#!/bin/bash

# relaytool 1.2
# Copyright 2004-2005 Mike Hearn <mike@plan99.net>
# Copyright 2005 Vincent Béron <vberon@mecano.gme.usherb.ca>
# Copyright 2006 Psyche <psyche@ruidoabsurdo.com>
# Copyright 2007 Taj Morton <tajmorton@gmail.com>
#
#############################################################################
#
# Permission is hereby granted, free of charge, to any person obtaining a copy
# of this software and associated documentation files (the "Software"), to deal
# in the Software without restriction, including without limitation the rights
# to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
# copies of the Software, and to permit persons to whom the Software is
# furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL THE
# COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
# IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
# CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
#
#############################################################################
#
# TODO:
#   - Figure out how to grab the GOT addr on PowerPC
#   - Port to more archs
#   - Figure out a way to check if we're on an ELF platform or not,
#     maybe check for _GLOBAL_OFFSET_TABLE_ ?

using_partial_map=false
using_minimal_list=false
using_multilink=false
outdir="."

if [[ "$1" == "--version" ]]; then
    echo "Relaytool 1.11"
    echo "Copyright 2004 Mike Hearn"
    echo "Copyright 2005 Vincent Béron"
    echo
    echo "See $0 for license details."
    exit 1
fi

if [[ "$@" == "" ]] || [[ "$1" == "--help" ]] || [[ "$1" == "-h" ]]; then
    echo "Relaytool will generate a file that can be used instead of linking"
    echo "directly against a library, which will dlopen the DSO at init time"
    echo
    echo "Usage: relaytool [OPTION]... [LINKER COMMAND]..."
    echo
    echo "Options:"
    echo "  --relay LIB               If a matching -lLIB is found, generate a file"
    echo "                            that can be used instead of linking directly to"
    echo "                            LIB. The name of the file is echoed on stdout."
    echo "                            Multiple --relay can be used together, a file will"
    echo "                            be generated for each matching ones."
    echo "  --replace-all-libs        Generate a file for every -lLIB parameter."
    echo "  --minimal-list OBJ_LIST   Will look in OBJ_LIST for undefined symbols, and"
    echo "                            generate a file creating only the needed symbols"
    echo "                            for each LIB."
    echo "  --partial-map MAP_FILE    Generate a file creating only the symbols contained"
    echo "                            in MAP_FILE. Will apply to all further -lLIB"
    echo "                            parameters, so in general is not suitable to"
    echo "                            multiple libs in the same invocation of relaytool."
    echo "  --no-replace              Echo -lLIB on stdout even if a --relay LIB is"
    echo "                            found, so it'll be linked in normally."
    echo "  --multilink [SONAMES...]  If a library has different SONAMES on different"
    echo "                            Linux distributions you can specify the various"
    echo "                            SONAMES that it's known by here. Relaytool will"
    echo "                            attempt to load them (in the order provided) until"
    echo "                            one if found. This cannot be used with multiple"
    echo "                            --relay options. The first SONAME in the list will"
    echo "                            be used as the name in the _is_present variable and"
    echo "                            _symbol_is_present function."
    echo "  --out-dir DIRECTORY       Write stub file to DIRECTORY instead of CWD."
    echo "Linker commands:"
    echo "  -LPATH                    Add PATH to the list of paths to search for LIBs."
    echo "  -lLIB                     If a matching --relay LIB is found (or if"
    echo "                            --replace-all-libs is specified), generate a file"
    echo "                            that can be used instead of linking directly to"
    echo "                            LIB. If there's no --relay LIB, echo -lLIB to"
    echo "                            stdout."
    echo " All other linker commands are passed as is to stdout."
    echo "Other commands:"
    echo "  --help|-h                 Print this help."
    echo "  --version                 Print version information."
    exit 1
fi

function error() {
    echo $@ >/dev/stderr
    exit 1
}

function readfinallink() {
    link_name="$1"
    while [ -L "$link_name" ]; do
        new_name=$( readlink "$link_name" )
        if [ "${new_name:0:1}" == "/" ]; then
            link_name="$new_name"
        else
            link_name="`dirname "$link_name"`/$new_name"
        fi
    done
    if [ -f "$link_name" ]; then
        echo -n "$link_name"
        exit 0
    else
        exit 1
    fi
}

