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changeset 5498:ac6438eb46c6

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Add base64.
author Simon Josefsson <simon@josefsson.org>
date Tue, 30 Nov 2004 20:46:52 +0000
parents 9e5eab61b552
children 41fd04e6a198
files ChangeLog MODULES.html.sh lib/ChangeLog lib/base64.c lib/base64.h m4/ChangeLog m4/base64.m4 modules/base64 tests/test-base64.c
diffstat 9 files changed, 667 insertions(+), 0 deletions(-) [+]
line wrap: on
line diff
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,12 @@
+2004-11-30  Simon Josefsson  <jas@extundo.com>
+
+	* MODULES.html.sh (Extra functions based on ANSI C 89): Add
+	base64.
+
+	* tests/test-base64.c: New file.
+
+	* modules/base64: New file.
+
 2004-11-30  Simon Josefsson  <jas@extundo.com>
 
 	* modules/restrict (License): Change to LGPL.
--- a/MODULES.html.sh
+++ b/MODULES.html.sh
@@ -1605,6 +1605,7 @@
   func_echo "$element"
 
   func_begin_table
+  func_module base64
   func_module diacrit
   func_module getline
   func_module getnline
--- a/lib/ChangeLog
+++ b/lib/ChangeLog
@@ -1,3 +1,7 @@
+2004-11-28  Simon Josefsson  <jas@extundo.com>
+
+	* base64.h, base64.c: New file.
+
 2004-11-27  Paul Eggert  <eggert@cs.ucla.edu>
 
 	* getcwd.h: New file, which I forgot to check in on 2004-11-25.
new file mode 100644
--- /dev/null
+++ b/lib/base64.c
@@ -0,0 +1,403 @@
+/* base64.c -- Encode binary data using printable characters.
+   Copyright (C) 1999, 2000, 2001, 2004 Free Software Foundation, Inc.
+
+   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 2, 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, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+/* Written by Simon Josefsson.  Partially adapted from GNU MailUtils
+ * (mailbox/filter_trans.c, as of 2004-11-28).  Improved by review
+ * from Paul Eggert, Bruno Haible, and Stepan Kasal.
+ *
+ * See also RFC 3548 <http://www.ietf.org/rfc/rfc3548.txt>.
+ *
+ * Be careful with error checking.  Here is how you would typically
+ * use these functions:
+ *
+ * bool ok = base64_decode_alloc (in, inlen, &out, &outlen);
+ * if (!ok)
+ *   FAIL: input was not valid base64
+ * if (out == NULL)
+ *   FAIL: memory allocation error
+ * OK: data in OUT/OUTLEN
+ *
+ * size_t outlen = base64_encode_alloc (in, inlen, &out);
+ * if (out == NULL && outlen == 0 && inlen != 0)
+ *   FAIL: input too long
+ * if (out == NULL)
+ *   FAIL: memory allocation error
+ * OK: data in OUT/LEN.
+ *
+ */
+
+#ifdef HAVE_CONFIG_H
+# include <config.h>
+#endif
+
+/* Get prototype. */
+#include "base64.h"
+
+/* Get malloc. */
+#include <stdlib.h>
+
+/* C89 compliant way to cast 'char' to 'unsigned char'. */
+static inline unsigned char
+to_uchar (char ch)
+{
+  return ch;
+}
+
+/* Base64 encode IN array of size INLEN into OUT array of size OUTLEN.
