binutils-gdb/gdb/testsuite/gdb.base/compare-sections.exp

# Copyright 2014-2022 Free Software Foundation, Inc.

# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

# Test the compare-sections command.

standard_testfile

if {[prepare_for_testing "failed to prepare" $testfile $srcfile {debug}]} {
    return -1
}

set is_pie [exec_is_pie $binfile]

# Run the compare-sections command along with any options as specified
# by OPTIONS, and check that no mismatch is found.
proc compare_sections { {options ""} } {
    global gdb_prompt

    if {$options != ""} {
	set command "compare-sections $options"
    } else {
	set command "compare-sections"
    }
    set test $command
    gdb_test_multiple $command $test {
	-re "MIS-MATCHED.*$gdb_prompt $" {
	    fail $test
	}
	-re "warning.*One or more sections.*does not match.*loaded file.*$gdb_prompt $" {
	    fail $test
	}
	-re "Section.*matched.*$gdb_prompt $" {
	    pass $test
	}
    }
}

gdb_file_cmd $binfile

with_test_prefix "after file" {
    # Before starting the target, we're just comparing the
    # executable's sections against themselves...  This should never
    # find a mismatch.
    compare_sections
    compare_sections "-r"
}

# Load the file into the target.
gdb_reload

with_test_prefix "after reload" {
    # We're presumabily still stopped at the entry point.  All
    # sections should match.
    compare_sections
    compare_sections "-r"
}

# Try comparing just one section.  Assume there's a .text section,
# which is a pretty safe bet.
set command "compare-sections .text"
set command_re [string_to_regexp $command]
set test $command
gdb_test_multiple $command $test {
    -re "^$command_re\r\nSection .text, range $hex -- $hex. matched\.\r\n$gdb_prompt $" {
	pass $test
    }
}

# Now get past startup code.
if ![runto_main] then {
    return 0
}

with_test_prefix "after run to main" {
    # Assume all targets' startup code changes some loaded variable.
    gdb_test "compare-sections" \
	"MIS-MATCHED.*warning.*One or more sections.*does not match.*loaded file"

    if { $is_pie == 1 } {
	gdb_test "compare-sections -r" \
	    "MIS-MATCHED.*warning.*One or more sections.*does not match.*loaded file"
    } else {
	# Assume startup code doesn't change read-only sections.
	compare_sections "-r"
    }
}

# Now test that "compare-sections -r" works as expected.  Look for an
# address in a read-only section, patch it, and check that
# "compare-sections -r" detects a mismatch.
with_test_prefix "read-only" {
    set ro_address 0
    set has_ro_sections 0
    set test "list read-only sections"
    gdb_test_multiple "maint info sections READONLY" $test {
	-re "($hex)->$hex at $hex. \[^\r\n\]* READONLY.*$gdb_prompt $" {
	    set ro_address $expect_out(1,string)
	    set has_ro_sections 1
	    pass $test
	}
	-re "$gdb_prompt $" {
	    pass $test
	}
    }

    if {!$has_ro_sections} {
	unsupported "no read-only sections"
	return -1;
    }

    set orig -1

    set test "get value of read-only section"
    gdb_test_multiple "print /u *(unsigned char *) $ro_address" "$test" {
	-re " = (\[0-9\]*).*$gdb_prompt $" {
	    set orig $expect_out(1,string)
	    pass "$test"
	}
    }

    if {$orig == -1} {
	untested "couldn't read address of read-only section"
	return -1
    }

    # Come up with different value.
    set patch [expr 255 - $orig]

    # Write PATCH to memory.
    set written -1
    set test "corrupt read-only section"
    gdb_test_multiple "print /u *(unsigned char *) $ro_address = $patch" "$test" {
	-re " = .*Cannot access memory at address $ro_address.*$gdb_prompt $" {
	    pass "$test (cannot write)"
	}
	-re " = (\[0-9\]*).*$gdb_prompt $" {
	    set written $expect_out(1,string)
	    pass "$test"
	}
    }

    if { $written != $patch } {
	unsupported "can't patch read-only section"
	return -1
    }

    gdb_test "compare-sections -r" \
	"MIS-MATCHED.*warning.*One or more sections.*does not match.*loaded file.*"
}