Source Code 1994 March/Source_Code_CD-ROM_Walnut_Creek_March_1994.iso/compsrcs/misc/volume33/problem1/part07

Text File | 1992-11-12 | 37.6 KB | 1,330 lines

Newsgroups: comp.sources.misc
From: [e-mail] (Mike Lijewski)
Subject:  v33i078:  problem1.1 - A Problem Database Manager, Part07/07
Message-ID: <[e-mail]>
X-Md4-Signature: ec05e6a723a2d76d1bd57a490ae1b7aa
Date: Thu, 12 Nov 1992 19:56:23 GMT
Approved: [e-mail]

Submitted-by: [e-mail] (Mike Lijewski)
Posting-number: Volume 33, Issue 78
Archive-name: problem1.1/part07
Environment: UNIX, C++, GDBM, Termcap
Supersedes: problem: Volume 33, Issue 2-9

#! /bin/sh
# This is a shell archive.  Remove anything before this line, then unpack
# it by saving it into a file and typing "sh file".  To overwrite existing
# files, type "sh file -c".  You can also feed this as standard input via
# unshar, or by typing "sh <file", e.g..  If this archive is complete, you
# will see the following message at the end:
#        "End of archive 7 (of 7)."
# Contents:  utilities.C
# Wrapped by lijewski@xtesoc2 on Wed Nov 11 16:20:14 1992
PATH=/bin:/usr/bin:/usr/ucb ; export PATH
if test -f 'utilities.C' -a "${1}" != "-c" ; then
  echo shar: Will not clobber existing file \"'utilities.C'\"
else
echo shar: Extracting \"'utilities.C'\" \(35328 characters\)
sed "s/^X//" >'utilities.C' <<'END_OF_FILE'
X/*
X** utilities.C - utility functions
X**
X** utilities.C utilities.C 1.65   Delta\'d: 08:41:30 11/4/92   Mike Lijewski, CNSF
X**
X** Copyright \(c\) 1991, 1992 Cornell University
X** All rights reserved.
X**
X** Redistribution and use in source and binary forms are permitted
X** provided that: \(1\) source distributions retain this entire copyright
X** notice and comment, and \(2\) distributions including binaries display
X** the following acknowledgement:  ``This product includes software
X** developed by Cornell University\'\' in the documentation or other
X** materials provided with the distribution and in all advertising
X** materials mentioning features or use of this software. Neither the
X** name of the University nor the names of its contributors may be used
X** to endorse or promote products derived from this software without
X** specific prior written permission.
X**
X** THIS SOFTWARE IS PROVIDED ``AS IS\'\' AND WITHOUT ANY EXPRESS OR
X** IMPLIED WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED
X** WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
X*/
X
X#include <ctype.h>
X
X#ifndef _IBMR2
X#include <libc.h>
X#endif
X
X#include <fcntl.h>
X
X#include <osfcn.h>
X#include <pwd.h>
X#include <signal.h>
X#include <stdarg.h>
X#include <stdlib.h>
X#include <stdio.h>
X
X#ifndef _IBMR2
X#include <unistd.h>
X#endif
X
X// access is prototyped in <sys/access.h> on RS/6000s
X#ifdef _IBMR2
X#include <sys/access.h>
X#include <sys/lockf.h>
X#endif
X
X#include <sys/stat.h>
X#include <sys/types.h>
X#ifdef ESIX
Xtypedef int pid_t;
X#endif
X#include <sys/wait.h>
X#include <string.h>
X#include <sys/errno.h>
X
X// this header file is badly busted on RS/6000s
X#ifndef _IBMR2
X#include <unistd.h>
X#endif
X
X#if defined FLOCK || !defined(R_OK)
X#include <sys/file.h>
X#endif
X
X#include "classes.h"
X#include "display.h"
X#include "lister.h"
X#include "problem.h"
X#include "utilities.h"
X
X/* remove this once GNU gets it fixed -- this stuff should be in <unistd.h> */
X#ifdef __GNUG__
Xextern "C" int lockf(int, int, long);
Xextern "C" int flock(int, int);
X#ifndef LOCK_UN
X#define LOCK_UN 8
X#endif
X#ifndef LOCK_EX
X#define LOCK_EX 2
X#endif
X#ifndef F_LOCK
X#define F_LOCK   1
X#endif
X#ifndef F_ULOCK
X#define F_ULOCK  0
X#endif
X#endif /*__GNUG__*/
X
Xconst char KEY_CR    = '\r';   // carriage return
Xconst char KEY_BKSP  = '\b';   // backspace
Xconst char KEY_CTL_L = '\f';   // repaint screen -- CTR-L
Xconst char KEY_DEL   = 127;    // ASCII DELETE
X
X/*
X** fgetline - returns a pointer to the start of a line read from fp,
X**            or the null pointer if we hit eof or get an error from
X**            fgets. Exits if new fails. Strips the newline from
X**            the line. Caller should free memory if desired. size
X**            is the expected length of the line to be read.
