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[base16] Add buffer size parameter to base16_encode() and base16_decode()

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The current API for Base16 (and Base64) encoding requires the caller
to always provide sufficient buffer space.  This prevents the use of
the generic encoding/decoding functionality in some situations, such
as in formatting the hex setting types.

Implement a generic hex_encode() (based on the existing
format_hex_setting()), implement base16_encode() and base16_decode()
in terms of the more generic hex_encode() and hex_decode(), and update
all callers to provide the additional buffer length parameter.

Signed-off-by: Michael Brown <mcb30@ipxe.org>
This commit is contained in:
Michael Brown
2015-04-24 14:34:32 +01:00
parent b56b482fa3
commit 9aa8090d06
12 changed files with 111 additions and 126 deletions
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79
src/core/base16.c
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@@ -28,6 +28,7 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
#include <errno.h>
#include <assert.h>
#include <ipxe/string.h>
#include <ipxe/vsprintf.h>
#include <ipxe/base16.h>
/** @file
@@ -37,48 +38,42 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
*/
/**
* Base16-encode data
* Encode hexadecimal string (with optional byte separator character)
*
* @v separator Byte separator character, or 0 for no separator
* @v raw Raw data
* @v len Length of raw data
* @v encoded Buffer for encoded string
*
* The buffer must be the correct length for the encoded string. Use
* something like
*
* char buf[ base16_encoded_len ( len ) + 1 ];
*
* (the +1 is for the terminating NUL) to provide a buffer of the
* correct size.
* @v raw_len Length of raw data
* @v data Buffer
* @v len Length of buffer
* @ret len Encoded length
*/
void base16_encode ( const uint8_t *raw, size_t len, char *encoded ) {
const uint8_t *raw_bytes = raw;
char *encoded_bytes = encoded;
size_t remaining = len;
size_t hex_encode ( char separator, const void *raw, size_t raw_len,
char *data, size_t len ) {
const uint8_t *bytes = raw;
const char delimiter[2] = { separator, '\0' };
size_t used = 0;
unsigned int i;
/* Encode each byte */
for ( ; remaining-- ; encoded_bytes += 2 ) {
sprintf ( encoded_bytes, "%02x", *(raw_bytes++) );
if ( len )
data[0] = 0; /* Ensure that a terminating NUL exists */
for ( i = 0 ; i < raw_len ; i++ ) {
used += ssnprintf ( ( data + used ), ( len - used ),
"%s%02x", ( used ? delimiter : "" ),
bytes[i] );
}
/* Ensure terminating NUL exists even if length was zero */
*encoded_bytes = '\0';
DBG ( "Base16-encoded to \"%s\":\n", encoded );
DBG_HDA ( 0, raw, len );
assert ( strlen ( encoded ) == base16_encoded_len ( len ) );
return used;
}
/**
* Decode hexadecimal string
* Decode hexadecimal string (with optional byte separator character)
*
* @v encoded Encoded string
* @v separator Byte separator character, or 0 for no separator
* @v encoded Encoded string
* @v data Buffer
* @v len Length of buffer
* @ret len Length of data, or negative error
*/
int hex_decode ( const char *encoded, char separator, void *data, size_t len ) {
int hex_decode ( char separator, const char *encoded, void *data, size_t len ) {
uint8_t *out = data;
unsigned int count = 0;
unsigned int sixteens;
@@ -110,31 +105,3 @@ int hex_decode ( const char *encoded, char separator, void *data, size_t len ) {
}
return count;
}
/**
* Base16-decode data
*
* @v encoded Encoded string
* @v raw Raw data
* @ret len Length of raw data, or negative error
*
* The buffer must be large enough to contain the decoded data. Use
* something like
*
* char buf[ base16_decoded_max_len ( encoded ) ];
*
* to provide a buffer of the correct size.
*/
int base16_decode ( const char *encoded, uint8_t *raw ) {
int len;
len = hex_decode ( encoded, 0, raw, -1UL );
if ( len < 0 )
return len;
DBG ( "Base16-decoded \"%s\" to:\n", encoded );
DBG_HDA ( 0, raw, len );
assert ( len <= ( int ) base16_decoded_max_len ( encoded ) );
return len;
}