function relay() {
    lib="$1"
    if $using_multilink; then
        libname=$( echo $( basename ${multilinklist[0]} ) | sed 's/\.so.*//' | tr '-' '_' | tr '.' '_' )
    else
        libname=$( echo $( basename "$lib" ) | sed 's/\.so.*//' | tr '-' '_' | tr '.' '_' )
    fi
    soname=$( objdump -x "$lib" |grep SONAME | awk '{print $2}' )
    outfile="$outdir/`basename "$soname"`.stub.c"

    echo -n "$outfile"

    if $using_partial_map; then
        functions=$( grep "^F " "$partial_map" | cut -d' ' -f2 )
        variables=$( grep "^V " "$partial_map" | cut -d' ' -f2 )
    else
        functions=$( nm --extern-only -D "$lib" | awk '{ if (($2 == "T") || ($2 == "W")) print $3; }' | LC_ALL=C grep -v '\(\<_init\>\|\<_fini\>\)' | LC_ALL=C sort -u )
        variables=$( nm --extern-only -D "$lib" | awk '{ if (($2 == "D") || ($2 == "G") || ($2 == "B") || ($2 == "V")) print $3; }' | LC_ALL=C sort -u )
    fi
    if $using_minimal_list; then
        functions="$functions
$( nm `echo "$object_list"` | awk '{ if ($1 == "U") print $2; }' | LC_ALL=C sort -u )"
        functions=$( echo "$functions" | LC_ALL=C sort | LC_ALL=C uniq -d )
        variables="$variables
$( nm `echo "$object_list"` | awk '{ if ($1 == "U") print $2; }' | LC_ALL=C sort -u )"
        variables=$( echo "$variables" | LC_ALL=C sort | LC_ALL=C uniq -d )
    fi

    if [ "$functions" == "" ] && [ "$variables" == "" ]; then
        # Nothing will be used, so do nothing for that lib
        exit 1
    fi

    cat <<EOF >"$outfile"
/* automatically generated: `date` by `id -un`@`uname -n`, do not edit
 *
 * Built by relaytool, a program for building delay-load jumptables
 * relaytool is (C) 2004 Mike Hearn <mike@navi.cx>
 * See http://autopackage.org/ for details.
 */
#include <dlfcn.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>
#include <sys/mman.h>

#ifdef __cplusplus
    extern "C" {
#endif

static void **ptrs;
static char *functions[] = {
EOF

    for s in $functions; do
        echo "    \"$s\"," >>"$outfile"
    done
    echo "    0" >>"$outfile"

    cat <<EOF >>"$outfile"
};

static char *variables[] = {
EOF

    for s in $variables; do
        echo "    \"$s\"," >>"$outfile"
    done
    echo "    0" >>"$outfile"

    cat <<EOF >>"$outfile"
};

/* 1 if present, 0 if not */
int ${libname}_is_present = 0;

static void *handle = 0;

/* 1 if present, 0 if not, 0 with warning to stderr if lib not present or symbol not found */
int ${libname}_symbol_is_present(char *s)
{
    int i;

    if( !${libname}_is_present ) {
        fprintf(stderr, "%s: relaytool: `basename "$lib"` not present so cannot check for symbol %s.\n", getenv("_"), s);
        fprintf(stderr, "%s: relaytool: This probably indicates a bug in the application, please report.\n", getenv("_"));
        return 0;
    }

    i = 0;
    while (functions[i++]) if (!strcmp( functions[i - 1], s )) return ptrs[i - 1] > 0 ? 1 : 0;
    i = 0;
    while (variables[i++]) if (!strcmp( variables[i - 1], s )) return dlsym( handle, s ) > 0 ? 1 : 0;

    fprintf( stderr, "%s: relaytool: %s is an unknown symbol in `basename "$lib"`.\n", getenv("_"), s );
    fprintf( stderr, "%s: relaytool: If you are the developer of this program, please correct the symbol name or rerun relaytool.\n", getenv("_") );
    return 0;
}