X*/
X
Xchar *fgetline(FILE *fp, int size)
X{
X    char *buffer = new char[size];
X
X    char *result= fgets(buffer, size, fp);
X    if (result == 0)
X    {
X        //
X        // Either error or at eof.
X        //
X        DELETE buffer;
X        return 0;
X    }
X
X    if (buffer[strlen(buffer) - 1] != '\n' && !feof(fp))
X    {
X        //
X        // Longer line than buffer can hold.
X        //
X        char *restofline = fgetline(fp, size);
X
X        if (restofline == 0) return 0; // eof or error
X
X        char *longline = new char[strlen(buffer) + strlen(restofline) + 1];
X        (void)strcat(strcpy(longline, buffer), restofline);
X
X        DELETE restofline;
X        DELETE buffer;
X
X        if (longline[strlen(longline) - 1] == '\n')
X            longline[strlen(longline) - 1] = 0;
X
X        return longline;
X    }
X    else
X    {
X        if (buffer[strlen(buffer) - 1] == '\n')
X            buffer[strlen(buffer) - 1] = 0;
X        return buffer;
X    }
X}
X
X/*
X** display_string - prints a string to the given the display, guaranteeing not
X**                  to print more than columns characters.  If the string
X**                  exceeds the width of the window, a ! is placed in
X**                  the final column.  len is the length of the string,
X**                  if known, which defaults to zero. offset, which
X**                  defaults to zero, is non-zero in those cases where we have
X**                  already printed offset characters to the screen line.
X**                  We never call this when trying to write to the last
X**                  row on the screen.  That is the dominion of message.
X*/
X
Xvoid display_string(const char *str, int length, int offset)
X{
X    int len = (length == 0 ? (int) strlen(str) : length) + offset;
X
X    if (len < columns())
X    {
X        (void)fputs(str, stdout);
X        cursor_wrap();
X    }
X    else if (len > columns())
X    {
X        (void)printf("%*.*s%c", columns() - offset - 1, columns() - offset - 1,
X                     str, '!');
X        if (!AM || XN) cursor_wrap();
X    }
X    else
X    {
X        (void)fputs(str, stdout);
X        if (!AM || XN) cursor_wrap();
X    }
X}
X
X/*
X** error - Prints error message so it can be read.  This is the error
X**         function we call once we have initialized the display.
X*/
X
Xvoid error(const char *format, ...)
X{
X    va_list ap;
X    va_start(ap, format);
X    move_to_message_line();
X    clear_to_end_of_line();
X    deinit_screen_and_kbdr();
X    (void) vfprintf(stdout, format, ap);
X    putchar('\n');
X    va_end(ap);
X    exit(1);
X}
X
X/*
X** execute - executes command using exec.  Returns 1 if the exec
X**           went OK, otherwise it returns 0.  Assumes that the execd
X**           program wants our open file descriptors.
X**           Forces the effective uid to the real uid in the child.
X**           If prompt is true, we prompt for a keypress before returning.
X**           Prompt defaults to false.
X*/
X
Xint execute(const char *file, const char *argv[], int prompt)
X{
X    deinit_screen_and_kbdr();
X    unset_signals();
X
X    int status;
X    pid_t pid = fork();
X
X    switch(pid)
X    {
X      case -1:
X        //
X        // error
X        //
X        return 0;
X      case 0:
X        //
X        // in the child
X        //
X        if (setuid(getuid()) < 0)
X            error("file %s, line %d, setuid() failed" __FILE__, __LINE__);
X
X        execvp(file, (char *const *)argv);
X
X        //
X        // exec failed
X        //
X        exit(1);
X      default:
X        //
X        // in the parent
X        //
X#ifdef NOWAITPID
X        while (wait(&status) != pid) ;
X#else
X        waitpid(pid, &status, 0);
X#endif
X
X        set_signals();
X        setraw();
X
X        if (prompt)
X            //
X            // eat a character  -- print in standout mode
X            //
X            (void)yes_or_no("Press Any Key to Continue", 0, Yes, 1);
X
X        enter_cursor_addressing_mode();
X        enter_visual_mode();
X        enable_keypad();
X        synch_display();
X
X        return status == 0 ? 1 : 0;
X    }
X}
X
X#ifdef SIGWINCH
X
X/*
X** winch - set flag indicating window size changed.
X*/
X
Xint windowSizeChanged;  // should be a sig_atomic_t
X
Xvoid winch(int)
X{
X    (void)signal(SIGWINCH, SIG_IGN);
X    windowSizeChanged = 1;
X    (void)signal(SIGWINCH, winch);
X}
X
X#ifdef M_UNIX
X#include <sys/unistd.h>
X#include <sys/stream.h>
X#include <sys/ptem.h>
X#endif
X
X#include <sys/ioctl.h>
X
X/*
X** adjust_window - called to adjust our window after getting a SIGWINCH
X*/
X
Xvoid adjust_window()
X{
X#ifdef TIOCGWINSZ
X    struct winsize w;
X    if (ioctl(fileno(stdout), TIOCGWINSZ, (char *)&w) == 0 && w.ws_row > 0)
X        LI = w.ws_row;
X    if (ioctl(fileno(stdout), TIOCGWINSZ, (char *)&w) == 0 && w.ws_col > 0)
X        CO = w.ws_col;
X#endif
X    if (LI < 5 || CO < 20)
X        error("screen too small to be useful");
X}
X
X#endif
X
X/*
X** prompt - displays msg prompt and then collects the response.
