more: remove kill_line() in favor of erase_prompt()

[thirdparty/util-linux.git] / text-utils / more.c

/*
 * Copyright (C) 1980 The Regents of the University of California.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms are permitted
 * provided that the above copyright notice and this paragraph are
 * duplicated in all such forms and that any documentation,
 * advertising materials, and other materials related to such
 * distribution and use acknowledge that the software was developed
 * by the University of California, Berkeley.  The name of the
 * University may not be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR
 * IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
 */

/* more.c - General purpose tty output filter and file perusal program
 *
 * by Eric Shienbrood, UC Berkeley
 *
 * modified by Geoff Peck
 *      UCB to add underlining, single spacing
 * modified by John Foderaro
 *      UCB to add -c and MORE environment variable
 * modified by Erik Troan <ewt@redhat.com>
 *      to be more posix and so compile on linux/axp.
 * modified by Kars de Jong <jongk@cs.utwente.nl>
 *      to use terminfo instead of termcap.
 * 1999-02-22 Arkadiusz Miśkiewicz <misiek@pld.ORG.PL>
 *      added Native Language Support
 * 1999-03-19 Arnaldo Carvalho de Melo <acme@conectiva.com.br>
 *      more nls translatable strings
 * 1999-05-09 aeb
 *      applied a RedHat patch (setjmp->sigsetjmp); without it a second
 *      ^Z would fail.
 * 1999-05-09 aeb
 *      undone Kars' work, so that more works without libcurses (and
 *      hence can be in /bin with libcurses being in
 *      /usr/lib which may not be mounted).  However, when termcap is not
 *      present curses can still be used.
 * 2010-10-21 Davidlohr Bueso <dave@gnu.org>
 *      modified mem allocation handling for util-linux
 */

#include <stdio.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdarg.h>
#include <sys/param.h>
#include <ctype.h>
#include <signal.h>
#include <errno.h>
#include <fcntl.h>
#include <termios.h>
#include <sys/ioctl.h>
#include <sys/stat.h>
#include <sys/file.h>
#include <sys/ttydefaults.h>
#include <sys/wait.h>
#include <regex.h>
#include <assert.h>
#include <poll.h>
#include <sys/signalfd.h>
#include <paths.h>

#if defined(HAVE_NCURSESW_TERM_H)
# include <ncursesw/term.h>
#elif defined(HAVE_NCURSES_TERM_H)
# include <ncurses/term.h>
#elif defined(HAVE_TERM_H)
# include <term.h>
#endif

#include "strutils.h"
#include "nls.h"
#include "xalloc.h"
#include "widechar.h"
#include "closestream.h"
#include "rpmatch.h"

#ifdef TEST_PROGRAM
# define NON_INTERACTIVE_MORE 1
#endif

#define BACKSPACE       "\b"
#define CARAT           "^"

#define MIN_LINE_SZ     256     /* minimal line_buf buffer size */
#define ESC             '\033'
#define SCROLL_LEN      11
#define LINES_PER_PAGE  24
#define NUM_COLUMNS     80
#define TERMINAL_BUF    4096
#define INIT_BUF        80
#define COMMAND_BUF     200
#define REGERR_BUF      NUM_COLUMNS

#define TERM_AUTO_RIGHT_MARGIN    "am"
#define TERM_BACKSPACE            "cub1"
#define TERM_CEOL                 "xhp"
#define TERM_CLEAR                "clear"
#define TERM_CLEAR_TO_LINE_END    "el"
#define TERM_CLEAR_TO_SCREEN_END  "ed"
#define TERM_COLS                 "cols"
#define TERM_CURSOR_ADDRESS       "cup"
#define TERM_EAT_NEW_LINE         "xenl"
#define TERM_ENTER_UNDERLINE      "smul"
#define TERM_EXIT_STANDARD_MODE   "rmso"
#define TERM_EXIT_UNDERLINE       "rmul"
#define TERM_HARD_COPY            "hc"
#define TERM_HOME                 "home"
#define TERM_LINE_DOWN            "cud1"
#define TERM_LINES                "lines"
#define TERM_OVER_STRIKE          "os"
#define TERM_STANDARD_MODE        "smso"
#define TERM_STD_MODE_GLITCH      "xmc"
#define TERM_UNDERLINE_CHAR       "uc"
#define TERM_UNDERLINE            "ul"

struct more_control {
        struct termios output_tty;      /* output terminal */
        struct termios original_tty;    /* original terminal settings */
        FILE *current_file;             /* currently open input file */
        off_t file_position;            /* file position */
        off_t file_size;                /* file size */
        int argv_position;              /* argv[] position */
        int lines_per_screen;           /* screen size in lines */
        int d_scroll_len;               /* number of lines scrolled by 'd' */
        int prompt_len;                 /* message prompt length */
        int current_line;               /* line we are currently at */
        char **file_names;              /* The list of file names */
        int num_files;                  /* Number of files left to process */
        char *shell;                    /* name of the shell to use */
        int sigfd;                      /* signalfd() file descriptor */
        sigset_t sigset;                /* signal operations */
        char *line_buf;                 /* line buffer */
        size_t line_sz;                 /* size of line_buf buffer */
        int lines_per_page;             /* lines per page */
        char *clear;                    /* clear screen */
        char *erase_line;               /* erase line */
        char *enter_std;                /* enter standout mode */
        char *exit_std;                 /* exit standout mode */
        char *enter_underline;          /* enter underline mode */
        char *exit_underline;           /* exit underline mode */
        char *underline_ch;             /* underline character */
        char *backspace_ch;             /* backspace character */
        char *go_home;                  /* go to home */
        char *move_line_down;           /* move line down */
        char *clear_rest;               /* clear rest of screen */
        int num_columns;                /* number of columns */
        char *previous_search;          /* previous search() buf[] item */
        struct {
                off_t row_num;          /* row file position */
                long line_num;          /* line number */
        } context,
          screen_start;
        cc_t last_key_command;          /* previous more key command */
        int last_key_arg;               /* previous key command argument */
        int last_colon_command;         /* is a colon-prefixed key command */
        char *shell_line;               /* line to execute in subshell */
        unsigned int
                bad_stdout:1,           /* true if overwriting does not turn off standout */
                catch_suspend:1,        /* we should catch the SIGTSTP signal */
                clear_line_ends:1,      /* do not scroll, paint each screen from the top */
                clear_first:1,          /* is first character in file \f */
                dumb_tty:1,             /* is terminal type known */
                eat_newline:1,          /* is newline ignored after 80 cols */
                enable_underlining:1,   /* underline as best we can */
                erase_input_ok:1,       /* is erase input supported */
                erase_previous_ok:1,    /* is erase previous supported */
                first_file:1,           /* is the input file the first in list */
                fold_long_lines:1,      /* fold long lines */
                hard_tabs:1,            /* print spaces instead of '\t' */
                hard_tty:1,             /* is this hard copy terminal (a printer or such) */
                jump_at_start:1,        /* jump to line N defined at start up */
                is_paused:1,            /* is output paused */
                no_quit_dialog:1,       /* suppress quit dialog */
                no_scroll:1,            /* do not scroll, clear the screen and then display text */
                no_tty_in:1,            /* is input in interactive mode */
                no_tty_out:1,           /* is output in interactive mode */
                print_banner:1,         /* print file name banner */
                report_errors:1,        /* is an error reported */
                run_previous_command:1, /* run previous key command */
                search_at_start:1,      /* search pattern defined at start up */
                search_called:1,        /* previous more command was a search */
                squeeze_spaces:1,       /* suppress white space */
                stdout_glitch:1,        /* terminal has standout mode glitch */
                stop_after_formfeed:1,  /* stop after form feeds */
                suppress_bell:1,        /* suppress bell */
                underline_glitch:1,     /* terminal has underline mode glitch */
                underline_state:1,      /* current UL state */
                wrap_margin:1;          /* set if automargins */
};

static void __attribute__((__noreturn__)) usage(void)
{
        FILE *out = stdout;
        fputs(USAGE_HEADER, out);
        fprintf(out, _(" %s [options] <file>...\n"), program_invocation_short_name);

        fputs(USAGE_SEPARATOR, out);
        fputs(_("A file perusal filter for CRT viewing.\n"), out);

        fputs(USAGE_OPTIONS, out);
        fputs(_(" -d          display help instead of ringing bell\n"), out);
        fputs(_(" -f          count logical rather than screen lines\n"), out);
        fputs(_(" -l          suppress pause after form feed\n"), out);
        fputs(_(" -c          do not scroll, display text and clean line ends\n"), out);
        fputs(_(" -p          do not scroll, clean screen and display text\n"), out);
        fputs(_(" -s          squeeze multiple blank lines into one\n"), out);
        fputs(_(" -u          suppress underlining\n"), out);
        fputs(_(" -<number>   the number of lines per screenful\n"), out);
        fputs(_(" +<number>   display file beginning from line number\n"), out);
        fputs(_(" +/<string>  display file beginning from search string match\n"), out);

