520596f2eb
When setting a breakpoint on a line in an executable without debug line info,
we run into an abort.
The problem occurs when calling set_default_source_symtab_and_line, which
calls select_source_symtab (0), which is where we try to find the line number
for main:
...
/* Make the default place to list be the function `main'
if one exists. */
block_symbol bsym = lookup_symbol (main_name (), 0, VAR_DOMAIN, 0);
if (bsym.symbol != nullptr && SYMBOL_CLASS (bsym.symbol) == LOC_BLOCK)
{
symtab_and_line sal = find_function_start_sal (bsym.symbol, true);
loc->set (sal.symtab, std::max (sal.line - (lines_to_list - 1), 1));
return;
}
...
However, due to the missing debug line info, find_function_start_sal returns a
sal with sal.symtab == 0:
...
(gdb) p /x sal
$2 = {pspace = 0x1a4a7f0, symtab = 0x0, symbol = 0x1d9e480, section = 0x1d5b398,
msymbol = 0x0, line = 0x0, pc = 0x4004ab, end = 0x0, explicit_pc = 0x0,
explicit_line = 0x0, is_stmt = 0x0, prob = 0x0, objfile = 0x0}
...
which eventually causes an segfault in create_sals_line_offset because
self->default_symtab->filename is accessed while self->default_symtab == NULL.
Fix this by handling sal.symtab == NULL in select_source_symtab.
Tested on x86_64-linux.
gdb/ChangeLog:
2020-10-17 Tom de Vries <tdevries@suse.de>
PR symtab/26317
* source.c (select_source_symtab): Handling sal.symtab == NULL for
symbol main.
gdb/testsuite/ChangeLog:
2020-10-17 Tom de Vries <tdevries@suse.de>
PR symtab/26317
* gdb.dwarf2/dw2-main-no-line-number.exp: New file.
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README for GNU development tools This directory contains various GNU compilers, assemblers, linkers, debuggers, etc., plus their support routines, definitions, and documentation. If you are receiving this as part of a GDB release, see the file gdb/README. If with a binutils release, see binutils/README; if with a libg++ release, see libg++/README, etc. That'll give you info about this package -- supported targets, how to use it, how to report bugs, etc. It is now possible to automatically configure and build a variety of tools with one command. To build all of the tools contained herein, run the ``configure'' script here, e.g.: ./configure make To install them (by default in /usr/local/bin, /usr/local/lib, etc), then do: make install (If the configure script can't determine your type of computer, give it the name as an argument, for instance ``./configure sun4''. You can use the script ``config.sub'' to test whether a name is recognized; if it is, config.sub translates it to a triplet specifying CPU, vendor, and OS.) If you have more than one compiler on your system, it is often best to explicitly set CC in the environment before running configure, and to also set CC when running make. For example (assuming sh/bash/ksh): CC=gcc ./configure make A similar example using csh: setenv CC gcc ./configure make Much of the code and documentation enclosed is copyright by the Free Software Foundation, Inc. See the file COPYING or COPYING.LIB in the various directories, for a description of the GNU General Public License terms under which you can copy the files. REPORTING BUGS: Again, see gdb/README, binutils/README, etc., for info on where and how to report problems.