X**          The keys of the response are echoed as they are collected.
X**          The response should be deleted when no longer needed.
X**          A response can contain any graphical character. Backspace
X**          works as expected. Carriage return indicates the end of
X**          response. Non-graphical characters are ignored.  If we
X**          get suspended and resumed in prompt, redisplay is
X**          the function to call to fixed up all but the message line
X**          of the display.  We rely on signals interrupting read.
X*/
X
Xchar *prompt(const char *msg, void (*redisplay)())
X{
X    size_t written = 0;  // number of characters written to message line
X    size_t len = strlen(msg);
X    String nmsg(msg);
X
X    clear_message_line();
X
X    if (len < columns())
X    {
X        (void)fputs(nmsg, stdout);
X        written = len;
X    }
X    else
X    {
X        //
X        // Leave space for columns2 + 1 characters.
X        //
X        (void)fputs((const char *)nmsg + (len-columns()/2+1), stdout);
X        written = columns()/2 - 1;
X    }
X    synch_display();
X
X    //
X    // We never echo into the last position in the message window.
X    //
X    size_t space_available = columns() - written; // available spaces in line
X    char *response = new char[space_available + 1];
X    size_t pos = 0;  // index of next character in response
X
X    char key;
X    for (;;)
X    {
X        if (resumingAfterSuspension ||
X#ifdef SIGWINCH
X            windowSizeChanged       ||
X#endif
X            read(0, &key, 1) < 0    || // assume only fails when errno == EINTR
X            key == KEY_CTL_L)
X        {
X#ifdef SIGWINCH
X            if (windowSizeChanged)
X            {
X                windowSizeChanged = 0;
X                adjust_window();
X            }
X#endif
X            resumingAfterSuspension = 0;
X            redisplay();
X            clear_message_line();  // make sure we are on the message line
X            response[pos] = 0;
X            if (pos + len < columns())
X            {
X                //
X                // Output message and response-to-date.
X                //
X                (void)fputs(nmsg, stdout);
X                (void)fputs(response, stdout);
X                space_available = columns() - pos - len;
X            }
X            else if (pos < columns())
X            {
X                //
X                // Display the response.
X                //
X                (void)fputs(response, stdout);
X                space_available = columns() - strlen(response);
X            }
X            else
X            {
X                //
X                // Display the backend of the response.
X                //
X                (void)fputs(&response[pos - columns()/2 + 1], stdout);
X                space_available = columns()/2 + 1;
X            }
X            synch_display();
X        }
X        else if (isprint(key))
X        {
X            //
X            // echo character to message window and wait for another
X            //
X            response[pos++] = key;
X            space_available--;
X            if (!space_available)
X            {
X                //
X                // Need to allocate more room for the response.
X                // Note that strlen\(response\) == pos
X                //
X                space_available = columns()/2 + 1;
X                char *nresponse = new char[pos + space_available + 1];
X                response[pos] = 0;  // stringify response
X                (void)strcpy(nresponse, response);
X
X                DELETE response;
X                response = nresponse;
X
X                //
X                // Shift prompt in message window so we
X                // always have the end in view to which we are
X                // adding characters as they are typed.
X                //
X                clear_message_line();
X                (void)fputs(&response[pos - columns()/2 + 1], stdout);
X                key = 0;  // nullify key
X            }
X            else
X            {
X                putchar(key);
X                key = 0;  // nullify key
X            }
X            synch_display();
X        }
X        else
X            switch (key)
X            {
X              case KEY_CR: // we have the complete response
X                response[pos] = 0;
X                clear_message_line();
X                synch_display();
X                return response;
X              case KEY_DEL:
X              case KEY_BKSP: // back up one character
X                if (pos == 0)
X                {
X                    ding();
X                    break;
X                }
X                backspace();
X                DC ? delete_char_at_cursor() : clear_to_end_of_line();
X                --pos;
X                ++space_available;
X                if (space_available == columns())
X                {
X                    //
X                    // The only way this can happen is if we
X                    // had previously shifted the response to the left.
X                    // Now we must shift the response to the right.
X                    //
X                    clear_message_line();
X                    response[pos] = 0;
X                    if (pos + len < columns())
X                    {
X                        //
X                        // Output message and response-to-date.
X                        //
X                        (void)fputs(nmsg, stdout);
X                        (void)fputs(response, stdout);
X                        space_available = columns() - pos - len;
X                    }
X                    else if (pos < columns())
X                    {
X                        //
X                        // Display the response.
