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/****************************  relink.cpp  ***********************************

* Author:        Agner Fog

* date created:  2017-12-07

* Last modified: 2018-03-30

* Version:       1.10

* Project:       Binary tools for ForwardCom instruction set

* Description:

* This module contains the relinking feature of the linker.

*

* Copyright 2017-2020 GNU General Public License http://www.gnu.org/licenses

*****************************************************************************/

#include "stdafx.h"

// load executable file to be relinked

void CLinker::loadExeFile() {

    // Read input file

    const char * inputFileName = cmd.getFilename(cmd.inputFile);

    inputFile.read(inputFileName);

    if (err.number()) return;

    inputFile.split();

    if (!(inputFile.fileHeader.e_flags & EF_RELINKABLE)) {

        err.submit(ERR_INPUT_NOT_RELINKABLE, inputFileName);

        return;

    }

    // get names of modules and libraries to remove or replace

    getReplaceNames();

#if 0   

    for (int i = 0; i < rnames.numEntries(); i++) {

        printf("\n%4X %s", rnames[i].command, cmd.getFilename(rnames[i].filename));

    }

#endif

    markSectionsInInputFile();

}

// get names of modules and libraries to remove or replace

void CLinker::getReplaceNames() {

    uint32_t i, j;                               // loop counter. command index

    const char * fname;                          // file name or module name

    SLCommand cmd2;                              // copy of command line item

    numObjects = 0;                              // number of object files to add

    numLibraries = 0;                            // number of library files to add

    bool isLib;                                  // file name indicates a library (.li or .a)

    // make a list of removed and replaced modules and libraries

    // and count number of object files and library files

    for (i = 0; i < cmd.lcommands.numEntries(); i++) {

        cmd2.command = 0;

        // name of module

        fname = cmd.getFilename(cmd.lcommands[i].filename);

        // is it a library?

        isLib = false;

        // find last '.'

        for (j = (int32_t)strlen(fname) - 1; j > 0; j--) {

            if (fname[j] == '.') break;

        }

        if ((j > 0 && strncasecmp_(fname + j, ".li", 3) == 0) || fname[j+1] == 'a') {

            isLib = true;

        }

        if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDMODULE) {

            // remove path

            cmd.lcommands[i].value = cmd.fileNameBuffer.pushString(removePath(fname));

            if (isLib) {                // this is a library

                numLibraries++;

                cmd.lcommands[i].command = CMDL_LINK_ADDLIBRARY | (cmd.lcommands[i].command & CMDL_LINK_RELINKABLE);

            }

            else {                  // assume that this is an object file

                numObjects++;

            }

            cmd2 = cmd.lcommands[i];

            cmd2.command |= CMDL_LINK_REPLACE;

        }

        if ((cmd.lcommands[i].command & 0xFF) == CMDL_LINK_ADDLIBMODULE) {

            // object module from library file

            // remove path

            cmd.lcommands[i].value = cmd.fileNameBuffer.pushString(removePath(fname));

            numObjects++;

            cmd2 = cmd.lcommands[i];

            cmd2.command |= CMDL_LINK_REPLACE;

        }

        if ((uint8_t)cmd.lcommands[i].command == CMDL_LINK_REMOVE) {

            // remove module from relinkable file

            // remove path

            cmd.lcommands[i].value = cmd.fileNameBuffer.pushString(removePath(fname));

            cmd2 = cmd.lcommands[i];

            if (isLib) cmd2.command |= CMDL_LINK_ADDLIBRARY;

            else cmd2.command |= CMDL_LINK_ADDMODULE;

        }

        // add command to rnames

        if (cmd2.command) {

            int32_t r = rnames.findFirst(cmd2);

            if (r >= 0) {

                // already in list. combine commands

                rnames[r].command |= cmd2.command;

            }

            else {

                // new name. add to list

                rnames.addUnique(cmd2);

