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/* readtokens.c -- Functions for reading tokens from an input stream.
Copyright (C) 1990-1991, 1999-2004, 2006, 2009-2022 Free Software
Foundation, Inc.
This program is free software: you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation, either version 3 of the License, or
(at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.
Written by Jim Meyering. */
/* This almost supersedes xreadline stuff -- using delim="\n"
gives the same functionality, except that these functions
would never return empty lines. */
#include <config.h>
#include "readtokens.h"
#include <limits.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <stdbool.h>
#include "xalloc.h"
#if USE_UNLOCKED_IO
# include "unlocked-io.h"
#endif
/* Initialize a tokenbuffer. */
void
init_tokenbuffer (token_buffer *tokenbuffer)
{
tokenbuffer->size = 0;
tokenbuffer->buffer = NULL;
}
typedef size_t word;
enum { bits_per_word = sizeof (word) * CHAR_BIT };
static bool
get_nth_bit (size_t n, word const *bitset)
{
return bitset[n / bits_per_word] >> n % bits_per_word & 1;
}
static void
set_nth_bit (size_t n, word *bitset)
{
size_t one = 1;
bitset[n / bits_per_word] |= one << n % bits_per_word;
}
/* Read a token from STREAM into TOKENBUFFER.
A token is delimited by any of the N_DELIM bytes in DELIM.
Upon return, the token is in tokenbuffer->buffer and
has a trailing '\0' instead of any original delimiter.
The function value is the length of the token not including
the final '\0'. Upon EOF (i.e. on the call after the last
token is read) or error, return -1 without modifying tokenbuffer.
The EOF and error conditions may be distinguished in the caller
by testing ferror (STREAM).
This function works properly on lines containing NUL bytes
and on files that do not end with a delimiter. */
size_t
readtoken (FILE *stream,
const char *delim,
size_t n_delim,
token_buffer *tokenbuffer)
{
int c;
idx_t i;
word isdelim[(UCHAR_MAX + bits_per_word) / bits_per_word];
memset (isdelim, 0, sizeof isdelim);
for (i = 0; i < n_delim; i++)
{
unsigned char ch = delim[i];
set_nth_bit (ch, isdelim);
}
/* skip over any leading delimiters */
for (c = getc (stream); c >= 0 && get_nth_bit (c, isdelim); c = getc (stream))
{
/* empty */
}
char *p = tokenbuffer->buffer;
idx_t n = tokenbuffer->size;
i = 0;
for (;;)
{
if (c < 0 && i == 0)
return -1;
if (i == n)
p = xpalloc (p, &n, 1, -1, sizeof *p);
if (c < 0)
{
p[i] = 0;
break;
}
if (get_nth_bit (c, isdelim))
{
p[i] = 0;
break;
}
p[i++] = c;
c = getc (stream);
}
tokenbuffer->buffer = p;
tokenbuffer->size = n;
return i;
}
/* Build a NULL-terminated array of pointers to tokens
read from STREAM. Return the number of tokens read.
All storage is obtained through calls to xmalloc-like functions.
%%% Question: is it worth it to do a single
%%% realloc() of 'tokens' just before returning? */
size_t
readtokens (FILE *stream,
size_t projected_n_tokens,
const char *delim,
size_t n_delim,
char ***tokens_out,
size_t **token_lengths)
{
token_buffer tb, *token = &tb;
char **tokens;
size_t *lengths;
idx_t sz, n_tokens;
if (projected_n_tokens == 0)
projected_n_tokens = 64;
else
projected_n_tokens++; /* add one for trailing NULL pointer */
sz = projected_n_tokens;
tokens = xnmalloc (sz, sizeof *tokens);
lengths = xnmalloc (sz, sizeof *lengths);
n_tokens = 0;
init_tokenbuffer (token);
for (;;)
{
char *tmp;
size_t token_length = readtoken (stream, delim, n_delim, token);
if (n_tokens >= sz)
{
tokens = xpalloc (tokens, &sz, 1, -1, sizeof *tokens);
lengths = xreallocarray (lengths, sz, sizeof *lengths);
}
if (token_length == (size_t) -1)
{
/* don't increment n_tokens for NULL entry */
tokens[n_tokens] = NULL;
lengths[n_tokens] = 0;
break;
}
tmp = xnmalloc (token_length + 1, sizeof *tmp);
lengths[n_tokens] = token_length;
tokens[n_tokens] = memcpy (tmp, token->buffer, token_length + 1);
n_tokens++;
}
free (token->buffer);
*tokens_out = tokens;
if (token_lengths != NULL)
*token_lengths = lengths;
else
free (lengths);
return n_tokens;
}
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