This is the mail archive of the gdb-patches@sourceware.org mailing list for the GDB project.


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]
Other format: [Raw text]

RFC: fix PR symtab/14931


This fixes PR symtab/14931.

The bug is that if the DWARF reader throws an exception, then the entire
objfile is destroyed.  This is bad -- there is no reason to also discard
the minimal symbols in this situation.

This patch fixes the problem by having the DWARF reader intercept
exceptions and reset the state of the objfile on failure.

This patch isn't completely ideal, as it may leave a substantial amount
of memory allocated but unused on failure.  I considered resetting the
objfile's obstack, but this seemed dangerous.  The memory here is not
really leaked, since if the objfile is destroyed it is still correctly
deallocated.

Built and regested on x86-64 Fedora 16.
New test case included.

Tom

2012-12-19  Tom Tromey  <tromey@redhat.com>

	PR symtab/14931:
	* psymtab.c (struct psymtab_state): New.
	(discard_psymtabs_upto, make_cleanup_discard_psymtabs): New
	functions.
	* psympriv.h (make_cleanup_discard_psymtabs): Declare.
	* dwarf2read.c (dwarf2_build_psymtabs): Catch exceptions.

2012-12-19  Tom Tromey  <tromey@redhat.com>

	* gdb.dwarf2/dw2-error.exp: New file.
	* gdb.dwarf2/dw2-error.c: New file.
	* gdb.dwarf2/dw2-error.S: New file.

diff --git a/gdb/dwarf2read.c b/gdb/dwarf2read.c
index beb2ea8..968a6a7 100644
--- a/gdb/dwarf2read.c
+++ b/gdb/dwarf2read.c
@@ -3759,12 +3759,25 @@ dwarf2_initialize_objfile (struct objfile *objfile)
 void
 dwarf2_build_psymtabs (struct objfile *objfile)
 {
+  volatile struct gdb_exception except;
+
   if (objfile->global_psymbols.size == 0 && objfile->static_psymbols.size == 0)
     {
       init_psymbol_list (objfile, 1024);
     }
 
-  dwarf2_build_psymtabs_hard (objfile);
+  TRY_CATCH (except, RETURN_MASK_ERROR)
+    {
+      /* This isn't really ideal: all the data we allocate on the
+	 objfile's obstack is still uselessly kept around.  However,
+	 freeing it seems unsafe.  */
+      struct cleanup *cleanups = make_cleanup_discard_psymtabs (objfile);
+
+      dwarf2_build_psymtabs_hard (objfile);
+      discard_cleanups (cleanups);
+    }
+  if (except.reason < 0)
+    exception_print (gdb_stderr, except);
 }
 
 /* Return the total length of the CU described by HEADER.  */
diff --git a/gdb/psympriv.h b/gdb/psympriv.h
index ec9aa4a..71ba992 100644
--- a/gdb/psympriv.h
+++ b/gdb/psympriv.h
@@ -230,6 +230,8 @@ extern struct partial_symtab *allocate_psymtab (const char *,
 
 extern void discard_psymtab (struct objfile *, struct partial_symtab *);
 
+extern struct cleanup *make_cleanup_discard_psymtabs (struct objfile *);
+
 /* Traverse all psymtabs in one objfile.  */
 
 #define	ALL_OBJFILE_PSYMTABS(objfile, p) \
diff --git a/gdb/psymtab.c b/gdb/psymtab.c
index 027ad38..89c90f7 100644
--- a/gdb/psymtab.c
+++ b/gdb/psymtab.c
@@ -1813,6 +1813,44 @@ discard_psymtab (struct objfile *objfile, struct partial_symtab *pst)
   objfile->free_psymtabs = pst;
 }
 
+/* An object of this type is passed to discard_psymtabs_upto.  */
+
+struct psymtab_state
+{
+  /* The objfile where psymtabs are discarded.  */
+
+  struct objfile *objfile;
+
+  /* The first psymtab to save.  */
+
+  struct partial_symtab *save;
+};
+
+/* A cleanup function used by make_cleanup_discard_psymtabs.  */
+
+static void
+discard_psymtabs_upto (void *arg)
+{
+  struct psymtab_state *state = arg;
+
+  while (state->objfile->psymtabs != state->save)
+    discard_psymtab (state->objfile, state->objfile->psymtabs);
+}
+
+/* Return a new cleanup that discards all psymtabs created in OBJFILE
+   after this function is called.  */
+
+struct cleanup *
+make_cleanup_discard_psymtabs (struct objfile *objfile)
+{
+  struct psymtab_state *state = XNEW (struct psymtab_state);
+
+  state->objfile = objfile;
+  state->save = objfile->psymtabs;
+
+  return make_cleanup_dtor (discard_psymtabs_upto, state, xfree);
+}
+
 
