/* work.cpp -- main work driver

   This file is part of the UPX executable compressor.

   Copyright (C) 1996-2025 Markus Franz Xaver Johannes Oberhumer
   Copyright (C) 1996-2025 Laszlo Molnar
   All Rights Reserved.

   UPX and the UCL library are free software; you can redistribute them
   and/or modify them 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; see the file COPYING.
   If not, write to the Free Software Foundation, Inc.,
   59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.

   Markus F.X.J. Oberhumer              Laszlo Molnar
   <markus@oberhumer.com>               <ezerotven+github@gmail.com>
 */

// This file implements the central loop, and it uses class PackMaster to
// dispatch. PackMaster by itself will instantiate a concrete subclass of
// class PackerBase which then does the actual work; search for "HERE".
// And see p_com.cpp for a simple executable format.
//
// Additionally this file also has the burden to deal with all those pesky
// low-level file handling issues.

#define WANT_WINDOWS_LEAN_H 1 // _get_osfhandle, GetFileTime, SetFileTime
#include "util/system_headers.h"
#if USE_UTIMENSAT
#include <sys/types.h>
#include <fcntl.h>
#include <sys/stat.h>
#endif
#include "conf.h"
#include "file.h"
#include "packmast.h"
#include "ui.h"
#include "util/membuffer.h"

#if USE_UTIMENSAT && defined(AT_FDCWD)
#elif defined(_WIN32) || defined(__CYGWIN__)
#define USE_SETFILETIME 1
#elif (ACC_OS_DOS32) && defined(__DJGPP__)
#define USE_FTIME 1
#elif ((ACC_OS_WIN32 || ACC_OS_WIN64) && (ACC_CC_INTELC || ACC_CC_MSC))
#define USE__FUTIME 1
#elif HAVE_UTIME
#define USE_UTIME 1
#endif

#if !defined(SH_DENYRW)
#define SH_DENYRW (-1)
#endif
#if !defined(SH_DENYWR)
#define SH_DENYWR (-1)
#endif

/*************************************************************************
// file util
**************************************************************************/

namespace {

struct XStat final {
    struct stat st;
#if USE_SETFILETIME
    FILETIME ft_atime;
    FILETIME ft_mtime;
#elif USE_FTIME
    struct ftime ft_ftime;
#endif
};

// ignore errors in some cases and silence __attribute__((__warn_unused_result__))
#define IGNORE_ERROR(var) ACC_UNUSED(var)

enum OpenMode { RO_MUST_EXIST, WO_MUST_EXIST_TRUNCATE, WO_MUST_CREATE, WO_CREATE_OR_TRUNCATE };

static constexpr int get_open_flags(OpenMode om) noexcept {
    constexpr int wo_flags = O_WRONLY | O_BINARY;
    if (om == WO_MUST_EXIST_TRUNCATE)
        return wo_flags | O_TRUNC; // will cause an error if file does not exist
    if (om == WO_MUST_CREATE)
        return wo_flags | O_CREAT | O_EXCL; // will cause an error if file already exists
    if (om == WO_CREATE_OR_TRUNCATE)
        return wo_flags | O_CREAT | O_TRUNC; // create if not exists, otherwise truncate
    // RO_MUST_EXIST
    return O_RDONLY | O_BINARY; // will cause an error if file does not exist
}

// set file time of an open file
static void set_fd_timestamp(int fd, const XStat *xst) noexcept {
#if USE_SETFILETIME
    BOOL r = SetFileTime((HANDLE) _get_osfhandle(fd), nullptr, &xst->ft_atime, &xst->ft_mtime);
    IGNORE_ERROR(r);
#elif USE_FTIME
    struct ftime ft_ftime = xst->ft_ftime; // djgpp2 libc bug/feature: not const, so use a copy
    int r = setftime(fd, &ft_ftime);
    IGNORE_ERROR(r);
#elif USE__FUTIME
    struct _utimbuf u = {};
    u.actime = xst->st.st_atime;
    u.modtime = xst->st.st_mtime;
    int r = _futime(fd, &u);
    IGNORE_ERROR(r);
#endif
    // maybe unused
    UNUSED(fd);
    UNUSED(xst);
}

