Mercurial > hg > octave-nkf > gnulib-hg
annotate lib/base64.c @ 6739:68c436fda425
Doc fix.
| author | Simon Josefsson <simon@josefsson.org> |
|---|---|
| date | Wed, 19 Apr 2006 14:30:15 +0000 |
| parents | 9ad514083e7f |
| children | 3f3ba5c21147 |
| rev | line source |
|---|---|
| 5498 | 1 /* base64.c -- Encode binary data using printable characters. |
| 6714 | 2 Copyright (C) 1999, 2000, 2001, 2004, 2005, 2006 Free Software |
| 3 Foundation, Inc. | |
| 5498 | 4 |
| 5 This program is free software; you can redistribute it and/or modify | |
| 6 it under the terms of the GNU General Public License as published by | |
| 7 the Free Software Foundation; either version 2, or (at your option) | |
| 8 any later version. | |
| 9 | |
| 10 This program is distributed in the hope that it will be useful, | |
| 11 but WITHOUT ANY WARRANTY; without even the implied warranty of | |
| 12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the | |
| 13 GNU General Public License for more details. | |
| 14 | |
| 15 You should have received a copy of the GNU General Public License | |
| 16 along with this program; if not, write to the Free Software Foundation, | |
|
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17 Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. */ |
| 5498 | 18 |
| 19 /* Written by Simon Josefsson. Partially adapted from GNU MailUtils | |
| 20 * (mailbox/filter_trans.c, as of 2004-11-28). Improved by review | |
| 21 * from Paul Eggert, Bruno Haible, and Stepan Kasal. | |
| 22 * | |
| 23 * See also RFC 3548 <http://www.ietf.org/rfc/rfc3548.txt>. | |
| 24 * | |
| 25 * Be careful with error checking. Here is how you would typically | |
| 26 * use these functions: | |
| 27 * | |
| 28 * bool ok = base64_decode_alloc (in, inlen, &out, &outlen); | |
| 29 * if (!ok) | |
| 30 * FAIL: input was not valid base64 | |
| 31 * if (out == NULL) | |
| 32 * FAIL: memory allocation error | |
| 33 * OK: data in OUT/OUTLEN | |
| 34 * | |
| 35 * size_t outlen = base64_encode_alloc (in, inlen, &out); | |
| 36 * if (out == NULL && outlen == 0 && inlen != 0) | |
| 37 * FAIL: input too long | |
| 38 * if (out == NULL) | |
| 39 * FAIL: memory allocation error | |
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40 * OK: data in OUT/OUTLEN. |
| 5498 | 41 * |
| 42 */ | |
| 43 | |
| 44 #ifdef HAVE_CONFIG_H | |
| 45 # include <config.h> | |
| 46 #endif | |
| 47 | |
| 48 /* Get prototype. */ | |
| 49 #include "base64.h" | |
| 50 | |
| 51 /* Get malloc. */ | |
| 52 #include <stdlib.h> | |
| 53 | |
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54 /* Get UCHAR_MAX. */ |
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55 #include <limits.h> |
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56 |
| 5498 | 57 /* C89 compliant way to cast 'char' to 'unsigned char'. */ |
| 58 static inline unsigned char | |
| 59 to_uchar (char ch) | |
| 60 { | |
| 61 return ch; | |
| 62 } | |
| 63 | |
| 64 /* Base64 encode IN array of size INLEN into OUT array of size OUTLEN. | |
| 65 If OUTLEN is less than BASE64_LENGTH(INLEN), write as many bytes as | |
| 66 possible. If OUTLEN is larger than BASE64_LENGTH(INLEN), also zero | |
| 67 terminate the output buffer. */ | |
| 68 void | |
| 69 base64_encode (const char *restrict in, size_t inlen, | |
| 70 char *restrict out, size_t outlen) | |
| 71 { | |
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72 static const char b64str[64] = |
| 5498 | 73 "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/"; |
| 74 | |
| 75 while (inlen && outlen) | |
| 76 { | |