        fputs(USAGE_SEPARATOR, out);
        printf( "     --help     %s\n", USAGE_OPTSTR_HELP);
        printf( " -V, --version  %s\n", USAGE_OPTSTR_VERSION);
        printf(USAGE_MAN_TAIL("more(1)"));
        exit(EXIT_SUCCESS);
}


static void arg_parser(struct more_control *ctl, char *s)
{
        int seen_num = 0;

        while (*s != '\0') {
                switch (*s) {
                case '0':
                case '1':
                case '2':
                case '3':
                case '4':
                case '5':
                case '6':
                case '7':
                case '8':
                case '9':
                        if (!seen_num) {
                                ctl->lines_per_screen = 0;
                                seen_num = 1;
                        }
                        ctl->lines_per_screen = ctl->lines_per_screen * 10 + *s - '0';
                        break;
                case 'd':
                        ctl->suppress_bell = 1;
                        break;
                case 'l':
                        ctl->stop_after_formfeed = 0;
                        break;
                case 'f':
                        ctl->fold_long_lines = 0;
                        break;
                case 'p':
                        ctl->no_scroll = 1;
                        break;
                case 'c':
                        ctl->clear_line_ends = 1;
                        break;
                case 's':
                        ctl->squeeze_spaces = 1;
                        break;
                case 'u':
                        ctl->enable_underlining = 0;
                        break;
                case '-':
                case ' ':
                case '\t':
                        break;
                case 'V':
                        print_version(EXIT_SUCCESS);
                        exit(EXIT_SUCCESS);
                        break;
                default:
                        warnx(_("unknown option -%s"), s);
                        errtryhelp(EXIT_FAILURE);
                        break;
                }
                s++;
        }
}

static void more_fseek(struct more_control *ctl, off_t pos)
{
        ctl->file_position = pos;
        fseeko(ctl->current_file, pos, SEEK_SET);
}

static int more_getc(struct more_control *ctl)
{
        int ret = getc(ctl->current_file);
        ctl->file_position = ftello(ctl->current_file);
        return ret;
}

static int more_ungetc(struct more_control *ctl, int c)
{
        int ret = ungetc(c, ctl->current_file);
        ctl->file_position = ftello(ctl->current_file);
        return ret;
}

static void print_separator(const int c, int n)
{
        while (n--)
                putchar(c);
        putchar('\n');
}

/* magic --
 *      check for file magic numbers.  This code would best be shared
 *      with the file(1) program or, perhaps, more should not try to be
 *      so smart. */
static int check_magic(FILE *f, char *fs)
{
        signed char twobytes[2];

        /* don't try to look ahead if the input is unseekable */
        if (fseek(f, 0L, SEEK_SET))
                return 0;

        if (fread(twobytes, 2, 1, f) == 1) {
                switch (twobytes[0] + (twobytes[1] << 8)) {
                case 0407:      /* a.out obj */
                case 0410:      /* a.out exec */
                case 0413:      /* a.out demand exec */
                case 0405:
                case 0411:
                case 0177545:
                case 0x457f:    /* simple ELF detection */
                        printf(_("\n******** %s: Not a text file ********\n\n"),
                               fs);
                        return 1;
                }
        }
        fseek(f, 0L, SEEK_SET); /* rewind() not necessary */
        return 0;
}

/* Check whether the file named by fs is an ASCII file which the user may
 * access.  If it is, return the opened file.  Otherwise return NULL. */
static void checkf(struct more_control *ctl, char *fs)
{
        struct stat st;
        int c;

        if (stat(fs, &st) == -1) {
                fflush(stdout);
                if (ctl->clear_line_ends)
                        putp(ctl->erase_line);
                warn(_("stat of %s failed"), fs);
                ctl->current_file = NULL;
                return;
        }
        if ((st.st_mode & S_IFMT) == S_IFDIR) {
                printf(_("\n*** %s: directory ***\n\n"), fs);
                ctl->current_file = NULL;
                return;
        }
        ctl->current_line = 0;
        ctl->file_position = 0;
        if ((ctl->current_file = fopen(fs, "r")) == NULL) {
                fflush(stdout);
                warn(_("cannot open %s"), fs);
                return;
        }
        if (check_magic(ctl->current_file, fs)) {
                fclose(ctl->current_file);
                ctl->current_file = NULL;
                return;
        }
        fcntl(fileno(ctl->current_file), F_SETFD, FD_CLOEXEC);
        c = more_getc(ctl);
        ctl->clear_first = (c == '\f');
        more_ungetc(ctl, c);
        if ((ctl->file_size = st.st_size) == 0)
                ctl->file_size = ~((off_t)0);
}

static void prepare_line_buffer(struct more_control *ctl)
{
        size_t sz = ctl->num_columns * 4;

        if (ctl->line_sz >= sz)
                return;

        if (sz < MIN_LINE_SZ)
                sz = MIN_LINE_SZ;

        /* alloc sz and extra space for \n\0 */
        ctl->line_buf = xrealloc(ctl->line_buf, sz + 2);
        ctl->line_sz = sz;
}

/* Get a logical line */
static int get_line(struct more_control *ctl, int *length)
{
        int c;
        char *p;
        int column;
        static int column_wrap;

#ifdef HAVE_WIDECHAR
        size_t i;
        wchar_t wc;
        int wc_width;
        mbstate_t state, state_bak;     /* Current status of the stream. */
        char mbc[MB_LEN_MAX];           /* Buffer for one multibyte char. */
        size_t mblength;                /* Byte length of multibyte char. */
        size_t mbc_pos = 0;             /* Position of the MBC. */
        int use_mbc_buffer_flag = 0;    /* If 1, mbc has data. */
        int break_flag = 0;             /* If 1, exit while(). */
        off_t file_position_bak = ctl->file_position;

        memset(&state, '\0', sizeof(mbstate_t));
#endif

        p = ctl->line_buf;
        column = 0;
        c = more_getc(ctl);
        if (column_wrap && c == '\n') {
                ctl->current_line++;
                c = more_getc(ctl);
        }
        while (p < &ctl->line_buf[ctl->line_sz - 1]) {
#ifdef HAVE_WIDECHAR
                if (ctl->fold_long_lines && use_mbc_buffer_flag && MB_CUR_MAX > 1) {
                        use_mbc_buffer_flag = 0;
                        state_bak = state;
                        mbc[mbc_pos++] = c;
 process_mbc:
                        mblength = mbrtowc(&wc, mbc, mbc_pos, &state);

                        switch (mblength) {
                        case (size_t)-2:        /* Incomplete multibyte character. */
                                use_mbc_buffer_flag = 1;
                                state = state_bak;
                                break;

                        case (size_t)-1:        /* Invalid as a multibyte character. */
                                *p++ = mbc[0];
                                state = state_bak;
                                column++;
                                file_position_bak++;
                                if (column >= ctl->num_columns) {
                                        more_fseek(ctl, file_position_bak);
                                } else {
                                        memmove(mbc, mbc + 1, --mbc_pos);
                                        if (mbc_pos > 0) {
                                                mbc[mbc_pos] = '\0';
                                                goto process_mbc;
                                        }
                                }
                                break;

                        default:
                                wc_width = wcwidth(wc);
                                if (column + wc_width > ctl->num_columns) {
                                        more_fseek(ctl, file_position_bak);
                                        break_flag = 1;
                                } else {
                                        for (i = 0; p < &ctl->line_buf[ctl->line_sz - 1] &&
                                                    i < mbc_pos; i++)
                                                *p++ = mbc[i];
                                        if (wc_width > 0)
                                                column += wc_width;
                                }
                        }

                        if (break_flag || column >= ctl->num_columns)
                                break;

                        c = more_getc(ctl);
                        continue;
                }
#endif  /* HAVE_WIDECHAR */
                if (c == EOF) {
                        if (p > ctl->line_buf) {
                                *p = '\0';
                                *length = p - ctl->line_buf;
                                return column;
                        }
                        *length = p - ctl->line_buf;
                        return EOF;
                }
                if (c == '\n') {
                        ctl->current_line++;
                        break;
                }

