nsprpub/tools/tail.c

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* ***** BEGIN LICENSE BLOCK *****
   3  * Version: MPL 1.1/GPL 2.0/LGPL 2.1
   4  *
   5  * The contents of this file are subject to the Mozilla Public License Version
   6  * 1.1 (the "License"); you may not use this file except in compliance with
   7  * the License. You may obtain a copy of the License at
   8  * http://www.mozilla.org/MPL/
   9  *
  10  * Software distributed under the License is distributed on an "AS IS" basis,
  11  * WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
  12  * for the specific language governing rights and limitations under the
  13  * License.
  14  *
  15  * The Original Code is the Netscape Portable Runtime (NSPR).
  16  *
  17  * The Initial Developer of the Original Code is
  18  * Netscape Communications Corporation.
  19  * Portions created by the Initial Developer are Copyright (C) 1998-2000
  20  * the Initial Developer. All Rights Reserved.
  21  *
  22  * Contributor(s):
  23  *
  24  * Alternatively, the contents of this file may be used under the terms of
  25  * either the GNU General Public License Version 2 or later (the "GPL"), or
  26  * the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
  27  * in which case the provisions of the GPL or the LGPL are applicable instead
  28  * of those above. If you wish to allow use of your version of this file only
  29  * under the terms of either the GPL or the LGPL, and not to allow others to
  30  * use your version of this file under the terms of the MPL, indicate your
  31  * decision by deleting the provisions above and replace them with the notice
  32  * and other provisions required by the GPL or the LGPL. If you do not delete
  33  * the provisions above, a recipient may use your version of this file under
  34  * the terms of any one of the MPL, the GPL or the LGPL.
  35  *
  36  * ***** END LICENSE BLOCK ***** */
  37
  38 #include "prio.h"
  39 #include "prprf.h"
  40 #include "prinit.h"
  41 #include "prthread.h"
  42 #include "prinrval.h"
  43
  44 #include "plerror.h"
  45 #include "plgetopt.h"
  46
  47 #include <stdlib.h>
  48
  49 #define BUFFER_SIZE 500
  50
  51 static PRFileDesc *out = NULL, *err = NULL;
  52
  53 static void Help(void)
  54 {
  55     PR_fprintf(err, "Usage: tail [-n <n>] [-f] [-h] <filename>\n");
  56     PR_fprintf(err, "\t-t <n>   Dally time in milliseconds\n");
  57     PR_fprintf(err, "\t-n <n>   Number of bytes before <eof>\n");
  58     PR_fprintf(err, "\t-f       Follow the <eof>\n");
  59     PR_fprintf(err, "\t-h       This message and nothing else\n");
  60 }  /* Help */
  61
  62 PRIntn main(PRIntn argc, char **argv)
  63 {
  64         PRIntn rv = 0;
  65     PLOptStatus os;
  66         PRStatus status;
  67         PRFileDesc *file;
  68         PRFileInfo fileInfo;
  69         PRIntervalTime dally;
  70         char buffer[BUFFER_SIZE];
  71         PRBool follow = PR_FALSE;
  72         const char *filename = NULL;
  73         PRUint32 position = 0, seek = 0, time = 0;
  74     PLOptState *opt = PL_CreateOptState(argc, argv, "hfn:");
  75
  76     out = PR_GetSpecialFD(PR_StandardOutput);
  77     err = PR_GetSpecialFD(PR_StandardError);
  78
  79     while (PL_OPT_EOL != (os = PL_GetNextOpt(opt)))
  80     {
  81         if (PL_OPT_BAD == os) continue;
  82         switch (opt->option)
  83         {
  84                 case 0:  /* it's the filename */
  85                         filename = opt->value;
  86                         break;
  87         case 'n':  /* bytes before end of file */
  88             seek = atoi(opt->value);
  89             break;
  90         case 't':  /* dally time */
  91             time = atoi(opt->value);
  92             break;
  93         case 'f':  /* follow the end of file */
  94             follow = PR_TRUE;
  95             break;
  96         case 'h':  /* user wants some guidance */
  97             Help();  /* so give him an earful */
  98             return 2;  /* but not a lot else */
  99             break;
 100          default:
 101             break;
 102         }
 103     }
 104     PL_DestroyOptState(opt);
 105
 106         if (0 == time) time = 1000;
 107         dally = PR_MillisecondsToInterval(time);
 108
 109     if (NULL == filename)
 110     {
 111         (void)PR_fprintf(out, "Input file not specified\n");
 112         rv = 1; goto done;
 113     }
 114         file = PR_Open(filename, PR_RDONLY, 0);
 115         if (NULL == file)
 116         {
 117                 PL_FPrintError(err, "File cannot be opened for reading");
 118                 return 1;
 119         }
 120
 121         status = PR_GetOpenFileInfo(file, &fileInfo);
 122         if (PR_FAILURE == status)
 123         {
 124                 PL_FPrintError(err, "Cannot acquire status of file");
 125                 rv = 1; goto done;
 126         }
 127         if (seek > 0)
 128         {
 129             if (seek > fileInfo.size) seek = 0;
 130                 position = PR_Seek(file, (fileInfo.size - seek), PR_SEEK_SET);
 131                 if (-1 == (PRInt32)position)
 132                         PL_FPrintError(err, "Cannot seek to starting position");
 133         }
 134
 135         do
 136         {
 137                 while (position < fileInfo.size)
 138                 {
 139                         PRInt32 read, bytes = fileInfo.size - position;
 140                         if (bytes > sizeof(buffer)) bytes = sizeof(buffer);
 141                         read = PR_Read(file, buffer, bytes);
 142                         if (read != bytes)
 143                                 PL_FPrintError(err, "Cannot read to eof");
 144                         position += read;
 145                         PR_Write(out, buffer, read);
 146                 }
 147
 148                 if (follow)
 149                 {
 150                         PR_Sleep(dally);
 151                         status = PR_GetOpenFileInfo(file, &fileInfo);
 152                         if (PR_FAILURE == status)
 153                         {
 154                                 PL_FPrintError(err, "Cannot acquire status of file");
 155                                 rv = 1; goto done;
 156                         }
 157                 }
 158         } while (follow);
 159
 160 done:
 161         PR_Close(file);
 162
 163         return rv;
 164 }  /* main */
 165
 166 /* tail.c */