 
 void
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.S b/gdb/testsuite/gdb.dwarf2/dw2-error.S
new file mode 100644
index 0000000..2896645
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-error.S
@@ -0,0 +1,160 @@
+/* Copyright (C) 2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+   This was created using gcc -g -dA dw2-error.c, then hand-editing
+   it to change the DWARF version.
+
+  */
+
+	.file	"dw2-error.c"
+	.text
+.Ltext0:
+	.globl	main
+	.type	main, @function
+main:
+.LFB0:
+	.file 1 "dw2-error.c"
+	# dw2-error.c:19
+	.loc 1 19 0
+	.cfi_startproc
+	# basic block 2
+	pushq	%rbp
+	.cfi_def_cfa_offset 16
+	.cfi_offset 6, -16
+	movq	%rsp, %rbp
+	.cfi_def_cfa_register 6
+	# dw2-error.c:20
+	.loc 1 20 0
+	movl	$23, %eax
+	# dw2-error.c:21
+	.loc 1 21 0
+	popq	%rbp
+	.cfi_def_cfa 7, 8
+	ret
+	.cfi_endproc
+.LFE0:
+	.size	main, .-main
+.Letext0:
+	.section	.debug_info,"",@progbits
+.Ldebug_info0:
+	.long	0x4e	# Length of Compilation Unit Info
+	.value	0x99	# DWARF version number
+	.long	.Ldebug_abbrev0	# Offset Into Abbrev. Section
+	.byte	0x8	# Pointer Size (in bytes)
+	.uleb128 0x1	# (DIE (0xb) DW_TAG_compile_unit)
+	.long	.LASF0	# DW_AT_producer: "GNU C 4.6.3 20120306 (Red Hat 4.6.3-2) -mtune=generic -march=x86-64 -g"
+	.byte	0x1	# DW_AT_language
+	.long	.LASF1	# DW_AT_name: "dw2-error.c"
+	.long	.LASF2	# DW_AT_comp_dir: "/tmp"
+	.quad	.Ltext0	# DW_AT_low_pc
+	.quad	.Letext0	# DW_AT_high_pc
+	.long	.Ldebug_line0	# DW_AT_stmt_list
+	.uleb128 0x2	# (DIE (0x2d) DW_TAG_subprogram)
+			# DW_AT_external
+	.long	.LASF3	# DW_AT_name: "main"
+	.byte	0x1	# DW_AT_decl_file (dw2-error.c)
+	.byte	0x12	# DW_AT_decl_line
+	.long	0x4a	# DW_AT_type
+	.quad	.LFB0	# DW_AT_low_pc
+	.quad	.LFE0	# DW_AT_high_pc
+	.uleb128 0x1	# DW_AT_frame_base
+	.byte	0x9c	# DW_OP_call_frame_cfa
+			# DW_AT_GNU_all_call_sites
+	.uleb128 0x3	# (DIE (0x4a) DW_TAG_base_type)
+	.byte	0x4	# DW_AT_byte_size
+	.byte	0x5	# DW_AT_encoding
+	.ascii "int\0"	# DW_AT_name
+	.byte	0	# end of children of DIE 0xb
+	.section	.debug_abbrev,"",@progbits
+.Ldebug_abbrev0:
+	.uleb128 0x1	# (abbrev code)
+	.uleb128 0x11	# (TAG: DW_TAG_compile_unit)
+	.byte	0x1	# DW_children_yes
+	.uleb128 0x25	# (DW_AT_producer)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x13	# (DW_AT_language)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x1b	# (DW_AT_comp_dir)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x10	# (DW_AT_stmt_list)
+	.uleb128 0x17	# (DW_FORM_sec_offset)
+	.byte	0
+	.byte	0
+	.uleb128 0x2	# (abbrev code)
+	.uleb128 0x2e	# (TAG: DW_TAG_subprogram)
+	.byte	0	# DW_children_no
+	.uleb128 0x3f	# (DW_AT_external)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0xe	# (DW_FORM_strp)
+	.uleb128 0x3a	# (DW_AT_decl_file)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3b	# (DW_AT_decl_line)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x49	# (DW_AT_type)
+	.uleb128 0x13	# (DW_FORM_ref4)
+	.uleb128 0x11	# (DW_AT_low_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x12	# (DW_AT_high_pc)
+	.uleb128 0x1	# (DW_FORM_addr)
+	.uleb128 0x40	# (DW_AT_frame_base)
+	.uleb128 0x18	# (DW_FORM_exprloc)
+	.uleb128 0x2117	# (DW_AT_GNU_all_call_sites)
+	.uleb128 0x19	# (DW_FORM_flag_present)
+	.byte	0
