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utils-std

Collection of commonly available Unix tools git clone https://anongit.hacktivis.me/git/utils-std.git

base64.c (6773B)

    

  1. // utils-std: Collection of commonly available Unix tools
  2. // SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
  3. // SPDX-FileCopyrightText: 2018 The NetBSD Foundation, Inc.
  4. // SPDX-License-Identifier: MPL-2.0 AND BSD-2-Clause
  6. #define _POSIX_C_SOURCE 200809L
  7. #include <assert.h> /* assert */
  8. #include <ctype.h>  /* isspace */
  9. #include <errno.h>  /* errno */
  10. #include <stdint.h> /* uint8_t */
  11. #include <stdio.h>  /* fopen(), fprintf(), BUFSIZ */
  12. #include <stdlib.h> /* abort */
  13. #include <string.h> /* strerror(), strncmp() */
  14. #include <unistd.h> /* read(), write(), close(), getopt(), opt* */
  16. // 64(26+26+10+2) + NULL
  17. static const char *b64_encmap = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  18. static size_t c_out = 0;
  19. // 76 is lowest of all base64 related RFCs
  20. static long wrap_nl = 76;
  22. static int
  23. xputc(int c, FILE *stream)
  24. {
  25. 	assert(errno == 0);
  26. 	if(fputc(c, stream) == EOF)
  27. 	{
  28. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  29. 		errno = 0;
  30. 		return 1;
  31. 	}
  33. 	assert(errno == 0);
  34. 	int err = ferror(stream);
  35. 	if(err != 0)
  36. 	{
  37. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  38. 		errno = 0;
  39. 		return 1;
  40. 	}
  42. 	return 0;
  43. }
  45. static inline uint8_t
  46. b64_get(uint8_t pos)
  47. {
  48. 	assert(pos <= 64);
  49. 	return b64_encmap[pos];
  50. }
  52. static void
  53. b64encode(uint8_t out[4], uint8_t in[3])
  54. {
  55. 	out[0] = b64_get(in[0] >> 2);
  56. 	out[1] = b64_get((uint8_t)(((in[0] & 0x03) << 4) | (in[1] >> 4)));
  57. 	out[2] = b64_get((uint8_t)(((in[1] & 0x0f) << 2) | (in[2] >> 6)));
  58. 	out[3] = b64_get(in[2] & 0x3f);
  59. }
  61. static int
  62. encode(FILE *fin, const char *name)
  63. {
  64. 	while(1)
  65. 	{
  66. 		uint8_t obuf[4] = "----";
  67. 		uint8_t ibuf[3] = {0, 0, 0};
  68. 		uint8_t pad = 0;
  70. 		size_t c = 0;
  71. 		for(; c < 3; c++)
  72. 		{
  73. 			int buf = getc(fin);
  74. 			if(buf == EOF)
  75. 			{
  76. 				break;
  77. 			}
  78. 			ibuf[c] = buf;
  79. 		}
  80. 		if(c == 0)
  81. 		{
  82. 			return 0;
  83. 		};
  84. 		assert(errno == 0);
  85. 		if(ferror(fin))
  86. 		{
  87. 			fprintf(stderr, "base64: Error reading ‘%s’: %s\n", name, strerror(errno));
  88. 			errno = 0;
  89. 			return 1;
  90. 		}
  91. 		for(; c < 3; pad++, c++)
  92. 		{
  93. 			ibuf[c] = 0;
  94. 		}
  95. 		assert(c == 3);
  96. 		assert(pad <= 3);
  98. 		b64encode(obuf, (uint8_t *)ibuf);
  100. 		for(; pad > 0; pad--)
  101. 		{
  102. 			obuf[4 - pad] = '=';
  103. 		}
  105. 		if(fwrite((char *)obuf, 4, 1, stdout) <= 0)
  106. 		{
  107. 			fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  108. 			errno = 0;
  109. 			return 1;
  110. 		}
  111. 		c_out += 4;
  112. 		assert(errno == 0);
  114. 		if(wrap_nl != 0 && (c_out + 4) > wrap_nl)
  115. 		{
  116. 			c_out = 0;
  117. 			if(xputc('\n', stdout) != 0) return 1;
  118. 		}
  120. 		if(feof(fin))
  121. 		{
  122. 			assert(errno == 0);
