1 /* readtokens.c -- Functions for reading tokens from an input stream.
2
3 Copyright (C) 1990-1991, 1999-2004, 2006, 2009-2018 Free Software
4 Foundation, Inc.
5
6 This program is free software: you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <https://www.gnu.org/licenses/>.
18
19 Written by Jim Meyering. */
20
21 /* This almost supersedes xreadline stuff -- using delim="\n"
22 gives the same functionality, except that these functions
23 would never return empty lines. */
24
25 #include <config.h>
26
27 #include "readtokens.h"
28
29 #include <limits.h>
30 #include <stdio.h>
31 #include <stdlib.h>
32 #include <string.h>
33 #include <stdbool.h>
34
35 #include "xalloc.h"
36
37 #if USE_UNLOCKED_IO
38 # include "unlocked-io.h"
39 #endif
40
41 /* Initialize a tokenbuffer. */
42
43 void
init_tokenbuffer(token_buffer * tokenbuffer)44 init_tokenbuffer (token_buffer *tokenbuffer)
45 {
46 tokenbuffer->size = 0;
47 tokenbuffer->buffer = NULL;
48 }
49
50 typedef size_t word;
51 enum { bits_per_word = sizeof (word) * CHAR_BIT };
52
53 static bool
get_nth_bit(size_t n,word const * bitset)54 get_nth_bit (size_t n, word const *bitset)
55 {
56 return bitset[n / bits_per_word] >> n % bits_per_word & 1;
57 }
58
59 static void
set_nth_bit(size_t n,word * bitset)60 set_nth_bit (size_t n, word *bitset)
61 {
62 size_t one = 1;
63 bitset[n / bits_per_word] |= one << n % bits_per_word;
64 }
65
66 /* Read a token from STREAM into TOKENBUFFER.
67 A token is delimited by any of the N_DELIM bytes in DELIM.
68 Upon return, the token is in tokenbuffer->buffer and
69 has a trailing '\0' instead of any original delimiter.
70 The function value is the length of the token not including
71 the final '\0'. Upon EOF (i.e. on the call after the last
72 token is read) or error, return -1 without modifying tokenbuffer.
73 The EOF and error conditions may be distinguished in the caller
74 by testing ferror (STREAM).
75
76 This function works properly on lines containing NUL bytes
77 and on files that do not end with a delimiter. */
78
79 size_t
readtoken(FILE * stream,const char * delim,size_t n_delim,token_buffer * tokenbuffer)80 readtoken (FILE *stream,
81 const char *delim,
82 size_t n_delim,
83 token_buffer *tokenbuffer)
84 {
85 char *p;
86 int c;
87 size_t i, n;
88 word isdelim[(UCHAR_MAX + bits_per_word) / bits_per_word];
89
90 memset (isdelim, 0, sizeof isdelim);
91 for (i = 0; i < n_delim; i++)
92 {
93 unsigned char ch = delim[i];
94 set_nth_bit (ch, isdelim);
95 }
96
97 /* skip over any leading delimiters */
98 for (c = getc (stream); c >= 0 && get_nth_bit (c, isdelim); c = getc (stream))
99 {
100 /* empty */
101 }
102
103 p = tokenbuffer->buffer;
104 n = tokenbuffer->size;
105 i = 0;
106 for (;;)
107 {
108 if (c < 0 && i == 0)
109 return -1;
110
111 if (i == n)
112 p = x2nrealloc (p, &n, sizeof *p);
113
114 if (c < 0)
115 {
116 p[i] = 0;
117 break;
118 }
119 if (get_nth_bit (c, isdelim))
120 {
121 p[i] = 0;
122 break;
123 }
124 p[i++] = c;
125 c = getc (stream);
126 }
127
128 tokenbuffer->buffer = p;
129 tokenbuffer->size = n;
130 return i;
131 }
132
133 /* Build a NULL-terminated array of pointers to tokens
134 read from STREAM. Return the number of tokens read.
135 All storage is obtained through calls to xmalloc-like functions.
136
137 %%% Question: is it worth it to do a single
138 %%% realloc() of 'tokens' just before returning? */
139
140 size_t
readtokens(FILE * stream,size_t projected_n_tokens,const char * delim,size_t n_delim,char *** tokens_out,size_t ** token_lengths)141 readtokens (FILE *stream,
142 size_t projected_n_tokens,
143 const char *delim,
144 size_t n_delim,
145 char ***tokens_out,
146 size_t **token_lengths)
147 {
148 token_buffer tb, *token = &tb;
149 char **tokens;
150 size_t *lengths;
151 size_t sz;
152 size_t n_tokens;
153
154 if (projected_n_tokens == 0)
155 projected_n_tokens = 64;
156 else
157 projected_n_tokens++; /* add one for trailing NULL pointer */
158
159 sz = projected_n_tokens;
160 tokens = xnmalloc (sz, sizeof *tokens);
161 lengths = xnmalloc (sz, sizeof *lengths);
162
163 n_tokens = 0;
164 init_tokenbuffer (token);
165 for (;;)
166 {
167 char *tmp;
168 size_t token_length = readtoken (stream, delim, n_delim, token);
169 if (n_tokens >= sz)
170 {
171 tokens = x2nrealloc (tokens, &sz, sizeof *tokens);
172 lengths = xnrealloc (lengths, sz, sizeof *lengths);
173 }
174
175 if (token_length == (size_t) -1)
176 {
177 /* don't increment n_tokens for NULL entry */
178 tokens[n_tokens] = NULL;
179 lengths[n_tokens] = 0;
180 break;
181 }
182 tmp = xnmalloc (token_length + 1, sizeof *tmp);
183 lengths[n_tokens] = token_length;
184 tokens[n_tokens] = memcpy (tmp, token->buffer, token_length + 1);
185 n_tokens++;
186 }
187
188 free (token->buffer);
189 *tokens_out = tokens;
190 if (token_lengths != NULL)
191 *token_lengths = lengths;
192 else
193 free (lengths);
194 return n_tokens;
195 }
196