+	.byte	0
+	.uleb128 0x3	# (abbrev code)
+	.uleb128 0x24	# (TAG: DW_TAG_base_type)
+	.byte	0	# DW_children_no
+	.uleb128 0xb	# (DW_AT_byte_size)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3e	# (DW_AT_encoding)
+	.uleb128 0xb	# (DW_FORM_data1)
+	.uleb128 0x3	# (DW_AT_name)
+	.uleb128 0x8	# (DW_FORM_string)
+	.byte	0
+	.byte	0
+	.byte	0
+	.section	.debug_aranges,"",@progbits
+	.long	0x2c	# Length of Address Ranges Info
+	.value	0x2	# DWARF Version
+	.long	.Ldebug_info0	# Offset of Compilation Unit Info
+	.byte	0x8	# Size of Address
+	.byte	0	# Size of Segment Descriptor
+	.value	0	# Pad to 16 byte boundary
+	.value	0
+	.quad	.Ltext0	# Address
+	.quad	.Letext0-.Ltext0	# Length
+	.quad	0
+	.quad	0
+	.section	.debug_line,"",@progbits
+.Ldebug_line0:
+	.section	.debug_str,"MS",@progbits,1
+.LASF0:
+	.string	"GNU C 4.6.3 20120306 (Red Hat 4.6.3-2) -mtune=generic -march=x86-64 -g"
+.LASF2:
+	.string	"/tmp"
+.LASF3:
+	.string	"main"
+.LASF1:
+	.string	"dw2-error.c"
+	.ident	"GCC: (GNU) 4.6.3 20120306 (Red Hat 4.6.3-2)"
+	.section	.note.GNU-stack,"",@progbits
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.c b/gdb/testsuite/gdb.dwarf2/dw2-error.c
new file mode 100644
index 0000000..ddf773c
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-error.c
@@ -0,0 +1,21 @@
+/* This testcase is part of GDB, the GNU debugger.
+
+   Copyright 2012 Free Software Foundation, Inc.
+
+   This program is free software; you can redistribute it and/or modify
+   it under the terms of the GNU General Public License as published by
+   the Free Software Foundation; either version 3 of the License, or
+   (at your option) any later version.
+
+   This program is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */
+
+int main ()
+{
+  return 23;
+}
diff --git a/gdb/testsuite/gdb.dwarf2/dw2-error.exp b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
new file mode 100644
index 0000000..22c7747
--- /dev/null
+++ b/gdb/testsuite/gdb.dwarf2/dw2-error.exp
@@ -0,0 +1,42 @@
+# Copyright 2012 Free Software Foundation, Inc.
+
+# This program is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation; either version 3 of the License, or
+# (at your option) any later version.
+#
+# This program is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with this program.  If not, see <http://www.gnu.org/licenses/>.
+
+load_lib dwarf.exp
+
+# This test can only be run on targets which support DWARF-2 and use gas.
+if {![dwarf2_support]} {
+    return 0  
+}
+
+standard_testfile .S
+
+# We can't use prepare_for_testing here because we need to check the
+# 'file' command's output.
+if {[build_executable $testfile.exp $testfile $srcfile {nodebug}]} {
+    return -1
+}
+
+gdb_exit
+gdb_start
+gdb_reinitialize_dir $srcdir/$subdir
+
+gdb_test_no_output "set breakpoint pending off"
+
+# First test that reading symbols fails.
+gdb_test "file $binfile" \
+    "Reading symbols.*Dwarf Error: wrong version in compilation unit header .is 153, should be 2, 3, or 4.*"
+
+# Now check that we can still break given the minimal symbol.
+gdb_test "break main" "Breakpoint $decimal.*"


Index Nav: [Date Index] [Subject Index] [Author Index] [Thread Index]
Message Nav: [Date Prev] [Date Next] [Thread Prev] [Thread Next]