Usenet 1994 January/usenetsourcesnewsgroupsinfomagicjanuary1994.iso/sources/unix/volume6/less2/part1/main.c

C/C++ Source or Header | 1986-11-30 | 4.7 KB | 294 lines

/*
 * Entry point, initialization, miscellaneous routines.
 */

#include "less.h"
#include "position.h"
#include <setjmp.h>

public int    ispipe;
public jmp_buf    main_loop;
public char *    first_cmd;
public char *    every_first_cmd;
public int    new_file;
public int    is_tty;
public char     current_file[128];
public int ac;
public char **av;
public int curr_ac;
#if EDITOR
public char *    editor;
#endif

extern int file;
extern int nbufs;
extern int sigs;
extern int quit_at_eof;
extern int p_nbufs, f_nbufs;
extern int back_scroll;
extern int top_scroll;
extern int sc_height;


/*
 * Edit a new file.
 * Filename "-" means standard input.
 * No filename means the "current" file, from the command line.
 */
    public void
edit(filename)
    char *filename;
{
    register int f;
    char message[100];
    static int any_edited = 0;
    static int hold_scroll = 0;

    if (filename == NULL || *filename == '\0')
    {
        if (curr_ac >= ac)
        {
            error("No current file");
            return;
        }
        filename = av[curr_ac];
    }
    if (strcmp(filename, "-") == 0)
        f = 0;    /* Standard input */
    else if ((f = open(filename, 0)) < 0)
    {
        sprintf(message, "Cannot open %.*s",
            error_width()-13, filename);
        if (any_edited)
            error(message);
        else
        {
            puts(message);
            hold_scroll = 1;
        }
        return;
    }

    if (isatty(f))
    {
        /*
         * Not really necessary to call this an error,
         * but if the control terminal (for commands)
         * and the input file (for data) are the same,
         * we get weird results at best.
         */
        error("Can't take input from a terminal");
        if (f > 0)
            close(f);
        return;
    }

    /*
     * Close the current input file and set up to use the new one.
     */
    if (file > 0)
        close(file);
    new_file = 1;
    strcpy(current_file, filename);
    ispipe = (f == 0);
    file = f;
    ch_init( (ispipe) ? p_nbufs : f_nbufs );
    init_mark();
    if (every_first_cmd != NULL)
        first_cmd = every_first_cmd;
    if (is_tty)
    {
        any_edited = 1;
        if (hold_scroll)
        {
            /*
             * Before erasing the screen contents,
             * display the file name and ask for a keystroke.
             */
            error(filename);
            hold_scroll = 0;
        }
        if (first_cmd == NULL || *first_cmd == '\0')
        {
            /*
             * Display the first screen.
             */
            jump_back(1);
        } else
        {
            /*
             * The first_cmd will hopefully redisplay the
             * screen, so we need not display anything yet.
             * Indicate there is nothing yet on the screen.
             */
            pos_clear();
        }
    }
}

/*
 * Edit the next file in the command line list.
 */
    public void
next_file(n)
    int n;
{
    if (curr_ac + n >= ac)
    {
        if (quit_at_eof)
            quit();
        error("No (N-th) next file");
    } else
        edit(av[curr_ac += n]);
}

/*
 * Edit the previous file in the command line list.
 */
    public void
prev_file(n)
    int n;
{
    if (curr_ac - n < 0)
        error("No (N-th) previous file");
    else
        edit(av[curr_ac -= n]);
}

/*
 * Copy a file directly to standard output.
 * Used if standard output is not a tty.
 */
    static void
cat_file()
{
    register int c;

    while ((c = ch_forw_get()) != EOF)
        putc(c);
    flush();
}

/*
 * Entry point.
 */
main(argc, argv)
    int argc;
    char *argv[];
{
    char *getenv();


    /*
     * Process command line arguments and LESS environment arguments.
     * Command line arguments override environment arguments.
     */
    init_option();
    scan_option(getenv("LESS"));
    argv++;
    while ( (--argc > 0) &&
        (argv[0][0] == '-' || argv[0][0] == '+') &&
        argv[0][1] != '\0')
        scan_option(*argv++);

#if EDITOR
    editor = getenv("EDITOR");
    if (editor == NULL || *editor == '\0')
        editor = EDIT_PGM;
#endif

    /*
     * Set up list of files to be examined.
     */
    ac = argc;
    av = argv;
    curr_ac = 0;

    /*
     * Set up terminal, etc.
     */
    is_tty = isatty(1);
    if (!is_tty)
    {
        /*
         * Output is not a tty.
         * Just copy the input file(s) to output.
         */
        if (ac < 1)
        {
            edit("-");
            cat_file();
        } else
        {
            do
            {
                edit((char *)NULL);
                if (file >= 0)
                    cat_file();
            } while (++curr_ac < ac);
        }
        exit(0);
    }

    raw_mode(1);
    get_term();
    open_getc();
    init();

    if (back_scroll < 0)
    {
        /* {{ KLUDGE }} */
        back_scroll = sc_height-1;
        if (top_scroll)
            back_scroll--;
    }

    if (setjmp(main_loop))
        quit();
    init_signals();

    /*
     * Select the first file to examine.
     */
    if (ac < 1)
        edit("-");    /* Standard input */
    else
    {
        /*
         * Try all the files named as command arguments.
         * We are simply looking for one which can be
         * opened without error.
         */
        do
        {
            edit((char *)NULL);
            if (file >= 0)
                /* We can open this file. */
                break;
            putc('\n');  flush();
        } while (++curr_ac < ac);
    }

    if (file >= 0)
        commands();
    quit();
}

/*
 * Exit the program.
 */
    public void
quit()
{
    /*
     * Put cursor at bottom left corner, clear the line,
     * reset the terminal modes, and exit.
     */
    lower_left();
    clear_eol();
    deinit();
    flush();
    raw_mode(0);
    exit(0);
}