test_one (&parser, "", 0);
diff --git a/gdb/symtab.c b/gdb/symtab.c
index 5eab8ad600a..d7317a758b1 100644
--- a/gdb/symtab.c
+++ b/gdb/symtab.c
@@ -630,14 +630,11 @@  compare_filenames_for_search (const char *filename, const char *search_name)
 	      && STRIP_DRIVE_SPEC (filename) == &filename[len - search_len]));
 }
 
-/* Return the first symtab in PSPACE matching NAME and for which
-   CALLBACK returns true.
-
-   See documentation for for_each_symtab for how exactly NAME is matched.  */
+/* See symtab.h.  */
 
 static symtab *
 find_symtab (program_space *pspace, const char *name,
-	     find_symtab_callback_ftype callback)
+	     LONGEST linker_ns, find_symtab_callback_ftype callback)
 {
   gdb::unique_xmalloc_ptr<char> real_path;
 
@@ -649,10 +646,23 @@  find_symtab (program_space *pspace, const char *name,
       gdb_assert (IS_ABSOLUTE_PATH (real_path.get ()));
     }
 
-  for (objfile &objfile : pspace->objfiles ())
+  std::vector<objfile *> objfiles_to_search;
+  if (linker_ns >= 0)
+    {
+      gdb_assert (pspace->solib_ops ()->supports_namespaces ());
+      objfiles_to_search
+	= get_objfiles_in_linker_namespace (linker_ns, pspace);
+    }
+  else
+    {
+      for (objfile &objf : pspace->objfiles ())
+	objfiles_to_search.push_back (&objf);
+    }
+
+  for (objfile *objfile : objfiles_to_search)
     if (symtab *result
-	  = objfile.find_symtab_matching_filename (name, real_path.get (),
-						   callback);
+	  = objfile->find_symtab_matching_filename (name, real_path.get (),
+						    callback);
 	result != nullptr)
       return result;
 
@@ -663,9 +673,9 @@  find_symtab (program_space *pspace, const char *name,
 
 void
 for_each_symtab (program_space *pspace, const char *name,
-		 for_each_symtab_callback_ftype callback)
+		 LONGEST linker_ns, for_each_symtab_callback_ftype callback)
 {
-  find_symtab (pspace, name, [&] (symtab *symtab)
+  find_symtab (pspace, name, linker_ns, [&] (symtab *symtab)
 	       {
 		 callback (symtab);
 		 return false;
@@ -675,9 +685,10 @@  for_each_symtab (program_space *pspace, const char *name,
 /* See symtab.h.  */
 
 symtab *
-lookup_symtab (program_space *pspace, const char *name)
+lookup_symtab (program_space *pspace, const char *name, LONGEST linker_ns)
 {
-  return find_symtab (pspace, name, [&] (symtab *symtab) { return true; });
+  return find_symtab (pspace, name, linker_ns,
+		      [&] (symtab *symtab) { return true; });
 }
 
 
@@ -6192,7 +6203,7 @@  collect_file_symbol_completion_matches (completion_tracker &tracker,
 
   /* Go through symtabs for SRCFILE and check the externs and statics
      for symbols which match.  */
-  for_each_symtab (current_program_space, srcfile, [&] (symtab *s)
+  for_each_symtab (current_program_space, srcfile, -1, [&] (symtab *s)
     {
       add_symtab_completions (s->compunit (),
 			      tracker, mode, lookup_name,
diff --git a/gdb/symtab.h b/gdb/symtab.h
index 3feac5fcf6c..f73aedd9c02 100644
--- a/gdb/symtab.h
+++ b/gdb/symtab.h
@@ -2074,7 +2074,8 @@  const char *multiple_symbols_select_mode (void);
 
 /* Lookup a symbol table in PSPACE by source file name.  */
 
-extern symtab *lookup_symtab (program_space *pspace, const char *name);
+extern symtab *lookup_symtab (program_space *pspace, const char *name,
+			      LONGEST linker_ns = -1);
 
 /* An object of this type is passed as the 'is_a_field_of_this'
    argument to lookup_symbol and lookup_symbol_in_language.  */
@@ -2806,6 +2807,7 @@  using for_each_symtab_callback_ftype = std::function<void (symtab *)>;
    Call CALLBACK with each symtab that is found.  */
 
 void for_each_symtab (program_space *pspace, const char *name,
+		      LONGEST linker_ns,
 		      for_each_symtab_callback_ftype callback);
 
 /* Callback type for function find_symtab.  */
diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c
index 02b2bbe6417..35c5124a65e 100644
--- a/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c
+++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids-main.c
@@ -24,6 +24,8 @@ 
 #include <unistd.h>
 #include <stdio.h>
 
+int global_main_file = 1312;
+
 int
 main (void)
 {
diff --git a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
index 72b92304325..78daed4518e 100644
--- a/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
+++ b/gdb/testsuite/gdb.base/dlmopen-ns-ids.exp
@@ -321,9 +321,15 @@  proc_with_prefix test_print_namespace_symbol {} {
     clean_restart
     gdb_load $::binfile
 
+    set ns0 [ns_id_for_command 0]
     set ns1 [ns_id_for_command 1]
     set ns2 [ns_id_for_command 2]
 
+    # Test printing variables before starting the inferior
+    gdb_test "print ${ns1}::gdb_dlmopen_glob" \
+	"Linker namespaces require an active inferior" \
+	"Before starting inferior"
+
     if { ![runto_main] } {
 	return
     }
@@ -355,12 +361,27 @@  proc_with_prefix test_print_namespace_symbol {} {
     gdb_test "print ${ns2}::func_with_other_call::n" \
 	"No frame is currently executing in block func_with_other_call."
 
+    # Test that complex expressions work with multiple namespaces.
+    # At this point, the global in namespace 1 is 0, and in namespace 2 is 1
+    # and the current namespace is 1.
+    gdb_test "print ${ns2}::gdb_dlmopen_glob + gdb_dlmopen_glob" ".* = 1"
+    gdb_test "print ${ns2}::'${::srcfile_lib}'::gdb_dlmopen_glob + gdb_dlmopen_glob" \
+	".* = 1"
+    gdb_test "print ${ns2}::'${::srcfile_lib}'::gdb_dlmopen_glob + '${::srcfile}'::global_main_file" \
+	".* = 1312"
+
     # Leave to default namespace.
     gdb_continue_to_breakpoint "TAG: first dlclose"
     # This global doesn't exist in the default namespace.  Rather than
     # returning a random one, we just say we didn't find one.
     gdb_test "print gdb_dlmopen_glob" \
 	"No symbol .gdb_dlmopen_glob. in the current linker namespace."
+
+    # Minimal testing for finding files in namespaces.
+    gdb_test "print ${ns1}::'${::srcfile_lib}'::gdb_dlmopen_glob" \
+	".* = 2"
+    gdb_test "print ${ns0}::'${::srcfile_lib}'::gdb_dlmopen_glob" \
+	"Nothing named .${::srcfile_lib}. in specified context."
 }
 
 test_info_shared