source: vbox/trunk/src/libs/xpcom18a4/nsprpub/tools/tail.c@ 27325

/* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* ***** BEGIN LICENSE BLOCK *****
 * Version: MPL 1.1/GPL 2.0/LGPL 2.1
 *
 * The contents of this file are subject to the Mozilla Public License Version
 * 1.1 (the "License"); you may not use this file except in compliance with
 * the License. You may obtain a copy of the License at
 * http://www.mozilla.org/MPL/
 *
 * Software distributed under the License is distributed on an "AS IS" basis,
 * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
 * for the specific language governing rights and limitations under the
 * License.
 *
 * The Original Code is the Netscape Portable Runtime (NSPR).
 *
 * The Initial Developer of the Original Code is
 * Netscape Communications Corporation.
 * Portions created by the Initial Developer are Copyright (C) 1998-2000
 * the Initial Developer. All Rights Reserved.
 *
 * Contributor(s):
 *
 * Alternatively, the contents of this file may be used under the terms of
 * either the GNU General Public License Version 2 or later (the "GPL"), or
 * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
 * in which case the provisions of the GPL or the LGPL are applicable instead
 * of those above. If you wish to allow use of your version of this file only
 * under the terms of either the GPL or the LGPL, and not to allow others to
 * use your version of this file under the terms of the MPL, indicate your
 * decision by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL or the LGPL. If you do not delete
 * the provisions above, a recipient may use your version of this file under
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 * ***** END LICENSE BLOCK ***** */

#include "prio.h"
#include "prprf.h"
#include "prinit.h"
#include "prthread.h"
#include "prinrval.h"

#include "plerror.h"
#include "plgetopt.h"

#include <stdlib.h>

#define BUFFER_SIZE 500

static PRFileDesc *out = NULL, *err = NULL;

static void Help(void)
{
    PR_fprintf(err, "Usage: tail [-n <n>] [-f] [-h] <filename>\n");
    PR_fprintf(err, "\t-t <n>   Dally time in milliseconds\n");
    PR_fprintf(err, "\t-n <n>   Number of bytes before <eof>\n");
    PR_fprintf(err, "\t-f       Follow the <eof>\n");
    PR_fprintf(err, "\t-h       This message and nothing else\n");
}  /* Help */

PRIntn main(PRIntn argc, char **argv)
{
        PRIntn rv = 0;
    PLOptStatus os;
        PRStatus status;
        PRFileDesc *file;
        PRFileInfo fileInfo;
        PRIntervalTime dally;
        char buffer[BUFFER_SIZE];
        PRBool follow = PR_FALSE;
        const char *filename = NULL;
        PRUint32 position = 0, seek = 0, time = 0;
    PLOptState *opt = PL_CreateOptState(argc, argv, "hfn:");

    out = PR_GetSpecialFD(PR_StandardOutput);
    err = PR_GetSpecialFD(PR_StandardError);

    while (PL_OPT_EOL != (os = PL_GetNextOpt(opt)))
    {
        if (PL_OPT_BAD == os) continue;
        switch (opt->option)
        {
                case 0:  /* it's the filename */
                        filename = opt->value;
                        break;
        case 'n':  /* bytes before end of file */
            seek = atoi(opt->value);
            break;
        case 't':  /* dally time */
            time = atoi(opt->value);
            break;
        case 'f':  /* follow the end of file */
            follow = PR_TRUE;
            break;
        case 'h':  /* user wants some guidance */
            Help();  /* so give him an earful */
            return 2;  /* but not a lot else */
            break;
         default:
            break;
        }
    }
    PL_DestroyOptState(opt);

        if (0 == time) time = 1000;
        dally = PR_MillisecondsToInterval(time);

    if (NULL == filename)
    {
        (void)PR_fprintf(out, "Input file not specified\n");
        rv = 1; goto done;
    }
        file = PR_Open(filename, PR_RDONLY, 0);
        if (NULL == file)
        {
                PL_FPrintError(err, "File cannot be opened for reading");
                return 1;
        }

        status = PR_GetOpenFileInfo(file, &fileInfo);
        if (PR_FAILURE == status)
        {
                PL_FPrintError(err, "Cannot acquire status of file");
                rv = 1; goto done;
        }
        if (seek > 0)
        {
            if (seek > fileInfo.size) seek = 0;
                position = PR_Seek(file, (fileInfo.size - seek), PR_SEEK_SET);
                if (-1 == (PRInt32)position)
                        PL_FPrintError(err, "Cannot seek to starting position");
        }

        do
        {
                while (position < fileInfo.size)
                {
                        PRInt32 read, bytes = fileInfo.size - position;
                        if (bytes > sizeof(buffer)) bytes = sizeof(buffer);
                        read = PR_Read(file, buffer, bytes);
                        if (read != bytes)
                                PL_FPrintError(err, "Cannot read to eof");
                        position += read;
                        PR_Write(out, buffer, read);
                }

                if (follow)
                {
                        PR_Sleep(dally);
                        status = PR_GetOpenFileInfo(file, &fileInfo);
                        if (PR_FAILURE == status)
                        {
                                PL_FPrintError(err, "Cannot acquire status of file");
                                rv = 1; goto done;
                        }
                }
        } while (follow);

done:
        PR_Close(file);

        return rv;
}  /* main */

/* tail.c */