__attribute__((noreturn)) void _relaytool_stubcall_${libname}(int offset)
{
    fprintf( stderr, "%s: relaytool: stub call to `basename "${lib}"`:%s, aborting.\n", getenv("_"),
             functions[offset / sizeof(void*)] );
    exit( 1 );
}

#if defined( __i386__ )
    #define FIXUP_GOT_RELOC(sym, addr) \\
        asm("\tmovl %0, %%eax\n" \\
            "\tmovl %%eax, " sym "@GOT(%%ebx)\n" : : "r" (addr));
#elif defined( __powerpc__ )

    /* The PowerPC ELF ABI is a twisted nightmare. Until I figure it out,
       for now we don't support GOT fixup on this architecture */
        
    #error Variables are not currently supported on PowerPC
        
#elif defined( __x86_64__ )
    #define FIXUP_GOT_RELOC(sym, addr) \\
        asm("\tmovq %0, %%rax\n" \\
            "\tmovq %%rax, " sym "@GOT(%%rbx)\n" : : "r" (addr));
#else        
    #error Please define FIXUP_GOT_RELOC for your architecture
#endif

void __attribute__((constructor)) _relaytool_init_${libname}()
{
    int i = 0;

    ptrs = malloc( sizeof(functions) );
    memset( ptrs, 0, sizeof(functions) );
EOF
    if $using_multilink; then
      echo -n "char *multilink_libs[${#multilinklist[@]}] = {" | cat >> "$outfile"
      for l in ${multilinklist[@]}; do
        echo -n "\"$l\"" | cat >> "$outfile";
        if [[ "$l" != "${multilinklist[${#multilinklist[@]}-1]}" ]]; then
            echo -n ", " | cat >> "$outfile";
        else
            echo "};" | cat >> "$outfile"
        fi
      done
      echo 'int multilink_count=0;' | cat >> "$outfile"
      
      echo 'while (!handle) {
          handle = dlopen(multilink_libs[multilink_count++], RTLD_LAZY );' | cat >> "$outfile"
      echo "if (multilink_count==${#multilinklist[@]}) break;}"| cat >> "$outfile"
    else
      echo "handle = dlopen( \"$soname\", RTLD_LAZY );" | cat >> "$outfile"
    fi
cat <<EOF >>"$outfile"
    if (!handle) return;
    
    ${libname}_is_present = 1;

    /* build function jumptable */
    while (functions[i++]) ptrs[i - 1] = dlsym( handle, functions[i - 1] );
    
EOF

    if [ "$variables" != "" ]; then echo "    /* now fixup the global offset table for variable imports */" >>"$outfile"; fi
    for s in $variables; do
        echo "    FIXUP_GOT_RELOC( \"$s\", dlsym(handle, \"$s\") );" >>"$outfile"
    done

    cat <<EOF >>"$outfile"
}

#if defined( __i386__ )

#define JUMP_SLOT(name, index)  \\
    asm(".section .text." name ", \"ax\", @progbits\n" \\
        ".globl  " name "\n" \\
        ".hidden " name "\n" \\
        "        .type " name ", @function\n"  \\
        name ":\n" \\
        "        movl ptrs, %eax\n" \\
        "        movl " #index "(%eax), %eax\n" \\
        "        test %eax, %eax\n" \\
        "        jnz  JS" #index "\n" \\
        "        push \$" #index "\n" \\
        "        call _relaytool_stubcall_${libname}\n" \\
        "JS" #index ":    jmp *%eax\n");


#elif defined( __x86_64__ )

#define JUMP_SLOT(name, index)  \\
    asm(".section .text." name ", \"ax\", @progbits\n" \\
        ".globl  " name "\n" \\
        ".hidden " name "\n" \\
        "        .type " name ", @function\n"  \\
        name ":\n" \\
        "        movq ptrs, %r11\n" \\
        "        movq " #index "(%r11), %r11\n" \\
        "        test %r11, %r11\n" \\
        "        jnz  JS" #index "\n" \\
        "        push $" #index "\n" \\
        "        call _relaytool_stubcall_${libname}\n" \\
        "JS" #index ":    jmp *%r11\n");
#elif defined( __powerpc__ )

