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/* hex-escape.c - Manage encoding and decoding of byte strings into path names
*
* Copyright (c) 2011 David Bremner
*
* 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 http://www.gnu.org/licenses/ .
*
* Author: David Bremner <david@tethera.net>
*/
#include <assert.h>
#include <string.h>
#include <talloc.h>
#include <ctype.h>
#include "error_util.h"
#include "hex-escape.h"
static const char *output_charset =
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+-_@=.,";
static const char escape_char = '%';
static int
is_output (char c)
{
return (strchr (output_charset, c) != NULL);
}
static int
maybe_realloc (void *ctx, size_t needed, char **out, size_t *out_size)
{
if (*out_size < needed) {
if (*out == NULL)
*out = talloc_size (ctx, needed);
else
*out = talloc_realloc (ctx, *out, char, needed);
if (*out == NULL)
return 0;
*out_size = needed;
}
return 1;
}
hex_status_t
hex_encode (void *ctx, const char *in, char **out, size_t *out_size)
{
const char *p;
char *q;
size_t needed = 1; /* for the NUL */
assert (ctx); assert (in); assert (out); assert (out_size);
for (p = in; *p; p++) {
needed += is_output (*p) ? 1 : 3;
}
if (*out == NULL)
*out_size = 0;
if (!maybe_realloc (ctx, needed, out, out_size))
return HEX_OUT_OF_MEMORY;
q = *out;
p = in;
while (*p) {
if (is_output (*p)) {
*q++ = *p++;
} else {
sprintf (q, "%%%02x", (unsigned char)*p++);
q += 3;
}
}
*q = '\0';
return HEX_SUCCESS;
}
/* Hex decode 'in' to 'out'.
*
* This must succeed for in == out to support hex_decode_inplace().
*/
static hex_status_t
hex_decode_internal (const char *in, unsigned char *out)
{
char buf[3];
while (*in) {
if (*in == escape_char) {
char *endp;
/* This also handles unexpected end-of-string. */
if (!isxdigit ((unsigned char) in[1]) ||
!isxdigit ((unsigned char) in[2]))
return HEX_SYNTAX_ERROR;
buf[0] = in[1];
buf[1] = in[2];
buf[2] = '\0';
*out = strtoul (buf, &endp, 16);
if (endp != buf + 2)
return HEX_SYNTAX_ERROR;
in += 3;
out++;
} else {
*out++ = *in++;
}
}
*out = '\0';
return HEX_SUCCESS;
}
hex_status_t
hex_decode_inplace (char *s)
{
/* A decoded string is never longer than the encoded one, so it is
* safe to decode a string onto itself. */
return hex_decode_internal (s, (unsigned char *) s);
}
hex_status_t
hex_decode (void *ctx, const char *in, char **out, size_t * out_size)
{
const char *p;
size_t needed = 1; /* for the NUL */
assert (ctx); assert (in); assert (out); assert (out_size);
for (p = in; *p; p++)
if ((p[0] == escape_char) && isxdigit (p[1]) && isxdigit (p[2]))
needed -= 1;
else
needed += 1;
if (!maybe_realloc (ctx, needed, out, out_size))
return HEX_OUT_OF_MEMORY;
return hex_decode_internal (in, (unsigned char *) *out);
}
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