+   If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as
+   possible.  If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero
+   terminate the output buffer. */
+void
+base64_encode (const char *restrict in, size_t inlen,
+	       char *restrict out, size_t outlen)
+{
+  const char b64[64] =
+    "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
+
+  while (inlen && outlen)
+    {
+      *out++ = b64[to_uchar (in[0]) >> 2];
+      if (!--outlen)
+	break;
+      *out++ = b64[((to_uchar (in[0]) << 4)
+		    + (--inlen ? to_uchar (in[1]) >> 4 : 0)) & 0x3f];
+      if (!--outlen)
+	break;
+      *out++ =
+	(inlen
+	 ? b64[((to_uchar (in[1]) << 2)
+		+ (--inlen ? to_uchar (in[2]) >> 6 : 0)) & 0x3f] : '=');
+      if (!--outlen)
+	break;
+      *out++ = inlen ? b64[to_uchar (in[2]) & 0x3f] : '=';
+      if (!--outlen)
+	break;
+      if (inlen)
+	inlen--;
+      in += 3;
+    }
+
+  if (outlen)
+    *out = '\0';
+}
+
+/* Allocate a buffer and store zero terminated base64 encoded data
+   from array IN of size INLEN, returning BASE64_LENGTH(INLEN), i.e.,
+   the length of the encoded data, excluding the terminating zero.  On
+   return, the OUT variable will hold a pointer to newly allocated
+   memory that must be deallocated by the caller.  If output string
+   length would overflow, 0 is returned and OUT is set to NULL.  If
+   memory allocation fail, OUT is set to NULL, and the return value
+   indicate length of the requested memory block, i.e.,
+   BASE64_LENGTH(inlen) + 1. */
+size_t
+base64_encode_alloc (const char *in, size_t inlen, char **out)
+{
+  size_t outlen = 1 + BASE64_LENGTH (inlen);
+
+  /* Check for overflow in outlen computation.
+   *
+   * If there is no overflow, outlen >= inlen.
+   *
+   * If the operation (inlen + 2) overflows then it yields at most +1, so
+   * outlen is 0.
+   *
+   * If the multiplication overflows, we lose at least half of the
+   * correct value, so the result is < ((inlen + 2) / 3) * 2, which is
+   * less than (inlen + 2) * 0.66667, which is less than inlen as soon as
+   * (inlen > 4).
+   */
+  if (inlen > outlen)
+    {
+      *out = NULL;
+      return 0;
+    }
+
+  *out = malloc (outlen);
+  if (*out)
+    base64_encode (in, inlen, *out, outlen);
+
+  return outlen - 1;
+}
+
+/* With this approach this file works independent of the charset used
+   (think EBCDIC).  However, it does assume that the characters in the
+   Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255.  POSIX
+   1003.1-2001 require that char and unsigned char are 8-bit
+   quantities, though, taking care of that problem.  But this may be a
+   potential problem on non-POSIX C99 platforms.  */
+#define B64(x)					\
+  ((x) == 'A' ? 0				\
+   : (x) == 'B' ? 1				\
+   : (x) == 'C' ? 2				\
+   : (x) == 'D' ? 3				\
+   : (x) == 'E' ? 4				\
+   : (x) == 'F' ? 5				\
+   : (x) == 'G' ? 6				\
+   : (x) == 'H' ? 7				\
+   : (x) == 'I' ? 8				\
+   : (x) == 'J' ? 9				\
+   : (x) == 'K' ? 10				\
+   : (x) == 'L' ? 11				\
+   : (x) == 'M' ? 12				\
+   : (x) == 'N' ? 13				\
+   : (x) == 'O' ? 14				\
+   : (x) == 'P' ? 15				\
+   : (x) == 'Q' ? 16				\
+   : (x) == 'R' ? 17				\
+   : (x) == 'S' ? 18				\
+   : (x) == 'T' ? 19				\
+   : (x) == 'U' ? 20				\
+   : (x) == 'V' ? 21				\
+   : (x) == 'W' ? 22				\
+   : (x) == 'X' ? 23				\