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77 *out++ = b64str[(to_uchar (in[0]) >> 2) & 0x3f]; |
| 5498 | 78 if (!--outlen) |
| 79 break; | |
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80 *out++ = b64str[((to_uchar (in[0]) << 4) |
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81 + (--inlen ? to_uchar (in[1]) >> 4 : 0)) |
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82 & 0x3f]; |
| 5498 | 83 if (!--outlen) |
| 84 break; | |
| 85 *out++ = | |
| 86 (inlen | |
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87 ? b64str[((to_uchar (in[1]) << 2) |
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88 + (--inlen ? to_uchar (in[2]) >> 6 : 0)) |
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89 & 0x3f] |
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90 : '='); |
| 5498 | 91 if (!--outlen) |
| 92 break; | |
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93 *out++ = inlen ? b64str[to_uchar (in[2]) & 0x3f] : '='; |
| 5498 | 94 if (!--outlen) |
| 95 break; | |
| 96 if (inlen) | |
| 97 inlen--; | |
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98 if (inlen) |
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99 in += 3; |
| 5498 | 100 } |
| 101 | |
| 102 if (outlen) | |
| 103 *out = '\0'; | |
| 104 } | |
| 105 | |
| 106 /* Allocate a buffer and store zero terminated base64 encoded data | |
| 107 from array IN of size INLEN, returning BASE64_LENGTH(INLEN), i.e., | |
| 108 the length of the encoded data, excluding the terminating zero. On | |
| 109 return, the OUT variable will hold a pointer to newly allocated | |
| 110 memory that must be deallocated by the caller. If output string | |
| 111 length would overflow, 0 is returned and OUT is set to NULL. If | |
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112 memory allocation failed, OUT is set to NULL, and the return value |
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113 indicates length of the requested memory block, i.e., |
| 5498 | 114 BASE64_LENGTH(inlen) + 1. */ |
| 115 size_t | |
| 116 base64_encode_alloc (const char *in, size_t inlen, char **out) | |
| 117 { | |
| 118 size_t outlen = 1 + BASE64_LENGTH (inlen); | |
| 119 | |
| 120 /* Check for overflow in outlen computation. | |
| 121 * | |
| 122 * If there is no overflow, outlen >= inlen. | |
| 123 * | |
| 124 * If the operation (inlen + 2) overflows then it yields at most +1, so | |
| 125 * outlen is 0. | |
| 126 * | |
| 127 * If the multiplication overflows, we lose at least half of the | |
| 128 * correct value, so the result is < ((inlen + 2) / 3) * 2, which is | |
| 129 * less than (inlen + 2) * 0.66667, which is less than inlen as soon as | |
| 130 * (inlen > 4). | |
| 131 */ | |
| 132 if (inlen > outlen) | |
| 133 { | |
| 134 *out = NULL; | |
| 135 return 0; | |
| 136 } | |
| 137 | |
| 138 *out = malloc (outlen); | |
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139 if (!*out) |
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140 return outlen; |
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141 |
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142 base64_encode (in, inlen, *out, outlen); |
| 5498 | 143 |
| 144 return outlen - 1; | |
| 145 } | |
| 146 | |
| 147 /* With this approach this file works independent of the charset used | |
| 148 (think EBCDIC). However, it does assume that the characters in the | |
| 149 Base64 alphabet (A-Za-z0-9+/) are encoded in 0..255. POSIX | |
| 150 1003.1-2001 require that char and unsigned char are 8-bit | |
| 151 quantities, though, taking care of that problem. But this may be a | |
| 152 potential problem on non-POSIX C99 platforms. */ | |