            }

        }

    }

}

// check which sections to keep or remove in executable input file,

// and make list of modules and libraries to relink

void CLinker::markSectionsInInputFile() {

    uint32_t sec;                      // section index

    uint32_t rec;                      // rnames index

    const char * modName;              // module name

    const char * libName;              // library name

    SLCommand cmdrec;                  // command record used only for name search

    SRelinkModule relModul;            // name of relinked module

    zeroAllMembers(cmdrec);

    for (sec = 0; sec < inputFile.sectionHeaders.numEntries(); sec++) {

        ElfFwcShdr secHdr = inputFile.sectionHeaders[sec];

        if (secHdr.sh_type == 0) continue;

        inputFile.sectionHeaders[sec].sh_relink = 0;

        if (secHdr.sh_module && secHdr.sh_module < inputFile.secStringTableLen) {

            modName = inputFile.secStringTable + secHdr.sh_module;

        }

        else modName = "";

        if (secHdr.sh_library && secHdr.sh_library < inputFile.secStringTableLen) {

            libName = inputFile.secStringTable + secHdr.sh_library;

        }

        else libName = "";

        // search for module name and library name in rnames

        zeroAllMembers(cmdrec);

        zeroAllMembers(relModul);

        if (modName[0]) {

            cmdrec.value = relModul.moduleName = cmd.fileNameBuffer.pushString(modName);

            int32_t f1 = rnames.findFirst(cmdrec);

            if (f1 >= 0) {

                // module name is in list

                rnames[f1].command |= CMD_NAME_FOUND;  // mark name found

                cmdrec.command = rnames[f1].command & ~CMDL_LINK_ADDLIBRARY;

                if (inputFile.sectionHeaders[sec].sh_flags & SHF_RELINK) {

                    inputFile.sectionHeaders[sec].sh_relink = (uint8_t)rnames[f1].command; // mark section for replace or delete

                }

                else {

                    err.submit(ERR_CANT_RELINK_MODULE, modName);

                }

            }

        }

        if (libName[0]) {

            cmdrec.value = relModul.libraryName = cmd.fileNameBuffer.pushString(libName);

            int32_t f2 = rnames.findFirst(cmdrec);

            if (f2 >= 0) {

                // library name is in list

                rnames[f2].command |= CMD_NAME_FOUND;  // mark name found

                cmdrec.command = rnames[f2].command | CMDL_LINK_ADDLIBRARY;

                if (inputFile.sectionHeaders[sec].sh_flags & SHF_RELINK) {

                    inputFile.sectionHeaders[sec].sh_relink |= (uint8_t)rnames[f2].command; // mark section for replace or delete

                }

                else {

                    err.submit(ERR_CANT_RELINK_LIBRARY, modName);

                }

            }

        }

        // add module or library to relinkModules list unless it is removed or replaced

        if (cmdrec.value && !(cmdrec.command & (CMDL_LINK_REMOVE | CMDL_LINK_REPLACE))) {

            relinkModules.addUnique(relModul);

        }

#if 0   // testing only: list sections

        const char * secName;              // section name

        if (secHdr.sh_name < inputFile.stringBuffer.dataSize()) {

            secName = inputFile.stringBuffer.getString(secHdr.sh_name);

        }

        else secName = "";

        printf("\n: %2i >> %s %s %s %2X", sec, secName, libName, modName, inputFile.sectionHeaders[sec].sh_relink);

#endif

    }

#if 0   // testing only: list kept modules and libraries

    for (rec = 0; rec < relinkModules.numEntries(); rec++) {

        printf("\n# %s:%s", cmd.getFilename(relinkModules[rec].libraryName), cmd.getFilename(relinkModules[rec].moduleName));

    }

#endif

    // check if all remove/replace records in rnames have been matched by sections in input file

    for (rec = 0; rec < rnames.numEntries(); rec++) {

        if ((rnames[rec].command & CMDL_LINK_REMOVE) && !(rnames[rec].command & CMD_NAME_FOUND)) {

            // unmatched name

            modName = cmd.getFilename(uint32_t(rnames[rec].value));

            if (rnames[rec].command & CMDL_LINK_ADDMODULE) {

                err.submit(ERR_RELINK_MODULE_NOT_FOUND, modName);

            }

            else {

                err.submit(ERR_RELINK_LIBRARY_NOT_FOUND, modName);