                *p++ = c;
                if (c == '\t') {
                        if (!ctl->hard_tabs || (column < ctl->prompt_len && !ctl->hard_tty)) {
                                if (ctl->hard_tabs && ctl->erase_line && !ctl->dumb_tty) {
                                        column = 1 + (column | 7);
                                        putp(ctl->erase_line);
                                        ctl->prompt_len = 0;
                                } else {
                                        for (--p; p < &ctl->line_buf[ctl->line_sz - 1];) {
                                                *p++ = ' ';
                                                if ((++column & 7) == 0)
                                                        break;
                                        }
                                        if (column >= ctl->prompt_len)
                                                ctl->prompt_len = 0;
                                }
                        } else
                                column = 1 + (column | 7);
                } else if (c == '\b' && column > 0) {
                        column--;
                } else if (c == '\r') {
                        int next = more_getc(ctl);
                        if (next == '\n') {
                                p--;
                                ctl->current_line++;
                                break;
                        }
                        more_ungetc(ctl, c);
                        column = 0;
                } else if (c == '\f' && ctl->stop_after_formfeed) {
                        p[-1] = '^';
                        *p++ = 'L';
                        column += 2;
                        ctl->is_paused = 1;
                } else if (c == EOF) {
                        *length = p - ctl->line_buf;
                        return column;
                } else {
#ifdef HAVE_WIDECHAR
                        if (ctl->fold_long_lines && MB_CUR_MAX > 1) {
                                memset(mbc, '\0', MB_LEN_MAX);
                                mbc_pos = 0;
                                mbc[mbc_pos++] = c;
                                state_bak = state;

                                mblength = mbrtowc(&wc, mbc, mbc_pos, &state);
                                /* The value of mblength is always less than 2 here. */
                                switch (mblength) {
                                case (size_t)-2:
                                        p--;
                                        file_position_bak = ctl->file_position - 1;
                                        state = state_bak;
                                        use_mbc_buffer_flag = 1;
                                        break;

                                case (size_t)-1:
                                        state = state_bak;
                                        column++;
                                        break;

                                default:
                                        wc_width = wcwidth(wc);
                                        if (wc_width > 0)
                                                column += wc_width;
                                }
                        } else
#endif  /* HAVE_WIDECHAR */
                        {
                                if (isprint(c))
                                        column++;
                        }
                }

                if (column >= ctl->num_columns && ctl->fold_long_lines)
                        break;
#ifdef HAVE_WIDECHAR
                if (use_mbc_buffer_flag == 0 && p >= &ctl->line_buf[ctl->line_sz - 1 - 4])
                        /* don't read another char if there is no space for
                         * whole multibyte sequence */
                        break;
#endif
                c = more_getc(ctl);
        }
        if (column >= ctl->num_columns && ctl->num_columns > 0) {
                if (!ctl->wrap_margin) {
                        *p++ = '\n';
                }
        }
        column_wrap = column == ctl->num_columns && ctl->fold_long_lines;
        if (column_wrap && ctl->eat_newline && ctl->wrap_margin) {
                *p++ = '\n';    /* simulate normal wrap */
        }
        *length = p - ctl->line_buf;
        *p = 0;
        return column;
}

/* Erase the rest of the prompt, assuming we are starting at column col. */
static void erase_to_col(struct more_control *ctl, int col)
{

        if (ctl->prompt_len == 0)
                return;
        if (col == 0 && ctl->clear_line_ends)
                puts(ctl->erase_line);
        else if (ctl->hard_tty)
                putchar('\n');
        else {
                if (col == 0)
                        putchar('\r');
                if (!ctl->dumb_tty && ctl->erase_line)
                        putp(ctl->erase_line);
                else {
                        printf("%*s", ctl->prompt_len - col, "");
                        if (col == 0)
                                putchar('\r');
                }
        }
        ctl->prompt_len = col;
}

#ifdef HAVE_WIDECHAR
static UL_ASAN_BLACKLIST size_t xmbrtowc(wchar_t *wc, const char *s, size_t n,
                                  mbstate_t *mbstate)
{
        const size_t mblength = mbrtowc(wc, s, n, mbstate);
        if (mblength == (size_t)-2 || mblength == (size_t)-1)
                return 1;
        return mblength;
}
#endif

static int would_underline(char *s, int n)
{
        if (n < 2)
                return 0;
        if ((s[0] == '_' && s[1] == '\b') || (s[1] == '\b' && s[2] == '_'))
                return 1;
        return 0;
}

/* Print a buffer of n characters */
static void print_buf(struct more_control *ctl, char *s, int n)
{
        char c;         /* next output character */
        int state;      /* next output char's UL state */

        while (--n >= 0) {
                if (!ctl->enable_underlining) {
                        putchar(*s++);
                        continue;
                }
                if (*s == ' ' && ctl->underline_state == 0 && ctl->underline_glitch
                    && would_underline(s + 1, n - 1)) {
                        s++;
                        continue;
                }
                if ((state = would_underline(s, n)) != 0) {
                        c = (*s == '_') ? s[2] : *s;
                        n -= 2;
                        s += 3;
                } else
                        c = *s++;
                if (state != ctl->underline_state) {
                        if (c == ' ' && state == 0 && ctl->underline_glitch
                            && would_underline(s, n - 1))
                                state = 1;
                        else
                                putp(state ? ctl->enter_underline : ctl->exit_underline);
                }
                if (c != ' ' || ctl->underline_state == 0 || state != 0
                    || ctl->underline_glitch == 0) {
#ifdef HAVE_WIDECHAR
                        wchar_t wc;
                        size_t mblength;
                        mbstate_t mbstate;

                        memset(&mbstate, '\0', sizeof(mbstate_t));
                        s--;
                        n++;
                        mblength = xmbrtowc(&wc, s, n, &mbstate);
                        while (mblength--)
                                putchar(*s++);
                        n += mblength;
#else
                        putchar(c);
#endif
                }
                if (state && *ctl->underline_ch) {
                        fputs(ctl->move_line_down, stdout);
                        putp(ctl->underline_ch);
                }
                ctl->underline_state = state;
        }
}

static void output_prompt(struct more_control *ctl, char *filename)
{
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        else if (ctl->prompt_len > 0)
                erase_to_col(ctl, 0);
        if (!ctl->hard_tty) {
                ctl->prompt_len = 0;
                if (ctl->enter_std) {
                        putp(ctl->enter_std);
                        ctl->prompt_len += (2 * ctl->stdout_glitch);
                }
                if (ctl->clear_line_ends)
                        putp(ctl->erase_line);
                ctl->prompt_len += printf(_("--More--"));
                if (filename != NULL) {
                        ctl->prompt_len += printf(_("(Next file: %s)"), filename);
                } else if (!ctl->no_tty_in) {
                        ctl->prompt_len +=
                            printf("(%d%%)",
                                   (int)((ctl->file_position * 100) / ctl->file_size));
                }
                if (ctl->suppress_bell) {
                        ctl->prompt_len +=
                            printf(_("[Press space to continue, 'q' to quit.]"));
                }
                if (ctl->exit_std)
                        putp(ctl->exit_std);
                if (ctl->clear_line_ends)
                        putp(ctl->clear_rest);
                fflush(stdout);
        } else
                fprintf(stderr, "\a");
}

static void reset_tty(struct more_control *ctl)
{
        if (ctl->no_tty_out)
                return;
        if (ctl->underline_state) {
                putp(ctl->exit_underline);
                fflush(stdout);
                ctl->underline_state = 0;
        }
        ctl->output_tty.c_lflag |= ICANON | ECHO;
        ctl->output_tty.c_cc[VMIN] = ctl->original_tty.c_cc[VMIN];
        ctl->output_tty.c_cc[VTIME] = ctl->original_tty.c_cc[VTIME];
        tcsetattr(STDERR_FILENO, TCSANOW, &ctl->original_tty);
}

/* Clean up terminal state and exit. Also come here if interrupt signal received */
static void __attribute__((__noreturn__)) more_exit(struct more_control *ctl)
{
        reset_tty(ctl);
        if (ctl->clear_line_ends) {
                putchar('\r');
                putp(ctl->erase_line);
                fflush(stdout);
        } else if (!ctl->clear_line_ends && (ctl->prompt_len > 0)) {
                erase_to_col(ctl, 0);
                fflush(stdout);
        }
        free(ctl->previous_search);
        free(ctl->shell_line);
        free(ctl->line_buf);
        free(ctl->go_home);
        if (ctl->current_file)
                fclose(ctl->current_file);
        del_curterm(cur_term);
        _exit(EXIT_SUCCESS);
}

static cc_t read_user_input(struct more_control *ctl)
{
        cc_t c;

        errno = 0;
        if (read(STDERR_FILENO, &c, 1) <= 0) {
                if (errno != EINTR)
                        more_exit(ctl);
                else
                        c = ctl->output_tty.c_cc[VKILL];
        }
        return c;
}

