598 lines
20 KiB
C
598 lines
20 KiB
C
/* base64.c -- Encode binary data using printable characters.
|
|
Copyright (C) 1999-2001, 2004-2006, 2009-2023 Free Software Foundation, Inc.
|
|
|
|
This file is free software: you can redistribute it and/or modify
|
|
it under the terms of the GNU Lesser General Public License as
|
|
published by the Free Software Foundation; either version 2.1 of the
|
|
License, or (at your option) any later version.
|
|
|
|
This file 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 Lesser General Public License for more details.
|
|
|
|
You should have received a copy of the GNU Lesser General Public License
|
|
along with this program. If not, see <https://www.gnu.org/licenses/>. */
|
|
|
|
/* 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 4648 <https://www.ietf.org/rfc/rfc4648.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
|
|
*
|
|
* idx_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/OUTLEN.
|
|
*
|
|
*/
|
|
|
|
#include <config.h>
|
|
|
|
/* Get prototype. */
|
|
#include "base64.h"
|
|
|
|
/* Get imalloc. */
|
|
#include <ialloc.h>
|
|
|
|
#include <intprops.h>
|
|
|
|
/* Get UCHAR_MAX. */
|
|
#include <limits.h>
|
|
|
|
#include <string.h>
|
|
|
|
/* Convert 'char' to 'unsigned char' without casting. */
|
|
static unsigned char
|
|
to_uchar (char ch)
|
|
{
|
|
return ch;
|
|
}
|
|
|
|
static const char b64c[64] =
|
|
"ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
|
|
|
|
/* Base64 encode IN array of size INLEN into OUT array. OUT needs
|
|
to be of length >= BASE64_LENGTH(INLEN), and INLEN needs to be
|
|
a multiple of 3. */
|
|
static void
|
|
base64_encode_fast (const char *restrict in, idx_t inlen, char *restrict out)
|
|
{
|
|
while (inlen)
|
|
{
|
|
*out++ = b64c[(to_uchar (in[0]) >> 2) & 0x3f];
|
|
*out++ = b64c[((to_uchar (in[0]) << 4) + (to_uchar (in[1]) >> 4)) & 0x3f];
|
|
*out++ = b64c[((to_uchar (in[1]) << 2) + (to_uchar (in[2]) >> 6)) & 0x3f];
|
|
*out++ = b64c[to_uchar (in[2]) & 0x3f];
|
|
|
|
inlen -= 3;
|
|
in += 3;
|
|
}
|
|
}
|
|
|
|
/* 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, idx_t inlen,
|
|
char *restrict out, idx_t outlen)
|
|
{
|
|
/* Note this outlen constraint can be enforced at compile time.
|
|
I.E. that the output buffer is exactly large enough to hold
|
|
the encoded inlen bytes. The inlen constraints (of corresponding
|
|
to outlen, and being a multiple of 3) can change at runtime
|
|
at the end of input. However the common case when reading
|
|
large inputs is to have both constraints satisfied, so we depend
|
|
on both in base_encode_fast(). */
|
|
if (outlen % 4 == 0 && inlen == (outlen >> 2) * 3)
|
|
{
|
|
base64_encode_fast (in, inlen, out);
|
|
return;
|
|
}
|
|
|
|
while (inlen && outlen)
|
|
{
|
|
*out++ = b64c[(to_uchar (in[0]) >> 2) & 0x3f];
|
|
if (!--outlen)
|
|
break;
|
|
*out++ = b64c[((to_uchar (in[0]) << 4)
|
|
+ (--inlen ? to_uchar (in[1]) >> 4 : 0))
|
|
& 0x3f];
|
|
if (!--outlen)
|
|
break;
|
|
*out++ =
|
|
(inlen
|
|
? b64c[((to_uchar (in[1]) << 2)
|
|
+ (--inlen ? to_uchar (in[2]) >> 6 : 0))
|
|
& 0x3f]
|
|
: '=');
|
|
if (!--outlen)
|
|
break;
|
|
*out++ = inlen ? b64c[to_uchar (in[2]) & 0x3f] : '=';
|
|
if (!--outlen)
|
|
break;
|
|
if (inlen)
|
|
inlen--;
|
|
if (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 failed, OUT is set to NULL, and the return value
|
|
indicates length of the requested memory block, i.e.,
|
|
BASE64_LENGTH(inlen) + 1. */
|
|
idx_t
|
|
base64_encode_alloc (const char *in, idx_t inlen, char **out)
|
|
{
|
|
/* Check for overflow in outlen computation.
