Allow base16_encode() to re-use the input buffer as output

sjaeckel · sjaeckel · commit 19a5520936fa · 2025-09-06T15:00:00.000+02:00
Signed-off-by: Steffen Jaeckel &lt;s@jaeckel.eu&gt;
diff --git a/src/misc/base16/base16_encode.c b/src/misc/base16/base16_encode.c
@@ -52,10 +52,11 @@ int base16_encode(const unsigned char *in,  unsigned long  inlen,
       alphabet = alphabets[1];
    }
 
-   for (i = 0; i < x; i += 2) {
-      out[i]   = alphabet[(in[i/2] >> 4) & 0x0f];
-      out[i+1] = alphabet[in[i/2] & 0x0f];
+   for (i = x; i > 0; i -= 2) {
+      out[i-2] = alphabet[(in[(i-1)/2] >> 4) & 0x0f];
+      out[i-1] = alphabet[in[(i-1)/2] & 0x0f];
    }
+
    out[x] = '\0';
 
    return CRYPT_OK;

Original file line number	Diff line number	Diff line change
`@@ -52,10 +52,11 @@ int base16_encode(const unsigned char *in, unsigned long inlen,`
`52`	`52`	`alphabet = alphabets[1];`
`53`	`53`	`}`
`54`	`54`
`55`		`- for (i = 0; i < x; i += 2) {`
`56`		`- out[i] = alphabet[(in[i/2] >> 4) & 0x0f];`
`57`		`- out[i+1] = alphabet[in[i/2] & 0x0f];`
	`55`	`+ for (i = x; i > 0; i -= 2) {`
	`56`	`+ out[i-2] = alphabet[(in[(i-1)/2] >> 4) & 0x0f];`
	`57`	`+ out[i-1] = alphabet[in[(i-1)/2] & 0x0f];`
`58`	`58`	`}`
	`59`	`+`
`59`	`60`	`out[x] = '\0';`
`60`	`61`
`61`	`62`	`return CRYPT_OK;`