nsprpub/tools/tail.c

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "prio.h"
   7 #include "prprf.h"
   8 #include "prinit.h"
   9 #include "prthread.h"
  10 #include "prinrval.h"
  11
  12 #include "plerror.h"
  13 #include "plgetopt.h"
  14
  15 #include <stdlib.h>
  16
  17 #define BUFFER_SIZE 500
  18
  19 static PRFileDesc *out = NULL, *err = NULL;
  20
  21 static void Help(void)
  22 {
  23     PR_fprintf(err, "Usage: tail [-n <n>] [-f] [-h] <filename>\n");
  24     PR_fprintf(err, "\t-t <n>   Dally time in milliseconds\n");
  25     PR_fprintf(err, "\t-n <n>   Number of bytes before <eof>\n");
  26     PR_fprintf(err, "\t-f       Follow the <eof>\n");
  27     PR_fprintf(err, "\t-h       This message and nothing else\n");
  28 }  /* Help */
  29
  30 PRIntn main(PRIntn argc, char **argv)
  31 {
  32         PRIntn rv = 0;
  33     PLOptStatus os;
  34         PRStatus status;
  35         PRFileDesc *file;
  36         PRFileInfo fileInfo;
  37         PRIntervalTime dally;
  38         char buffer[BUFFER_SIZE];
  39         PRBool follow = PR_FALSE;
  40         const char *filename = NULL;
  41         PRUint32 position = 0, seek = 0, time = 0;
  42     PLOptState *opt = PL_CreateOptState(argc, argv, "hfn:");
  43
  44     out = PR_GetSpecialFD(PR_StandardOutput);
  45     err = PR_GetSpecialFD(PR_StandardError);
  46
  47     while (PL_OPT_EOL != (os = PL_GetNextOpt(opt)))
  48     {
  49         if (PL_OPT_BAD == os) continue;
  50         switch (opt->option)
  51         {
  52                 case 0:  /* it's the filename */
  53                         filename = opt->value;
  54                         break;
  55         case 'n':  /* bytes before end of file */
  56             seek = atoi(opt->value);
  57             break;
  58         case 't':  /* dally time */
  59             time = atoi(opt->value);
  60             break;
  61         case 'f':  /* follow the end of file */
  62             follow = PR_TRUE;
  63             break;
  64         case 'h':  /* user wants some guidance */
  65             Help();  /* so give him an earful */
  66             return 2;  /* but not a lot else */
  67             break;
  68          default:
  69             break;
  70         }
  71     }
  72     PL_DestroyOptState(opt);
  73
  74         if (0 == time) time = 1000;
  75         dally = PR_MillisecondsToInterval(time);
  76
  77     if (NULL == filename)
  78     {
  79         (void)PR_fprintf(out, "Input file not specified\n");
  80         rv = 1; goto done;
  81     }
  82         file = PR_Open(filename, PR_RDONLY, 0);
  83         if (NULL == file)
  84         {
  85                 PL_FPrintError(err, "File cannot be opened for reading");
  86                 return 1;
  87         }
  88
  89         status = PR_GetOpenFileInfo(file, &fileInfo);
  90         if (PR_FAILURE == status)
  91         {
  92                 PL_FPrintError(err, "Cannot acquire status of file");
  93                 rv = 1; goto done;
  94         }
  95         if (seek > 0)
  96         {
  97             if (seek > fileInfo.size) seek = 0;
  98                 position = PR_Seek(file, (fileInfo.size - seek), PR_SEEK_SET);
  99                 if (-1 == (PRInt32)position)
 100                         PL_FPrintError(err, "Cannot seek to starting position");
 101         }
 102
 103         do
 104         {
 105                 while (position < fileInfo.size)
 106                 {
 107                         PRInt32 read, bytes = fileInfo.size - position;
 108                         if (bytes > sizeof(buffer)) bytes = sizeof(buffer);
 109                         read = PR_Read(file, buffer, bytes);
 110                         if (read != bytes)
 111                                 PL_FPrintError(err, "Cannot read to eof");
 112                         position += read;
 113                         PR_Write(out, buffer, read);
 114                 }
 115
 116                 if (follow)
 117                 {
 118                         PR_Sleep(dally);
 119                         status = PR_GetOpenFileInfo(file, &fileInfo);
 120                         if (PR_FAILURE == status)
 121                         {
 122                                 PL_FPrintError(err, "Cannot acquire status of file");
 123                                 rv = 1; goto done;
 124                         }
 125                 }
 126         } while (follow);
 127
 128 done:
 129         PR_Close(file);
 130
 131         return rv;
 132 }  /* main */
 133
 134 /* tail.c */