Re: [gdb/testsuite] Fix error handling in gdb_file_cmd

Tom de Vries
2020-06-04T14:38:24Z

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On 04-06-2020 13:51, Pedro Alves wrote:
> On 6/4/20 11:45 AM, Tom de Vries wrote:
>>> [gdb/testsuite] Fix PATH error in gdb_file_cmd
>>
>> And a follow-up patch fixing another problem in gdb_file_cmd.
>
> LGTM.

Updated log message to accommodate for commit 0cfcd4f003
"[gdb/testsuite] Fix use of fail in gdb_cmd_file", committed as attached.

Thanks,
- Tom

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[gdb/testsuite] Fix error handling in gdb_file_cmd

Consider a gdb_load patch to call the gdb_file_cmd twice:
...
proc gdb_load { arg } {
if { $arg != "" } {
+ set res [gdb_file_cmd $arg]
+ if { $res != 0 } {
+ return $res
+ }
return [gdb_file_cmd $arg]
}
return 0
}
...

When running test-case gdb.base/index-cache.exp, we run into:
...
ERROR: Couldn't load outputs/gdb.base/index-cache/index-cache, other program \
already loaded (timeout).
FAIL: gdb.base/index-cache.exp: test_cache_enabled_miss: check index-cache \
stats (GDB internal error)
ERROR: Couldn't load outputs/gdb.base/index-cache/index-cache, other program \
already loaded (timeout).
...

The first timeout in more detail:
...
(gdb) file outputs/gdb.base/index-cache/index-cache^M
Load new symbol table from "index-cache"? (y or n) y^M
Reading symbols from index-cache...^M
src/gdb/dwarf2/read.c:2540: internal-error: \
void create_cus_from_index(dwarf2_per_bfd*, const gdb_byte*, offset_type, \
const gdb_byte*, offset_type): \
Assertion `per_bfd->all_comp_units.empty ()' failed.^M
A problem internal to GDB has been detected,^M
further debugging may prove unreliable.^M
Quit this debugging session? (y or n) ERROR: Couldn't load index-cache, \
other program already loaded (timeout).
...

Proc gdb_file_cmd has a gdb_expect handling the result of the file command,
and if the result is a "Load new symbol table from index-cache? (y or n) "
prompt, it sends a "y" and enters in a nested gdb_expect to handle the
result.

The first gdb_expect contains code to handle "A problem internal to GDB has
been detected", but the second one doesn't, which causes the timeout.

Fix this by removing the nested gdb_expect, and using exp_continue instead,
such that we have instead:
...
ERROR: Couldn't load outputs/gdb.base/index-cache/index-cache -- with new \
symbol table into gdb (GDB internal error).
ERROR: Couldn't load outputs/gdb.base/index-cache/index-cache -- with new \
symbol table into gdb (GDB internal error).
...

Tested on x86_64-linux.

gdb/testsuite/ChangeLog:

2020-06-04 Tom de Vries <tdevries@suse.de>

* lib/gdb.exp (gdb_file_cmd): Replace incomplete gdb_expect by
exp_continue.

---
gdb/testsuite/lib/gdb.exp | 23 ++++++++---------------
1 file changed, 8 insertions(+), 15 deletions(-)

diff --git a/gdb/testsuite/lib/gdb.exp b/gdb/testsuite/lib/gdb.exp
index 63a9e3da53..3cdaefaa9c 100644
--- a/gdb/testsuite/lib/gdb.exp
+++ b/gdb/testsuite/lib/gdb.exp
@@ -1761,6 +1761,7 @@ proc gdb_file_cmd { arg } {
}

send_gdb "file $arg\n"
+ set new_symbol_table 0
gdb_expect 120 {
-re "Reading symbols from.*LZMA support was disabled.*$gdb_prompt $" {
verbose "\t\tLoaded $arg into $GDB; .gnu_debugdata found but no LZMA available"
@@ -1778,22 +1779,14 @@ proc gdb_file_cmd { arg } {
return 0
}
-re "Load new symbol table from \".*\".*y or n. $" {
+ if { $new_symbol_table > 0 } {
+ perror "Couldn't load $arg, interactive prompt loop detected."
+ return -1
+ }
send_gdb "y\n" answer
- gdb_expect 120 {
- -re "Reading symbols from.*$gdb_prompt $" {
- verbose "\t\tLoaded $arg with new symbol table into $GDB"
- set gdb_file_cmd_debug_info "debug"
- return 0
- }
- timeout {
- perror "Couldn't load $arg, other program already loaded (timeout)."
- return -1
- }
- eof {
- perror "Couldn't load $arg, other program already loaded (eof)."
- return -1
- }
- }
+ incr new_symbol_table
+ set arg "$arg -- with new symbol table"
+ exp_continue
}
-re "No such file or directory.*$gdb_prompt $" {
perror "($arg) No such file or directory"