+   : (x) == 'Y' ? 24				\
+   : (x) == 'Z' ? 25				\
+   : (x) == 'a' ? 26				\
+   : (x) == 'b' ? 27				\
+   : (x) == 'c' ? 28				\
+   : (x) == 'd' ? 29				\
+   : (x) == 'e' ? 30				\
+   : (x) == 'f' ? 31				\
+   : (x) == 'g' ? 32				\
+   : (x) == 'h' ? 33				\
+   : (x) == 'i' ? 34				\
+   : (x) == 'j' ? 35				\
+   : (x) == 'k' ? 36				\
+   : (x) == 'l' ? 37				\
+   : (x) == 'm' ? 38				\
+   : (x) == 'n' ? 39				\
+   : (x) == 'o' ? 40				\
+   : (x) == 'p' ? 41				\
+   : (x) == 'q' ? 42				\
+   : (x) == 'r' ? 43				\
+   : (x) == 's' ? 44				\
+   : (x) == 't' ? 45				\
+   : (x) == 'u' ? 46				\
+   : (x) == 'v' ? 47				\
+   : (x) == 'w' ? 48				\
+   : (x) == 'x' ? 49				\
+   : (x) == 'y' ? 50				\
+   : (x) == 'z' ? 51				\
+   : (x) == '0' ? 52				\
+   : (x) == '1' ? 53				\
+   : (x) == '2' ? 54				\
+   : (x) == '3' ? 55				\
+   : (x) == '4' ? 56				\
+   : (x) == '5' ? 57				\
+   : (x) == '6' ? 58				\
+   : (x) == '7' ? 59				\
+   : (x) == '8' ? 60				\
+   : (x) == '9' ? 61				\
+   : (x) == '+' ? 62				\
+   : (x) == '/' ? 63				\
+   : -1)
+
+static const signed char b64[0x100] = {
+  B64 (0), B64 (1), B64 (2), B64 (3),
+  B64 (4), B64 (5), B64 (6), B64 (7),
+  B64 (8), B64 (9), B64 (10), B64 (11),
+  B64 (12), B64 (13), B64 (14), B64 (15),
+  B64 (16), B64 (17), B64 (18), B64 (19),
+  B64 (20), B64 (21), B64 (22), B64 (23),
+  B64 (24), B64 (25), B64 (26), B64 (27),
+  B64 (28), B64 (29), B64 (30), B64 (31),
+  B64 (32), B64 (33), B64 (34), B64 (35),
+  B64 (36), B64 (37), B64 (38), B64 (39),
+  B64 (40), B64 (41), B64 (42), B64 (43),
+  B64 (44), B64 (45), B64 (46), B64 (47),
+  B64 (48), B64 (49), B64 (50), B64 (51),
+  B64 (52), B64 (53), B64 (54), B64 (55),
+  B64 (56), B64 (57), B64 (58), B64 (59),
+  B64 (60), B64 (61), B64 (62), B64 (63),
+  B64 (64), B64 (65), B64 (66), B64 (67),
+  B64 (68), B64 (69), B64 (70), B64 (71),
+  B64 (72), B64 (73), B64 (74), B64 (75),
+  B64 (76), B64 (77), B64 (78), B64 (79),
+  B64 (80), B64 (81), B64 (82), B64 (83),
+  B64 (84), B64 (85), B64 (86), B64 (87),
+  B64 (88), B64 (89), B64 (90), B64 (91),
+  B64 (92), B64 (93), B64 (94), B64 (95),
+  B64 (96), B64 (97), B64 (98), B64 (99),
+  B64 (100), B64 (101), B64 (102), B64 (103),
+  B64 (104), B64 (105), B64 (106), B64 (107),
+  B64 (108), B64 (109), B64 (110), B64 (111),
+  B64 (112), B64 (113), B64 (114), B64 (115),
+  B64 (116), B64 (117), B64 (118), B64 (119),
+  B64 (120), B64 (121), B64 (122), B64 (123),
+  B64 (124), B64 (125), B64 (126), B64 (127),
+  B64 (128), B64 (129), B64 (130), B64 (131),
+  B64 (132), B64 (133), B64 (134), B64 (135),
+  B64 (136), B64 (137), B64 (138), B64 (139),
+  B64 (140), B64 (141), B64 (142), B64 (143),
+  B64 (144), B64 (145), B64 (146), B64 (147),
+  B64 (148), B64 (149), B64 (150), B64 (151),
+  B64 (152), B64 (153), B64 (154), B64 (155),
+  B64 (156), B64 (157), B64 (158), B64 (159),
+  B64 (160), B64 (161), B64 (162), B64 (163),
+  B64 (164), B64 (165), B64 (166), B64 (167),
+  B64 (168), B64 (169), B64 (170), B64 (171),
+  B64 (172), B64 (173), B64 (174), B64 (175),
+  B64 (176), B64 (177), B64 (178), B64 (179),
+  B64 (180), B64 (181), B64 (182), B64 (183),
+  B64 (184), B64 (185), B64 (186), B64 (187),
+  B64 (188), B64 (189), B64 (190), B64 (191),
+  B64 (192), B64 (193), B64 (194), B64 (195),
+  B64 (196), B64 (197), B64 (198), B64 (199),
