# Copyright 2015-2020 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/>.

# This testsuite is to test examining memory backward by specifying a negative
# number in the 'x' command.

standard_testfile
if { [prepare_for_testing "failed to prepare for examine-backward" \
        ${testfile} ${srcfile}] } {
    return -1
}

if ![runto_main] {
    untested "could not run to main"
    return -1
}

proc get_first_mapped_address {} {
    global gdb_prompt

    set addr "0"
    gdb_test_multiple "info proc mappings" "info proc mappings" {
        -re "objfile\[\r\n\t \]+(0x\[0-9a-fA-F\]+).*\[\r\n\]*$gdb_prompt $" {
            set addr $expect_out(1,string)
        }
        -re "$gdb_prompt $" {
            unsupported "current target does not support 'info proc mappings'"
        }
    }
    return ${addr}
}

with_test_prefix "invalid format" {
    gdb_test "x/- 10xb main" "Invalid number \"10xb\"\." \
        "a whitespace after a leading hyphen"
    gdb_test "x/--10xb main" "Invalid number \"10xb\"\." \
        "double hyphen"
    gdb_test "x/-a10xb main" "Invalid number \"10xb\"\." \
        "an alphabet after a leading hyphen"
    gdb_test_no_output "x/-0i main" "zero with backward disassemble"
    gdb_test_no_output "x/-0sh main" "zero with backward examine string"
}

with_test_prefix "memory page boundary" {
    set boundary [get_first_mapped_address]
    if {![is_address_zero_readable] && $boundary != 0} {
        gdb_test_no_output "set print elements 0"
        gdb_test_sequence "x/3s ${boundary}" "take 3 strings forward" {
            "0x"
            "0x"
            "0x"
        }
        gdb_test_sequence "x/-4s" "take 4 strings backward" {
            "Cannot access memory at address 0x"
            "0x"
            "0x"
            "0x"
        }
        gdb_test_sequence "x/3s ${boundary}" "take 3 strings forward again" {
            "0x"
            "0x"
            "0x"
        }
        gdb_test_sequence "x/-3s" "take 3 strings backward" {
            "Cannot access memory at address 0x"
            "0x"
            "0x"
            "0x"
        }
    }
}

with_test_prefix "address zero boundary" {
    global gdb_prompt

    set address_zero "0x0"
    set byte "\t0x\[0-9a-f\]+"

    set test "examine 3 bytes forward from ${address_zero}"
    gdb_test_multiple "x/3xb ${address_zero}" "$test" {
	-re "0x\[0-9a-f\]*0.*:${byte}${byte}${byte}\[\r\n\]*$gdb_prompt $" {
	    pass $test
	}
	-re "0x\[0-9a-f\]*0.*:\tCannot access memory at address 0x\[0-9a-f\]*0\[\r\n\]*$gdb_prompt $" {
	    # If we failed to read address 0 then this is fine, so
	    # long as we're not expecting to be able to read from
	    # address 0.
	    if {![is_address_zero_readable]} {
		# The next test assumes that the last address examined
		# would be 0x2.  As we just failed to read address 0x0
		# things are going to go wrong unless we now tell GDB
		# to examine address 0x2.  We assume here that if we
		# can't read 0x0 we can't read 0x2 either.
		gdb_test "x/3xb 0x2" "Cannot access memory at address 0x\[0-9a-f\]*2" \
		    "set last examined address to 0x2"
		pass $test
	    } else {
		fail $test
	    }
	}
    }

    set test "examine 6 bytes backward"
    gdb_test_multiple "x/-6x" "$test" {
	-re "0x\[0-9a-f\]+fd.*:${byte}${byte}${byte}${byte}${byte}${byte}.*\[\r\n\]*$gdb_prompt $" {
	    pass $test
	}
	-re "0x\[0-9a-f\]+fd.*:\tCannot access memory at address 0x\[0-9a-f\]+fd.*\[\r\n\]*$gdb_prompt $" {
	    # We may, or may not have managed to read from address 0x0
	    # in the previous test, however, being able to read 0x0 is
	    # no guarantee that we can read from the other end of the
	    # address space.  If we get an error about trying to read
	    # from the expected address then we count that as a pass,
	    # GDB did try to read the correct location, and this test
	    # is (mostly) about does GDB calculate the correct address
	    # when wrapping around.
	    pass $test
	}
    }