|
|
Treat negative INLEN as overflow, for better compatibility with
|
|
pre-2021-08-27 API, which used size_t. */
|
|
idx_t in_over_3 = inlen / 3 + (inlen % 3 != 0), outlen;
|
|
if (! INT_MULTIPLY_OK (in_over_3, 4, &outlen) || inlen < 0)
|
|
{
|
|
*out = NULL;
|
|
return 0;
|
|
}
|
|
outlen++;
|
|
|
|
*out = imalloc (outlen);
|
|
if (!*out)
|
|
return outlen;
|
|
|
|
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.
|
|
|
|
IBM C V6 for AIX mishandles "#define B64(x) ...'x'...", so use "_"
|
|
as the formal parameter rather than "x". */
|
|
#define B64(_) \
|
|
((_) == 'A' ? 0 \
|
|
: (_) == 'B' ? 1 \
|
|
: (_) == 'C' ? 2 \
|
|
: (_) == 'D' ? 3 \
|
|
: (_) == 'E' ? 4 \
|
|
: (_) == 'F' ? 5 \
|
|
: (_) == 'G' ? 6 \
|
|
: (_) == 'H' ? 7 \
|
|
: (_) == 'I' ? 8 \
|
|
: (_) == 'J' ? 9 \
|
|
: (_) == 'K' ? 10 \
|
|
: (_) == 'L' ? 11 \
|
|
: (_) == 'M' ? 12 \
|
|
: (_) == 'N' ? 13 \
|
|
: (_) == 'O' ? 14 \
|
|
: (_) == 'P' ? 15 \
|
|
: (_) == 'Q' ? 16 \
|
|
: (_) == 'R' ? 17 \
|
|
: (_) == 'S' ? 18 \
|
|
: (_) == 'T' ? 19 \
|
|
: (_) == 'U' ? 20 \
|
|
: (_) == 'V' ? 21 \
|
|
: (_) == 'W' ? 22 \
|
|
: (_) == 'X' ? 23 \
|
|
: (_) == 'Y' ? 24 \
|
|
: (_) == 'Z' ? 25 \
|
|
: (_) == 'a' ? 26 \
|
|
: (_) == 'b' ? 27 \
|
|
: (_) == 'c' ? 28 \
|
|
: (_) == 'd' ? 29 \
|
|
: (_) == 'e' ? 30 \
|
|
: (_) == 'f' ? 31 \
|
|
: (_) == 'g' ? 32 \
|
|
: (_) == 'h' ? 33 \
|
|
: (_) == 'i' ? 34 \
|
|
: (_) == 'j' ? 35 \
|
|
: (_) == 'k' ? 36 \
|
|
: (_) == 'l' ? 37 \
|
|
: (_) == 'm' ? 38 \
|
|
: (_) == 'n' ? 39 \
|
|
: (_) == 'o' ? 40 \
|
|
: (_) == 'p' ? 41 \
|
|
: (_) == 'q' ? 42 \
|
|
: (_) == 'r' ? 43 \
|
|
: (_) == 's' ? 44 \
|
|
: (_) == 't' ? 45 \
|
|
: (_) == 'u' ? 46 \
|
|
: (_) == 'v' ? 47 \
|
|
: (_) == 'w' ? 48 \
|
|
: (_) == 'x' ? 49 \
|
|
: (_) == 'y' ? 50 \
|
|
: (_) == 'z' ? 51 \
|
|
: (_) == '0' ? 52 \
|
|
: (_) == '1' ? 53 \
|
|
: (_) == '2' ? 54 \
|
|
: (_) == '3' ? 55 \
|
|
: (_) == '4' ? 56 \
|
|
: (_) == '5' ? 57 \
|
|
: (_) == '6' ? 58 \
|
|
: (_) == '7' ? 59 \
|
|
: (_) == '8' ? 60 \
|
|
: (_) == '9' ? 61 \
|
|
: (_) == '+' ? 62 \
|
|
: (_) == '/' ? 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)
|
|
};
|
|
|
|
#if UCHAR_MAX == 255
|
|
# define uchar_in_range(c) true
|
|
#else
|
|
# define uchar_in_range(c) ((c) <= 255)
|
|
#endif
|
|
|
|
/* Return true if CH is a character from the Base64 alphabet, and
|
|
false otherwise. Note that '=' is padding and not considered to be
|
|
part of the alphabet. */
|
|
bool
|
|
isbase64 (char ch)
|
|
{
|
|
return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)];
|
|
}
|
|
|
|
/* Initialize decode-context buffer, CTX. */
|
|
void
|
|
base64_decode_ctx_init (struct base64_decode_context *ctx)
|
|
{
|
|
ctx->i = 0;
|
|
}
|
|
|
|
/* If CTX->i is 0 or 4, there are four or more bytes in [*IN..IN_END), and
|
|
none of those four is a newline, then return *IN. Otherwise, copy up to
|
|
4 - CTX->i non-newline bytes from that range into CTX->buf, starting at
|
|
index CTX->i and setting CTX->i to reflect the number of bytes copied,