static void copy_file_contents(const char *iname, const char *oname, OpenMode om,
                               const XStat *oname_timestamp) may_throw {
    InputFile fi;
    fi.sopen(iname, get_open_flags(RO_MUST_EXIST), SH_DENYWR);
    fi.seek(0, SEEK_SET);
    int flags = get_open_flags(om);
    int shmode = SH_DENYWR;
    int omode = 0600; // affected by umask; ignored unless O_CREAT
    OutputFile fo;
    fo.sopen(oname, flags, shmode, omode);
    fo.seek(0, SEEK_SET);
    MemBuffer buf(256 * 1024 * 1024);
    for (;;) {
        size_t bytes = fi.read(buf, buf.getSize());
        if (bytes == 0)
            break;
        fo.write(buf, bytes);
    }
    if (oname_timestamp != nullptr)
        set_fd_timestamp(fo.getFd(), oname_timestamp);
    fi.closex();
    fo.closex();
}

static void copy_file_attributes(const XStat *xst, const char *oname, bool preserve_mode,
                                 bool preserve_ownership, bool preserve_timestamp) noexcept {
    const struct stat *const st = &xst->st;
    // copy time stamp
    if (preserve_timestamp) {
#if USE_UTIMENSAT && defined(AT_FDCWD)
        struct timespec times[2] = {};
#if HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC
        // macOS
        times[0] = st->st_atimespec;
        times[1] = st->st_mtimespec;
#else
        // POSIX.1-2008
        times[0] = st->st_atim;
        times[1] = st->st_mtim;
#endif
        int r = utimensat(AT_FDCWD, oname, &times[0], 0);
        IGNORE_ERROR(r);
#elif USE_UTIME
        struct utimbuf u = {};
        u.actime = st->st_atime;
        u.modtime = st->st_mtime;
        int r = utime(oname, &u);
        IGNORE_ERROR(r);
#endif
    }
#if HAVE_CHOWN
    // copy the group ownership
    if (preserve_ownership) {
        int r = chown(oname, -1, st->st_gid);
        IGNORE_ERROR(r);
    }
#endif
#if HAVE_CHMOD
    // copy permissions
    if (preserve_mode) {
        int r = chmod(oname, st->st_mode);
        IGNORE_ERROR(r);
    }
#endif
#if HAVE_CHOWN
    // copy the user ownership
    if (preserve_ownership) {
        int r = chown(oname, st->st_uid, -1);
        IGNORE_ERROR(r);
    }
#endif
    // maybe unused
    UNUSED(xst);
    UNUSED(st);
    UNUSED(oname);
    UNUSED(preserve_mode);
    UNUSED(preserve_ownership);
    UNUSED(preserve_timestamp);
}

} // namespace

/*************************************************************************
// process one file
**************************************************************************/

void do_one_file(const char *const iname, char *const oname) may_throw {
    oname[0] = 0; // make empty

    // check iname stat
    XStat xst = {};
    struct stat &st = xst.st;
#if HAVE_LSTAT
    int rr = lstat(iname, &st);
#else
    int rr = stat(iname, &st);
#endif
    if (rr != 0) {
        if (errno == ENOENT)
            throw FileNotFoundException(iname, errno);
        else
            throwIOException(iname, errno);
    }
#if HAVE_LSTAT
    if (S_ISLNK(st.st_mode))
        throwIOException("is a symlink -- skipped");
#endif
    if (S_ISDIR(st.st_mode))
        throwIOException("is a directory -- skipped");
    if (!(S_ISREG(st.st_mode)))
        throwIOException("not a regular file -- skipped");
#if defined(__unix__)
    // no special bits may be set
    if ((st.st_mode & (S_ISUID | S_ISGID | S_ISVTX)) != 0)
        throwIOException("file has special permissions -- skipped");
#endif
    if (st.st_size <= 0)
        throwIOException("empty file -- skipped");
    if (st.st_size < 512)
        throwIOException("file is too small -- skipped");
    if (!mem_size_valid_bytes(st.st_size))
        throwIOException("file is too large -- skipped");
    if ((st.st_mode & S_IWUSR) == 0) {
        bool skip = true;
        if (opt->output_name)
            skip = false;
        else if (opt->to_stdout)
            skip = false;
        else if (opt->backup)
            skip = false;
        if (skip)
            throwIOException("file is write protected -- skipped");
    }