#define JUMP_SLOT(name, index) \                                \
    asm(".section .text." name ", \"ax\", @progbits\n" \\
        ".globl  " name "\n" \\
        ".hidden " name "\n" \\
        "        .type " name ", @function\n" \\
        name ":\n" \\
        "        lis r11, ptrs@ha\n" \\
        "        lwz r11, " #index "(r11)\n" \\
        "        cmpi cr0,r11,0\n" \\
        "        beq- 1f\n" \\
        "        mtctr r11\n" \\
        "        bctr\n" \\
        "1:      li r3, " #index "\n" \\
        "        b _relaytool_stubcall_${libname}\n" \\
        );
        
#else        
    #error Please define JUMP_SLOT for your architecture
#endif

/* define placeholders for the variable imports: their type doesn't matter,
   however we must restrict ELF symbol scope to prevent the definition in the imported
   shared library being bound to this dummy symbol (not all libs are compiled -Bsymbolic)
 */
EOF

    for s in $variables; do
        echo "int $s __attribute__(( visibility(\"hidden\") )) = -1;" >>"$outfile"
    done

    cat <<EOF >>"$outfile"

/* define each jump slot in its own section. this increases generated code
   size, but it means unused slots can be deleted by the linker when
   --gc-sections is used.
 */
EOF

# now generate the stubs
    c=0
    for s in $functions; do
        echo "JUMP_SLOT(\"$s\", $[c * $arch_ptr_size]);" >>"$outfile"
        (( c++ ))
    done

    echo >>"$outfile"

    cat <<EOF >>"$outfile"

#ifdef __cplusplus
    }
#endif
EOF
    
}

function fakerelay() {
    lib="$1"
    libname=$( echo $( basename "$lib" ) | sed 's/\.so.*//' | tr '-' '_' | tr '.' '_' )
    soname=$( objdump -x "$lib" |grep SONAME | awk '{print $2}' )
    outfile="$outdir/`basename "$soname"`.stub.c"

    echo -n "$outfile"

    cat <<EOF >"$outfile"
/* automatically generated: `date` by `id -un`@`uname -n`, do not edit
 *
 * Built by relaytool, a program for building delay-load jumptables
 * relaytool is (C) 2004 Mike Hearn <mike@navi.cx>
 * See http://autopackage.org/ for details.
 */

#ifdef __cplusplus
    extern "C" {
#endif

/* 1 if present, 0 if not */
int ${libname}_is_present = 1;

/* 1 if present, 0 if not, 0 with warning to stderr if lib not present or symbol not found */
int ${libname}_symbol_is_present(char * s)
{
    return 1;
}

#ifdef __cplusplus
    }
#endif
EOF
    
}

no_replace=false
replace_all=false
arch_ok=false
arch_ptr_size=0
case `uname -m` in
    i386 | i486 | i586 | i686 )
        arch_ok=true
        arch_ptr_size=4
        ;;
    x86_64)
        arch_ok=true
        arch_ptr_size=8
        ;;                                   
esac

searchpath=( "/usr/lib" "/usr/local/lib" "/lib" `pwd` )
multilinklist=( )
relaylist=( )

# process arguments
i=1
while (( i <= $# )); do
    a="${!i}"
    
    if [ "${a:0:2}" == "-L" ]; then
        searchpath[${#searchpath}]="${a:2}"
        echo -n "$a " # copy to stdout

    elif [ "$a" == "--replace-all-libs" ]; then
        replace_all=true

    elif [ "$a" == "--partial-map" ]; then
        using_partial_map=true
        (( i++ ))
        partial_map="${!i}"

    elif [ "$a" == "--minimal-list" ]; then
        using_minimal_list=true
        (( i++ ))
        object_list="${!i}"

