[RFA] Add shared object relocation tests

[Raoul Gough]

I've written a test for load-time relocation of shared objects, to verify
that the symbols in gdb match the real (loaded) locations in memory.
This was originally designed to test some patches to coffread.c, but
is probably appropriate wherever shared objects are available. This
is related to PR 1132 in Gnats. Tested under i686-pc-cygwin and
i686-pc-linux.

There may be problems on systems where shared objects are not
supported - this will probably result in compilation or linkage
failures during the test (and I think the test is then skipped?).

This would add the following files to src/gdb/testsuite/gdb.base:

shreloc.exp
shreloc.c
shreloc1.c
shreloc2.c

Should I go ahead and add the new files?

Regards,
Raoul Gough

------------------------- shreloc.exp --------------------------

# Copyright (C) 2003 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 2 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, write to the Free Software
# Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
#

# Please email any bugs, comments, and/or additions to this file to:
# bug-gdb@prep.ai.mit.edu

# Tests for shared object file relocation. If two shared objects have
# the same load address (actually, overlapping load spaces), one of
# them gets relocated at load-time. Check that gdb gets the right
# values for the debugging and minimal symbols.

if $tracelevel then {
    strace $tracelevel
}

#
# This file uses shreloc.c, shreloc1.c and shreloc2.c
#

set prms_id 0
set bug_id 0

set workdir ${objdir}/${subdir}

foreach module [list "shreloc" "shreloc1" "shreloc2"] {
    if {[gdb_compile "${srcdir}/${subdir}/${module}.c" "${workdir}/${module}.o" object {debug}] != ""} {
 gdb_suppress_entire_file "${module}.c compile failed, so all tests in this file will automatically fail."
 return -1
    }
}

set additional_flags "additional_flags=-shared"

if {([istarget "*pc-cygwin"] || [istarget "*pc-mingw32"]) } {
    set additional_flags "${additional_flags} -Wl,--image-base,0x04000000"
}

foreach module [list "shreloc1" "shreloc2"] {
    if {[gdb_compile "${workdir}/${module}.o" "${workdir}/${module}.dll" executable [list debug $additional_flags]] != ""} {
 gdb_suppress_entire_file "${module}.dll link failed, so all tests in this file will automatically fail."
 return -1
    }
}

if {[gdb_compile [list "${workdir}/shreloc.o" "${workdir}/shreloc1.dll" "${workdir}/shreloc2.dll"] "${workdir}/shreloc" executable
debug] != ""} {
    gdb_suppress_entire_file "shreloc link failed, so all tests in this file will automatically fail."
    return -1
}

gdb_exit
gdb_start
gdb_reinitialize_dir $srcdir/$subdir
gdb_load ${workdir}/shreloc

# Load up the shared objects
if ![runto_main] then {
    fail "Can't run to main"
    return 0
}

proc get_var_address { var } {
  global gdb_prompt hex

  send_gdb "print &${var}\n"
  # Match output like:
  # $1 = (int *) 0x0
  # $5 = (int (*)()) 0
  # $6 = (int (*)()) 0x24 <function_bar>
  gdb_expect {
    -re "\\\$\[0-9\]+ = \\(.*\\) (0|$hex)( <${var}>)?\[\r\n\]+${gdb_prompt} $"
 {
   pass "get address of ${var}"
   if { $expect_out(1,string) == "0" } {
     return "0x0"
   } else {
     return $expect_out(1,string)
   }
 }
    -re "${gdb_prompt} $"
 { fail "get address of ${var} (unknown output)" }
    timeout
 { fail "get address of ${var} (timeout)" }
  }
  return ""
}

#
# Check debugging symbol relocations
#

# Check extern function for relocation
set fn_1_addr [get_var_address fn_1]
set fn_2_addr [get_var_address fn_2]

if { "${fn_1_addr}" == "${fn_2_addr}" } {
  fail "relocated extern functions have different addresses"
} else {
  pass "relocated extern functions have different addresses"
}

# Check extern var for relocation
set extern_var_1_addr [get_var_address extern_var_1]
set extern_var_2_addr [get_var_address extern_var_2]

if { "${extern_var_1_addr}" == "${extern_var_2_addr}" } {
  fail "relocated extern variables have different addresses"
} else {
  pass "relocated extern variables have different addresses"
}

# Check static var for relocation
set static_var_1_addr [get_var_address static_var_1]
set static_var_2_addr [get_var_address static_var_2]

if { "${static_var_1_addr}" == "${static_var_2_addr}" } {
  fail "relocated static variables have different addresses"
} else {
  pass "relocated static variables have different addresses"
}