X                        //
X                        (void)fputs(response, stdout);
X                        space_available = columns() - strlen(response);
X                    }
X                    else
X                    {
X                        //
X                        // Display the backend of the response
X                        //
X                        (void)fputs(&response[pos - columns()/2 + 1], stdout);
X                        space_available = columns()/2 + 1;
X                    }
X                }
X                synch_display();
X                break;
X              default: ding(); break; // ignore other characters
X            }
X    }
X}
X
X/*
X** message - prints a message on the last line of the screen.
X**           It is up to the calling process to put the cursor
X**           back where it belongs.  Synchs the display.  It can
X**           be called as either:
X**
X**                message\(msg\);
X**           or
X**                message\(fmt, str\);
X**
X**           In the later case it must be the case that the format fmt
X**           has exactly one % into which the str will be substituted
X**           as in the ?printf functions.  Prints in standout mode.
X*/
X
X//
X// the definition -- declared in utilities.h
X//
Xint message_window_dirty = 0;
X
Xvoid message(const char *fmt, const char *str)
X{
X    String msg;          // the complete message to be output
X
X    clear_message_line();
X
X    if (str)
X    {
X        const char *token = strchr(fmt, '%');
X        if (token == 0)
X            //
X            // This should not happen.  But if it does, let us
X            // just print the format fmt.
X            //
X            msg = fmt;
X        else
X        {
X            msg  = String(fmt, token - fmt);
X            msg += str;
X            msg += token + 1;
X        }
X    }
X    else
X        msg = fmt;
X
X    if (msg.length() < columns())
X        (void)fputs(msg, stdout);
X    else
X        (void)printf("%*.*s", columns() - 1, columns() - 1, (const char *)msg);
X
X    synch_display();
X    message_window_dirty = 1;
X}
X
X/*
X** yes_or_no - returns true if a y or Y is typed in response to
X**             the msg. We deal with being suspended and resumed.
X**
X**             defResponse is the assumed default response.
X**
X**                 defResponse == Yes ==> that return value is true unless
X**                                        n or N is typed.
X**
X**                 defResponse == No  ==> that return value is true only if
X**                                        y or Y is typed; else it
X**                                        return false.
X**
X**             If standout is true the message is displayed in standout mode.
X**
X**             It is assumed that the message that is printed somehow indicates
X**             whether the default response is true or false.
X*/
X
Xint yes_or_no(const char *msg,
X              void (*redisplay)(),
X              Response defResponse,
X              int standout)
X{
X    if (standout) enter_standout_mode();
X    message(msg);
X    if (standout) end_standout_mode();
X
X    char key;
X    while (1)
X        //
X        // read a character dealing with interruption
X        //
X        if (resumingAfterSuspension ||
X#ifdef SIGWINCH
X            windowSizeChanged       ||
X#endif
X            read(0, &key, 1) < 0    || // assume only fails when errno==EINTR
X            key == KEY_CTL_L)
X        {
X#ifdef SIGWINCH
X            if (windowSizeChanged)
X            {
X                windowSizeChanged = 0;
X                adjust_window();
X            }
X#endif
X            resumingAfterSuspension = 0;
X            if (redisplay) redisplay();
X            if (standout) enter_standout_mode();
X            message(msg);
X            if (standout) end_standout_mode();
X        }
X        else
X            break;
X
X    clear_message_line();
X    synch_display();
X
X    switch (defResponse)
X    {
X      case Yes:
X        return !(key == 'n' || key == 'N');
X      case No:
X        return   key == 'y' || key == 'Y';
X    }
X}
X
X/*
X** lock_file - lock the file opened with file descriptor fd.
X**             Exits on error.
X*/
X
Xvoid lock_file(int fd)
X{
X    if (lseek(fd, 0, 0) < 0) error("lseek() failed");
X#ifdef FLOCK
X    if (flock(fd, LOCK_EX) < 0) error("flock - LOCK_EX");
X#else
X    if (lockf(fd, F_LOCK, 0) < 0) error("lockf - F_LOCK");
X#endif
X}
X
X/*
X** unlock_file - unlock file with file descriptor fd.
X**               Exits on error.
X*/
X
Xvoid unlock_file(int fd)
X{
X    if (lseek(fd, 0, 0) < 0) error("lseek() failed");
X#ifdef FLOCK
X    if (flock(fd, LOCK_UN) < 0) error("flock - LOCK_UN");
X#else
X    if (lockf(fd, F_ULOCK, 0) < 0) error("lockf - F_ULOCK");
X#endif
X}
X
X/*
X** quit - cleanup and exit.  Called after a SIGHUP, SIGTERM, SIGQUIT
X**        or SIGINT, or on normal termination.  sig defaults to 0.
X*/
X
Xvoid quit(int sig) { deinit_screen_and_kbdr(); exit(sig); }
X
X/*
X** username - returns the username pertaining to the real uid.