|
|
and return CTX->buf. In either case, advance *IN to point to the byte
|
|
after the last one processed, and set *N_NON_NEWLINE to the number of
|
|
verified non-newline bytes accessible through the returned pointer. */
|
|
static char *
|
|
get_4 (struct base64_decode_context *ctx,
|
|
char const *restrict *in, char const *restrict in_end,
|
|
idx_t *n_non_newline)
|
|
{
|
|
if (ctx->i == 4)
|
|
ctx->i = 0;
|
|
|
|
if (ctx->i == 0)
|
|
{
|
|
char const *t = *in;
|
|
if (4 <= in_end - *in && memchr (t, '\n', 4) == NULL)
|
|
{
|
|
/* This is the common case: no newline. */
|
|
*in += 4;
|
|
*n_non_newline = 4;
|
|
return (char *) t;
|
|
}
|
|
}
|
|
|
|
{
|
|
/* Copy non-newline bytes into BUF. */
|
|
char const *p = *in;
|
|
while (p < in_end)
|
|
{
|
|
char c = *p++;
|
|
if (c != '\n')
|
|
{
|
|
ctx->buf[ctx->i++] = c;
|
|
if (ctx->i == 4)
|
|
break;
|
|
}
|
|
}
|
|
|
|
*in = p;
|
|
*n_non_newline = ctx->i;
|
|
return ctx->buf;
|
|
}
|
|
}
|
|
|
|
#define return_false \
|
|
do \
|
|
{ \
|
|
*outp = out; \
|
|
return false; \
|
|
} \
|
|
while (false)
|
|
|
|
/* Decode up to four bytes of base64-encoded data, IN, of length INLEN
|
|
into the output buffer, *OUT, of size *OUTLEN bytes. Return true if
|
|
decoding is successful, false otherwise. If *OUTLEN is too small,
|
|
as many bytes as possible are written to *OUT. On return, advance
|
|
*OUT to point to the byte after the last one written, and decrement
|
|
*OUTLEN to reflect the number of bytes remaining in *OUT. */
|
|
static bool
|
|
decode_4 (char const *restrict in, idx_t inlen,
|
|
char *restrict *outp, idx_t *outleft)
|
|
{
|
|
char *out = *outp;
|
|
if (inlen < 2)
|
|
return false;
|
|
|
|
if (!isbase64 (in[0]) || !isbase64 (in[1]))
|
|
return false;
|
|
|
|
if (*outleft)
|
|
{
|
|
*out++ = ((b64[to_uchar (in[0])] << 2)
|
|
| (b64[to_uchar (in[1])] >> 4));
|
|
--*outleft;
|
|
}
|
|
|
|
if (inlen == 2)
|
|
return_false;
|
|
|
|
if (in[2] == '=')
|
|
{
|
|
if (inlen != 4)
|
|
return_false;
|
|
|
|
if (in[3] != '=')
|
|
return_false;
|
|
}
|
|
else
|
|
{
|
|
if (!isbase64 (in[2]))
|
|
return_false;
|
|
|
|
if (*outleft)
|
|
{
|
|
*out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0)
|
|
| (b64[to_uchar (in[2])] >> 2));
|
|
--*outleft;
|
|
}
|
|
|
|
if (inlen == 3)
|
|
return_false;
|
|
|
|
if (in[3] == '=')
|
|
{
|
|
if (inlen != 4)
|
|
return_false;
|
|
}
|
|
else
|
|
{
|
|
if (!isbase64 (in[3]))
|
|
return_false;
|
|
|
|
if (*outleft)
|
|
{
|
|
*out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0)
|
|
| b64[to_uchar (in[3])]);
|
|
--*outleft;
|
|
}
|
|
}
|
|
}
|
|
|
|
*outp = out;
|
|
return true;
|
|
}
|
|
|
|
/* Decode base64-encoded input array IN of length INLEN to output array
|
|
OUT that can hold *OUTLEN bytes. The input data may be interspersed
|
|
with newlines. 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, non-newline character is encountered, decoding
|
|
is stopped and false is returned. If INLEN is zero, then process
|
|
only whatever data is stored in CTX.