    set test "examine 3 bytes backward from ${address_zero}"
    gdb_test_multiple "x/-3x ${address_zero}" "$test" {
	-re "0x\[0-9a-f\]+fd.*:${byte}${byte}${byte}.*\[\r\n\]*$gdb_prompt $" {
	    pass $test
	}
	-re "0x\[0-9a-f\]+fd.*:\tCannot access memory at address 0x\[0-9a-f\]+fd.*\[\r\n\]*$gdb_prompt $" {
	    # See previous test for why this is a pass.
	    pass $test
	}
    }
}

gdb_test_no_output "set charset ASCII"

with_test_prefix "char-width=1, print-max=20" {
    gdb_test_no_output "set print elements 20"
    gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward" {
        "\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "\"UVWXYZ\""
        "\"\""
        "\"\""
        "\"[^\"]+\""
        "\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-1xb" "0x39" "take 1 char backward"
    gdb_test_sequence "x/-6s" "take 6 strings backward" {
        "\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "\"UVWXYZ\""
        "\"\""
        "\"\""
        "\"[^\"]+\""
        "\"01234567890123456789\"\.\.\."
    }
    gdb_test_sequence "x/6s &TestStrings" "take 6 strings forward again" {
        "\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "\"UVWXYZ\""
        "\"\""
        "\"\""
        "\"[^\"]+\""
        "\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-xb" "0x39" "take 1 char backward again"
    gdb_test "x/-s" "\"01234567890123456789\"\.\.\." \
        "take 1 string backward (1/6)"
    gdb_test "x/-s" "\".+\"" \
        "take 1 string backward (2/6)"
    gdb_test "x/-s" "\"\"" \
        "take 1 string backward (3/6)"
    gdb_test "x/-s" "\"\"" \
        "take 1 string backward (4/6)"
    gdb_test "x/-s" "\"GHIJKLMNOPQRSTUVWXYZ\"" \
        "take 1 string backward (5/6)"
    gdb_test "x/-s" "\"ABCDEFGHIJKLMNOPQRST\"\.\.\." \
        "take 1 string backward (6/6)"
}

with_test_prefix "char-width=2, print-max=20" {
    gdb_test_no_output "set print elements 20"
    gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
        "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "u\"UVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"[^\"]+\""
        "u\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-1xh" "0x0039" "take 1 char backward"
    gdb_test_sequence "x/-6sh" "take 6 strings backward" {
        "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "u\"UVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"[^\"]+\""
        "u\"01234567890123456789\"\.\.\."
    }
    gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
        "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "u\"UVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"[^\"]+\""
        "u\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-xh" "0x0039" "take 1 char backward again"
    gdb_test "x/-sh" "u\"01234567890123456789\"\.\.\." \
        "take 1 string backward (1/6)"
    gdb_test "x/-sh" "u\".+\"" \
        "take 1 string backward (2/6)"
    gdb_test "x/-sh" "u\"\"" \
        "take 1 string backward (3/6)"
    gdb_test "x/-sh" "u\"\"" \
        "take 1 string backward (4/6)"
    gdb_test "x/-sh" "u\"GHIJKLMNOPQRSTUVWXYZ\"" \
        "take 1 string backward (5/6)"
    gdb_test "x/-sh" "u\"ABCDEFGHIJKLMNOPQRST\"\.\.\." \
        "take 1 string backward (6/6)"
}

with_test_prefix "char-width=4, print-max=20" {
    gdb_test_no_output "set print elements 20"
    gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward" {
        "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "U\"UVWXYZ\""
        "U\"\""
        "U\"\""
        "U\"[^\"]+\""
        "U\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-1xw" "0x00000039" "take 1 char backward"
    gdb_test_sequence "x/-6sw" "take 6 strings backward" {
        "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "U\"UVWXYZ\""
        "U\"\""
        "U\"\""
        "U\"[^\"]+\""
        "U\"01234567890123456789\"\.\.\."
    }
    gdb_test_sequence "x/6sw &TestStringsW" "take 6 strings forward again" {
        "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\."
        "U\"UVWXYZ\""
        "U\"\""
        "U\"\""
        "U\"[^\"]+\""
        "U\"01234567890123456789\"\.\.\."
    }
    gdb_test "x/-xw" "0x00000039" "take 1 char backward again"
    gdb_test "x/-sw" "U\"01234567890123456789\"\.\.\." \
        "take 1 string backward (1/6)"
    gdb_test "x/-sw" "U\".+\"" \
        "take 1 string backward (2/6)"
    gdb_test "x/-sw" "U\"\"" \
        "take 1 string backward (3/6)"
    gdb_test "x/-sw" "U\"\"" \
        "take 1 string backward (4/6)"
    gdb_test "x/-sw" "U\"GHIJKLMNOPQRSTUVWXYZ\"" \
        "take 1 string backward (5/6)"
    gdb_test "x/-sw" "U\"ABCDEFGHIJKLMNOPQRST\"\.\.\." \
        "take 1 string backward (6/6)"
}