    // open input file
    InputFile fi;
    fi.sopen(iname, get_open_flags(RO_MUST_EXIST), SH_DENYWR);

    if (opt->preserve_timestamp) {
#if USE_SETFILETIME
        if (GetFileTime((HANDLE) _get_osfhandle(fi.getFd()), nullptr, &xst.ft_atime,
                        &xst.ft_mtime) == 0)
            throwIOException("cannot determine file timestamp");
#elif USE_FTIME
        if (getftime(fi.getFd(), &xst.ft_ftime) != 0)
            throwIOException("cannot determine file timestamp");
#endif
    }

    // open output file
    // NOTE: only use "preserve_link" if you really need it, e.g. it can fail
    //   with ETXTBSY and other unexpected errors; renaming files is much safer
    OutputFile fo;
    bool preserve_link = opt->preserve_link;
    bool copy_timestamp_only = false;
    if (opt->cmd == CMD_COMPRESS || opt->cmd == CMD_DECOMPRESS) {
        if (opt->to_stdout) {
            preserve_link = false; // not needed
            if (!fo.openStdout(1, opt->force ? true : false))
                throwIOException("data not written to a terminal; Use '-f' to force.");
        } else {
            char tname[ACC_FN_PATH_MAX + 1];
            if (opt->output_name) {
                strcpy(tname, opt->output_name);
                if ((opt->force_overwrite || opt->force >= 2) && !preserve_link)
                    (void) FileBase::unlink_noexcept(tname); // IGNORE_ERROR
            } else {
                if (st.st_nlink < 2)
                    preserve_link = false; // not needed
                if (!maketempname(tname, sizeof(tname), iname, ".upx"))
                    throwIOException("could not create a temporary file name");
            }
            int flags = get_open_flags(WO_MUST_CREATE); // don't overwrite files by default
            if (opt->output_name && preserve_link) {
                flags = get_open_flags(WO_CREATE_OR_TRUNCATE);
#if HAVE_LSTAT
                struct stat ost = {};
                int r = lstat(tname, &ost);
                if (r == 0 && S_ISREG(ost.st_mode)) {
                    preserve_link = ost.st_nlink >= 2;
                } else if (r == 0 && S_ISLNK(ost.st_mode)) {
                    // output_name is a symlink (valid or dangling)
                    (void) FileBase::unlink_noexcept(tname); // IGNORE_ERROR
                    preserve_link = false;                   // not needed
                } else {
                    preserve_link = false; // not needed
                }
#endif
                if (preserve_link) {
                    flags = get_open_flags(WO_MUST_EXIST_TRUNCATE);
                    copy_timestamp_only = true;
                }
            } else if (opt->force_overwrite || opt->force) {
                flags = get_open_flags(WO_CREATE_OR_TRUNCATE);
            }
            int shmode = SH_DENYWR;
#if (ACC_ARCH_M68K && ACC_OS_TOS && ACC_CC_GNUC) && defined(__MINT__)
            // TODO later: check current mintlib if this hack is still needed
            flags |= O_TRUNC;
            shmode = O_DENYRW;
#endif
            // cannot rely on open() because of umask
            // int omode = st.st_mode | 0600;
            int omode = opt->preserve_mode ? 0600 : 0666; // affected by umask; only for O_CREAT
            fo.sopen(tname, flags, shmode, omode);
            // open succeeded - now set oname[]
            strcpy(oname, tname);
        }
    }

    // handle command - actual work starts HERE
    PackMaster pm(&fi, opt);
    if (opt->cmd == CMD_COMPRESS)
        pm.pack(&fo);
    else if (opt->cmd == CMD_DECOMPRESS)
        pm.unpack(&fo);
    else if (opt->cmd == CMD_TEST)
        pm.test();
    else if (opt->cmd == CMD_LIST)
        pm.list();
    else if (opt->cmd == CMD_FILEINFO)
        pm.fileInfo();
    else
        throwInternalError("invalid command");

    // copy time stamp
    if (oname[0] && opt->preserve_timestamp && fo.isOpen())
        set_fd_timestamp(fo.getFd(), &xst);

    // close files
    fi.closex();
    fo.closex();