            }

        }

    }

}

// extract a module from executable input file

void CLinker::extractModule(CELF & modul, uint32_t libname, uint32_t name) {

    // libname: library name as index into cmd.fileNameBuffer. Zero if not a library member

    // name: module name as index into cmd.fileNameBuffer. Zero to build a module of all non-relinkable sections

    uint32_t sec;                                // section index in inputFile

    uint32_t seci;                               // section index in modul

    uint32_t sym;                                // symbol index in inputFile

    uint32_t symi;                               // symbol index in modul

    uint32_t rel;                                // relocation index in inputFile

    const char * modName;                        // module name of section

    const char * libName;                        // library name of library

    const char * modName1;                       // module name to search for

    const char * libName1;                       // library name to search for

    uint32_t * symp;                             // pointer to symbol index

    modName1 = cmd.getFilename(name);            // will be "" if name = 0

    libName1 = cmd.getFilename(libname);         // will be "" if libname = 0

    CDynamicArray<uint32_t> symbolTranslate;     // list for translating symbol indexes from inputFile to modul

    CDynamicArray<uint32_t> sectionTranslate;    // list for translating section indexes from inputFile to modul

    CDynamicArray<SSymbol2> externalSymbols;     // list of external symbols referenced by current module    

    CDynamicArray<uint32_t> symbolTranslate2;    // list for translating symbol indexes from externalSymbols to modul

    ElfFwcSym symrec;                           // symbol record

    // prepare translation of symbol indexes

    symbolTranslate.setNum(inputFile.symbols.numEntries());

    sectionTranslate.setNum(inputFile.sectionHeaders.numEntries());

    zeroAllMembers(symrec);

    modul.addSymbol(symrec, inputFile.stringBuffer);  // make symbol zero empty

    // loop through sections of input file

    for (sec = 0; sec < inputFile.sectionHeaders.numEntries(); sec++) {

        ElfFwcShdr secHdr = inputFile.sectionHeaders[sec];

        if (secHdr.sh_type == 0) continue;     // skip first empty section

        if (secHdr.sh_flags & SHF_RELINK) {

            // relinkable section. check name match

            if (secHdr.sh_module && secHdr.sh_module < inputFile.secStringTableLen) {

                modName = inputFile.secStringTable + secHdr.sh_module;

            }

            else continue;

            if (strcmp(modName, modName1) != 0) continue; // name doesn't match

            // check library name

            if (secHdr.sh_library && secHdr.sh_library < inputFile.secStringTableLen) {

                libName = inputFile.secStringTable + secHdr.sh_library;

                if (libname == 0) continue;  // library member not requested

                if (strcmp(libName, libName1) != 0) continue; // library name doesn't match

            }

            else if (libname) continue;  // not a library member

        }

        else {

            // non-relinkable section

            if (name || libname) continue;      // name = 0 for collecting non-relinkable sections

            // non-relinkable sections must have fixed addresses relative to each other because the

            // corresponding relocation records are not preserved.

            // Insert address relative to ip_base, datap_base, or threadp_base:

            switch (secHdr.sh_flags & SHF_BASEPOINTER) {

            case SHF_IP:

                secHdr.sh_addr = secHdr.sh_addr - inputFile.fileHeader.e_ip_base;

                break;

            case SHF_DATAP:

                secHdr.sh_addr = secHdr.sh_addr - inputFile.fileHeader.e_datap_base;

                break;

            case SHF_THREADP:

                secHdr.sh_addr = secHdr.sh_addr - inputFile.fileHeader.e_threadp_base;

                break;

            }

        }

        // all sections that do not match name and libname have been skipped now

        if (secHdr.sh_flags & SHF_AUTOGEN) continue; // auto-generated section. will be re-made

        // add this section to the module

        seci = modul.addSection(secHdr, inputFile.stringBuffer, inputFile.dataBuffer);

        sectionTranslate[sec] = seci;

        // find symbols in this section

        for (sym = 0; sym < inputFile.symbols.numEntries(); sym++) {

            if (inputFile.symbols[sym].st_section == sec) {

                // save symbol

                symrec = inputFile.symbols[sym];

                symrec.st_section = seci;

                symi = modul.addSymbol(symrec, inputFile.stringBuffer);

                symbolTranslate[sym] = symi;

