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From FEDORA_PATCHES Mon Sep 17 00:00:00 2001
From: Kevin Buettner <kevinb@redhat.com>
Date: Thu, 20 Aug 2020 20:52:12 -0700
Subject: gdb-rhbz1869484-deleted-working-directory
;; Backport patches fixing abort when working directory is deleted.
Guard against 'current_directory == NULL' on gdb_abspath (PR gdb/23613)
Ref.: https://bugzilla.redhat.com/show_bug.cgi?id=1728147
Ref.: https://sourceware.org/bugzilla/show_bug.cgi?id=23613
Hi,
This bug has been reported against Fedora GDB, but there's also an
upstream bug. The problem reported is that GDB segfaults when the
working directory is deleted. It's pretty use to reproduce it:
mkdir bla
cd bla
rmdir ../bla
gdb echo
Debugging the problem is a bit tricky, because, since the current
directory doesn't exist anymore, a corefile cannot be saved there.
After a few attempts, I came up with the following:
gdb -ex 'shell mkdir bla' -ex 'cd bla' -ex 'shell rmdir ../bla' -ex 'r echo' ./gdb/gdb
This assumes that you're inside a build directory which contains
./gdb/gdb, of course.
After investigating it, I found that the problem happens at
gdb_abspath, where we're dereferencing 'current_directory' without
checking if it's NULL:
...
(concat (current_directory,
IS_DIR_SEPARATOR (current_directory[strlen (current_directory) - 1])
? "" : SLASH_STRING,
...
So I fixed the problem with the patch below. The idea is that, if
'current_directory' is NULL, then the final string returned should be
just the "path".
After fixing the bug, I found a similar one reported against our
bugzilla: PR gdb/23613. The problem is the same, but the reproducer
is a bit different.
I really tried writing a testcase for this, but unfortunately it's
apparently not possible to start GDB inside a non-existent directory
with DejaGNU.
I regression tested this patch on the BuildBot, and no regressions
were found.
gdb/ChangeLog:
2019-12-14 Sergio Durigan Junior <sergiodj@redhat.com>
https://bugzilla.redhat.com/show_bug.cgi?id=1728147
PR gdb/23613
* bsd-kvm.c (bsd_kvm_target_open): Use 'gdb_abspath'.
* corelow.c: Include 'gdbsupport/pathstuff.h'.
(core_target_open): Use 'gdb_abspath'.
* gdbsupport/pathstuff.c (gdb_abspath): Guard against
'current_directory == NULL' case.
* gdbsupport/pathstuff.h (gdb_abspath): Expand comment and
explain what happens when 'current_directory' is NULL.
* go32-nat.c (go32_nat_target::wait): Check if
'current_directory' is NULL before call to 'chdir'.
* source.c (add_path): Use 'gdb_abspath'.
* top.c: Include 'gdbsupport/pathstuff.h'.
(init_history): Use 'gdb_abspath'.
(set_history_filename): Likewise.
* tracefile-tfile.c: Include 'gdbsupport/pathstuff.h'.
(tfile_target_open): Use 'gdb_abspath'.
Change-Id: Ibb0932fa25bc5c2d3ae4a7f64bd7f32885ca403b
diff --git a/gdb/bsd-kvm.c b/gdb/bsd-kvm.c
--- a/gdb/bsd-kvm.c
+++ b/gdb/bsd-kvm.c
@@ -114,14 +114,13 @@ bsd_kvm_target_open (const char *arg, int from_tty)
if (arg)
{
- char *temp;
-
filename = tilde_expand (arg);
if (filename[0] != '/')
{
- temp = concat (current_directory, "/", filename, (char *)NULL);
+ gdb::unique_xmalloc_ptr<char> temp (gdb_abspath (filename));
+
xfree (filename);
- filename = temp;
+ filename = temp.release ();
}
}
diff --git a/gdb/corelow.c b/gdb/corelow.c
--- a/gdb/corelow.c
+++ b/gdb/corelow.c
@@ -48,6 +48,7 @@
#include "completer.h"
#include "gdbsupport/filestuff.h"
#include "build-id.h"
+#include "gdbsupport/pathstuff.h"
#ifndef O_LARGEFILE
#define O_LARGEFILE 0
@@ -407,8 +408,7 @@ core_target_open (const char *arg, int from_tty)
gdb::unique_xmalloc_ptr<char> filename (tilde_expand (arg));
if (!IS_ABSOLUTE_PATH (filename.get ()))
- filename.reset (concat (current_directory, "/",
- filename.get (), (char *) NULL));
+ filename = gdb_abspath (filename.get ());
flags = O_BINARY | O_LARGEFILE;
if (write_files)
diff --git a/gdb/gdbsupport/pathstuff.c b/gdb/gdbsupport/pathstuff.c
--- a/gdb/gdbsupport/pathstuff.c
+++ b/gdb/gdbsupport/pathstuff.c
@@ -134,7 +134,7 @@ gdb_abspath (const char *path)
if (path[0] == '~')
return gdb_tilde_expand_up (path);
- if (IS_ABSOLUTE_PATH (path))
+ if (IS_ABSOLUTE_PATH (path) || current_directory == NULL)
return make_unique_xstrdup (path);
/* Beware the // my son, the Emacs barfs, the botch that catch... */
diff --git a/gdb/gdbsupport/pathstuff.h b/gdb/gdbsupport/pathstuff.h
--- a/gdb/gdbsupport/pathstuff.h
+++ b/gdb/gdbsupport/pathstuff.h
@@ -44,7 +44,10 @@ extern gdb::unique_xmalloc_ptr<char>
Contrary to "gdb_realpath", this function uses CURRENT_DIRECTORY
for the path expansion. This may lead to scenarios the current
- working directory (CWD) is different than CURRENT_DIRECTORY. */
+ working directory (CWD) is different than CURRENT_DIRECTORY.