/* Read a decimal number from the terminal.  Set cmd to the non-digit
 * which terminates the number. */
static int read_number(struct more_control *ctl, cc_t *cmd)
{
        int i;
        cc_t ch;

        i = 0;
        ch = ctl->output_tty.c_cc[VKILL];
        for (;;) {
                ch = read_user_input(ctl);
                if (isdigit(ch))
                        i = i * 10 + ch - '0';
                else if (ch == ctl->output_tty.c_cc[VKILL])
                        i = 0;
                else {
                        *cmd = ch;
                        break;
                }
        }
        return i;
}

/* Change displayed file from command line list to next nskip, where nskip
 * is relative position in argv and can be negative, that is a previous
 * file.  */
static void change_file(struct more_control *ctl, int nskip)
{
        if (nskip == 0)
                return;
        if (nskip > 0) {
                if (ctl->argv_position + nskip > ctl->num_files - 1)
                        nskip = ctl->num_files - ctl->argv_position - 1;
        }
        ctl->argv_position += nskip;
        if (ctl->argv_position < 0)
                ctl->argv_position = 0;
        puts(_("\n...Skipping "));
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        if (nskip > 0)
                fputs(_("...Skipping to file "), stdout);
        else
                fputs(_("...Skipping back to file "), stdout);
        puts(ctl->file_names[ctl->argv_position]);
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        putchar('\n');
        ctl->argv_position--;
}

static void show(struct more_control *ctl, char c)
{
        if ((c < ' ' && c != '\n' && c != ESC) || c == CERASE) {
                c += (c == CERASE) ? -0100 : 0100;
                fputs(CARAT, stderr);
                ctl->prompt_len++;
        }
        fputc(c, stderr);
        ctl->prompt_len++;
}

static void more_error(struct more_control *ctl, char *mess)
{
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        else
                erase_to_col(ctl, 0);
        ctl->prompt_len += strlen(mess);
        if (ctl->enter_std)
                putp(ctl->enter_std);
        fputs(mess, stdout);
        if (ctl->exit_std)
                putp(ctl->exit_std);
        fflush(stdout);
        ctl->report_errors++;
}

static void erase_one_column(struct more_control *ctl)
{
        if (ctl->erase_previous_ok)
                fprintf(stderr, "%s ", ctl->backspace_ch);
        fputs(ctl->backspace_ch, stderr);
}

static void ttyin(struct more_control *ctl, char buf[], int nmax, char pchar)
{
        char *sp;
        cc_t c;
        int slash = 0;
        int maxlen;

        sp = buf;
        maxlen = 0;
        while (sp - buf < nmax) {
                if (ctl->prompt_len > maxlen)
                        maxlen = ctl->prompt_len;
                c = read_user_input(ctl);
                if (c == '\\') {
                        slash++;
                } else if (c == ctl->output_tty.c_cc[VERASE] && !slash) {
                        if (sp > buf) {
#ifdef HAVE_WIDECHAR
                                if (MB_CUR_MAX > 1) {
                                        wchar_t wc;
                                        size_t pos = 0, mblength;
                                        mbstate_t state, state_bak;

                                        memset(&state, '\0', sizeof(mbstate_t));

                                        while (1) {
                                                state_bak = state;
                                                mblength =
                                                    mbrtowc(&wc, buf + pos,
                                                            sp - buf, &state);

                                                switch (mblength) {
                                                case (size_t)-2:
                                                case (size_t)-1:
                                                        state = state_bak;
                                                        /* fallthrough */
                                                case 0:
                                                        mblength = 1;
                                                }
                                                if (buf + pos + mblength >= sp)
                                                        break;

                                                pos += mblength;
                                        }

                                        if (mblength == 1) {
                                                erase_one_column(ctl);
                                        } else {
                                                int wc_width;
                                                wc_width = wcwidth(wc);
                                                wc_width =
                                                    (wc_width <
                                                     1) ? 1 : wc_width;
                                                while (wc_width--) {
                                                        erase_one_column(ctl);
                                                }
                                        }

                                        while (mblength--) {
                                                --ctl->prompt_len;
                                                --sp;
                                        }
                                } else
#endif  /* HAVE_WIDECHAR */
                                {
                                        --ctl->prompt_len;
                                        erase_one_column(ctl);
                                        --sp;
                                }

                                if ((*sp < ' ' && *sp != '\n') || *sp == CERASE) {
                                        --ctl->prompt_len;
                                        erase_one_column(ctl);
                                }
                                continue;
                        } else {
                                if (!ctl->erase_line)
                                        ctl->prompt_len = maxlen;
                        }
                } else if (c == ctl->output_tty.c_cc[VKILL] && !slash) {
                        if (ctl->hard_tty) {
                                show(ctl, c);
                                putchar('\n');
                                putchar(pchar);
                        } else {
                                putchar('\r');
                                putchar(pchar);
                                if (ctl->erase_line)
                                        erase_to_col(ctl, 1);
                                else if (ctl->erase_input_ok)
                                        while (ctl->prompt_len-- > 1)
                                                fprintf(stderr, "%s %s", ctl->backspace_ch, ctl->backspace_ch);
                                ctl->prompt_len = 1;
                        }
                        sp = buf;
                        fflush(stdout);
                        continue;
                }
                if (slash && (c == ctl->output_tty.c_cc[VKILL] ||
                              c == ctl->output_tty.c_cc[VERASE])) {
                        erase_one_column(ctl);
                        --sp;
                }
                if (c != '\\')
                        slash = 0;
                *sp++ = c;
                if ((c < ' ' && c != '\n' && c != ESC) || c == CERASE) {
                        c += (c == CERASE) ? -0100 : 0100;
                        fputs(CARAT, stderr);
                        ctl->prompt_len++;
                }
                if (c != '\n' && c != ESC) {
                        fputc(c, stderr);
                        ctl->prompt_len++;
                } else
                        break;
        }
        *--sp = '\0';
        if (!ctl->erase_line)
                ctl->prompt_len = maxlen;
        if (sp - buf >= nmax - 1)
                more_error(ctl, _("Line too long"));
}

/* Expand shell command line. */
static void expand(struct more_control *ctl, char *inbuf)
{
        char *inpstr;
        char *outstr;
        char c;
        char *temp;
        int tempsz, xtra, offset;

        xtra = strlen(ctl->file_names[ctl->argv_position]) + strlen(ctl->shell_line) + 1;
        tempsz = COMMAND_BUF + xtra;
        temp = xmalloc(tempsz);
        inpstr = inbuf;
        outstr = temp;
        while ((c = *inpstr++) != '\0') {
                offset = outstr - temp;
                if (tempsz - offset - 1 < xtra) {
                        tempsz += COMMAND_BUF + xtra;
                        temp = xrealloc(temp, tempsz);
                        outstr = temp + offset;
                }
                switch (c) {
                case '%':
                        if (!ctl->no_tty_in) {
                                strcpy(outstr, ctl->file_names[ctl->argv_position]);
                                outstr += strlen(ctl->file_names[ctl->argv_position]);
                        } else
                                *outstr++ = c;
                        break;
                case '!':
                        if (ctl->shell_line) {
                                strcpy(outstr, ctl->shell_line);
                                outstr += strlen(ctl->shell_line);
                        } else
                                more_error(ctl, _
                                           ("No previous command to substitute for"));
                        break;
                case '\\':
                        if (*inpstr == '%' || *inpstr == '!') {
                                *outstr++ = *inpstr++;
                                break;
                        }
                        /* fallthrough */
                default:
                        *outstr++ = c;
                }
        }
        *outstr++ = '\0';
        free(ctl->shell_line);
        ctl->shell_line = temp;
}

static void set_tty(struct more_control *ctl)
{
        ctl->output_tty.c_lflag &= ~(ICANON | ECHO);
        ctl->output_tty.c_cc[VMIN] = 1; /* read at least 1 char */
        ctl->output_tty.c_cc[VTIME] = 0;        /* no timeout */
        tcsetattr(STDERR_FILENO, TCSANOW, &ctl->output_tty);
}

/* Come here if a quit signal is received */
static void sigquit_handler(struct more_control *ctl)
{
        if (!ctl->dumb_tty && ctl->no_quit_dialog) {
                ctl->prompt_len += fprintf(stderr, _("[Use q or Q to quit]"));
                ctl->no_quit_dialog = 0;
        } else
                more_exit(ctl);
}