+  B64 (200), B64 (201), B64 (202), B64 (203),
+  B64 (204), B64 (205), B64 (206), B64 (207),
+  B64 (208), B64 (209), B64 (210), B64 (211),
+  B64 (212), B64 (213), B64 (214), B64 (215),
+  B64 (216), B64 (217), B64 (218), B64 (219),
+  B64 (220), B64 (221), B64 (222), B64 (223),
+  B64 (224), B64 (225), B64 (226), B64 (227),
+  B64 (228), B64 (229), B64 (230), B64 (231),
+  B64 (232), B64 (233), B64 (234), B64 (235),
+  B64 (236), B64 (237), B64 (238), B64 (239),
+  B64 (240), B64 (241), B64 (242), B64 (243),
+  B64 (244), B64 (245), B64 (246), B64 (247),
+  B64 (248), B64 (249), B64 (250), B64 (251),
+  B64 (252), B64 (253), B64 (254), B64 (255)
+};
+
+static inline bool
+isb64 (unsigned char ch)
+{
+  return ch <= 255 && 0 <= b64[ch];
+}
+
+/* Decode base64 encoded input array IN of length INLEN to output
+   array OUT that can hold *OUTLEN bytes.  Return true if decoding was
+   successful, i.e. if the input was valid base64 data, false
+   otherwise.  If *OUTLEN is too small, as many bytes as possible will
+   be written to OUT.  On return, *OUTLEN holds the length of decoded
+   bytes in OUT.  Note that as soon as any non-alphabet characters are
+   encountered, decoding is stopped and false is returned. */
+bool
+base64_decode (const char *restrict in, size_t inlen,
+	       char *restrict out, size_t * outlen)
+{
+  size_t outleft = *outlen;
+
+  while (inlen >= 2)
+    {
+      if (!isb64 (in[0]) || !isb64 (in[1]))
+	break;
+
+      if (outleft)
+	{
+	  *out++ = ((b64[to_uchar (in[0])] << 2)
+		    | (b64[to_uchar (in[1])] >> 4));
+	  outleft--;
+	}
+
+      if (inlen == 2)
+	break;
+
+      if (in[2] == '=')
+	{
+	  if (inlen != 4)
+	    break;
+
+	  if (in[3] != '=')
+	    break;
+
+	}
+      else
+	{
+	  if (!isb64 (in[2]))
+	    break;
+
+	  if (outleft)
+	    {
+	      *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
+			| (b64[to_uchar (in[2])] >> 2));
+	      outleft--;
+	    }
+
+	  if (inlen == 3)
+	    break;
+
+	  if (in[3] == '=')
+	    {
+	      if (inlen != 4)
+		break;
+	    }
+	  else
+	    {
+	      if (!isb64 (in[3]))
+		break;
+
+	      if (outleft)
+		{
+		  *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
+			    | b64[to_uchar (in[3])]);
+		  outleft--;
+		}
+	    }
+	}
+
+      in += 4;
+      inlen -= 4;
+    }
+
+  *outlen -= outleft;
+
+  if (inlen != 0)
+    return false;
+
+  return true;
+}
+
+/* Allocate an output buffer in *OUT, and decode the base64 encoded
+   data stored in IN of size INLEN to the *OUT buffer.  On return, the
+   size of the decoded data is stored in *OUTLEN.  OUTLEN may be NULL,
+   if the caller is not interested in the decoded length.  *OUT may be
+   NULL to indicate an out of memory error, in which case *OUTLEN
+   contain the size of the memory block needed.  The function return
+   true on successful decoding and memory allocation errors.  (Use the
+   *OUT and *OUTLEN parameters to differentiate between successful
+   decoding and memory error.)  The function return false if the input
+   was invalid, in which case *OUT is NULL and *OUTLEN is
+   undefined. */
+bool
+base64_decode_alloc (const char *in, size_t inlen, char **out,
+		     size_t * outlen)
+{
+  /* This may allocate a few bytes too much, depending on input,
+     but it's not worth the extra CPU time to compute the exact amount.
