| Summary: | FAIL: gdb.linespec/explicit.exp: complete after -line: cmd complete "b -line argument " (timeout) | ||
|---|---|---|---|
| Product: | gdb | Reporter: | Tom de Vries <vries> |
| Component: | cli | Assignee: | Not yet assigned to anyone <unassigned> |
| Status: | RESOLVED FIXED | ||
| Severity: | normal | CC: | jan, pedro |
| Priority: | P2 | ||
| Version: | HEAD | ||
| Target Milestone: | --- | ||
| Host: | Target: | ||
| Build: | Last reconfirmed: | ||
The master branch has been updated by Tom de Vries <vries@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=fb7806c7a49d6eb75cdbff183d10d00f75968c0f commit fb7806c7a49d6eb75cdbff183d10d00f75968c0f Author: Tom de Vries <tdevries@suse.de> Date: Tue May 21 16:32:41 2019 +0200 [gdb/cli] Fix use of uninitialized variable in complete_command When building gdb on ubuntu 16.04 with gcc 5.4.0, and running the gdb testsuite we run into: ... FAIL: gdb.linespec/explicit.exp: complete after -line: \ cmd complete "b -line argument " (timeout) ... The failure is reproducible outside the testsuite like this: ... $ gdb -q build/gdb/testsuite/outputs/gdb.linespec/explicit/explicit \ -ex "complete b -line argument" Reading symbols from \ build/gdb/testsuite/outputs/gdb.linespec/explicit/explicit... terminate called after throwing an instance of 'std::length_error' what(): basic_string::_M_create Aborted (core dumped) ... The problem is here in complete_command: ... completion_result result = complete (arg, &word, "e_char); std::string arg_prefix (arg, word - arg); if (result.number_matches != 0) ... The problem is that the word variable is not initialized when result.number_matches == 0, but the variable is still used in the arg_prefix initialization. Fix this by guarding the arg_prefix initialization with the 'result.number_matches != 0' test. Build and tested on x86_64-linux. gdb/ChangeLog: 2019-05-21 Tom de Vries <tdevries@suse.de> PR cli/24587 * cli/cli-cmds.c (complete_command): Fix use of unitialized variable. Patch committed, marking resolved-fixed. Tom,
thanks for taking care of this!
I was actually working on a fix at the moment. In addition to move arg_prefix
into the block, I'd also initialize word properly in complete() as:
--- a/gdb/completer.c
+++ b/gdb/completer.c
@@ -1622,6 +1622,7 @@ complete (const char *line, char const **word, int *quote_char)
completion_tracker tracker_handle_completions;
completion_tracker *tracker;
+ *word = line;
try
{
*word = completion_find_completion_word (tracker_handle_brkchars,
or - elsewise - document that complete may leave word uninitialized in "some cases" (like, result.number_matches == 0). I prefer initializing it.
This initialization alone also fixes the problem.
What do you think? Shall I submit a patch with initialization in complete()?
(In reply to Jan Vrany from comment #3) > Tom, > > thanks for taking care of this! > > I was actually working on a fix at the moment. In addition to move arg_prefix > into the block, I'd also initialize word properly in complete() as: > > --- a/gdb/completer.c > +++ b/gdb/completer.c > @@ -1622,6 +1622,7 @@ complete (const char *line, char const **word, int > *quote_char) > completion_tracker tracker_handle_completions; > completion_tracker *tracker; > > + *word = line; > try > { > *word = completion_find_completion_word (tracker_handle_brkchars, > > or - elsewise - document that complete may leave word uninitialized in "some > cases" (like, result.number_matches == 0). I prefer initializing it. > This initialization alone also fixes the problem. > > What do you think? Shall I submit a patch with initialization in complete()? Hi, I'd say if 'word' can be initialized to something valid, we should do so. The master branch has been updated by Jan Vrany <jv@sourceware.org>: https://sourceware.org/git/gitweb.cgi?p=binutils-gdb.git;h=0ef209f22c24b9243de68c35c576f7111198f915 commit 0ef209f22c24b9243de68c35c576f7111198f915 Author: Jan Vrany <jan.vrany@fit.cvut.cz> Date: Thu May 30 13:04:26 2019 +0100 Initialize variable word in complete The complete function should set parameter word to the end of the word to complete. However, completion_find_completion_word may fail, leaving word uninitialized. To make sure word is always set, initialize it to the completion point which is the end of the line parameter. gdb/Changelog PR cli/24587 * completer.c (complete): Initialize variable word. |
