ref: e934530ee4512f033952e4efa80a80058607b741
parent: c848ca62673689df20e7fef74d1d5180f37fcea6
author: Ori Bernstein <ori@eigenstate.org>
date: Sat Jul 3 16:03:17 EDT 2021
libc: add encode(2) variants for custom alphabets There are a number of alphabets in common use for base32 and base64 encoding, such as url-safe encodings. This adds support for passing a function to encode into arbitary alphabets.
--- a/sys/include/libc.h
+++ b/sys/include/libc.h
@@ -385,10 +385,15 @@
extern char* cleanname(char*);
extern int decrypt(void*, void*, int);
extern int encrypt(void*, void*, int);
+
extern int dec64(uchar*, int, char*, int);
extern int enc64(char*, int, uchar*, int);
+extern int dec64x(uchar*, int, char*, int, int (*)(int));
+extern int enc64x(char*, int, uchar*, int, int (*)(int));
extern int dec32(uchar*, int, char*, int);
extern int enc32(char*, int, uchar*, int);
+extern int dec32x(uchar*, int, char*, int, int (*)(int));
+extern int enc32x(char*, int, uchar*, int, int (*)(int));
extern int dec16(uchar*, int, char*, int);
extern int enc16(char*, int, uchar*, int);
extern int dec64chr(int);
@@ -397,6 +402,7 @@
extern int enc32chr(int);
extern int dec16chr(int);
extern int enc16chr(int);
+
extern int encodefmt(Fmt*);
extern void exits(char*);
extern double frexp(double, int*);
--- a/sys/man/2/encode
+++ b/sys/man/2/encode
@@ -1,6 +1,7 @@
.TH ENCODE 2
.SH NAME
dec64, enc64, dec32, enc32, dec16, enc16, \
+dec64x, enc64x, dec32x, enc32x, \
dec64chr, enc64chr, dec32chr, enc32chr, dec16chr, enc16chr, \
encodefmt \- encoding byte arrays as strings
.SH SYNOPSIS
@@ -12,15 +13,27 @@
int dec64(uchar *out, int lim, char *in, int n)
.PP
.B
+int dec64x(uchar *out, int lim, char *in, int n, int (*map)(int))
+.PP
+.B
int enc64(char *out, int lim, uchar *in, int n)
.PP
.B
+int enc64x(char *out, int lim, uchar *in, int n, int (*map)(int))
+.PP
+.B
int dec32(uchar *out, int lim, char *in, int n)
.PP
.B
+int dec32x(uchar *out, int lim, char *in, int n, int (*map)(int))
+.PP
+.B
int enc32(char *out, int lim, uchar *in, int n)
.PP
.B
+int enc32x(char *out, int lim, uchar *in, int n, int (*map)(int))
+.PP
+.B
int dec16(uchar *out, int lim, char *in, int n)
.PP
.B
@@ -82,6 +95,31 @@
.I enc64chr
encode a symbol of the alphabet given a value.
if the value is out of range then zero is returned.
+.PP
+The
+.I enc64x
+and
+.I enc32x
+variants are identical to the above, except that they take a
+function mapping from an arbitrary index in the alphabet to
+the encoded character.
+For example, in the following 32-character alphabet,
+.EX
+.I ABCDEFGHIJKLMNOPQRSTUVWXYZ234567
+.EE
+the chr function would map the value
+.I 3
+to the character
+.IR D .
+
+The
+.I dec64x
+and
+.I dec32x
+variants are similar to the above, however the function passed
+maps from a character within the alphabet to the index within
+the alphabet.
