[PATCH 03/24] Fix TID parser bug

Pedro Alves
2019-05-22T20:53:35Z

I noticed this inconsistency in the error messages below:

(gdb) print --1
Left operand of assignment is not an lvalue.

(gdb) thread apply 1 print --1

Thread 1 (Thread 0x7ffff7fb6740 (LWP 17805)):
inverted range

The "inverted range" error happens because get_number_trailer returns
0 to indicate error, but number_or_range_parser::get_number is not
checking for that. I tried detected the error there, but that doesn't
work because number_of_range_parser is used in places that _do_ want
to legitimately handle 0. IMO we should fix get_number_trailer's
interface or use something else when we want to parse 0 too.

I've decided to fix it in a different way, similarly to how
number_or_range_parser::finished was changed in commit 529c08b25ec7
("Add helper functions parse_flags and parse_flags_qcs").

Seems like a good change, even if we tweaked
number_or_range_parser::get_number, as it simplifies
thread_apply_command and makes them consistent with
number_or_range_parser::finished().

We now get the same error message in both cases:

(gdb) print --1
Left operand of assignment is not an lvalue.

(gdb) thread apply 1 print --1

Thread 1 (Thread 0x7ffff7fb6740 (LWP 17805)):
Left operand of assignment is not an lvalue.

gdb/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* thread.c (thread_apply_command): Adjust TID parsing.
* tid-parse.c (tid_range_parser::finished): Ensure parsing end is
detected before end of string.
(tid_is_in_list): Error out if LIST is invalid.

gdb/testsuite/ChangeLog:
yyyy-mm-dd Pedro Alves <palves@redhat.com>

* gdb.multi/tids.exp: Adjust expected output. Add "thread apply 1
foo --1" test.
---
gdb/testsuite/gdb.multi/tids.exp | 16 ++++++++++++++--
gdb/thread.c | 15 ++++++---------
gdb/tid-parse.c | 10 +++++++++-
3 files changed, 29 insertions(+), 12 deletions(-)

diff --git a/gdb/testsuite/gdb.multi/tids.exp b/gdb/testsuite/gdb.multi/tids.exp
index 617a1b0299c..3b0e1c1860a 100644
--- a/gdb/testsuite/gdb.multi/tids.exp
+++ b/gdb/testsuite/gdb.multi/tids.exp
@@ -350,8 +350,13 @@ with_test_prefix "two inferiors" {
thr_apply_info_thr_error "${prefix}1-" "inverted range"
thr_apply_info_thr_error "${prefix}2-1" "inverted range"
thr_apply_info_thr_error "${prefix}2-\$one" "inverted range"
- thr_apply_info_thr_error "${prefix}-1" "negative value"
- thr_apply_info_thr_error "${prefix}-\$one" "negative value"
+ if {$prefix == ""} {
+ thr_apply_info_thr_error "${prefix}-1" "Invalid thread ID: -1"
+ thr_apply_info_thr_error "${prefix}-\$one" "Invalid thread ID: -\\\$one"
+ } else {
+ thr_apply_info_thr_error "${prefix}-1" "negative value"
+ thr_apply_info_thr_error "${prefix}-\$one" "negative value"
+ }
thr_apply_info_thr_error "${prefix}\$minus_one" \
"negative value: ${prefix_re}\\\$minus_one"

@@ -374,6 +379,13 @@ with_test_prefix "two inferiors" {
gdb_test "thread apply 1.*" $output
}

+ # Check that thread ID list parsing stops at the non-number token
+ # "foo" in a corner case where the "foo" is followed by hyphens.
+ # In this corner case, GDB used to skip past "foo", and then parse
+ # "--1" as a tid range for the current inferior.
+ gdb_test "thread apply 1 foo --1" \
+ "Undefined command: \"foo\". Try \"help\"\\."
+
# Check that we do parse the inferior number and don't confuse it.
gdb_test "info threads 3.1" \
"No threads match '3.1'\."
diff --git a/gdb/thread.c b/gdb/thread.c
index 9a6a7735950..a84dbf9fa1e 100644
--- a/gdb/thread.c
+++ b/gdb/thread.c
@@ -1560,7 +1560,6 @@ thread_apply_command (const char *tidlist, int from_tty)
{
qcs_flags flags;
const char *cmd = NULL;
- const char *cmd_or_flags;
tid_range_parser parser;

if (tidlist == NULL || *tidlist == '\000')
@@ -1572,17 +1571,15 @@ thread_apply_command (const char *tidlist, int from_tty)
int inf_num, thr_start, thr_end;

if (!parser.get_tid_range (&inf_num, &thr_start, &thr_end))
- {
- cmd = parser.cur_tok ();
- break;
- }
+ break;
}

- cmd_or_flags = cmd;
- while (cmd != NULL && parse_flags_qcs ("thread apply", &cmd, &flags))
+ cmd = parser.cur_tok ();
+
+ while (parse_flags_qcs ("thread apply", &cmd, &flags))
;

- if (cmd == NULL)
+ if (*cmd == '\0')
error (_("Please specify a command following the thread ID list"));

if (tidlist == cmd || !isalpha (cmd[0]))
@@ -1591,7 +1588,7 @@ thread_apply_command (const char *tidlist, int from_tty)
scoped_restore_current_thread restore_thread;

parser.init (tidlist, current_inferior ()->num);
- while (!parser.finished () && parser.cur_tok () < cmd_or_flags)
+ while (!parser.finished ())
{
struct thread_info *tp = NULL;
struct inferior *inf;
diff --git a/gdb/tid-parse.c b/gdb/tid-parse.c
index 828362ea94b..07d7d2c3b2a 100644
--- a/gdb/tid-parse.c
+++ b/gdb/tid-parse.c
@@ -139,7 +139,13 @@ tid_range_parser::finished () const
switch (m_state)
{
case STATE_INFERIOR:
- return *m_cur_tok == '\0';
+ /* Parsing is finished when at end of string or null string,
+ or we are not in a range and not in front of an integer, negative
+ integer, convenience var or negative convenience var. */
+ return (*m_cur_tok == '\0'
+ || !(isdigit (*m_cur_tok)
+ || *m_cur_tok == '$'
+ || *m_cur_tok == '*'));
case STATE_THREAD_RANGE:
case STATE_STAR_RANGE:
return m_range_parser.finished ();
@@ -311,6 +317,8 @@ tid_is_in_list (const char *list, int default_inferior,
return 1;

tid_range_parser parser (list, default_inferior);
+ if (parser.finished ())
+ invalid_thread_id_error (parser.cur_tok ());
while (!parser.finished ())
{
int tmp_inf, tmp_thr_start, tmp_thr_end;
--
2.14.5