1// Copyright 2009 The Go Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style
3// license that can be found in the LICENSE file.
4
5// Simple file i/o and string manipulation, to avoid
6// depending on strconv and bufio and strings.
7
8package net
9
10import (
11	"io"
12	"os"
13)
14
15type file struct {
16	file  *os.File
17	data  []byte
18	atEOF bool
19}
20
21func (f *file) close() { f.file.Close() }
22
23func (f *file) getLineFromData() (s string, ok bool) {
24	data := f.data
25	i := 0
26	for i = 0; i < len(data); i++ {
27		if data[i] == '\n' {
28			s = string(data[0:i])
29			ok = true
30			// move data
31			i++
32			n := len(data) - i
33			copy(data[0:], data[i:])
34			f.data = data[0:n]
35			return
36		}
37	}
38	if f.atEOF && len(f.data) > 0 {
39		// EOF, return all we have
40		s = string(data)
41		f.data = f.data[0:0]
42		ok = true
43	}
44	return
45}
46
47func (f *file) readLine() (s string, ok bool) {
48	if s, ok = f.getLineFromData(); ok {
49		return
50	}
51	if len(f.data) < cap(f.data) {
52		ln := len(f.data)
53		n, err := io.ReadFull(f.file, f.data[ln:cap(f.data)])
54		if n >= 0 {
55			f.data = f.data[0 : ln+n]
56		}
57		if err == io.EOF || err == io.ErrUnexpectedEOF {
58			f.atEOF = true
59		}
60	}
61	s, ok = f.getLineFromData()
62	return
63}
64
65func open(name string) (*file, error) {
66	fd, err := os.Open(name)
67	if err != nil {
68		return nil, err
69	}
70	return &file{fd, make([]byte, os.Getpagesize())[0:0], false}, nil
71}
72
73func byteIndex(s string, c byte) int {
74	for i := 0; i < len(s); i++ {
75		if s[i] == c {
76			return i
77		}
78	}
79	return -1
80}
81
82// Count occurrences in s of any bytes in t.
83func countAnyByte(s string, t string) int {
84	n := 0
85	for i := 0; i < len(s); i++ {
86		if byteIndex(t, s[i]) >= 0 {
87			n++
88		}
89	}
90	return n
91}
92
93// Split s at any bytes in t.
94func splitAtBytes(s string, t string) []string {
95	a := make([]string, 1+countAnyByte(s, t))
96	n := 0
97	last := 0
98	for i := 0; i < len(s); i++ {
99		if byteIndex(t, s[i]) >= 0 {
100			if last < i {
101				a[n] = string(s[last:i])
102				n++
103			}
104			last = i + 1
105		}
106	}
107	if last < len(s) {
108		a[n] = string(s[last:])
109		n++
110	}
111	return a[0:n]
112}
113
114func getFields(s string) []string { return splitAtBytes(s, " \r\t\n") }
115
116// Bigger than we need, not too big to worry about overflow
117const big = 0xFFFFFF
118
119// Decimal to integer starting at &s[i0].
120// Returns number, new offset, success.
121func dtoi(s string, i0 int) (n int, i int, ok bool) {
122	n = 0
123	for i = i0; i < len(s) && '0' <= s[i] && s[i] <= '9'; i++ {
124		n = n*10 + int(s[i]-'0')
125		if n >= big {
126			return 0, i, false
127		}
128	}
129	if i == i0 {
130		return 0, i, false
131	}
132	return n, i, true
133}
134
135// Hexadecimal to integer starting at &s[i0].
136// Returns number, new offset, success.
137func xtoi(s string, i0 int) (n int, i int, ok bool) {
138	n = 0
139	for i = i0; i < len(s); i++ {
140		if '0' <= s[i] && s[i] <= '9' {
141			n *= 16
142			n += int(s[i] - '0')
143		} else if 'a' <= s[i] && s[i] <= 'f' {
144			n *= 16
145			n += int(s[i]-'a') + 10
146		} else if 'A' <= s[i] && s[i] <= 'F' {
147			n *= 16
148			n += int(s[i]-'A') + 10
149		} else {
150			break
151		}
152		if n >= big {
153			return 0, i, false
154		}
155	}
156	if i == i0 {
157		return 0, i, false
158	}
159	return n, i, true
160}
161
162// xtoi2 converts the next two hex digits of s into a byte.
163// If s is longer than 2 bytes then the third byte must be e.
164// If the first two bytes of s are not hex digits or the third byte
165// does not match e, false is returned.
166func xtoi2(s string, e byte) (byte, bool) {
167	if len(s) > 2 && s[2] != e {
168		return 0, false
169	}
170	n, ei, ok := xtoi(s[:2], 0)
171	return byte(n), ok && ei == 2
172}
173
174// Integer to decimal.
175func itoa(i int) string {
176	var buf [30]byte
177	n := len(buf)
178	neg := false
179	if i < 0 {
180		i = -i
181		neg = true
182	}
183	ui := uint(i)
184	for ui > 0 || n == len(buf) {
185		n--
186		buf[n] = byte('0' + ui%10)
187		ui /= 10
188	}
189	if neg {
190		n--
191		buf[n] = '-'
192	}
193	return string(buf[n:])
194}
195
196// Convert i to decimal string.
197func itod(i uint) string {
198	if i == 0 {
199		return "0"
200	}
201
202	// Assemble decimal in reverse order.
203	var b [32]byte
204	bp := len(b)
205	for ; i > 0; i /= 10 {
206		bp--
207		b[bp] = byte(i%10) + '0'
208	}
209
210	return string(b[bp:])
211}
212
213// Convert i to hexadecimal string.
214func itox(i uint, min int) string {
215	// Assemble hexadecimal in reverse order.
216	var b [32]byte
217	bp := len(b)
218	for ; i > 0 || min > 0; i /= 16 {
219		bp--
220		b[bp] = "0123456789abcdef"[byte(i%16)]
221		min--
222	}
223
224	return string(b[bp:])
225}
226
227// Number of occurrences of b in s.
228func count(s string, b byte) int {
229	n := 0
230	for i := 0; i < len(s); i++ {
231		if s[i] == b {
232			n++
233		}
234	}
235	return n
236}
237
238// Index of rightmost occurrence of b in s.
239func last(s string, b byte) int {
240	i := len(s)
241	for i--; i >= 0; i-- {
242		if s[i] == b {
243			break
244		}
245	}
246	return i
247}
248