    elif [ "$a" == "--no-replace" ]; then
        no_replace=true

    elif [ "$a" == "--multilink" ]; then
        using_multilink=true
        (( i++ ))
	while [[ $i -lt $# && ${!i:0:2} != "--" ]]; do
		multilinklist[${#multilinklist[@]}]="${!i}"
		(( i++ ))
	done
	continue # $i has already been incremented, just continue with the loop

    elif [ "$a" == "--relay" ]; then
        (( i++ ))
        relaylist[${#relaylist[@]}]="${!i}"

    elif [ "$a" == "--out-dir" ]; then
        (( i++ ))
        outdir="${!i}"

    elif [ "$a" == "-ldl" ]; then
        # libdl won't ever be supported by relaytool, so just pass it to stdout
        echo -n "$a "

    elif [ "${a:0:2}" == "-l" ]; then
        lib="${a:2}"
        
        # is this lib meant to be relayed?
        if $replace_all; then
            found=true
        else
            found=false
            for b in ${relaylist[@]}; do
                if [ "$b" == "$lib" ]; then
                    found=true
                fi
            done
        fi

        if $found && $arch_ok; then
        
            # yes, so let's find its absolute filename by checking in each search path directory
            spfound=false
            for d in ${searchpath[@]}; do
                if [ -e "$d/lib$lib.so" ]; then
                
                    absname=$( readfinallink "$d/lib$lib.so" )
                    if [ $? != 0 ] || [ ! -f "$absname" ]; then
                        error broken symlink "$absname"
                    fi
                    
                    stubfile=$( relay "$absname" )

                    # now we have to compile the stub
                    if [ $? == 0 ]; then
                        stubobj=$( echo "$stubfile" | sed 's/\.c$/\.o/' )
                        # remove -include flags from CFLAGS, if any
                        CFLAGS=$( echo $CFLAGS | sed 's/-include .*\.h//g' )
                        if [ -e /dev/tty ]; then
                            ${CC:-gcc} ${CFLAGS} -fPIC -c -o "$stubobj" "$stubfile" 2>/dev/tty
                        else
                            ${CC:-gcc} ${CFLAGS} -fPIC -c -o "$stubobj" "$stubfile"
                        fi
                        echo -n "$stubobj "
                    fi

                    if $no_replace; then
                        echo -n "-l$lib "
                    fi
                    
                    spfound=true
                    break;
                fi
            done

            if ! $spfound; then
                error could not find "$lib" in search path
            fi
        elif $found && ! $arch_ok; then
            # yes, so let's find its absolute filename by checking in each search path directory
            spfound=false
            for d in ${searchpath[@]}; do
                if [ -e "$d/lib$lib.so" ]; then
                
                    absname=$( readfinallink "$d/lib$lib.so" )
                    if [ $? != 0 ] || [ ! -f "$absname" ]; then
                        error broken symlink "$absname"
                    fi
                    
                    # Create a stub C source that just contains dummy 
                    # libwhatever_... support functions
                    stubfile=$( fakerelay "$absname" )

                    # now we have to compile the stub
                    if [ $? == 0 ]; then
                        stubobj=$( echo "$stubfile" | sed 's/\.c$/\.o/' )
                        # remove -include flags from CFLAGS, if any
                        CFLAGS=$( echo $CFLAGS | sed 's/-include .*\.h//g' )
                        if [ -e /dev/tty ]; then
                            ${CC:-gcc} ${CFLAGS} -fPIC -c -o "$stubobj" "$stubfile" 2>/dev/tty
                        else
                            ${CC:-gcc} ${CFLAGS} -fPIC -c -o "$stubobj" "$stubfile"
                        fi
                        echo -n "$stubobj "
                    fi

                    if $no_replace; then
                        echo -n "-l$lib "
                    fi
                    
                    spfound=true
                    break;
                fi
            done

            if ! $spfound; then
                error could not find "$lib" in search path
            fi
        else
            echo -n "$a "
        fi
        
    else
        # just copy whatever we don't recognise
        echo -n "$a "
    fi
    
    (( i++ ))
done
echo