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
Help(void)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
main(PRIntn argc,char ** argv)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 */
145