X**            Exits on error;
X*/
X
Xconst char *username()
X{
X    static String user;
X    if (user == "")
X    {
X        struct passwd *entry = getpwuid(getuid());
X        if (!entry)
X            error("file %s, line %d, getpwuid() failed", __FILE__, __LINE__);
X        user =  entry->pw_name;
X    }
X    return user;
X}
X
X/*
X** write_to_pipe - writes the data to the pipe on the file descriptor.
X**                 Exits on error.
X*/
X
Xvoid write_to_pipe(int fd, const char *data, int size)
X{
X    int nwritten = 0;
X    while (size > 0)
X    {
X        nwritten = write(fd, data, size);
X        if (nwritten <= 0)
X            error("file %s, line %d, write() failed", __FILE__, __LINE__);
X        size -= nwritten;
X        data += nwritten;
X    }
X
X}
X
X/*
X** read_file - reads the file pointed to by fp into the array lines.
X**             lines must have been previously allocated in the caller,
X**             to size size. len is the expected length of the lines
X**             in the file. pos is the position in lines
X**             to which we start adding the lines; it defaults to zero.
X**             In general, this will be zero, but in one case when I am
X**             building an argv for an execv, I want a non-zero offset.
X**             Returns the number of lines in lines or -1 on error.
X**             lines is null-terminated.
X**
X**             This is used only for reading files containing
X**             relatively few lines.  It skips over lines with a "#"
X**             in the first column and blank lines.
X*/
X
Xint read_file(FILE *fp, char** &lines, int size, int linelen, int pos)
X{
X    const int chunksize = 20;  // chunksize to grow by
X    int nlines = 0;            // number of lines added to lines
X
X    char *line = fgetline(fp, linelen);
X    for (; line; line = fgetline(fp, linelen))
X    {
X        //
X        // Skip comment lines and empty lines.
X        //
X        if (*line == '#' || strcmp(line, "") ==  0)
X        {
X            DELETE line;
X            continue;
X        }
X
X        //
X        // strip off newline
X        //
X        if (line[strlen(line) - 1] == '\n') line[strlen(line) - 1] = 0;
X        lines[pos++] = line;
X        nlines++;
X        if (pos == size)
X        {
X            //
X            // grow Areas
X            //
X            char **newspace = new char*[size += chunksize];
X            for (int i = 0; i < pos; i++) newspace[i] = lines[i];
X            DELETE lines;
X            lines = newspace;
X        }
X    }
X    if (feof(fp) && !ferror(fp))
X    {
X        //
X        // null terminate lines
X        //
X        if (pos == size)
X        {
X            //
X            // got to grow one more
X            //
X            char **newspace = new char*[size + 1];
X            for (int i = 0; i < pos; i++) newspace[i] = lines[i];
X            DELETE lines;
X            lines = newspace;
X        }
X        lines[pos] = 0;
X        return nlines;
X    }
X    else
X        return -1;
X}
X
X/*
X** tokenize - returns a null-terminated vector of the words in line
X**            The vector and its elements are in volatile storage
X**            which we manage here.
X*/
X
Xconst char **tokenize(const char *line, const char *separators)
X{
X    //
X    // Since strtok modifies its argument, we use a copy of line.
X    //
X    static char *newline;     // volatile storage of vector elements
X    DELETE newline;
X    newline = new char[strlen(line) + 1];
X    (void)strcpy(newline, line);
X
X    const int chunksize = 5;  // chunksize to grow by
X    int size   = chunksize;   // total size of vector
X    int nwords = 0;           // number of words in vector
X    static char **words;      // volatile storage for the word pointers
X    DELETE words;
X    words = new char*[chunksize];
X
X    if ((words[nwords++] = strtok(newline, separators)) == 0)
X        return (const char **)words;
X
X    while (words[nwords++] = strtok(0, separators))
X        if (nwords == size)
X        {
X            //
X            // Grow words.
X            //
X            char **newspace = new char*[size += chunksize];
X            for (int i = 0; i < nwords; i++) newspace[i] = words[i];
X            DELETE words;
X            words = newspace;
X        }
X    return (const char **)words;
X}
X
X/*
X** read_and_exec_perm - returns non-zero if we have read and execute
X**                      permission on the file, otherwise 0.
X**                      Returns 0 on error.
X*/
X
Xint read_and_exec_perm(const char *file)
X{
X    return access(file, R_OK | X_OK) == -1 ? 0 : 1;
X}
X
X/*
X** expand_tilde - expects a string of the form "~ ...".
X**                Returns a new string in volatile storage
X**                with the user\'s home directory in place of the ~.
X**                The user\'s home directory is always appended
X**                in the form: "/usr/staff/mjlx"; a slash is not added to
X**                the end of the home directory string.  Returns the original
X**                string if we cannot get the user\'s home directory.