            }

        }

    }

    // find relocations in any section belonging to this module

    for (rel = 0; rel < inputFile.relocations.numEntries(); rel++) {

        sec = inputFile.relocations[rel].r_section;

        if (sec < sectionTranslate.numEntries()) {

            seci = sectionTranslate[sec];

            if (seci) {

                ElfFwcReloc reloc = inputFile.relocations[rel];

                reloc.r_section = seci;

                // loop to cover both symbol and reference symbol in relocation record

                for (int i = 0; i < 2; i++) {

                    symp = i ? &reloc.r_refsym : &reloc.r_sym;

                    if (*symp) {

                        // there is a symbol index

                        if (*symp < symbolTranslate.numEntries() && symbolTranslate[*symp]) {

                            // symbol is in same module. Translate to index in modul

                            *symp = symbolTranslate[*symp];

                        }

                        else if (*symp < inputFile.symbols.numEntries()) {

                            // symbol is external. make external symbol record

                            SSymbol2 symbol2 = inputFile.symbols[*symp];

                            symbol2.st_section = 0;      // make symbol external

                            symbol2.st_value = 0;

                            // put symbol name in global symbolNameBuffer for the purpose of sorting

                            if (symbol2.st_name >= inputFile.stringBuffer.dataSize()) {

                                err.submit(ERR_ELF_INDEX_RANGE);  return;

                            }

                            const char * symname = (char*)inputFile.stringBuffer.buf() + symbol2.st_name;

                            symbol2.st_name = symbolNameBuffer.pushString(symname);

                            // add to list of external symbols, avoid duplicates

                            externalSymbols.addUnique(symbol2);

                            // remember that symbol index is not resolved yet

                            *symp |= 0x80000000;

                        }

                        else err.submit(ERR_ELF_INDEX_RANGE);

                    }

                }

                // save relocation record

                modul.addRelocation(reloc);

            }

        }

    }

    // add external symbols to modul and remember new indexes

    symbolTranslate2.setNum(externalSymbols.numEntries());

    for (sym = 0; sym < externalSymbols.numEntries(); sym++) {

        symrec = externalSymbols[sym];

        if (symrec.st_bind == STB_UNRESOLVED) {

            symrec.st_bind = STB_GLOBAL;     // unresolved symbol from incomplete executable. attempt to resolve it again

        }

        symbolTranslate2[sym] = modul.addSymbol(symrec, symbolNameBuffer);

    }

    // resolve external symbol indexes in relocation records in new module

    for (rel = 0; rel < modul.relocations.numEntries(); rel++) {

        ElfFwcReloc & modulReloc = modul.relocations[rel];

        // loop to cover both symbol and reference symbol in relocation record

        for (int i = 0; i < 2; i++) {

            uint32_t * symp = i ? &modulReloc.r_refsym : &modulReloc.r_sym;

            if (*symp & 0x80000000) {

                // find symbol index in externalSymbols

                SSymbol2 sym2 = inputFile.symbols[*symp & 0x7FFFFFFF];

                const char * symname = (char*)inputFile.stringBuffer.buf() + sym2.st_name;

                sym2.st_name = symbolNameBuffer.pushString(symname);

                int32_t eindex = externalSymbols.findFirst(sym2);

                if (eindex < 0) {

                    err.submit(ERR_INDEX_OUT_OF_RANGE); // should not occur

                    return;

                }

                *symp = symbolTranslate2[(uint32_t)eindex];

            }

        }

    }

    ElfFwcEhdr head;

    zeroAllMembers(head);

    modul.join(&head);

}

// count number of modules and libraries to reuse when relinking

void CLinker::countReusedModules() {

    uint32_t rec;                                          // record index

    const char * libname;                                  // library name

    const char * lastlibname = "";                         // library name of preceding record

    numRelinkObjects = 1;                                  // including modules1[0] which contains all reused non-relinkable modules

    numRelinkLibraries = 0;                                // number of relinkable modules