+     The exact amount is 3 * inlen / 4, minus 1 if the input ends
+     with "=" and minus another 1 if the input ends with "==".
+     Dividing before multiplying avoids the possibility of overflow.  */
+  size_t needlen = 3 * (inlen / 4) + 2;
+
+  *out = malloc (needlen);
+  if (!*out)
+    return true;
+
+  if (!base64_decode (in, inlen, *out, &needlen))
+    {
+      free (*out);
+      *out = NULL;
+      return false;
+    }
+
+  if (outlen)
+    *outlen = needlen;
+
+  return true;
+}
new file mode 100644
--- /dev/null
+++ b/lib/base64.h
@@ -0,0 +1,43 @@
+/* base64.h -- Encode binary data using printable characters.
+   Copyright (C) 2004 Free Software Foundation, Inc.
+   Written by Simon Josefsson.
+
+   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 2, 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, write to the Free Software Foundation,
+   Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.  */
+
+#ifndef BASE64_H
+# define BASE64_H
+
+/* Get size_t. */
+#include <stddef.h>
+
+/* Get bool. */
+#include <stdbool.h>
+
+/* This uses that the expression (n+(k-1))/k means the smallest
+   integer >= n/k, i.e., the ceiling of n/k.  */
+#define BASE64_LENGTH(inlen) ((((inlen) + 2) / 3) * 4)
+
+extern void base64_encode (const char *restrict in, size_t inlen,
+			   char *restrict out, size_t outlen);
+
+extern size_t base64_encode_alloc (const char *in, size_t inlen, char **out);
+
+extern bool base64_decode (const char *restrict in, size_t inlen,
+			   char *restrict out, size_t * outlen);
+
+extern bool base64_decode_alloc (const char *in, size_t inlen,
+				 char **out, size_t * outlen);
+
+#endif /* BASE64_H */
--- a/m4/ChangeLog
+++ b/m4/ChangeLog
@@ -1,3 +1,7 @@
+2004-11-30  Simon Josefsson  <jas@extundo.com>
+
+	* base64.m4: New file.
+
 2004-11-30  Simon Josefsson  <jas@extundo.com>
 
 	* restrict.m4: Add copyright and copying conditions.
new file mode 100644
--- /dev/null
+++ b/m4/base64.m4
@@ -0,0 +1,18 @@
+# base64.m4 serial 1
+dnl Copyright (C) 2004 Free Software Foundation, Inc.
+dnl This file is free software, distributed under the terms of the GNU
+dnl General Public License.  As a special exception to the GNU General
+dnl Public License, this file may be distributed as part of a program
+dnl that contains a configuration script generated by Autoconf, under
+dnl the same distribution terms as the rest of that program.
+
+AC_DEFUN([gl_FUNC_BASE64],
+[
+  gl_PREREQ_BASE64
+])
+
+# Prerequisites of lib/base64.c.