| 153 #define B64(x) \ | |
| 154 ((x) == 'A' ? 0 \ | |
| 155 : (x) == 'B' ? 1 \ | |
| 156 : (x) == 'C' ? 2 \ | |
| 157 : (x) == 'D' ? 3 \ | |
| 158 : (x) == 'E' ? 4 \ | |
| 159 : (x) == 'F' ? 5 \ | |
| 160 : (x) == 'G' ? 6 \ | |
| 161 : (x) == 'H' ? 7 \ | |
| 162 : (x) == 'I' ? 8 \ | |
| 163 : (x) == 'J' ? 9 \ | |
| 164 : (x) == 'K' ? 10 \ | |
| 165 : (x) == 'L' ? 11 \ | |
| 166 : (x) == 'M' ? 12 \ | |
| 167 : (x) == 'N' ? 13 \ | |
| 168 : (x) == 'O' ? 14 \ | |
| 169 : (x) == 'P' ? 15 \ | |
| 170 : (x) == 'Q' ? 16 \ | |
| 171 : (x) == 'R' ? 17 \ | |
| 172 : (x) == 'S' ? 18 \ | |
| 173 : (x) == 'T' ? 19 \ | |
| 174 : (x) == 'U' ? 20 \ | |
| 175 : (x) == 'V' ? 21 \ | |
| 176 : (x) == 'W' ? 22 \ | |
| 177 : (x) == 'X' ? 23 \ | |
| 178 : (x) == 'Y' ? 24 \ | |
| 179 : (x) == 'Z' ? 25 \ | |
| 180 : (x) == 'a' ? 26 \ | |
| 181 : (x) == 'b' ? 27 \ | |
| 182 : (x) == 'c' ? 28 \ | |
| 183 : (x) == 'd' ? 29 \ | |
| 184 : (x) == 'e' ? 30 \ | |
| 185 : (x) == 'f' ? 31 \ | |
| 186 : (x) == 'g' ? 32 \ | |
| 187 : (x) == 'h' ? 33 \ | |
| 188 : (x) == 'i' ? 34 \ | |
| 189 : (x) == 'j' ? 35 \ | |
| 190 : (x) == 'k' ? 36 \ | |
| 191 : (x) == 'l' ? 37 \ | |
| 192 : (x) == 'm' ? 38 \ | |
| 193 : (x) == 'n' ? 39 \ | |
| 194 : (x) == 'o' ? 40 \ | |
| 195 : (x) == 'p' ? 41 \ | |
| 196 : (x) == 'q' ? 42 \ | |
| 197 : (x) == 'r' ? 43 \ | |
| 198 : (x) == 's' ? 44 \ | |
| 199 : (x) == 't' ? 45 \ | |
| 200 : (x) == 'u' ? 46 \ | |
| 201 : (x) == 'v' ? 47 \ | |
| 202 : (x) == 'w' ? 48 \ | |
| 203 : (x) == 'x' ? 49 \ | |
| 204 : (x) == 'y' ? 50 \ | |
| 205 : (x) == 'z' ? 51 \ | |
| 206 : (x) == '0' ? 52 \ | |
| 207 : (x) == '1' ? 53 \ | |
| 208 : (x) == '2' ? 54 \ | |
| 209 : (x) == '3' ? 55 \ | |
| 210 : (x) == '4' ? 56 \ | |
| 211 : (x) == '5' ? 57 \ | |
| 212 : (x) == '6' ? 58 \ | |
| 213 : (x) == '7' ? 59 \ | |
| 214 : (x) == '8' ? 60 \ | |
| 215 : (x) == '9' ? 61 \ | |
| 216 : (x) == '+' ? 62 \ | |
| 217 : (x) == '/' ? 63 \ | |
| 218 : -1) | |
| 219 | |
| 220 static const signed char b64[0x100] = { | |
| 221 B64 (0), B64 (1), B64 (2), B64 (3), | |
| 222 B64 (4), B64 (5), B64 (6), B64 (7), | |
| 223 B64 (8), B64 (9), B64 (10), B64 (11), | |
| 224 B64 (12), B64 (13), B64 (14), B64 (15), | |
| 225 B64 (16), B64 (17), B64 (18), B64 (19), | |
| 226 B64 (20), B64 (21), B64 (22), B64 (23), | |
| 227 B64 (24), B64 (25), B64 (26), B64 (27), | |
| 228 B64 (28), B64 (29), B64 (30), B64 (31), | |
| 229 B64 (32), B64 (33), B64 (34), B64 (35), | |
| 230 B64 (36), B64 (37), B64 (38), B64 (39), | |
| 231 B64 (40), B64 (41), B64 (42), B64 (43), | |
| 232 B64 (44), B64 (45), B64 (46), B64 (47), | |
| 233 B64 (48), B64 (49), B64 (50), B64 (51), | |
| 234 B64 (52), B64 (53), B64 (54), B64 (55), | |
| 235 B64 (56), B64 (57), B64 (58), B64 (59), | |
| 236 B64 (60), B64 (61), B64 (62), B64 (63), | |
| 237 B64 (64), B64 (65), B64 (66), B64 (67), | |
| 238 B64 (68), B64 (69), B64 (70), B64 (71), | |
| 239 B64 (72), B64 (73), B64 (74), B64 (75), | |
| 240 B64 (76), B64 (77), B64 (78), B64 (79), | |
| 241 B64 (80), B64 (81), B64 (82), B64 (83), | |
| 242 B64 (84), B64 (85), B64 (86), B64 (87), | |
| 243 B64 (88), B64 (89), B64 (90), B64 (91), | |
| 244 B64 (92), B64 (93), B64 (94), B64 (95), | |
| 245 B64 (96), B64 (97), B64 (98), B64 (99), | |
| 246 B64 (100), B64 (101), B64 (102), B64 (103), | |
| 247 B64 (104), B64 (105), B64 (106), B64 (107), | |
| 248 B64 (108), B64 (109), B64 (110), B64 (111), | |
| 249 B64 (112), B64 (113), B64 (114), B64 (115), | |
| 250 B64 (116), B64 (117), B64 (118), B64 (119), | |
| 251 B64 (120), B64 (121), B64 (122), B64 (123), | |