On ubuntu 16.04, I see: ... FAIL: gdb.linespec/explicit.exp: complete after -line: cmd complete "b -line argument " (timeout) FAIL: gdb.linespec/explicit.exp: complete after -line -qualified: tab complete "b -line 10 -qualified " (first tab) (timeout) FAIL: gdb.linespec/explicit.exp: complete after -line -qualified: tab complete "b -line 10 -qualified " (clearing input line) (timeout) ERROR: GDB process no longer exists UNRESOLVED: gdb.linespec/explicit.exp: complete after -line -qualified: cmd complete "b -line 10 -qualified " ERROR: Couldn't send complete b -line 10 -qualified thr to GDB. UNRESOLVED: gdb.linespec/explicit.exp: complete after -line -qualified: cmd complete "b -line 10 -qualified thr" ... To reproduce: ... $ gdb -q /home/vries/gdb/build/gdb/testsuite/outputs/gdb.linespec/explicit/explicit -ex "complete b -line argument" Reading symbols from /home/vries/gdb/build/gdb/testsuite/outputs/gdb.linespec/explicit/explicit... terminate called after throwing an instance of 'std::length_error' what(): basic_string::_M_create Aborted (core dumped) ... With abort backtrace: ... (gdb) bt #0 0x00007ffff6c5c428 in __GI_raise (sig=sig@entry=6) at ../sysdeps/unix/sysv/linux/raise.c:54 #1 0x00007ffff6c5e02a in __GI_abort () at abort.c:89 #2 0x0000000000b0b6ed in __gnu_cxx::__verbose_terminate_handler() () #3 0x0000000000a911e6 in __cxxabiv1::__terminate(void (*)()) () #4 0x0000000000a91231 in std::terminate() () #5 0x0000000000a90449 in __cxa_throw () #6 0x0000000000ab3ecf in std::__throw_length_error(char const*) () #7 0x0000000000acfa69 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_create(unsigned long&, unsigned long) () #8 0x0000000000437819 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::_M_construct<char const*> (this=0x7fffffffd830, __beg=0x7fffffffe1ff "b -line argument", __end=0x800000001 <error: Cannot access memory at address 0x800000001>) at /usr/include/c++/5/bits/basic_string.tcc:223 #9 0x0000000000ad22e5 in std::__cxx11::basic_string<char, std::char_traits<char>, std::allocator<char> >::basic_string(char const*, unsigned long, std::allocator<char> const&) () #10 0x00000000004ea89b in complete_command (arg=0x7fffffffe1ff "b -line argument", from_tty=1) at /home/vries/gdb/src/gdb/cli/cli-cmds.c:251 #11 0x00000000004f1e8c in do_const_cfunc (c=0x13200b0, args=0x7fffffffe1ff "b -line argument", from_tty=1) at /home/vries/gdb/src/gdb/cli/cli-decode.c:106 #12 0x00000000004f505d in cmd_func (cmd=0x13200b0, args=0x7fffffffe1ff "b -line argument", from_tty=1) at /home/vries/gdb/src/gdb/cli/cli-decode.c:1892 #13 0x00000000008a6a6c in execute_command (p=0x7fffffffe1ff "b -line argument", from_tty=1) at /home/vries/gdb/src/gdb/top.c:630 #14 0x000000000071cb66 in catch_command_errors ( command=0x8a660f <execute_command(char const*, int)>, arg=0x7fffffffe1f6 "complete b -line argument", from_tty=1) at /home/vries/gdb/src/gdb/main.c:372 #15 0x000000000071de9b in captured_main_1 (context=0x7fffffffdcb0) ---Type <return> to continue, or q <return> to quit--- at /home/vries/gdb/src/gdb/main.c:1139 #16 0x000000000071dfe3 in captured_main (data=0x7fffffffdcb0) at /home/vries/gdb/src/gdb/main.c:1163 #17 0x000000000071e04e in gdb_main (args=0x7fffffffdcb0) at /home/vries/gdb/src/gdb/main.c:1188 #18 0x000000000040950c in main (argc=5, argv=0x7fffffffddb8) at /home/vries/gdb/src/gdb/gdb.c:32 ... AFAIU, the problem is that variable word is used unitialized in "std::string arg_prefix (arg, word - arg)" in complete_command. Tentative patch: ... diff --git a/gdb/cli/cli-cmds.c b/gdb/cli/cli-cmds.c index 332078b..daf409a 100644 --- a/gdb/cli/cli-cmds.c +++ b/gdb/cli/cli-cmds.c @@ -248,10 +248,10 @@ complete_command (const char *arg, int from_tty) completion_result result = complete (arg, &word, "e_char); - std::string arg_prefix (arg, word - arg); - if (result.number_matches != 0) { + std::string arg_prefix (arg, word - arg); + if (result.number_matches == 1) printf_unfiltered ("%s%s\n", arg_prefix.c_str (), result.match_list[0]); else ...