/* Come here when we get a suspend signal from the terminal */
static void sigtstp_handler(struct more_control *ctl)
{
        reset_tty(ctl);
        fflush(stdout);
        kill(0, SIGSTOP);
        /* We're back */
        set_tty(ctl);
}

/* Come here if a signal for a window size change is received */
static void sigwinch_handler(struct more_control *ctl)
{
        struct winsize win;

        if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) != -1) {
                if (win.ws_row != 0) {
                        ctl->lines_per_page = win.ws_row;
                        ctl->d_scroll_len = ctl->lines_per_page / 2 - 1;
                        if (ctl->d_scroll_len < 1)
                                ctl->d_scroll_len = 1;
                        ctl->lines_per_screen = ctl->lines_per_page - 1;
                }
                if (win.ws_col != 0)
                        ctl->num_columns = win.ws_col;
        }
        prepare_line_buffer(ctl);
}

static void execute(struct more_control *ctl, char *filename, char *cmd, ...)
{
        int id;
        int n;
        va_list argp;
        char *arg;
        char **args;
        int argcount;

        fflush(stdout);
        for (n = 10; (id = fork()) < 0 && n > 0; n--)
                sleep(5);
        if (id == 0) {
                int errsv;
                if (!isatty(STDIN_FILENO)) {
                        close(STDIN_FILENO);
                        open("/dev/tty", 0);
                }
                reset_tty(ctl);

                va_start(argp, cmd);
                arg = va_arg(argp, char *);
                argcount = 0;
                while (arg) {
                        argcount++;
                        arg = va_arg(argp, char *);
                }
                va_end(argp);

                args = alloca(sizeof(char *) * (argcount + 1));
                args[argcount] = NULL;

                va_start(argp, cmd);
                arg = va_arg(argp, char *);
                argcount = 0;
                while (arg) {
                        args[argcount] = arg;
                        argcount++;
                        arg = va_arg(argp, char *);
                }
                va_end(argp);

                if (geteuid() != getuid() || getegid() != getgid()) {
                        if (setuid(getuid()) < 0)
                                err(EXIT_FAILURE, _("setuid failed"));
                        if (setgid(getgid()) < 0)
                                err(EXIT_FAILURE, _("setgid failed"));
                }

                execvp(cmd, args);
                errsv = errno;
                fputs(_("exec failed\n"), stderr);
                exit(errsv == ENOENT ? EX_EXEC_ENOENT : EX_EXEC_FAILED);
        }
        if (id > 0) {
                while (wait(NULL) > 0)
                        /* nothing */ ;
        } else
                fputs(_("can't fork\n"), stderr);
        set_tty(ctl);
        print_separator('-', 24);
        output_prompt(ctl, filename);
}

static void run_shell(struct more_control *ctl, char *filename)
{
        char cmdbuf[COMMAND_BUF];

        erase_to_col(ctl, 0);
        putchar('!');
        fflush(stdout);
        ctl->prompt_len = 1;
        if (ctl->run_previous_command && ctl->shell_line)
                fputs(ctl->shell_line, stdout);
        else {
                ttyin(ctl, cmdbuf, sizeof(cmdbuf) - 2, '!');
                if (strpbrk(cmdbuf, "%!\\"))
                        expand(ctl, cmdbuf);
                else {
                        free(ctl->shell_line);
                        ctl->shell_line = xstrdup(cmdbuf);
                }
                erase_to_col(ctl, 0);
                ctl->prompt_len = printf("!%s", ctl->shell_line);
        }
        fflush(stdout);
        fputc('\n', stderr);
        ctl->prompt_len = 0;
        execute(ctl, filename, ctl->shell, ctl->shell, "-c", ctl->shell_line, 0);
}

/* Execute a colon-prefixed command.  Returns <0 if not a command that
 * should cause more of the file to be printed. */
static int colon_command(struct more_control *ctl, char *filename, int cmd, int nlines)
{
        char ch;

        if (cmd == 0)
                ch = read_user_input(ctl);
        else
                ch = cmd;
        ctl->last_colon_command = ch;
        switch (ch) {
        case 'f':
                erase_to_col(ctl, 0);
                if (!ctl->no_tty_in)
                        ctl->prompt_len =
                            printf(_("\"%s\" line %d"), ctl->file_names[ctl->argv_position], ctl->current_line);
                else
                        ctl->prompt_len = printf(_("[Not a file] line %d"), ctl->current_line);
                fflush(stdout);
                return -1;
        case 'n':
                if (nlines == 0) {
                        if (ctl->argv_position >= ctl->num_files - 1)
                                more_exit(ctl);
                        nlines++;
                }
                putchar('\r');
                erase_to_col(ctl, 0);
                change_file(ctl, nlines);
                return 0;
        case 'p':
                if (ctl->no_tty_in) {
                        fprintf(stderr, "\a");
                        return -1;
                }
                putchar('\r');
                erase_to_col(ctl, 0);
                if (nlines == 0)
                        nlines++;
                change_file(ctl, -nlines);
                return 0;
        case '!':
                run_shell(ctl, filename);
                return -1;
        case 'q':
        case 'Q':
                more_exit(ctl);
        default:
                fprintf(stderr, "\a");
                return -1;
        }
}

/* Skip n lines in the file f */
static void skip_lines(struct more_control *ctl, int n)
{
        int c;

        while (n > 0) {
                while ((c = more_getc(ctl)) != '\n')
                        if (c == EOF)
                                return;
                n--;
                ctl->current_line++;
        }
}

/*  Clear the screen */
static void more_clear_screen(struct more_control *ctl)
{
        if (ctl->clear && !ctl->hard_tty) {
                putp(ctl->clear);
                /* Put out carriage return so that system doesn't get
                 * confused by escape sequences when expanding tabs */
                putchar('\r');
                ctl->prompt_len = 0;
        }
}

static void read_line(struct more_control *ctl)
{
        int c;
        char *p;

        p = ctl->line_buf;
        while ((c = more_getc(ctl)) != '\n' && c != EOF
               && (ptrdiff_t)p != (ptrdiff_t)(ctl->line_buf + ctl->line_sz - 1))
                *p++ = c;
        if (c == '\n')
                ctl->current_line++;
        *p = '\0';
}

static int more_poll(struct more_control *ctl, int timeout)
{
        struct pollfd pfd[2];

        pfd[0].fd = ctl->sigfd;
        pfd[0].events = POLLIN | POLLERR | POLLHUP;
        pfd[1].fd = STDIN_FILENO;
        pfd[1].events = POLLIN;

        if (poll(pfd, 2, timeout) < 0) {
                if (errno == EAGAIN)
                        return 1;
                more_error(ctl, _("poll failed"));
                return 1;
        }
        if (pfd[0].revents != 0) {
                struct signalfd_siginfo info;
                ssize_t sz;

                sz = read(pfd[0].fd, &info, sizeof(info));
                assert(sz == sizeof(info));
                switch (info.ssi_signo) {
                case SIGINT:
                        more_exit(ctl);
                        break;
                case SIGQUIT:
                        sigquit_handler(ctl);
                        break;
                case SIGTSTP:
                        sigtstp_handler(ctl);
                        break;
                case SIGWINCH:
                        sigwinch_handler(ctl);
                        break;
                default:
                        abort();
                }
        }
        if (pfd[1].revents == 0)
                return 1;
        return 0;
}

/* Search for nth occurrence of regular expression contained in buf in
 * the file */
static void search(struct more_control *ctl, char buf[], int n)
{
        off_t startline = ctl->file_position;
        off_t line1 = startline;
        off_t line2 = startline;
        off_t line3;
        int lncount;
        int saveln, rc;
        regex_t re;