| 252 B64 (124), B64 (125), B64 (126), B64 (127), | |
| 253 B64 (128), B64 (129), B64 (130), B64 (131), | |
| 254 B64 (132), B64 (133), B64 (134), B64 (135), | |
| 255 B64 (136), B64 (137), B64 (138), B64 (139), | |
| 256 B64 (140), B64 (141), B64 (142), B64 (143), | |
| 257 B64 (144), B64 (145), B64 (146), B64 (147), | |
| 258 B64 (148), B64 (149), B64 (150), B64 (151), | |
| 259 B64 (152), B64 (153), B64 (154), B64 (155), | |
| 260 B64 (156), B64 (157), B64 (158), B64 (159), | |
| 261 B64 (160), B64 (161), B64 (162), B64 (163), | |
| 262 B64 (164), B64 (165), B64 (166), B64 (167), | |
| 263 B64 (168), B64 (169), B64 (170), B64 (171), | |
| 264 B64 (172), B64 (173), B64 (174), B64 (175), | |
| 265 B64 (176), B64 (177), B64 (178), B64 (179), | |
| 266 B64 (180), B64 (181), B64 (182), B64 (183), | |
| 267 B64 (184), B64 (185), B64 (186), B64 (187), | |
| 268 B64 (188), B64 (189), B64 (190), B64 (191), | |
| 269 B64 (192), B64 (193), B64 (194), B64 (195), | |
| 270 B64 (196), B64 (197), B64 (198), B64 (199), | |
| 271 B64 (200), B64 (201), B64 (202), B64 (203), | |
| 272 B64 (204), B64 (205), B64 (206), B64 (207), | |
| 273 B64 (208), B64 (209), B64 (210), B64 (211), | |
| 274 B64 (212), B64 (213), B64 (214), B64 (215), | |
| 275 B64 (216), B64 (217), B64 (218), B64 (219), | |
| 276 B64 (220), B64 (221), B64 (222), B64 (223), | |
| 277 B64 (224), B64 (225), B64 (226), B64 (227), | |
| 278 B64 (228), B64 (229), B64 (230), B64 (231), | |
| 279 B64 (232), B64 (233), B64 (234), B64 (235), | |
| 280 B64 (236), B64 (237), B64 (238), B64 (239), | |
| 281 B64 (240), B64 (241), B64 (242), B64 (243), | |
| 282 B64 (244), B64 (245), B64 (246), B64 (247), | |
| 283 B64 (248), B64 (249), B64 (250), B64 (251), | |
| 284 B64 (252), B64 (253), B64 (254), B64 (255) | |
| 285 }; | |
| 286 | |
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287 #if UCHAR_MAX == 255 |
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288 # define uchar_in_range(c) true |
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289 #else |
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290 # define uchar_in_range(c) ((c) <= 255) |
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291 #endif |
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292 |
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293 /* Return true if CH is a character from the Base64 alphabet, and |
| 6717 | 294 false otherwise. Note that '=' is padding and not considered to be |
| 295 part of the alphabet. */ | |
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296 bool |
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297 isbase64 (char ch) |
| 5498 | 298 { |
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299 return uchar_in_range (to_uchar (ch)) && 0 <= b64[to_uchar (ch)]; |
| 5498 | 300 } |
| 301 | |
| 302 /* Decode base64 encoded input array IN of length INLEN to output | |
| 303 array OUT that can hold *OUTLEN bytes. Return true if decoding was | |
| 304 successful, i.e. if the input was valid base64 data, false | |
| 305 otherwise. If *OUTLEN is too small, as many bytes as possible will | |
| 306 be written to OUT. On return, *OUTLEN holds the length of decoded | |
| 307 bytes in OUT. Note that as soon as any non-alphabet characters are | |
| 6736 | 308 encountered, decoding is stopped and false is returned. This means |
| 6739 | 309 that, when applicable, you must remove any line terminators that is |
| 310 part of the data stream before calling this function. */ | |
| 5498 | 311 bool |
| 312 base64_decode (const char *restrict in, size_t inlen, | |
