third_party/exiv2
1
0
Fork 0
Code Issues Pull Requests Packages Projects Releases Wiki Activity

Replaced the ugly code in Exiv2::base64encode() and update the test suite.

Browse Source
This commit is contained in:
clanmills
2021-03-06 18:13:30 +00:00
parent 0ad46453ed
commit 5410395576
2 changed files with 73 additions and 97 deletions
Download Patch File Download Diff File Expand all files Collapse all files
src/futils.cpp
+47 -71
View File
@@ -140,77 +140,53 @@ namespace Exiv2 {
}
int base64encode(const void* data_buf, size_t dataLength, char* result, size_t resultSize) {
const char base64chars[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const uint8_t* data = (const uint8_t*)data_buf;
size_t resultIndex = 0;
size_t x;
uint32_t n = 0;
size_t padCount = dataLength % 3;
uint8_t n0, n1, n2, n3;
/* increment over the length of the string, three characters at a time */
for (x = 0; x < dataLength; x += 3)
{
/* these three 8-bit (ASCII) characters become one 24-bit number */
n = data[x] << 16;
if((x+1) < dataLength)
n += data[x+1] << 8;
if((x+2) < dataLength)
n += data[x+2];
/* this 24-bit number gets separated into four 6-bit numbers */
n0 = (uint8_t)(n >> 18) & 63;
n1 = (uint8_t)(n >> 12) & 63;
n2 = (uint8_t)(n >> 6) & 63;
n3 = (uint8_t)n & 63;
/*
* if we have one byte available, then its encoding is spread
* out over two characters
*/
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex++] = base64chars[n0];
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex++] = base64chars[n1];
/*
* if we have only two bytes available, then their encoding is
* spread out over three chars
*/
if((x+1) < dataLength)
{
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex++] = base64chars[n2];
}
/*
* if we have all three bytes available, then their encoding is spread
* out over four characters
*/
if((x+2) < dataLength)
{
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex++] = base64chars[n3];
}
}
/*
* create and add padding that is required if we did not have a multiple of 3
* number of characters available
*/
if (padCount > 0)
{
for (; padCount < 3; padCount++)
{
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex++] = '=';
}
}
if(resultIndex >= resultSize) return 0; /* indicate failure: buffer too small */
result[resultIndex] = 0;
return 1; /* indicate success */
// https://vorbrodt.blog/2019/03/23/base64-encoding/
const char kEncodeLookup[] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
const char kPadCharacter = '=';
std::string encoded;
encoded.reserve(((dataLength / 3) + (dataLength % 3 > 0)) * 4);
std::uint32_t temp ;
unsigned char* b = (unsigned char*) data_buf;
std::size_t i = 0 ;
while ( i < dataLength / 3 )
{
temp = b[i+0] << 16;
temp += b[i+1] << 8;
temp += b[i+2];
encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6 ]);
encoded.append(1, kEncodeLookup[(temp & 0x0000003F) ]);
i++ ;
}
switch(dataLength % 3)
{
case 1:
temp = b[i+0] << 16;
encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(2, kPadCharacter);
break;
case 2:
temp = b[i+0] << 16;
temp += b[i+1] << 8;
encoded.append(1, kEncodeLookup[(temp & 0x00FC0000) >> 18]);
encoded.append(1, kEncodeLookup[(temp & 0x0003F000) >> 12]);
encoded.append(1, kEncodeLookup[(temp & 0x00000FC0) >> 6 ]);
encoded.append(1, kPadCharacter);
break;
}
size_t length = encoded.size();
int rc = length < resultSize ? 1 : 0;
if (rc) {
::memcpy(result,encoded.c_str(),length);
result[length]=0;
}
return rc;
} // base64encode
long base64decode(const char *in, char *out, size_t out_size) {