    // rename or copy files
    if (oname[0] && !opt->output_name) {
        // both iname and oname do exist; rename oname to iname
        if (opt->backup) {
            char bakname[ACC_FN_PATH_MAX + 1];
            if (!makebakname(bakname, sizeof(bakname), iname))
                throwIOException("could not create a backup file name");
            if (preserve_link) {
                copy_file_contents(iname, bakname, WO_MUST_CREATE, &xst);
                copy_file_attributes(&xst, bakname, true, true, true);
                const XStat *xstamp = opt->preserve_timestamp ? &xst : nullptr;
                copy_file_contents(oname, iname, WO_MUST_EXIST_TRUNCATE, xstamp);
                FileBase::unlink(oname);
                copy_timestamp_only = true;
            } else {
                FileBase::rename(iname, bakname);
                FileBase::rename(oname, iname);
            }
        } else if (preserve_link) {
            const XStat *xstamp = opt->preserve_timestamp ? &xst : nullptr;
            copy_file_contents(oname, iname, WO_MUST_EXIST_TRUNCATE, xstamp);
            FileBase::unlink(oname);
            copy_timestamp_only = true;
        } else {
            FileBase::unlink(iname);
            FileBase::rename(oname, iname);
        }
        // now iname is the new packed/unpacked file and oname does not exist any longer
    }

    // copy file attributes
    if (oname[0]) {
        oname[0] = 0; // done with oname
        const char *name = opt->output_name ? opt->output_name : iname;
        if (copy_timestamp_only)
            copy_file_attributes(&xst, name, false, false, opt->preserve_timestamp);
        else
            copy_file_attributes(&xst, name, opt->preserve_mode, opt->preserve_ownership,
                                 opt->preserve_timestamp);
    }

    UiPacker::uiConfirmUpdate();
}

/*************************************************************************
// process all files from the commandline
**************************************************************************/

static void unlink_ofile(char *oname) noexcept {
    if (oname && oname[0]) {
        (void) FileBase::unlink_noexcept(oname); // IGNORE_ERROR
        oname[0] = 0;                            // done with oname
    }
}

int do_files(int i, int argc, char *argv[]) may_throw {
    upx_compiler_sanity_check();
    if (opt->verbose >= 1) {
        show_header();
        UiPacker::uiHeader();
    }

    for (; i < argc; i++) {
        infoHeader();

        const char *const iname = argv[i];
        char oname[ACC_FN_PATH_MAX + 1];
        oname[0] = 0;

        try {
            do_one_file(iname, oname);
        } catch (const Exception &e) {
            unlink_ofile(oname);
            if (opt->verbose >= 1 || (opt->verbose >= 0 && !e.isWarning()))
                printErr(iname, e);
            main_set_exit_code(e.isWarning() ? EXIT_WARN : EXIT_ERROR);
            // this is not fatal, continue processing more files
        } catch (const Error &e) {
            unlink_ofile(oname);
            printErr(iname, e);
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        } catch (std::bad_alloc *e) {
            unlink_ofile(oname);
            printErr(iname, "out of memory");
            UNUSED(e);
            // delete e;
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        } catch (const std::bad_alloc &) {
            unlink_ofile(oname);
            printErr(iname, "out of memory");
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        } catch (std::exception *e) {
            unlink_ofile(oname);
            printUnhandledException(iname, e);
            // delete e;
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        } catch (const std::exception &e) {
            unlink_ofile(oname);
            printUnhandledException(iname, &e);
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        } catch (...) {
            unlink_ofile(oname);
            printUnhandledException(iname, nullptr);
            main_set_exit_code(EXIT_ERROR);
            return -1; // fatal error
        }
    }

    if (opt->cmd == CMD_COMPRESS)
        UiPacker::uiPackTotal();
    else if (opt->cmd == CMD_DECOMPRESS)
        UiPacker::uiUnpackTotal();
    else if (opt->cmd == CMD_LIST)
        UiPacker::uiListTotal();
    else if (opt->cmd == CMD_TEST)
        UiPacker::uiTestTotal();
    else if (opt->cmd == CMD_FILEINFO)
        UiPacker::uiFileInfoTotal();
    return 0;
}

/* vim:set ts=4 sw=4 et: */