|
|
|
|
Initially, CTX must have been initialized via base64_decode_ctx_init.
|
|
Subsequent calls to this function must reuse whatever state is recorded
|
|
in that buffer. It is necessary for when a quadruple of base64 input
|
|
bytes spans two input buffers.
|
|
|
|
If CTX is NULL then newlines are treated as garbage and the input
|
|
buffer is processed as a unit. */
|
|
|
|
bool
|
|
base64_decode_ctx (struct base64_decode_context *ctx,
|
|
const char *restrict in, idx_t inlen,
|
|
char *restrict out, idx_t *outlen)
|
|
{
|
|
idx_t outleft = *outlen;
|
|
bool ignore_newlines = ctx != NULL;
|
|
bool flush_ctx = false;
|
|
unsigned int ctx_i = 0;
|
|
|
|
if (ignore_newlines)
|
|
{
|
|
ctx_i = ctx->i;
|
|
flush_ctx = inlen == 0;
|
|
}
|
|
|
|
|
|
while (true)
|
|
{
|
|
idx_t outleft_save = outleft;
|
|
if (ctx_i == 0 && !flush_ctx)
|
|
{
|
|
while (true)
|
|
{
|
|
/* Save a copy of outleft, in case we need to re-parse this
|
|
block of four bytes. */
|
|
outleft_save = outleft;
|
|
if (!decode_4 (in, inlen, &out, &outleft))
|
|
break;
|
|
|
|
in += 4;
|
|
inlen -= 4;
|
|
}
|
|
}
|
|
|
|
if (inlen == 0 && !flush_ctx)
|
|
break;
|
|
|
|
/* Handle the common case of 72-byte wrapped lines.
|
|
This also handles any other multiple-of-4-byte wrapping. */
|
|
if (inlen && *in == '\n' && ignore_newlines)
|
|
{
|
|
++in;
|
|
--inlen;
|
|
continue;
|
|
}
|
|
|
|
/* Restore OUT and OUTLEFT. */
|
|
out -= outleft_save - outleft;
|
|
outleft = outleft_save;
|
|
|
|
{
|
|
char const *in_end = in + inlen;
|
|
char const *non_nl;
|
|
|
|
if (ignore_newlines)
|
|
non_nl = get_4 (ctx, &in, in_end, &inlen);
|
|
else
|
|
non_nl = in; /* Might have nl in this case. */
|
|
|
|
/* If the input is empty or consists solely of newlines (0 non-newlines),
|
|
then we're done. Likewise if there are fewer than 4 bytes when not
|
|
flushing context and not treating newlines as garbage. */
|
|
if (inlen == 0 || (inlen < 4 && !flush_ctx && ignore_newlines))
|
|
{
|
|
inlen = 0;
|
|
break;
|
|
}
|
|
if (!decode_4 (non_nl, inlen, &out, &outleft))
|
|
break;
|
|
|
|
inlen = in_end - in;
|
|
}
|
|
}
|
|
|
|
*outlen -= outleft;
|
|
|
|
return inlen == 0;
|
|
}
|
|
|
|
/* 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
|
|
contains the size of the memory block needed. The function returns
|
|
true on successful decoding and memory allocation errors. (Use the
|
|
*OUT and *OUTLEN parameters to differentiate between successful
|
|
decoding and memory error.) The function returns false if the
|
|
input was invalid, in which case *OUT is NULL and *OUTLEN is
|
|
undefined. */
|
|
bool
|
|
base64_decode_alloc_ctx (struct base64_decode_context *ctx,
|
|
const char *in, idx_t inlen, char **out,
|
|
idx_t *outlen)
|
|
{
|
|
/* This may allocate a few bytes too many, depending on input,
|
|
but it's not worth the extra CPU time to compute the exact size.
|
|
The exact size is 3 * (inlen + (ctx ? ctx->i : 0)) / 4, minus 1 if the
|
|
input ends with "=" and minus another 1 if the input ends with "==".
|
|
Shifting before multiplying avoids the possibility of overflow. */
|
|
idx_t needlen = 3 * ((inlen >> 2) + 1);
|
|
|
|
*out = imalloc (needlen);
|
|
if (!*out)
|
|
return true;
|
|
|
|
if (!base64_decode_ctx (ctx, in, inlen, *out, &needlen))
|
|
{
|
|
free (*out);
|
|
*out = NULL;
|
|
return false;
|
|
}
|
|
|
|
if (outlen)
|
|
*outlen = needlen;
|
|
|
|
return true;
|
|
}
|