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99f1bc6aaa
Commit:
commit 724fd9ba43
Date: Mon Jan 27 17:37:20 2020 +0000
gdb: Restructure the completion_tracker class
caused the completion hash table to become corrupted if the table ever
needed to grow beyond its original size of 200 elements.
The hash table stores completion_tracker::completion_hash_entry
objects, but hashes them based on their name, which is only one field
of the object.
When possibly inserting a new element we compute the hash with
htab_hash_string of the new elements name, and then lookup matching
elements using htab_find_slot_with_hash. If there's not matching
element we create a completion_hash_entry object within the hash
table.
However, when we allocate the hash we pass htab_hash_string to
htab_create_alloc as the hash function, and this is not OK. This
means that when the hash table needs to grow, existing elements within
the hash are re-hashed by passing the completion_hash_entry pointer to
htab_hash_string, which obviously does not do what we expect.
The solution is to create a new hash function that takes a pointer to
a completion_hash_entry, and then calls htab_hash_string on the name
of the entry only.
This regression was spotted when running the gdb.base/completion.exp
test on the aarch64 target.
gdb/ChangeLog:
* completer.c (class completion_tracker::completion_hash_entry)
<hash_name>: New member function.
(completion_tracker::discard_completions): New callback to hash a
completion_hash_entry, pass this to htab_create_alloc.
gdb/testsuite/ChangeLog:
* gdb.base/many-completions.exp: New file.
93 lines
3.0 KiB
Plaintext
93 lines
3.0 KiB
Plaintext
# Copyright 2020 Free Software Foundation, Inc.
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License as published by
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# the Free Software Foundation; either version 3 of the License, or
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# (at your option) any later version.
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#
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# This program is distributed in the hope that it will be useful,
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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# GNU General Public License for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program. If not, see <http://www.gnu.org/licenses/>.
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# Test the case where we have so many completions that we require the
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# completions hash table within GDB to grow. Make sure that afte the
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# hash table has grown we try to add duplicate entries into the
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# hash. This checks that GDB doesn't corrupt the hash table when
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# resizing it.
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#
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# In this case we create a test with more functions than the default
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# number of entires in the completion hash table (which is 200), then
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# complete on all function names.
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#
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# GDB will add all the function names from the DWARF, and then from
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# the ELF symbol table, this ensures that we should have duplicates
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# added after resizing the table.
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# Create a test source file and return the name of the file. COUNT is
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# the number of dummy functions to create, this should be more than
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# the default number of entries in the completion hash table within
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# GDB (see gdb/completer.c).
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proc prepare_test_source_file { count } {
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global gdb_test_file_name
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set filename [standard_output_file "$gdb_test_file_name.c"]
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set outfile [open $filename w]
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puts $outfile "
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#define MAKE_FUNC(NUM) \\
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void \\
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func_ ## NUM (void) \\
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{ /* Nothing. */ }
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#define CALL_FUNC(NUM) \\
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func_ ## NUM ()
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"
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for { set i 0 } { $i < $count } { incr i } {
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puts $outfile "MAKE_FUNC ([format {%03d} $i])"
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}
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puts $outfile "\nint\nmain ()\n{"
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for { set i 0 } { $i < $count } { incr i } {
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puts $outfile " CALL_FUNC ([format {%03d} $i]);"
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}
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puts $outfile " return 0;\n}"
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close $outfile
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return $filename
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}
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# Build a source file and compile it.
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set filename [prepare_test_source_file 250]
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standard_testfile $filename
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if {[prepare_for_testing "failed to prepare" "$testfile" $srcfile \
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{ debug }]} {
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return -1
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}
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# Start the test.
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if {![runto_main]} {
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fail "couldn't run to main"
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return
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}
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# We don't want to stop gathering completions too early.
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gdb_test_no_output "set max-completions unlimited"
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# Collect all possible completions, and check for duplictes.
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set completions [capture_command_output "complete break func_" ""]
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set duplicates 0
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foreach {-> name} [regexp -all -inline -line {^break (\w+\S*)} $completions] {
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incr all_funcs($name)
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if { $all_funcs($name) > 1 } {
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incr duplicates
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verbose -log "Duplicate entry for '$name' found"
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}
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}
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gdb_assert { $duplicates == 0 } "duplicate check"
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