summaryrefslogtreecommitdiff
path: root/lib/memxfrm.c
blob: dc6eda1fa25617e49ee1952cef00d0421f738236 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
/* Locale dependent memory area transformation for comparison.
   Copyright (C) 2009 Free Software Foundation, Inc.
   Written by Bruno Haible <bruno@clisp.org>, 2009.

   This program is free software: you can redistribute it and/or modify it
   under the terms of the GNU Lesser 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
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public License
   along with this program.  If not, see <http://www.gnu.org/licenses/>.  */

#include <config.h>

/* Specification.  */
#include "memxfrm.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>

char *
memxfrm (char *s, size_t n, char *resultbuf, size_t *lengthp)
{
  /* Result accumulator.  */
  char *result;
  size_t length;
  size_t allocated;

  char orig_sentinel;

  /* Initial memory allocation.  */
  if (resultbuf != NULL && *lengthp > 0)
    {
      result = resultbuf;
      allocated = *lengthp;
    }
  else
    {
      allocated = (n > 0 ? n : 1);
      result = (char *) malloc (allocated);
      if (result == NULL)
	goto out_of_memory_2;
    }
  length = 0;

  /* Add sentinel.byte.  */
  orig_sentinel = s[n];
  s[n] = '\0';

  /* Iterate through S, transforming each NUL terminated segment.
     Accumulate the resulting transformed segments in result, separated by
     NULs.  */
  {
    const char *p_end = s + n + 1;
    const char *p;

    p = s;
    for (;;)
      {
	/* Search next NUL byte.  */
	const char *q = p + strlen (p);

	for (;;)
	  {
	    size_t k;

	    errno = 0;
	    k = strxfrm (result + length, p, allocated - length);
	    if (errno != 0)
	      goto fail;
	    if (k >= allocated - length)
	      {
		/* Grow the result buffer.  */
		char *new_result;

		allocated = 2 * allocated;
		if (allocated < 64)
		  allocated = 64;
		if (result == resultbuf)
		  new_result = (char *) malloc (allocated);
		else
		  new_result = (char *) realloc (result, allocated);
		if (new_result == NULL)
		  goto out_of_memory_1;
		result = new_result;
	      }
	    else
	      {
		length += k;
		break;
	      }
	  }

	p = q + 1;
	if (p == p_end)
	  break;
	result[length] = '\0';
        length++;
      }
  }

  /* Shrink the allocated memory if possible.  */
  if (result != resultbuf && (length > 0 ? length : 1) < allocated)
    {
      char *memory = (char *) realloc (result, length > 0 ? length : 1);
      if (memory != NULL)
	result = memory;
    }

  s[n] = orig_sentinel;
  *lengthp = length;
  return result;

 fail:
  {
    int saved_errno = errno;
    if (result != resultbuf)
      free (result);
    s[n] = orig_sentinel;
    errno = saved_errno;
    return NULL;
  }

 out_of_memory_1:
  if (result != resultbuf)
    free (result);
  s[n] = orig_sentinel;
 out_of_memory_2:
  errno = ENOMEM;
  return NULL;
}