X*/
X
Xconst char *expand_tilde(char *str)
X{
X    static char *home = getenv("HOME");
X    if (home == NULL)
X    {
X        struct passwd *user = getpwuid(getuid());
X        if (user == NULL) return str;
X        home = user->pw_dir;
X    }
X    if (*str != '~') return str;
X    static String expansion;
X    expansion  = home;
X    expansion += (str + 1);
X    return expansion;
X}
X
X/*
X** update_screen_line
X**
X**     oldline is what is currently on the screen in row y
X**     newline is what we want on the screen in row y
X**
X**     We make a good attempt to optimize the output of characters to
X**     the screen.  We want to display newline on the screen,
X**     assuming oldline is what is currently displayed.  This
X**     will be "good" if oldline and newline are quite similar.
X**     That is to say, this should only be called when there is an
X**     expectation that oldline and newline are "almost" the same.
X*/
X
Xvoid update_screen_line(const char *oldline, const char *newline, int y)
X{
X    if (strcmp(oldline, newline) == 0) return;
X
X    size_t olen = strlen(oldline);
X    size_t nlen = strlen(newline);
X    size_t  len = olen < nlen ? olen : nlen;
X
X    //
X    // Never display more than columns characters.
X    //
X    int chop = 0;  // do we need to chop off the tail?
X    if (len > columns()) { chop = 1; len = columns(); }
X
X    char *equal = new char[len];
X
X    //
X    // How similar are the two strings?
X    //
X    int differences = 0;
X    for (int i = 0; i < len; i++) equal[i] = 1;
X    for (i = 0; i < len; i++)
X        if (oldline[i] != newline[i]) { differences++; equal[i] = 0; }
X
X    if (differences > columns()/2)
X    {
X        //
X        // We just display the new line.
X        //
X        clear_to_end_of_line();
X        (void)fputs(newline, stdout);
X        DELETE equal;
X        return;
X    }
X
X    if (!OS)
X    {
X        //
X        // We can just overwrite the old with the new.
X        //
X        int last = -2;  // position of last character written
X        for (i = 0; i < len; i++)
X        {
X            if (equal[i]) continue;
X            if (i - 1 != last) move_cursor(y, i);
X            (i == len - 1 && chop) ? putchar('!') : putchar(newline[i]);
X            last = i;
X        }
X        if (nlen > olen)
X        {
X            //
X            // Have more characters to output.
X            //
X            chop = len > columns();
X            move_cursor(y, i);
X            for (i = (int)len; i < nlen && i < columns(); i++)
X                (i == columns()-1 && chop) ? putchar('!') : putchar(newline[i]);
X        }
X        else if (nlen < olen)
X        {
X            move_cursor(y, i);
X            clear_to_end_of_line();
X        }
X    }
X    else
X    {
X        //
X        // We can not overwrite.  Truncate at first difference.
X        //
X        int first = 0;
X        for (i = 0; i < len; i++)
X            if (!equal[i])
X            {
X                first = i;
X                break;
X            }
X        move_cursor(y, i);
X        clear_to_end_of_line();
X        for (; i < nlen && i < columns(); i++)
X            (i == columns() - 1) ? putchar('!') : putchar(newline[i]);
X    }
X    DELETE equal;
X}
X
X/*
X** update_modeline - this routine concatenates the two strings
X**                   into the modeline.  The modeline
X**                   is displayed in standout mode if possible.
X**                   We never put more than columns characters into
X**                   the modeline.  The modeline is the penultimate
X**                   line on the terminal screen.  It does not
X**                   synch the display.  If head == tail == 0, we
X**                   just display the old modeline.  This happens
X**                   if for some reason we had to clear the screen.
X*/
X
X//
X// the current modeline
X//
Xchar *current_modeline;
X
Xvoid update_modeline(const char *head, const char *tail)
X{
X    move_to_modeline();
X    enter_standout_mode();
X
X    if (head == 0)   // actually, head == tail == 0
X    {
X        //
X        // Redisplay old modeline.
X        //
X        (void)fputs(current_modeline, stdout);
X        end_standout_mode();
X        return;
X    }
X
X    int len = (int) strlen(head);
X    char *new_modeline = new char[columns() + 1];
X    (void)strncpy(new_modeline, head, columns());
X    new_modeline[columns()] = 0;  // ensure it is null-terminated
X
X    if (len < columns())
X    {
X        //
X        // Write exactly columns characters to modeline.
X        //
X        for (int i = len; i < columns() - 1 && tail && *tail; i++, tail++)
X            new_modeline[i] = *tail;
X        if (i < columns() - 1)
X        {
X            new_modeline[i++] = ' ';
X            for (; i < columns(); i++) new_modeline[i] = '-';
X        }
X        else if (tail && *tail)
X            //
X            // The tail was overly long.  Put a ! in the last space
X            // on the modeline to signify truncation.
X            //
X            new_modeline[columns() - 1] = '!';
X        else
X            //
X            // Here len == columns-1 && there is nothing else in tail.