#
# Check minimal symbol relocations
#

proc send_gdb_discard { command } {
    # Send a command to gdb and discard output up to the next prompt

    global gdb_prompt

    send_gdb "${command}\n"

    # Discard output
    gdb_expect {
 -re ".*\[\r\n]+${gdb_prompt} $" {
     return 1
 }
 timeout {
     fail "{$command} (timeout)"
     return 0
 }
    }
}

proc get_msym_addrs { var msymfile } {
    # Extract the list of values for symbols matching var in the
    # minimal symbol output file

    global gdb_prompt hex
    set result ""

    send_gdb "shell grep -E \" ${var}(\[ \t\]+.*)?\$\" ${msymfile}\n"

    while 1 {
 gdb_expect {
     -re "\[\[\]\[ 0-9\]+\] . (${hex}) ${var}(\[ \t\]+\[^\r\n\]*)?\[\r\n\]+" {
  set result [concat $result $expect_out(1,string)]
     }

     -re "$gdb_prompt $" {
  pass "get_msym_addrs ${var} (${result})"
  return "${result}"
     }

     -re "\[^\r\n\]*\[\r\n\]+" {
  # Skip
     }

     timeout {
  fail "get_msym_addrs ${var} (timeout)"
  return -1
     }
 }
    }
}

proc check_same {var msymfile} {
    # Check that the minimal symbol values matching var are the same

    set len [llength [lsort -unique [get_msym_addrs "${var}" "${msymfile}"]]]

    if { $len == 1 } {
 return 1
    } else {
 return 0
    }
}

proc check_different {var msymfile} {
    # Check that the minimal symbol values matching var are different

    set addr_list [lsort [get_msym_addrs "${var}" "${msymfile}"]]
    set prev ""

    if { [llength ${addr_list}] < 2 } {
 return 0
    }

    foreach addr ${addr_list} {
 if { ${prev} == ${addr} } {
   return 0
 }
 set prev ${addr}
    }

    return 1
}

set msymfile "${workdir}/shreloc.txt"

if [send_gdb_discard "maint print msymbols ${msymfile}"] {
    if {[check_different "static_var_\[12\]" "${msymfile}"]} {
 pass "(msymbol) relocated static vars have different addresses"
    } else {
 fail "(msymbol) relocated static vars have different addresses"
    }

    if {[check_different "extern_var_\[12\]" "${msymfile}"]} {
 pass "(msymbol) relocated extern vars have different addresses"
    } else {
 fail "(msymbol) relocated extern vars have different addresses"
    }

    if {[check_different "fn_\[12\]" "${msymfile}"]} {
 pass "(msymbol) relocated functions have different addresses"
    } else {
 fail "(msymbol) relocated functions have different addresses"
    }
}

if {([istarget "*pc-cygwin"] || [istarget "*pc-mingw32"]) } {
    #
    # We know the names of some absolute symbols included in the
    # portable-executable (DLL) format. Check that they didn't get
    # relocated.
    #
    # A better approach would be include absolute symbols via the assembler.
    #
    if {[check_same "_minor_os_version__" "${msymfile}"]} {
 pass "Absolute symbols not relocated"
    } else {
 fail "Absolute symbols not relocated"
    }
}


------------------------- shreloc.c --------------------------

#if defined(_WIN32) || defined(__CYGWIN__)
# define ATTRIBUTES __attribute((__dllimport__))
#else
# define ATTRIBUTES
#endif

extern ATTRIBUTES void fn_1 (int);
extern ATTRIBUTES void fn_2 (int);
extern ATTRIBUTES int extern_var_1;
extern ATTRIBUTES int extern_var_2;

int main ()
{
  fn_1 (extern_var_1);
  fn_2 (extern_var_2);

  return 0;
}

------------------------- shreloc1.c --------------------------

#if defined(_WIN32) || defined(__CYGWIN__)
# define ATTRIBUTES __attribute((__dllexport__))
#else
# define ATTRIBUTES
#endif

static int static_var_1;

ATTRIBUTES void fn_1 (int unused) { }
ATTRIBUTES int extern_var_1 = 0;

------------------------- shreloc2.c --------------------------

#if defined(_WIN32) || defined(__CYGWIN__)
# define ATTRIBUTES __attribute((__dllexport__))
#else
# define ATTRIBUTES
#endif

static int static_var_2;

ATTRIBUTES void fn_2 (int unused) { }
ATTRIBUTES int extern_var_2 = 0;