        ctl->context.line_num = saveln = ctl->current_line;
        ctl->context.row_num = startline;
        lncount = 0;
        if (!buf)
                goto notfound;
        if ((rc = regcomp(&re, buf, REG_NOSUB)) != 0) {
                char s[REGERR_BUF];
                regerror(rc, &re, s, sizeof s);
                more_error(ctl, s);
                return;
        }
        while (!feof(ctl->current_file)) {
                line3 = line2;
                line2 = line1;
                line1 = ctl->file_position;
                read_line(ctl);
                lncount++;
                if (regexec(&re, ctl->line_buf, 0, NULL, 0) == 0 && --n == 0) {
                        if ((1 < lncount && ctl->no_tty_in) || 3 < lncount) {
                                putchar('\n');
                                if (ctl->clear_line_ends)
                                        putp(ctl->erase_line);
                                fputs(_("...skipping\n"), stdout);
                        }
                        if (!ctl->no_tty_in) {
                                ctl->current_line -= (lncount < 3 ? lncount : 3);
                                more_fseek(ctl, line3);
                                if (ctl->no_scroll) {
                                        if (ctl->clear_line_ends) {
                                                putp(ctl->go_home);
                                                putp(ctl->erase_line);
                                        } else
                                                more_clear_screen(ctl);
                                }
                        } else {
                                erase_to_col(ctl, 0);
                                if (ctl->no_scroll) {
                                        if (ctl->clear_line_ends) {
                                                putp(ctl->go_home);
                                                putp(ctl->erase_line);
                                        } else
                                                more_clear_screen(ctl);
                                }
                                puts(ctl->line_buf);
                        }
                        break;
                } else
                        more_poll(ctl, 1);
        }
        /* Move ctrl+c signal handling back to more_key_command(). */
        signal(SIGINT, SIG_DFL);
        sigaddset(&ctl->sigset, SIGINT);
        sigprocmask(SIG_BLOCK, &ctl->sigset, NULL);
        regfree(&re);
        if (feof(ctl->current_file)) {
                if (!ctl->no_tty_in) {
                        ctl->current_line = saveln;
                        more_fseek(ctl, startline);
                } else {
                        fputs(_("\nPattern not found\n"), stdout);
                        more_exit(ctl);
                }
                free(ctl->previous_search);
                ctl->previous_search = NULL;
notfound:
                more_error(ctl, _("Pattern not found"));
        }
}

static char *find_editor(void)
{
        static char *editor;

        editor = getenv("VISUAL");
        if (editor == NULL || *editor == '\0')
                editor = getenv("EDITOR");
        if (editor == NULL || *editor == '\0')
                editor = _PATH_VI;
        return editor;
}

static void runtime_usage(void)
{
        fputs(_("Most commands optionally preceded by integer argument k.  "
                "Defaults in brackets.\n"
                "Star (*) indicates argument becomes new default.\n"), stdout);
        print_separator('-', 79);
        fprintf(stdout,
                _
                ("<space>                 Display next k lines of text [current screen size]\n"
                 "z                       Display next k lines of text [current screen size]*\n"
                 "<return>                Display next k lines of text [1]*\n"
                 "d or ctrl-D             Scroll k lines [current scroll size, initially 11]*\n"
                 "q or Q or <interrupt>   Exit from more\n"
                 "s                       Skip forward k lines of text [1]\n"
                 "f                       Skip forward k screenfuls of text [1]\n"
                 "b or ctrl-B             Skip backwards k screenfuls of text [1]\n"
                 "'                       Go to place where previous search started\n"
                 "=                       Display current line number\n"
                 "/<regular expression>   Search for kth occurrence of regular expression [1]\n"
                 "n                       Search for kth occurrence of last r.e [1]\n"
                 "!<cmd> or :!<cmd>       Execute <cmd> in a subshell\n"
                 "v                       Start up '%s' at current line\n"
                 "ctrl-L                  Redraw screen\n"
                 ":n                      Go to kth next file [1]\n"
                 ":p                      Go to kth previous file [1]\n"
                 ":f                      Display current file name and line number\n"
                 ".                       Repeat previous command\n"),
                find_editor());
        print_separator('-', 79);
}

static void execute_editor(struct more_control *ctl, char *cmdbuf, char *filename)
{
        char *editor, *p;
        int split = 0;
        int n;

        if ((ctl->current_line - ctl->lines_per_screen) < 1)
                n = 1;
        else
                n = ctl->current_line - (ctl->lines_per_screen + 1) / 2;
        editor = find_editor();
        p = strrchr(editor, '/');
        if (p)
                p++;
        else
                p = editor;
        /*
         * Earlier: call vi +n file. This also works for emacs.
         * POSIX: call vi -c n file (when editor is vi or ex).
         */
        if (!strcmp(p, "vi") || !strcmp(p, "ex")) {
                sprintf(cmdbuf, "-c %d", n);
                split = 1;
        } else
                sprintf(cmdbuf, "+%d", n);

        erase_to_col(ctl, 0);
        printf("%s %s %s", editor, cmdbuf, ctl->file_names[ctl->argv_position]);
        if (split) {
                cmdbuf[2] = 0;
                execute(ctl, filename, editor, editor,
                        cmdbuf, cmdbuf + 3,
                        ctl->file_names[ctl->argv_position], (char *)0);
        } else
                execute(ctl, filename, editor, editor,
                        cmdbuf, ctl->file_names[ctl->argv_position], (char *)0);
}

static int skip_backwards(struct more_control *ctl, int nlines)
{
        int initline;
        int retval;

        if (nlines == 0)
                nlines++;

        putchar('\r');
        erase_to_col(ctl, 0);
        putchar('\n');
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        printf(P_("...back %d page", "...back %d pages", nlines), nlines);
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        putchar('\n');

        initline = ctl->current_line - ctl->lines_per_screen * (nlines + 1);
        if (!ctl->no_scroll)
                initline--;
        if (initline < 0)
                initline = 0;
        more_fseek(ctl, 0);
        ctl->current_line = 0;  /* skip_lines() will make current_line correct */
        skip_lines(ctl, initline);
        if (!ctl->no_scroll)
                retval = ctl->lines_per_screen + 1;
        else
                retval = ctl->lines_per_screen;
        return retval;
}

static int skip_forwards(struct more_control *ctl, int nlines, cc_t comchar)
{
        int c;

        if (nlines == 0)
                nlines++;
        if (comchar == 'f')
                nlines *= ctl->lines_per_screen;
        putchar('\r');
        erase_to_col(ctl, 0);
        putchar('\n');
        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        printf(P_("...skipping %d line",
                  "...skipping %d lines", nlines), nlines);

        if (ctl->clear_line_ends)
                putp(ctl->erase_line);
        putchar('\n');

        while (nlines > 0) {
                while ((c = more_getc(ctl)) != '\n')
                        if (c == EOF)
                                return 0;
                ctl->current_line++;
                nlines--;
        }
        return 1;
}