    // this is counted as one, even if unused

    if (cmd.job != CMDL_JOB_RELINK) return;                // not relinking

    // loop through relinkModules list

    for (rec = 0; rec < relinkModules.numEntries(); rec++) {

        if (relinkModules[rec].libraryName) {

            libname = cmd.getFilename(relinkModules[rec].libraryName);

            if (rec > 0 && strcmp(libname, lastlibname) == 0) {

                continue;  // multiple modules from same library: count only once

            }

            lastlibname = libname;

            numRelinkLibraries++;

        }

        else if (relinkModules[rec].moduleName) numRelinkObjects++;

    }

}

// get all relinked objects into modules1 metabuffer

void CLinker::getRelinkObjects() {

    uint32_t rec;                                          // record index

    uint32_t mod = 0;                                      // module index

    uint32_t sec = 0;                                      // section index

    const char * modname;                                  // module name

    // join all non-relinkable sections into first entry

    extractModule(modules1[0], 0, 0);

    mod++;

#if 1 // testing: write module file

    modules1[0].write("ff.ob");

#endif

    // mark all sections for fixed position because they have already been relocated

    for (sec = 0; sec < modules1[0].sectionHeaders.numEntries(); sec++) {

        modules1[0].sectionHeaders[sec].sh_flags |= SHF_FIXED;

    }

    if (cmd.verbose && numRelinkObjects > 1) {

        printf("\nReusing object modules:");

    }

    // loop through relinkModules list to search for non-library modules

    for (rec = 0; rec < relinkModules.numEntries(); rec++) {

        if (relinkModules[rec].libraryName == 0 && relinkModules[rec].moduleName != 0) {

            extractModule(modules1[mod], 0, relinkModules[rec].moduleName);

            modules1[mod].moduleName = relinkModules[rec].moduleName;

            modules1[mod].relinkable = true;

            extractModuleToFile(modules1[mod]);  // possibly extract to file

            mod++;

            // write name

            if (cmd.verbose) {

                modname = cmd.getFilename(relinkModules[rec].moduleName);

                printf(" %s", modname);

            }

        }

    }

}

// extract a module from relinkable file if requested

void CLinker::extractModuleToFile(CELF & modu) {

    // search for extract command

    if (!(cmd.libraryOptions & CMDL_LIBRARY_EXTRACTMEM)) return;

    uint32_t i;                                  // loop counter

    const char * modname1;                       // module name

    const char * modname2;                       // module name on command line

    bool extract = false;

    modname1 = cmd.getFilename(modu.moduleName);

    if (modname1[0] == 0) return;

    if (cmd.libraryOptions == CMDL_LIBRARY_EXTRACTALL) extract = true;

    for (i = 0; i < cmd.lcommands.numEntries(); i++) {

        if (cmd.lcommands[i].command == CMDL_LINK_EXTRACT) {

            // name of module

            modname2 = cmd.getFilename(cmd.lcommands[i].filename);

            if (strcmp(modname1, modname2) == 0) {

                extract = true;

                break;

            }

        }

    }

    if (!extract) return;                        // no request for extracting this module

    // make new name = old name prefixed by "x_"

    uint32_t newname = cmd.fileNameBuffer.dataSize();

    cmd.fileNameBuffer.push("x_", 2);

    cmd.fileNameBuffer.pushString(modname1);

    modname2 = cmd.getFilename(newname);

    modu.write(modname2);

}

// recover relinkable library modules

void CLinker::getRelinkLibraries() {

    if (cmd.job != CMDL_JOB_RELINK) return;                // not relinking

    uint32_t rec;                                          // record index

    const char * libname;                                  // library name

    const char * nextlibname = "";                         // library name of next record

    const char * modname;                                  // module name

    uint32_t iLibrary = numLibraries + 1;                  // library index

    CELF modul;                                            // recovered library module

    if (cmd.verbose && numRelinkLibraries) {

        printf("\nRecovering library modules:");

    }

    // loop through relinkModules list, looking for library modules

    for (rec = 0; rec < relinkModules.numEntries(); rec++) {

        if (relinkModules[rec].libraryName && relinkModules[rec].moduleName) {

            libname = cmd.getFilename(relinkModules[rec].libraryName);

            modname = cmd.getFilename(relinkModules[rec].moduleName);

            if (cmd.verbose) {

                printf(" %s:%s", libname, modname);