X            //
X            new_modeline[columns() - 1] = ' ';
X    }
X    else if (len > columns())
X        new_modeline[columns() - 1] = '!';
X
X    if (current_modeline)
X    {
X        update_screen_line(current_modeline, new_modeline, rows() - 2);
X        DELETE current_modeline;
X    }
X    else
X        (void)fputs(new_modeline, stdout);
X
X    current_modeline = new_modeline;
X    end_standout_mode();
X}
X
X/*
X** lines_displayed - returns the number of lines in the DList
X**                   currently displayed on the screen.
X*/
X
Xint lines_displayed(DList *dl)
X{
X    DLink *ln = dl->firstLine();
X    for (int i = 1; ln != dl->lastLine(); i++, ln = ln->next()) ;
X    return i;
X}
X
X/*
X** get_problem_number - returns the prob# of the current line of the DList
X**                      in volatile storage.  The line is of the form:
X**
X**                         prob# ...
X**
X**                      We know INTIMATELY how summary_lines
X**                      formats the output.
X*/
X
Xconst char *get_problem_number(const DList *dl)
X{
X    static String number; // our volatile storage
X
X    const char* begin = dl->currLine()->line();
X
X    //
X    // step over any spaces preceding Prob #
X    //
X    while (*begin == ' ') begin++;
X
X    number = String(begin, strchr(begin, ' ') - begin);
X
X    return (const char *)number;
X}
X
X/*
X** leftshift_current_line - shifts the current line in DList left until
X**                          its tail is visible.
X*/
X
Xvoid leftshift_current_line(DList *dl)
X{
X    int inc = dl->currLine()->length()-columns()+1;
X    move_cursor(dl->savedYPos(), 0);
X    clear_to_end_of_line();
X    display_string(&(dl->currLine()->line())[inc],columns()-1);
X    dl->saveYXPos(dl->savedYPos(), max(goal_column(dl)-inc, 0));
X    move_cursor(dl->savedYPos(), dl->savedXPos());
X}
X
X/*
X** rightshift_current_line - rightshifts current line to "natural" position.
X*/
X
Xvoid rightshift_current_line(DList *dl)
X{
X    move_cursor(dl->savedYPos(), 0);
X    clear_to_end_of_line();
X    display_string(dl->currLine()->line(), dl->currLine()->length());
X    dl->saveYXPos(dl->savedYPos(), goal_column(dl));
X    move_cursor(dl->savedYPos(), dl->savedXPos());
X}
X
X/*
X** initial_listing - prints the initial listing screen.
X**                   Adjusts firstLine, lastLine and currLine.
X*/
X
Xvoid initial_listing(DList *dl)
X{
X    DLink *ln = dl->head();
X    dl->setFirst(ln);
X    dl->setCurrLine(ln);
X
X    clear_display_area();
X
X    for (int i = 0; i < rows() - 2 && ln; ln = ln->next(), i++)
X        display_string(ln->line(), ln->length());
X
X    ln ? dl->setLast(ln->prev()) : dl->setLast(dl->tail());
X}
X
X/*
X** seconds_in_date - returns the number of seconds in a date string
X**                   of the form:
X**
X**                       "mmm dd mm:hh:ss yyyy"
X**
X**                   This is the format returned by ctime, with
X**                   the leading "day" name chopped off.  According to ANSI C,
X**                   a long must be able to hold values up to at least
X**                   2147483647.  This will keep this function working for
X**                   many years into the future.  Eventually, CurrentYear will
X**                   have to be incremented.
X*/
X
Xlong seconds_in_date(const char *date)
X{
X    //
X    // days\[i\] is the number of days preceding month i,
X    // where 0 <= i <= 11
X    //
X    static const int days[] = { 0,31,59,90,120,151,181,212,243,273,304,334 };
X
X    //
X    // mhash\[*date + *\(date+1\) + *\(date+2\) - 268\] hashes to an integer
X    // in the range 0-11 signifying the month.
X    //
X    static char mhash[] = { 11, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
X                            0, 0, 7, 0, 0, 2, 0, 0, 3, 0, 0, 9, 4, 8, 0,
X                            0, 6, 0, 5, 0, 0, 0, 0, 0, 10 };
X
X    const long SecondsPerDay  = 86400L;
X    const long SecondsPerYear = 31536000L;
X    const int CurrentYear = 1992;
X    const char *const fmt = "%d";
X    long total = 0;
X    int tmp, mon = mhash[*date + *(date + 1) + *(date + 2) - 268];
X
X    (void)sscanf(date + 13, fmt, &tmp);   // seconds
X    total += tmp;
X    (void)sscanf(date + 10, fmt, &tmp);   // minutes
X    total += tmp * 60;
X    (void)sscanf(date + 7 , fmt, &tmp);   // hours
X    total += tmp * 3600;
X    (void)sscanf(date + 4 , fmt, &tmp);   // day of the month
X    total += (tmp - 1) * SecondsPerDay;
X    total += days[mon] * SecondsPerDay;   // days in months preceding this one
X    (void)sscanf(date + 16, fmt, &tmp);   // the year
X    // leap year adjustment
X    if (tmp % 4 == 0 && tmp % 100 != 0 && mon >= 2) total += SecondsPerDay;
X    total += (tmp - CurrentYear) * SecondsPerYear;
X    return total;
X}
X
X/*
X** temporary_file - returns the name of a temporary file.  The temporary
X**                  is forced to have permission 666.  Note that
X**                  we force tmpnam to store the name for us in
X**                  volatile storage.