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313 char *restrict out, size_t *outlen) |
| 5498 | 314 { |
| 315 size_t outleft = *outlen; | |
| 316 | |
| 317 while (inlen >= 2) | |
| 318 { | |
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319 if (!isbase64 (in[0]) || !isbase64 (in[1])) |
| 5498 | 320 break; |
| 321 | |
| 322 if (outleft) | |
| 323 { | |
| 324 *out++ = ((b64[to_uchar (in[0])] << 2) | |
| 325 | (b64[to_uchar (in[1])] >> 4)); | |
| 326 outleft--; | |
| 327 } | |
| 328 | |
| 329 if (inlen == 2) | |
| 330 break; | |
| 331 | |
| 332 if (in[2] == '=') | |
| 333 { | |
| 334 if (inlen != 4) | |
| 335 break; | |
| 336 | |
| 337 if (in[3] != '=') | |
| 338 break; | |
| 339 | |
| 340 } | |
| 341 else | |
| 342 { | |
|
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343 if (!isbase64 (in[2])) |
| 5498 | 344 break; |
| 345 | |
| 346 if (outleft) | |
| 347 { | |
| 348 *out++ = (((b64[to_uchar (in[1])] << 4) & 0xf0) | |
| 349 | (b64[to_uchar (in[2])] >> 2)); | |
| 350 outleft--; | |
| 351 } | |
| 352 | |
| 353 if (inlen == 3) | |
| 354 break; | |
| 355 | |
| 356 if (in[3] == '=') | |
| 357 { | |
| 358 if (inlen != 4) | |
| 359 break; | |
| 360 } | |
| 361 else | |
| 362 { | |
|
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363 if (!isbase64 (in[3])) |
| 5498 | 364 break; |
| 365 | |
| 366 if (outleft) | |
| 367 { | |
| 368 *out++ = (((b64[to_uchar (in[2])] << 6) & 0xc0) | |
| 369 | b64[to_uchar (in[3])]); | |
| 370 outleft--; | |
| 371 } | |
| 372 } | |
| 373 } | |
| 374 | |
| 375 in += 4; | |
| 376 inlen -= 4; | |
| 377 } | |
| 378 | |
| 379 *outlen -= outleft; | |
| 380 | |
| 381 if (inlen != 0) | |
| 382 return false; | |
| 383 | |
| 384 return true; | |
| 385 } | |
| 386 | |
| 387 /* Allocate an output buffer in *OUT, and decode the base64 encoded | |
| 388 data stored in IN of size INLEN to the *OUT buffer. On return, the | |
| 389 size of the decoded data is stored in *OUTLEN. OUTLEN may be NULL, | |
| 390 if the caller is not interested in the decoded length. *OUT may be | |
| 391 NULL to indicate an out of memory error, in which case *OUTLEN | |
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392 contains the size of the memory block needed. The function returns |
| 5498 | 393 true on successful decoding and memory allocation errors. (Use the |
| 394 *OUT and *OUTLEN parameters to differentiate between successful | |
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395 decoding and memory error.) The function returns false if the |
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396 input was invalid, in which case *OUT is NULL and *OUTLEN is |
| 5498 | 397 undefined. */ |
| 398 bool | |
| 399 base64_decode_alloc (const char *in, size_t inlen, char **out, | |
|
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400 size_t *outlen) |
| 5498 | 401 { |
| 402 /* This may allocate a few bytes too much, depending on input, | |
| 403 but it's not worth the extra CPU time to compute the exact amount. | |
| 404 The exact amount is 3 * inlen / 4, minus 1 if the input ends | |
| 405 with "=" and minus another 1 if the input ends with "==". | |
| 406 Dividing before multiplying avoids the possibility of overflow. */ | |
| 407 size_t needlen = 3 * (inlen / 4) + 2; | |
| 408 | |
| 409 *out = malloc (needlen); | |
| 410 if (!*out) | |
| 411 return true; | |
| 412 | |
| 413 if (!base64_decode (in, inlen, *out, &needlen)) | |
| 414 { | |
| 415 free (*out); | |
| 416 *out = NULL; | |
| 417 return false; | |
| 418 } | |
| 419 | |
| 420 if (outlen) | |
| 421 *outlen = needlen; | |
| 422 | |
| 423 return true; | |
| 424 } |