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) {
  50             continue;
  51         }
  52         switch (opt->option)
  53         {
  54             case 0:  /* it's the filename */
  55                 filename = opt->value;
  56                 break;
  57             case 'n':  /* bytes before end of file */
  58                 seek = atoi(opt->value);
  59                 break;
  60             case 't':  /* dally time */
  61                 time = atoi(opt->value);
  62                 break;
  63             case 'f':  /* follow the end of file */
  64                 follow = PR_TRUE;
  65                 break;
  66             case 'h':  /* user wants some guidance */
  67                 Help();  /* so give him an earful */
  68                 return 2;  /* but not a lot else */
  69                 break;
  70             default:
  71                 break;
  72         }
  73     }
  74     PL_DestroyOptState(opt);
  75
  76     if (0 == time) {
  77         time = 1000;
  78     }
  79     dally = PR_MillisecondsToInterval(time);
  80
  81     if (NULL == filename)
  82     {
  83         (void)PR_fprintf(out, "Input file not specified\n");
  84         rv = 1; goto done;
  85     }
  86     file = PR_Open(filename, PR_RDONLY, 0);
  87     if (NULL == file)
  88     {
  89         PL_FPrintError(err, "File cannot be opened for reading");
  90         return 1;
  91     }
  92
  93     status = PR_GetOpenFileInfo(file, &fileInfo);
  94     if (PR_FAILURE == status)
  95     {
  96         PL_FPrintError(err, "Cannot acquire status of file");
  97         rv = 1; goto done;
  98     }
  99     if (seek > 0)
 100     {
 101         if (seek > fileInfo.size) {
 102             seek = 0;
 103         }
 104         position = PR_Seek(file, (fileInfo.size - seek), PR_SEEK_SET);
 105         if (-1 == (PRInt32)position) {
 106             PL_FPrintError(err, "Cannot seek to starting position");
 107         }
 108     }
 109
 110     do
 111     {
 112         while (position < fileInfo.size)
 113         {
 114             PRInt32 read, bytes = fileInfo.size - position;
 115             if (bytes > sizeof(buffer)) {
 116                 bytes = sizeof(buffer);
 117             }
 118             read = PR_Read(file, buffer, bytes);
 119             if (read != bytes) {
 120                 PL_FPrintError(err, "Cannot read to eof");
 121             }
 122             position += read;
 123             PR_Write(out, buffer, read);
 124         }
 125
 126         if (follow)
 127         {
 128             PR_Sleep(dally);
 129             status = PR_GetOpenFileInfo(file, &fileInfo);
 130             if (PR_FAILURE == status)
 131             {
 132                 PL_FPrintError(err, "Cannot acquire status of file");
 133                 rv = 1; goto done;
 134             }
 135         }
 136     } while (follow);
 137
 138 done:
 139     PR_Close(file);
 140
 141     return rv;
 142 }  /* main */
 143
 144 /* tail.c */