            }

            // extract library module from relinkable input file

            modul.reset();

            extractModule(modul, relinkModules[rec].libraryName, relinkModules[rec].moduleName);

            modul.moduleName = relinkModules[rec].moduleName;

            modul.library = iLibrary; //??

            extractModuleToFile(modul);          // extract to file if requested

            // build internal library

            libraries[iLibrary].addELF(modul);

            if (rec + 1 < relinkModules.numEntries()) {

                nextlibname = cmd.getFilename(relinkModules[rec+1].libraryName);

            }

            else nextlibname = "?/";

            if (strcmp(libname, nextlibname) != 0) {

                // last module for this library. Finish internal library

                libraries[iLibrary].makeInternalLibrary();

                libraries[iLibrary].libraryName = relinkModules[rec].libraryName;

                libraries[iLibrary].relinkable = true;

                iLibrary++;

            }

        }

    }

}

// write feedback to console

void CLinker::feedBackText2() {

    if (!(cmd.verbose)) return;                  // write feedback only if verbose

    uint32_t i;                                  // loop counter

    const char * name;                           // name of file or module

    const char * libname;                        // name of library

    bool written = false;                        // message has been written

    // search for removed objects

    for (i = 0; i < rnames.numEntries(); i++) {

        if (((uint8_t)rnames[i].command & CMDL_LINK_REMOVE) && !((uint8_t)rnames[i].command & CMDL_LINK_ADDLIBRARY)) {

            if (!written) printf("\nRemoving object files:");

            written = true;

            name = cmd.getFilename(uint32_t(rnames[i].value));

            printf(" %s", name);

            if (!(rnames[i].command & CMD_NAME_FOUND)) printf(" failed!");

        }

    }

    // list of added objects have already been written to console.

    // write replaced and removed objects

    written = false;

    // search for replaced objects

    for (i = 0; i < rnames.numEntries(); i++) {

        if ((rnames[i].command & CMDL_LINK_ADDMODULE) && (rnames[i].command & CMD_NAME_FOUND)

            &&!(rnames[i].command & CMDL_LINK_REMOVE)) {

            if (!written) printf("\nReplacing object files:");

            written = true;

            name = cmd.getFilename(uint32_t(rnames[i].value));

            printf(" %s", name);

        }

    }

    written = false;

    // search for removed libraries

    for (i = 0; i < rnames.numEntries(); i++) {

        if ((uint8_t)rnames[i].command == (CMDL_LINK_REMOVE | CMDL_LINK_ADDLIBRARY)) {

            if (!written) printf("\nRemoving library files:");

            written = true;

            name = cmd.getFilename(rnames[i].filename);

            printf(" %s", name);

            if (!(rnames[i].command & CMD_NAME_FOUND)) printf(" failed!");

        }

    }

    written = false;

    // search for added libraries

    for (i = 0; i < rnames.numEntries(); i++) {

        if ((uint8_t)rnames[i].command == (CMDL_LINK_REPLACE | CMDL_LINK_ADDLIBRARY)

            && !(rnames[i].command & CMD_NAME_FOUND)) {

            if (!written) printf("\nAdding library files:");

            written = true;

            name = cmd.getFilename(rnames[i].filename);

            printf(" %s", name);

        }

    }

    written = false;

    // search for replaced libraries

    for (i = 0; i < rnames.numEntries(); i++) {

        if ((rnames[i].command & CMDL_LINK_REPLACE)

            && (rnames[i].command & CMDL_LINK_ADDLIBRARY)

            && (rnames[i].command & CMD_NAME_FOUND)) {

            if (!written) printf("\nReplacing library files:");

            written = true;

            name = cmd.getFilename(rnames[i].filename);

            printf(" %s", name);

        }

    }

    written = false;

    // search for added library members

    for (i = 0; i < libmodules.numEntries(); i++) {

        uint32_t lib = libmodules[i].library & 0x7FFFFFFF;