+
+ If CURRENT_DIRECTORY is NULL, this function returns a copy of
+ PATH. */
extern gdb::unique_xmalloc_ptr<char> gdb_abspath (const char *path);
diff --git a/gdb/go32-nat.c b/gdb/go32-nat.c
--- a/gdb/go32-nat.c
+++ b/gdb/go32-nat.c
@@ -507,7 +507,8 @@ go32_nat_target::wait (ptid_t ptid, struct target_waitstatus *status,
}
getcwd (child_cwd, sizeof (child_cwd)); /* in case it has changed */
- chdir (current_directory);
+ if (current_directory != NULL)
+ chdir (current_directory);
if (a_tss.tss_irqn == 0x21)
{
diff --git a/gdb/source.c b/gdb/source.c
--- a/gdb/source.c
+++ b/gdb/source.c
@@ -542,8 +542,7 @@ add_path (const char *dirname, char **which_path, int parse_separators)
new_name_holder.reset (concat (name, ".", (char *) NULL));
#endif
else if (!IS_ABSOLUTE_PATH (name) && name[0] != '$')
- new_name_holder.reset (concat (current_directory, SLASH_STRING, name,
- (char *) NULL));
+ new_name_holder = gdb_abspath (name);
else
new_name_holder.reset (savestring (name, p - name));
name = new_name_holder.get ();
diff --git a/gdb/top.c b/gdb/top.c
--- a/gdb/top.c
+++ b/gdb/top.c
@@ -54,6 +54,7 @@
#include "gdb_select.h"
#include "gdbsupport/scope-exit.h"
#include "gdbarch.h"
+#include "gdbsupport/pathstuff.h"
/* readline include files. */
#include "readline/readline.h"
@@ -2020,12 +2021,13 @@ init_history (void)
that was read. */
#ifdef __MSDOS__
/* No leading dots in file names are allowed on MSDOS. */
- history_filename = concat (current_directory, "/_gdb_history",
- (char *)NULL);
+ const char *fname = "_gdb_history";
#else
- history_filename = concat (current_directory, "/.gdb_history",
- (char *)NULL);
+ const char *fname = ".gdb_history";
#endif
+
+ gdb::unique_xmalloc_ptr<char> temp (gdb_abspath (fname));
+ history_filename = temp.release ();
}
read_history (history_filename);
}
@@ -2103,8 +2105,12 @@ set_history_filename (const char *args,
directories the file written will be the same as the one
that was read. */
if (!IS_ABSOLUTE_PATH (history_filename))
- history_filename = reconcat (history_filename, current_directory, "/",
- history_filename, (char *) NULL);
+ {
+ gdb::unique_xmalloc_ptr<char> temp (gdb_abspath (history_filename));
+
+ xfree (history_filename);
+ history_filename = temp.release ();
+ }
}
static void
diff --git a/gdb/tracefile-tfile.c b/gdb/tracefile-tfile.c
--- a/gdb/tracefile-tfile.c
+++ b/gdb/tracefile-tfile.c
@@ -32,6 +32,7 @@
#include "xml-tdesc.h"
#include "target-descriptions.h"
#include "gdbsupport/buffer.h"
+#include "gdbsupport/pathstuff.h"
#include <algorithm>
#ifndef O_LARGEFILE
@@ -470,8 +471,7 @@ tfile_target_open (const char *arg, int from_tty)
gdb::unique_xmalloc_ptr<char> filename (tilde_expand (arg));
if (!IS_ABSOLUTE_PATH (filename.get ()))
- filename.reset (concat (current_directory, "/", filename.get (),
- (char *) NULL));
+ filename = gdb_abspath (filename.get ());
flags = O_BINARY | O_LARGEFILE;
flags |= O_RDONLY;
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