with_test_prefix "char-width=2, print-max=0" {
    gdb_test_no_output "set print elements 0"
    gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward" {
        "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"\\\\x307b\\\\x3052\\\\x307b\\\\x3052\""
        "u\"012345678901234567890123456789\""
        "u\"!!!!!!\""
    }
    gdb_test "x/-4xh" "0x0021\[\t \]+0x0021\[\t \]+0x0021\[\t \]+0x0000" \
        "take 4 characters backward"
    gdb_test_sequence "x/-6sh" "take 6 strings backward" {
        "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"[^\"]+\""
        "u\"012345678901234567890123456789\""
        "u\"!!!!!!\""
    }
    gdb_test_sequence "x/6sh &TestStringsH" "take 6 strings forward again" {
        "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\""
        "u\"\""
        "u\"\""
        "u\"\\\\x307b\\\\x3052\\\\x307b\\\\x3052\""
        "u\"012345678901234567890123456789\""
        "u\"!!!!!!\""
    }
    gdb_test "x/-xh" "0x0000" "take 1 char backward"
    gdb_test "x/-sh" "u\"!!!!!!\"" \
        "take 1 string backward (1/6)"
    gdb_test "x/-sh" "u\"012345678901234567890123456789\"" \
        "take 1 string backward (2/6)"
    gdb_test "x/-sh" "u\".+\"" \
        "take 1 string backward (3/6)"
    gdb_test "x/-sh" "u\"\"" \
        "take 1 string backward (4/6)"
    gdb_test "x/-sh" "u\"\"" \
        "take 1 string backward (5/6)"
    gdb_test "x/-sh" "u\"ABCDEFGHIJKLMNOPQRSTUVWXYZ\"" \
        "take 1 string backward (6/6)"
}

with_test_prefix "char-width=1, print-max=4" {
    gdb_test_no_output "set print elements 4"
    gdb_test_sequence "x/9s &TestStrings" "take 9 strings forward" {
        "\"ABCD\"\.\.\."
        "\"EFGH\"\.\.\."
        "\"IJKL\"\.\.\."
        "\"MNOP\"\.\.\."
        "\"QRST\"\.\.\."
        "\"UVWX\"\.\.\."
        "\"YZ\""
        "\"\""
        "\"\""
    }
    gdb_test "x/-xb" "0x00" "take 1 byte backward"
    gdb_test_sequence "x/-4s" "take 4 strings backward (1/2)" {
        "\"TUVW\"\.\.\."
        "\"XYZ\""
        "\"\""
        "\"\""
    }
    gdb_test_sequence "x/-4s" "take 4 strings backward (2/2)" {
        "\"CDEF\"\.\.\."
        "\"GHIJ\"\.\.\."
        "\"KLMN\"\.\.\."
        "\"OPQR\"\.\.\."
    }
}

with_test_prefix "backward disassemble general" {
    set length_to_examine {1 2 3 4 10}
    set disassmbly {}

    gdb_test "x/i main" "0x\[0-9a-fA-F\]+ <main>:\t.*" \
        "move the current position to main (x/i)"
    gdb_test "x/-i" "0x\[0-9a-fA-F\]+ <main>:\t.*" \
        "move the current position to main (x/-i)"
    for {set i 0} {$i < [llength $length_to_examine]} {incr i} {
        set len [lindex $length_to_examine $i]
        set instructions [capture_command_output "x/${len}i" ""]
        lappend disassmbly $instructions
    }
    for {set i 0} {$i < [llength $length_to_examine]} {incr i} {
        set idx [expr [llength $length_to_examine] - $i - 1]
        set len [lindex $length_to_examine $idx]
        set actual [capture_command_output "x/-${len}i" ""]
        set expected [lindex $disassmbly $idx]
        if {$actual == $expected} {
            pass "inst:$idx"
        } else {
            fail "inst:$idx"
        }
    }
}