+
.PP
.I Encodefmt
can be used with
--- a/sys/src/libc/port/u32.c
+++ b/sys/src/libc/port/u32.c
@@ -25,7 +25,7 @@
}
int
-dec32(uchar *dest, int ndest, char *src, int nsrc)
+dec32x(uchar *dest, int ndest, char *src, int nsrc, int (*chr)(int))
{uchar *start;
int i, j, u[8];
@@ -35,7 +35,7 @@
start = dest;
while(nsrc>=8){ for(i=0; i<8; i++){- j = dec32chr(src[i]);
+ j = chr(src[i]);
if(j < 0)
j = 0;
u[i] = j;
@@ -52,7 +52,7 @@
if(nsrc == 1 || nsrc == 3 || nsrc == 6)
return -1;
for(i=0; i<nsrc; i++){- j = dec32chr(src[i]);
+ j = chr(src[i]);
if(j < 0)
j = 0;
u[i] = j;
@@ -73,7 +73,7 @@
}
int
-enc32(char *dest, int ndest, uchar *src, int nsrc)
+enc32x(char *dest, int ndest, uchar *src, int nsrc, int (*chr)(int))
{char *start;
int j;
@@ -83,50 +83,62 @@
start = dest;
while(nsrc>=5){j = (0x1f & (src[0]>>3));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1c & (src[0]<<2)) | (0x03 & (src[1]>>6));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1f & (src[1]>>1));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x10 & (src[1]<<4)) | (0x0f & (src[2]>>4));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1e & (src[2]<<1)) | (0x01 & (src[3]>>7));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1f & (src[3]>>2));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x18 & (src[3]<<3)) | (0x07 & (src[4]>>5));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1f & (src[4]));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
src += 5;
nsrc -= 5;
}
if(nsrc){j = (0x1f & (src[0]>>3));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1c & (src[0]<<2));
if(nsrc == 1)
goto out;
j |= (0x03 & (src[1]>>6));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1f & (src[1]>>1));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x10 & (src[1]<<4));
if(nsrc == 2)
goto out;
j |= (0x0f & (src[2]>>4));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1e & (src[2]<<1));
if(nsrc == 3)
goto out;
j |= (0x01 & (src[3]>>7));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x1f & (src[3]>>2));
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
j = (0x18 & (src[3]<<3));
out:
- *dest++ = enc32chr(j);
+ *dest++ = chr(j);
}
*dest = 0;
return dest-start;
+}
+
+int
+enc32(char *dest, int ndest, uchar *src, int nsrc)
+{+ return enc32x(dest, ndest, src, nsrc, enc32chr);
+}
+
+int
+dec32(uchar *dest, int ndest, char *src, int nsrc)
+{+ return dec32x(dest, ndest, src, nsrc, dec32chr);
}
--- a/sys/src/libc/port/u64.c
+++ b/sys/src/libc/port/u64.c
@@ -30,7 +30,7 @@
}
int
-dec64(uchar *out, int lim, char *in, int n)
+dec64x(uchar *out, int lim, char *in, int n, int (*chr)(int))
{ulong b24;
uchar *start = out;
@@ -40,7 +40,7 @@
b24 = 0;
i = 0;
while(n-- > 0){- c = dec64chr(*in++);
+ c = chr(*in++);
if(c < 0)
continue;
switch(i){@@ -84,7 +84,7 @@
}
int
-enc64(char *out, int lim, uchar *in, int n)
+enc64x(char *out, int lim, uchar *in, int n, int (*chr)(int))
{int i;
ulong b24;
@@ -97,10 +97,10 @@
b24 |= *in++;
if(out + 4 >= e)
goto exhausted;
- *out++ = enc64chr(b24>>18);
- *out++ = enc64chr((b24>>12)&0x3f);
- *out++ = enc64chr((b24>>6)&0x3f);
- *out++ = enc64chr(b24&0x3f);
+ *out++ = chr(b24>>18);
+ *out++ = chr((b24>>12)&0x3f);
+ *out++ = chr((b24>>6)&0x3f);
+ *out++ = chr(b24&0x3f);
}
switch(n%3){@@ -109,9 +109,9 @@
b24 |= *in<<8;
if(out + 4 >= e)
goto exhausted;
- *out++ = enc64chr(b24>>18);
- *out++ = enc64chr((b24>>12)&0x3f);
- *out++ = enc64chr((b24>>6)&0x3f);
+ *out++ = chr(b24>>18);
+ *out++ = chr((b24>>12)&0x3f);
+ *out++ = chr((b24>>6)&0x3f);
*out++ = '=';
break;
case 1:
@@ -118,8 +118,8 @@
b24 = *in<<16;
if(out + 4 >= e)
goto exhausted;
- *out++ = enc64chr(b24>>18);
- *out++ = enc64chr((b24>>12)&0x3f);
+ *out++ = chr(b24>>18);
+ *out++ = chr((b24>>12)&0x3f);
*out++ = '=';
*out++ = '=';
break;
@@ -127,4 +127,16 @@
exhausted:
*out = 0;
return out - start;
+}
+
+int
+enc64(char *out, int lim, uchar *in, int n)
+{+ return enc64x(out, lim, in, n, enc64chr);
+}
+
+int
+dec64(uchar *out, int lim, char *in, int n)
+{+ return dec64x(out, lim, in, n, dec64chr);
}