+AC_DEFUN([gl_PREREQ_BASE64], [
+  AC_REQUIRE([AC_C_INLINE])
+  AC_REQUIRE([gl_C_RESTRICT])
+])
new file mode 100644
--- /dev/null
+++ b/modules/base64
@@ -0,0 +1,26 @@
+Description:
+Encode binary data using printable characters (base64).
+
+Files:
+lib/base64.h
+lib/base64.c
+m4/base64.m4
+
+Depends-on:
+stdbool
+restrict
+
+configure.ac:
+gl_FUNC_BASE64
+
+Makefile.am:
+lib_SOURCES += base64.h base64.c
+
+Include:
+"base64.h"
+
+License:
+LGPL
+
+Maintainer:
+Simon Josefsson
new file mode 100755
--- /dev/null
+++ b/tests/test-base64.c
@@ -0,0 +1,159 @@
+#include "base64.h"
+
+#include <stdio.h>
+#include <string.h>
+
+int
+main (int argc, char *argv[])
+{
+  const char *in = "abcdefghijklmnop";
+  const char *b64in = "YWJjZGVmZw==";
+  char out[255];
+  char *p;
+  size_t len;
+  bool ok;
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 0, out, 0);
+  if (out[0] != '\x42')
+    fprintf (stderr, "failure\n");
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 1, out, 1);
+  if (memcmp (out, "YQ==", 1) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 1, out, 2);
+  if (memcmp (out, "YQ==", 2) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 1, out, 3);
+  if (memcmp (out, "YQ==", 3) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 1, out, 4);
+  if (memcmp (out, "YQ==", 4) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 1, out, 8);
+  if (memcmp (out, "YQ==", 4) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 2, out, 4);
+  if (memcmp (out, "YWI=", 4) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 3, out, 4);
+  if (memcmp (out, "YWJj", 4) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 4, out, 5);
+  if (memcmp (out, "YWJjZA==", 5) != 0)
+    {
+      out[5] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  base64_encode (in, 4, out, 100);
+  if (memcmp (out, "YWJjZA==", 6) != 0)
+    {
+      out[6] = '\0';
+      fprintf (stderr, "failure (%s)\n", out);
+    }
+
+  /* Decode. */
+
+  memset (out, 0x42, sizeof (out));
+  len = 0;
+  ok = base64_decode (b64in, 4, out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 0)
+    fprintf (stderr, "failure (%d)\n", len);
+
+  memset (out, 0x42, sizeof (out));
+  len = 1;
+  ok = base64_decode (b64in, 4, out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 1 || memcmp (out, "abcdefg", 1) != 0)
+    {
+      out[2] = '\0';
+      fprintf (stderr, "failure (%d: %s)\n", len, out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  len = 2;
+  ok = base64_decode (b64in, 4, out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 2 || memcmp (out, "abcdefg", 2) != 0)
+    {
+      out[3] = '\0';
+      fprintf (stderr, "failure (%d: %s)\n", len, out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  len = 3;
+  ok = base64_decode (b64in, 4, out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 3 || memcmp (out, "abcdefg", 3) != 0)
+    {
+      out[4] = '\0';
+      fprintf (stderr, "failure (%d: %s)\n", len, out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  len = 4;
+  ok = base64_decode (b64in, 4, out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 3 || memcmp (out, "abcdefg", 3) != 0)
+    {
+      out[3] = '\0';
+      fprintf (stderr, "failure (%d: %s)\n", len, out);
+    }
+
+  memset (out, 0x42, sizeof (out));
+  len = 100;
+  ok = base64_decode (b64in, strlen (b64in), out, &len);
+  if (!ok)
+    fprintf (stderr, "decode failed\n");
+  if (len != 7 || memcmp (out, "abcdefg", 7) != 0)
+    {
+      out[7] = '\0';
+      fprintf (stderr, "failure (%d: %s)\n", len, out);
+    }
+
+  return 0;
+}