/* Read a command and do it.  A command consists of an optional integer
 * argument followed by the command character.  Return the number of
 * lines to display in the next screenful.  If there is nothing more to
 * display in the current file, zero is returned. */
static int more_key_command(struct more_control *ctl, char *filename)
{
        int nlines;
        int retval = 0;
        cc_t colonch;
        int done = 0;
        cc_t comchar;
        char cmdbuf[INIT_BUF];
        if (!ctl->report_errors)
                output_prompt(ctl, filename);
        else
                ctl->report_errors = 0;
        ctl->search_called = 0;
        for (;;) {
                if (more_poll(ctl, -1) != 0)
                        continue;
                nlines = read_number(ctl, &comchar);
                ctl->run_previous_command = colonch = 0;
                if (comchar == '.') {   /* Repeat last command */
                        ctl->run_previous_command++;
                        comchar = ctl->last_key_command;
                        nlines = ctl->last_key_arg;
                        if (ctl->last_key_command == ':')
                                colonch = ctl->last_colon_command;
                }
                ctl->last_key_command = comchar;
                ctl->last_key_arg = nlines;
                if (comchar == ctl->output_tty.c_cc[VERASE]) {
                        erase_to_col(ctl, 0);
                        output_prompt(ctl, filename);
                        continue;
                }
                switch (comchar) {
                case ':':
                        retval = colon_command(ctl, filename, colonch, nlines);
                        if (retval >= 0)
                                done++;
                        break;
                case 'b':
                case CTRL('B'):
                        if (ctl->no_tty_in) {
                                fprintf(stderr, "\a");
                                return -1;
                        }
                        retval = skip_backwards(ctl, nlines);
                        done = 1;
                        break;
                case ' ':
                case 'z':
                        if (nlines == 0)
                                nlines = ctl->lines_per_screen;
                        else if (comchar == 'z')
                                ctl->lines_per_screen = nlines;
                        retval = nlines;
                        done = 1;
                        break;
                case 'd':
                case CTRL('D'):
                        if (nlines != 0)
                                ctl->d_scroll_len = nlines;
                        retval = ctl->d_scroll_len;
                        done = 1;
                        break;
                case 'q':
                case 'Q':
                        more_exit(ctl);
                case 's':
                case 'f':
                case CTRL('F'):
                        if (skip_forwards(ctl, nlines, comchar))
                                retval = ctl->lines_per_screen;
                        done = 1;
                        break;
                case '\n':
                        if (nlines != 0)
                                ctl->lines_per_screen = nlines;
                        else
                                nlines = 1;
                        retval = nlines;
                        done = 1;
                        break;
                case '\f':
                        if (!ctl->no_tty_in) {
                                more_clear_screen(ctl);
                                more_fseek(ctl, ctl->screen_start.row_num);
                                ctl->current_line = ctl->screen_start.line_num;
                                retval = ctl->lines_per_screen;
                                done = 1;
                                break;
                        } else {
                                fprintf(stderr, "\a");
                                break;
                        }
                case '\'':
                        if (!ctl->no_tty_in) {
                                erase_to_col(ctl, 0);
                                fputs(_("\n***Back***\n\n"), stdout);
                                more_fseek(ctl, ctl->context.row_num);
                                ctl->current_line = ctl->context.line_num;
                                retval = ctl->lines_per_screen;
                                done = 1;
                                break;
                        } else {
                                fprintf(stderr, "\a");
                                break;
                        }
                case '=':
                        erase_to_col(ctl, 0);
                        ctl->prompt_len = printf("%d", ctl->current_line);
                        fflush(stdout);
                        break;
                case 'n':
                        if (!ctl->previous_search) {
                                more_error(ctl, _("No previous regular expression"));
                                break;
                        }
                        ctl->run_previous_command++;
                        /* fallthrough */
                case '/':
                        ctl->search_called = 1;
                        if (nlines == 0)
                                nlines++;
                        erase_to_col(ctl, 0);
                        putchar('/');
                        ctl->prompt_len = 1;
                        fflush(stdout);
                        if (ctl->run_previous_command) {
                                fputc('\r', stderr);
                                search(ctl, ctl->previous_search, nlines);
                        } else {
                                ttyin(ctl, cmdbuf, sizeof(cmdbuf) - 2, '/');
                                fputc('\r', stderr);
                                free(ctl->previous_search);
                                ctl->previous_search = xstrdup(cmdbuf);
                                search(ctl, cmdbuf, nlines);
                        }
                        retval = ctl->lines_per_screen - 1;
                        done = 1;
                        break;
                case '!':
                        run_shell(ctl, filename);
                        break;
                case '?':
                case 'h':
                        if (ctl->no_scroll)
                                more_clear_screen(ctl);
                        erase_to_col(ctl, 0);
                        runtime_usage();
                        output_prompt(ctl, filename);
                        break;
                case 'v':       /* This case should go right before default */
                        if (!ctl->no_tty_in) {
                                execute_editor(ctl, cmdbuf, filename);
                                break;
                        }
                        /* fallthrough */
                default:
                        if (ctl->suppress_bell) {
                                erase_to_col(ctl, 0);
                                if (ctl->enter_std)
                                        putp(ctl->enter_std);
                                ctl->prompt_len =
                                    printf(_("[Press 'h' for instructions.]"))
                                            + 2 * ctl->stdout_glitch;
                                if (ctl->exit_std)
                                        putp(ctl->exit_std);
                                fflush(stdout);
                        } else
                                fprintf(stderr, "\a");
                        break;
                }
                if (done)
                        break;
        }
        putchar('\r');
        ctl->no_quit_dialog = 1;
        return retval;
}

/* Print out the contents of the file f, one screenful at a time. */
static void screen(struct more_control *ctl, int num_lines)
{
        int c;
        int nchars;
        int length;                     /* length of current line */
        static int prev_len = 1;        /* length of previous line */

        for (;;) {
                while (num_lines > 0 && !ctl->is_paused) {
                        if ((nchars = get_line(ctl, &length)) == EOF) {
                                if (ctl->clear_line_ends)
                                        putp(ctl->clear_rest);
                                return;
                        }
                        if (ctl->squeeze_spaces && length == 0 && prev_len == 0)
                                continue;
                        prev_len = length;
                        if (ctl->bad_stdout
                            || ((ctl->enter_std && *ctl->enter_std == ' ') && (ctl->prompt_len > 0)))
                                erase_to_col(ctl, 0);
                        /* must clear before drawing line since tabs on
                         * some terminals do not erase what they tab
                         * over. */
                        if (ctl->clear_line_ends)
                                putp(ctl->erase_line);
                        print_buf(ctl, ctl->line_buf, length);
                        if (nchars < ctl->prompt_len)
                                erase_to_col(ctl, nchars);
                        ctl->prompt_len = 0;
                        if (nchars < ctl->num_columns || !ctl->fold_long_lines)
                                print_buf(ctl, "\n", 1);        /* will turn off UL if necessary */
                        num_lines--;
                }
                if (ctl->underline_state) {
                        putp(ctl->exit_underline);
                        ctl->underline_state = 0;
                }
                fflush(stdout);
                if ((c = more_getc(ctl)) == EOF) {
                        if (ctl->clear_line_ends)
                                putp(ctl->clear_rest);
                        return;
                }

                if (ctl->is_paused && ctl->clear_line_ends)
                        putp(ctl->clear_rest);
                more_ungetc(ctl, c);
                ctl->is_paused = 0;
                do {
                        if ((num_lines = more_key_command(ctl, NULL)) == 0)
                                return;
                } while (ctl->search_called && !ctl->previous_search);
                if (ctl->hard_tty && ctl->prompt_len > 0)
                        erase_to_col(ctl, 0);
                if (ctl->no_scroll && num_lines >= ctl->lines_per_screen) {
                        if (ctl->clear_line_ends)
                                putp(ctl->go_home);
                        else
                                more_clear_screen(ctl);
                }
                ctl->screen_start.line_num = ctl->current_line;
                ctl->screen_start.row_num = ctl->file_position;
        }
}

static void copy_file(FILE *f)
{
        char buf[BUFSIZ];
        size_t sz;

        while ((sz = fread(&buf, sizeof(char), sizeof(buf), f)) > 0)
                fwrite(&buf, sizeof(char), sz, stdout);
}


static void display_file(struct more_control *ctl, char *initbuf, int left)
{
        if (!ctl->current_file)
                return;
        ctl->context.line_num = ctl->context.row_num = 0;
        ctl->current_line = 0;
        if (ctl->first_file) {
                ctl->first_file = 0;
                if (ctl->search_at_start) {
                        free(ctl->previous_search);
                        ctl->previous_search = xstrdup(initbuf);
                        search(ctl, initbuf, 1);
                        if (ctl->no_scroll)
                                left--;
                } else if (ctl->jump_at_start)
                        skip_lines(ctl, ctl->search_at_start);
        } else if (ctl->argv_position < ctl->num_files && !ctl->no_tty_out)
                left =
                    more_key_command(ctl, ctl->file_names[ctl->argv_position]);
        if (left != 0) {
                if ((ctl->no_scroll || ctl->clear_first)
                    && ctl->file_size != ~((off_t)0)) {
                        if (ctl->clear_line_ends)
                                putp(ctl->go_home);
                        else
                                more_clear_screen(ctl);
                }
                if (ctl->print_banner) {
                        if (ctl->bad_stdout)
                                erase_to_col(ctl, 0);
                        if (ctl->clear_line_ends)
                                putp(ctl->erase_line);
                        if (ctl->prompt_len > 14)
                                erase_to_col(ctl, 14);
                        if (ctl->clear_line_ends)
                                putp(ctl->erase_line);
                        print_separator(':', 14);
                        puts(ctl->file_names[ctl->argv_position]);
                        if (ctl->clear_line_ends)
                                putp(ctl->erase_line);
                        print_separator(':', 14);
                        if (left > ctl->lines_per_page - 4)
                                left = ctl->lines_per_page - 4;
                }
                if (ctl->no_tty_out)
                        copy_file(ctl->current_file);
                else
                        screen(ctl, left);
        }
        fflush(stdout);
        fclose(ctl->current_file);
        ctl->current_file = NULL;
        ctl->screen_start.line_num = ctl->screen_start.row_num = 0;
        ctl->context.line_num = ctl->context.row_num = 0L;
}

static void initterm(struct more_control *ctl)
{
        int ret;
        char *term;
        struct winsize win;
        char *cursor_addr;

