From: David Bremner <bremner@debian.org> The character set is chosen to be suitable for pathnames, and the same as that used by contrib/nmbug. The new encoded/decoded strings are allocated using talloc. --- This isn't urgent, but it is useful for a couple projects I have brewing (nmbug compatible dump/restore and tag logging), so I thought I would get some feedback on it. util/Makefile.local | 4 +- util/hex-escape.c | 110 +++++++++++++++++++++++++++++++++++++++++++++++++++ util/hex-escape.h | 10 +++++ 3 files changed, 122 insertions(+), 2 deletions(-) create mode 100644 util/hex-escape.c create mode 100644 util/hex-escape.h diff --git a/util/Makefile.local b/util/Makefile.local index 0340899..2e63932 100644 --- a/util/Makefile.local +++ b/util/Makefile.local @@ -3,11 +3,11 @@ dir := util extra_cflags += -I$(srcdir)/$(dir) -libutil_c_srcs := $(dir)/xutil.c $(dir)/error_util.c +libutil_c_srcs := $(dir)/xutil.c $(dir)/error_util.c $(dir)/hex-escape.c libutil_modules := $(libutil_c_srcs:.c=.o) $(dir)/libutil.a: $(libutil_modules) $(call quiet,AR) rcs $@ $^ -CLEAN := $(CLEAN) $(dir)/xutil.o $(dir)/error_util.o $(dir)/libutil.a +CLEAN := $(CLEAN) $(libutil_modules) $(dir)/libutil.a diff --git a/util/hex-escape.c b/util/hex-escape.c new file mode 100644 index 0000000..c294bb5 --- /dev/null +++ b/util/hex-escape.c @@ -0,0 +1,110 @@ +/* hex-escape.c - Manage encoding and decoding of byte strings into + * a restricted character set. + * + * Copyright (c) 2011 David Bremner + * + * This program is free software: you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation, either version 3 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program. If not, see http://www.gnu.org/licenses/ . + * + * Author: David Bremner <david@tethera.net> + */ + +#include <string.h> +#include <talloc.h> +#include "error_util.h" +#include "hex-escape.h" + +static int +escapes_needed (const char *str){ + int escapes = 0; + + while (*str) { + if (index (HEX_NO_ESCAPE, *str) == NULL) + escapes++; + str++; + } + + return escapes; +} + +char * +hex_encode (void *ctx, const char *str) { + char *newstr = talloc_size (ctx, strlen (str)+3*escapes_needed (str)+1); + + char *out = newstr; + + while (*str) { + if (index (HEX_NO_ESCAPE, *str)) { + *out++ = *str++; + } else { + sprintf (out, "%%%02x", *str); + str++; + out += 3; + } + } + *out = 0; + return newstr; +} + +inline static int +_digit (char c) { + if ('0' <= c && c <= '9') + return c - '0'; + + if ('A' <= c && c <= 'F') + return c - 'A'; + + if ('a' <= c && c <= 'f') + return c - 'a'; + + INTERNAL_ERROR ("Illegal hex digit %c", c); + /*NOTREACHED*/ + return 0; +} + +char *hex_decode (void *ctx, const char *str) { + + int len = strlen(str); + + const char *p; + char *q; + char *newstr; + int escapes = 0; + + for (p = str; *p; p++) + escapes += (*p == HEX_ESCAPE_CHAR); + + newstr = talloc_size (ctx, len - escapes*2 + 1); + + p = str; + q = newstr; + + while (*p) { + + if (*p == HEX_ESCAPE_CHAR) { + + if (len < 3) INTERNAL_ERROR ("Syntax error decoding %s", str); + + *q = _digit(p[1]) * 16; + *q += _digit(p[2]); + + len -= 3; + p += 3; + q++; + } else { + *q++ = *p++; + } + } + + return newstr; +} diff --git a/util/hex-escape.h b/util/hex-escape.h new file mode 100644 index 0000000..7caff15 --- /dev/null +++ b/util/hex-escape.h @@ -0,0 +1,10 @@ +#ifndef _HEX_ESCAPE_H +#define _HEX_ESCAPE_H + +#define HEX_ESCAPE_CHAR '%' +#define HEX_NO_ESCAPE "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz" \ + "0123456789+-_@=.:," + +char *hex_encode (void *talloc_ctx, const char *string); +char *hex_decode (void *talloc_ctx, const char *hex); +#endif -- 1.7.7.3