// SPDX-License-Identifier: GPL-2.0 #include <linux/errno.h> int ceph_armor(char *dst, const char *src, const char *end);int ceph_unarmor(char *dst, const char *src, const char *end); /* * base64 encode/decode. */ static const char *pem_key =	"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; static int encode_bits(int c){	return pem_key[c];} static int decode_bits(char c){	if (c >= 'A' && c <= 'Z')		return c - 'A';	if (c >= 'a' && c <= 'z')		return c - 'a' + 26;	if (c >= '0' && c <= '9')		return c - '0' + 52;	if (c == '+')		return 62;	if (c == '/')		return 63;	if (c == '=')		return 0; /* just non-negative, please */	return -EINVAL;} int ceph_armor(char *dst, const char *src, const char *end){	int olen = 0;	int line = 0; 	while (src < end) {		unsigned char a, b, c; 		a = *src++;		*dst++ = encode_bits(a >> 2);		if (src < end) {			b = *src++;			*dst++ = encode_bits(((a & 3) << 4) | (b >> 4));			if (src < end) {				c = *src++;				*dst++ = encode_bits(((b & 15) << 2) |						     (c >> 6));				*dst++ = encode_bits(c & 63);			} else {				*dst++ = encode_bits((b & 15) << 2);				*dst++ = '=';			}		} else {			*dst++ = encode_bits(((a & 3) << 4));			*dst++ = '=';			*dst++ = '=';		}		olen += 4;		line += 4;		if (line == 64) {			line = 0;			*(dst++) = '\n';			olen++;		}	}	return olen;} int ceph_unarmor(char *dst, const char *src, const char *end){	int olen = 0; 	while (src < end) {		int a, b, c, d; 		if (src[0] == '\n') {			src++;			continue;		}		if (src + 4 > end)			return -EINVAL;		a = decode_bits(src[0]);		b = decode_bits(src[1]);		c = decode_bits(src[2]);		d = decode_bits(src[3]);		if (a < 0 || b < 0 || c < 0 || d < 0)			return -EINVAL; 		*dst++ = (a << 2) | (b >> 4);		if (src[2] == '=')			return olen + 1;		*dst++ = ((b & 15) << 4) | (c >> 2);		if (src[3] == '=')			return olen + 2;		*dst++ = ((c & 3) << 6) | d;		olen += 3;		src += 4;	}	return olen;}