#ifndef NON_INTERACTIVE_MORE
        ctl->no_tty_out = tcgetattr(STDOUT_FILENO, &ctl->output_tty);
#endif
        ctl->no_tty_in = tcgetattr(STDIN_FILENO, &ctl->output_tty);
        tcgetattr(STDERR_FILENO, &ctl->output_tty);
        ctl->original_tty = ctl->output_tty;
        ctl->hard_tabs = (ctl->output_tty.c_oflag & TABDLY) != TAB3;
        if (ctl->no_tty_out)
                return;

        ctl->output_tty.c_lflag &= ~(ICANON | ECHO);
        ctl->output_tty.c_cc[VMIN] = 1;
        ctl->output_tty.c_cc[VTIME] = 0;
        ctl->erase_previous_ok = (ctl->output_tty.c_cc[VERASE] != 255);
        ctl->erase_input_ok = (ctl->output_tty.c_cc[VKILL] != 255);
        if ((term = getenv("TERM")) == NULL) {
                ctl->dumb_tty = 1;
                ctl->enable_underlining = 0;
        }
        setupterm(term, 1, &ret);
        if (ret <= 0) {
                ctl->dumb_tty = 1;
                ctl->enable_underlining = 0;
                return;
        }
        if (ioctl(STDOUT_FILENO, TIOCGWINSZ, &win) < 0) {
                ctl->lines_per_page = tigetnum(TERM_LINES);
                ctl->num_columns = tigetnum(TERM_COLS);
        } else {
                if ((ctl->lines_per_page = win.ws_row) == 0)
                        ctl->lines_per_page = tigetnum(TERM_LINES);
                if ((ctl->num_columns = win.ws_col) == 0)
                        ctl->num_columns = tigetnum(TERM_COLS);
        }
        if ((ctl->lines_per_page <= 0) || tigetflag(TERM_HARD_COPY)) {
                ctl->hard_tty = 1;
                ctl->lines_per_page = LINES_PER_PAGE;
        }

        if (tigetflag(TERM_EAT_NEW_LINE))
                /* Eat newline at last column + 1; dec, concept */
                ctl->eat_newline++;
        if (ctl->num_columns <= 0)
                ctl->num_columns = NUM_COLUMNS;

        ctl->wrap_margin = tigetflag(TERM_AUTO_RIGHT_MARGIN);
        ctl->bad_stdout = tigetflag(TERM_CEOL);
        ctl->erase_line = tigetstr(TERM_CLEAR_TO_LINE_END);
        ctl->clear = tigetstr(TERM_CLEAR);
        if ((ctl->enter_std = tigetstr(TERM_STANDARD_MODE)) != NULL) {
                ctl->exit_std = tigetstr(TERM_EXIT_STANDARD_MODE);
                if (0 < tigetnum(TERM_STD_MODE_GLITCH))
                        ctl->stdout_glitch = 1;
        }

        /*
         * Set up for underlining.  Some terminals don't need it, others have
         * start/stop sequences, still others have an underline char sequence
         * which is assumed to move the cursor forward one character.  If
         * underline sequence isn't available, settle for standout sequence.
         */
        if (tigetflag(TERM_UNDERLINE) || tigetflag(TERM_OVER_STRIKE))
                ctl->enable_underlining = 0;
        ctl->enter_underline = tigetstr(TERM_ENTER_UNDERLINE);
        ctl->exit_underline = tigetstr(TERM_EXIT_UNDERLINE);
        ctl->underline_ch = tigetstr(TERM_UNDERLINE_CHAR);
        if (!ctl->underline_ch) {
                ctl->underline_ch = "";
                if (!ctl->enter_underline || !ctl->exit_underline) {
                        if (!ctl->enter_std || !ctl->exit_std) {
                                ctl->enter_underline = "";
                                ctl->exit_underline = "";
                        } else {
                                ctl->enter_underline = ctl->enter_std;
                                ctl->exit_underline = ctl->exit_std;
                                ctl->underline_glitch = ctl->stdout_glitch;
                        }
                } else
                        ctl->underline_glitch = 0;
        }

        cursor_addr = tigetstr(TERM_HOME);
        if (cursor_addr == NULL || *cursor_addr == '\0') {
                cursor_addr = tigetstr(TERM_CURSOR_ADDRESS);
                if (cursor_addr)
                        cursor_addr = tparm(cursor_addr, 0, 0);
        }
        if (cursor_addr)
                ctl->go_home = xstrdup(cursor_addr);

        if ((ctl->move_line_down = tigetstr(TERM_LINE_DOWN)) == NULL)
                ctl->move_line_down = BACKSPACE;
        ctl->clear_rest = tigetstr(TERM_CLEAR_TO_SCREEN_END);
        if ((ctl->backspace_ch = tigetstr(TERM_BACKSPACE)) == NULL)
                ctl->backspace_ch = BACKSPACE;

        if ((ctl->shell = getenv("SHELL")) == NULL)
                ctl->shell = _PATH_BSHELL;
}

int main(int argc, char **argv)
{
        char *s;
        int chr;
        int left;
        int start_at_line = 0;
        char *initbuf = NULL;
        struct more_control ctl = {
                .first_file = 1,
                .fold_long_lines = 1,
                .no_quit_dialog = 1,
                .stop_after_formfeed = 1,
                .enable_underlining = 1,
                .wrap_margin = 1,
                .lines_per_page = LINES_PER_PAGE,
                .num_columns = NUM_COLUMNS,
                .d_scroll_len = SCROLL_LEN,
                0
        };

        setlocale(LC_ALL, "");
        bindtextdomain(PACKAGE, LOCALEDIR);
        textdomain(PACKAGE);
        close_stdout_atexit();

        if (argc > 1) {
                /* first arg may be one of our standard longopts */
                if (!strcmp(argv[1], "--help"))
                        usage();
                if (!strcmp(argv[1], "--version"))
                        print_version(EXIT_SUCCESS);
        }

        ctl.num_files = argc;
        ctl.file_names = argv;
        setlocale(LC_ALL, "");
        initterm(&ctl);

        /* Auto set no scroll on when binary is called page */
        if (!(strcmp(program_invocation_short_name, "page")))
                ctl.no_scroll++;

        prepare_line_buffer(&ctl);

        ctl.d_scroll_len = ctl.lines_per_page / 2 - 1;
        if (ctl.d_scroll_len <= 0)
                ctl.d_scroll_len = 1;

        if ((s = getenv("MORE")) != NULL)
                arg_parser(&ctl, s);

        while (--ctl.num_files > 0) {
                if ((chr = (*++ctl.file_names)[0]) == '-') {
                        arg_parser(&ctl, *ctl.file_names + 1);
                } else if (chr == '+') {
                        s = *ctl.file_names;
                        if (*++s == '/') {
                                ctl.search_at_start = 1;
                                initbuf = xstrdup(s + 1);
                        } else {
                                ctl.jump_at_start = 1;
                                for (start_at_line = 0; *s != '\0'; s++)
                                        if (isdigit(*s))
                                                start_at_line =
                                                    start_at_line * 10 + *s - '0';
                                --start_at_line;
                        }
                } else
                        break;
        }
        /* allow clear_line_ends only if go_home and erase_line and clear_rest strings are
         * defined, and in that case, make sure we are in no_scroll mode */
        if (ctl.clear_line_ends) {
                if ((ctl.go_home == NULL) || (*ctl.go_home == '\0') ||
                    (ctl.erase_line == NULL) || (*ctl.erase_line == '\0') ||
                    (ctl.clear_rest == NULL) || (*ctl.clear_rest == '\0'))
                        ctl.clear_line_ends = 0;
                else
                        ctl.no_scroll = 1;
        }
        if (ctl.lines_per_screen == 0)
                ctl.lines_per_screen = ctl.lines_per_page - 1;
        left = ctl.lines_per_screen;
        if (ctl.num_files > 1)
                ctl.print_banner = 1;
        if (!ctl.no_tty_in && ctl.num_files == 0) {
                warnx(_("bad usage"));
                errtryhelp(EXIT_FAILURE);
        } else
                ctl.current_file = stdin;
        if (!ctl.no_tty_out) {
                if (signal(SIGTSTP, SIG_IGN) == SIG_DFL) {
                        ctl.catch_suspend++;
                }
                tcsetattr(STDERR_FILENO, TCSANOW, &ctl.output_tty);
        }
        sigemptyset(&ctl.sigset);
        sigaddset(&ctl.sigset, SIGINT);
        sigaddset(&ctl.sigset, SIGQUIT);
        sigaddset(&ctl.sigset, SIGTSTP);
        sigaddset(&ctl.sigset, SIGWINCH);
        sigprocmask(SIG_BLOCK, &ctl.sigset, NULL);
        ctl.sigfd = signalfd(-1, &ctl.sigset, SFD_CLOEXEC);
        if (ctl.no_tty_in) {
                if (ctl.no_tty_out)
                        copy_file(stdin);
                else {
                        ctl.current_file = stdin;
                        display_file(&ctl, initbuf, left);
                }
                ctl.no_tty_in = 0;
                ctl.print_banner = 1;
                ctl.first_file = 0;
        }

        while (ctl.argv_position < ctl.num_files) {
                checkf(&ctl, ctl.file_names[ctl.argv_position]);
                display_file(&ctl, initbuf, left);
                ctl.first_file = 0;
                ctl.argv_position++;
        }
        ctl.clear_line_ends = 0;
        ctl.prompt_len = 0;
        more_exit(&ctl);
}