X*/
X
Xconst char *temporary_file()
X{
X    char *file = tmpnam(0);
X    if (file == 0)
X        error("file %s, line %d, tmpnam() failed", __FILE__, __LINE__);
X    int fd;
X    if ((fd = open(file, O_RDWR|O_CREAT)) < 0)
X        error("file %s, line %d, open(%s) failed",
X              __FILE__, __LINE__, file);
X    if (chmod(file, 0666) < 0)
X        error("file %s, line %d, chmod(%s) failed",
X              __FILE__, __LINE__, file);
X    (void)close(fd);
X    return file;
X}
X
X/*
X** set_signals - set up our signal handlers
X*/
X
Xvoid set_signals()
X{
X    (void)signal(SIGHUP,  quit);
X    (void)signal(SIGINT,  quit);
X    (void)signal(SIGQUIT, quit);
X    (void)signal(SIGTERM, quit);
X#ifdef SIGTSTP
X    (void)signal(SIGTSTP, termstop);
X#endif
X#ifdef SIGWINCH
X    (void)signal(SIGWINCH, winch);
X#endif
X}
X
X/*
X** unset_signals - set signals back to defaults
X*/
X
Xvoid unset_signals()
X{
X    (void)signal(SIGHUP,  SIG_DFL);
X    (void)signal(SIGINT,  SIG_DFL);
X    (void)signal(SIGQUIT, SIG_DFL);
X    (void)signal(SIGTERM, SIG_DFL);
X#ifdef SIGTSTP
X    (void)signal(SIGTSTP, SIG_DFL);
X#endif
X#ifdef SIGWINCH
X    (void)signal(SIGWINCH, SIG_DFL);
X#endif
X}
X
X/*
X** block_tstp_and_winch - block SIGTSTP and SIGWINCH
X*/
X
X#ifdef BSDSIGS
Xstatic int oldmask;
X#elif POSIXSIGS
Xstatic sigset_t oldset;
X#endif
X
Xvoid block_tstp_and_winch()
X{
X#ifdef BSDSIGS
X    int oldmask = sigblock(sigmask(SIGTSTP)
X#ifdef SIGWINCH
X                           | sigmask(SIGWINCH)
X#endif
X                           );
X#elif POSIXSIGS
X    sigset_t newset;
X    sigemptyset(&newset);
X#ifdef SIGTSTP
X    sigaddset(&newset, SIGTSTP);
X#endif
X#ifdef SIGWINCH
X    sigaddset(&newset, SIGWINCH);
X#endif
X    if (sigprocmask(SIG_BLOCK, &newset, &oldset) < 0)
X        error("file %s, line %d, sigprocmask(SIG_BLOCK) failed\n",
X              __FILE__, __LINE__);
X#else
X    //
X    // We use ANSI C signals.  These can be "lost" but it is the
X    // best we can do.
X    //
X#ifdef SIGTSTP
X    (void)signal(SIGTSTP, SIG_IGN);
X#endif
X#ifdef SIGWINCH
X    (void)signal(SIGWINCH, SIG_IGN);
X#endif
X#endif
X}
X
X/*
X** unblock_tstp_and_winch - unblock SIGTSTP and SIGWINCH
X*/
X
Xvoid unblock_tstp_and_winch()
X{
X#ifdef BSDSIGS
X    (void)sigsetmask(oldmask);
X#elif POSIXSIGS
X    if (sigprocmask(SIG_SETMASK, &oldset, 0) < 0)
X        error("file %s, line %d, sigprocmask(SIG_SETMASK) failed\n",
X              __FILE__, __LINE__);
X#else
X#ifdef SIGTSTP
X    (void)signal(SIGTSTP, termstop);
X#endif
X#ifdef SIGWINCH
X    (void)signal(SIGWINCH, winch);
X#endif
X#endif
X}
X
END_OF_FILE
if test 35328 -ne `wc -c <'utilities.C'`; then
    echo shar: \"'utilities.C'\" unpacked with wrong size!
fi
# end of 'utilities.C'
fi
echo shar: End of archive 7 \(of 7\).
cp /dev/null ark7isdone
MISSING=""
for I in 1 2 3 4 5 6 7 ; do
    if test ! -f ark${I}isdone ; then
    MISSING="${MISSING} ${I}"
    fi
done
if test "${MISSING}" = "" ; then
    echo You have unpacked all 7 archives.
    rm -f ark[1-9]isdone
else
    echo You still need to unpack the following archives:
    echo "        " ${MISSING}
fi
##  End of shell archive.
exit 0

exit 0 # Just in case...