United Public Domain Gold 2/United Public Domain Gold 2.iso/music_utilities/pt030.dms/pt030.adf/Less/Src/os.c

C/C++ Source or Header | 1987-06-15 | 4KB | 252 lines

/*
 * Operating system dependent routines.
 *
 * Most of the stuff in here is based on Unix, but an attempt
 * has been made to make things work on other operating systems.
 * This will sometimes result in a loss of functionality, unless
 * someone rewrites code specifically for the new operating system.
 *
 * The makefile provides defines to decide whether various
 * Unix features are present.
 */

#include "less.h"
#include <signal.h>

char *getenv();

/*
 * Pass the specified command to a shell to be executed.
 * Like plain "system()", but handles resetting terminal modes, etc.
 */
    public void
lsystem(cmd)
    char *cmd;
{
    int inp;
    char cmdbuf[256];
    char *shell;

    /*
     * Print the command which is to be executed,
     * unless the command starts with a "-".
     */
    if (cmd[0] == '-')
        cmd++;
    else
    {
        lower_left();
        clear_eol();
        putstr("!");
        putstr(cmd);
        putstr("\n");
    }

    /*
     * De-initialize the terminal and take out of raw mode.
     */
    deinit();
    flush();
    raw_mode(0);

#ifdef AMIGA
    { extern int called_from_WB;
      extern long tty;

    if (called_from_WB)
        error("can't execute a CLI command from Workbench, sorry!");
    else
        if (cmd && *cmd)
            /* run a one shot */
            Execute(cmd, 0L, tty);
    }
#else
    /*
     * Restore signals to their defaults.
     */
    SIGNAL(SIGINT, SIG_DFL);
#ifdef SIGTSTP
    SIGNAL(SIGTSTP, SIG_DFL);
#endif
    /*
     * Force standard input to be the terminal, "/dev/tty",
     * even if less's standard input is coming from a pipe.
     */
    inp = dup(0);
    close(0);
    if (open("/dev/tty", 0) < 0)
        dup(inp);

    /*
     * Pass the command to the system to be executed.
     */
    if ((shell = getenv("SHELL")) != NULL)
    {
        sprintf(cmdbuf, "%s -c \"%s\"", shell, cmd);
        cmd = cmdbuf;
    }
    system(cmd);

    /*
     * Restore standard input, reset signals, raw mode, etc.
     */
    close(0);
    dup(inp);
    close(inp);

    init_signals();
    raw_mode(1);
    init();
#endif
}

/*
 * Expand a filename, substituting any environment variables, etc.
 * The implementation of this is necessarily very operating system
 * dependent.  This implementation is unabashedly only for Unix systems.
 */
#if GLOB

#include <stdio.h>
FILE *popen();

    public char *
glob(filename)
    char *filename;
{
    FILE *f;
    char *p;
    int ch;
    static char ECHO[] = "echo ";
    static char filebuf[FILENAME+sizeof(ECHO)+1];

    if (filename[0] == '#')
        return (filename);
    strcpy(filebuf, ECHO);
    strtcpy(filebuf+sizeof(ECHO)-1, filename, sizeof(filebuf)-sizeof(ECHO));
    if ((f = popen(filebuf, "r")) == NULL)
        return (filename);
    for (p = filebuf;  p < &filebuf[sizeof(filebuf)-1];  p++)
    {
        if ((ch = getc(f)) == '\n' || ch == EOF)
            break;
        *p = ch;
    }
    *p = '\0';
    pclose(f);
    return (filebuf);
}

#else

    public char *
glob(filename)
    char *filename;
{
    return (filename);
}

#endif


/*
 * Returns NULL if the file can be opened and
 * is an ordinary file, otherwise an error message
 * (if it cannot be opened or is a directory, etc.)
 */

#if STAT

#include <sys/types.h>
#include <sys/stat.h>

    public char *
bad_file(filename, message, len)
    char *filename;
    char *message;
    int len;
{
    struct stat statbuf;

    if (stat(filename, &statbuf) < 0)
        return (errno_message(filename, message, len));

    if ((statbuf.st_mode & S_IFMT) == S_IFDIR)
    {
        static char is_dir[] = " is a directory";
        strtcpy(message, filename, len-sizeof(is_dir)-1);
        strcat(message, is_dir);
        return (message);
    }
    if ((statbuf.st_mode & S_IFMT) != S_IFREG)
    {
        static char not_reg[] = " is not a regular file";
        strtcpy(message, filename, len-sizeof(not_reg)-1);
        strcat(message, not_reg);
        return (message);
    }
    return (NULL);
}

#else

    public char *
bad_file(filename, message, len)
    char *filename;
    char *message;
    int len;
{
    return (NULL);
}

#endif

/*
 * Return an error message based on the value of "errno".
 */

#if PERROR

    public char *
errno_message(filename, message, len)
    char *filename;
    char *message;
    int len;
{
    char *p;
    static char msg[16];

    extern char *sys_errlist[];
    extern int sys_nerr;
    extern int errno;

    if (errno < sys_nerr)
        p = sys_errlist[errno];
    else
    {
        sprintf(msg, "Error %d", errno);
        p = msg;
    }
    strtcpy(message, filename, len-strlen(p)-3);
    strcat(message, ": ");
    strcat(message, p);
    return (message);
}

#else

    public char *
errno_message(filename, message, len)
    char *filename;
    char *message;
    int len;
{
    static char msg[] = ": cannot open";

    strtcpy(message, filename, len-sizeof(msg)-1);
    strcat(message, msg);
    return (message);
}

#endif