  123. 			if(fflush(stdout))
  124. 			{
  125. 				fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  126. 				errno = 0;
  127. 				return 1;
  128. 			}
  129. 			int err = ferror(stdout);
  130. 			if(err != 0)
  131. 			{
  132. 				fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  133. 				return 1;
  134. 			}
  136. 			return 0;
  137. 		}
  138. 	}
  140. 	abort(); // unreachable
  141. }
  143. // This function is based on NetBSD's code, which contains the following notices:
  144. // Copyright (c) 2018 The NetBSD Foundation, Inc.
  145. //
  146. // This code is derived from software contributed to The NetBSD Foundation
  147. // by Christos Zoulas.
  148. static int
  149. decode(FILE *fin, const char *name)
  150. {
  151. 	int c = 0;
  152. 	uint8_t out = 0;
  153. 	int state = 0;
  155. 	while((c = getc(fin)) != EOF)
  156. 	{
  157. 		if(isspace(c)) continue;
  159. 		if(c == '=') break;
  161. 		uint8_t b = 65;
  162. 		for(uint8_t i = 0; i < 64; i++)
  163. 		{
  164. 			if(b64_encmap[i] == c)
  165. 			{
  166. 				b = i;
  167. 				break;
  168. 			}
  169. 		}
  170. 		if(b > 64)
  171. 		{
  172. 			fprintf(stderr, "base64: Invalid character %c\n", c);
  173. 			return 1;
  174. 		}
  176. 		//fprintf(stderr, "state: %d | c: %c (%d) | b: %d\n", state, c, c, b);
  178. 		switch(state)
  179. 		{
  180. 		case 0:
  181. 			out = (uint8_t)(b << 2);
  182. 			break;
  183. 		case 1:
  184. 			out |= b >> 4;
  185. 			if(xputc(out, stdout) != 0) return 1;
  186. 			out = (uint8_t)((b & 0xf) << 4);
  187. 			break;
  188. 		case 2:
  189. 			out |= b >> 2;
  190. 			if(xputc(out, stdout) != 0) return 1;
  191. 			out = (uint8_t)((b & 0x3) << 6);
  192. 			break;
  193. 		case 3:
  194. 			out |= b;
  195. 			if(xputc(out, stdout) != 0) return 1;
  196. 			out = 0;
  197. 			break;
  198. 		default:
  199. 			abort();
  200. 		}
  201. 		state = (state + 1) & 3;
  202. 	}
  204. 	//fprintf(stderr, "[outside] state: %d | c: %c (%d) | out: %d\n", state, c, c, out);
  206. 	if(c == '=')
  207. 	{
  208. 		switch(state)
  209. 		{
  210. 		case 0:
  211. 		case 1:
  212. 			fprintf(stderr, "base64: Invalid character %c (early '=')\n", c);
  213. 			return 1;
  214. 		case 2:
  215. 			while(isspace(c = getc(fin)))
  216. 				;
  218. 			if(c != '=')
  219. 			{
  220. 				fprintf(stderr, "base64: Invalid character %c (not '=')\n", c);
  221. 				return 1;
  222. 			}
  223. 			/* fallthrough */
  224. 		case 3:
  225. 			while(isspace(c = getc(fin)))
  226. 				;
  228. 			if(c != EOF)
  229. 			{
  230. 				fprintf(stderr, "base64: Invalid character %c (not EOF)\n", c);
  231. 				return 1;
  232. 			}
  233. 			return 0;
  234. 		default:
  235. 			abort();
  236. 		}
  237. 	}
  239. 	assert(c == EOF || state == 0);
  241. 	assert(errno == 0);
  242. 	if(fflush(stdout))
  243. 	{
  244. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  245. 		errno = 0;
  246. 		return 1;
  247. 	}
  248. 	assert(errno == 0);
  249. 	int err = ferror(stdout);
  250. 	if(err != 0)
  251. 	{
  252. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  253. 		errno = 0;
  254. 		return 1;
  255. 	}
  257. 	return 0;
  258. }
  260. int
  261. main(int argc, char *argv[])
  262. {
  263. 	int (*process)(FILE *, const char *) = &encode;
  265. 	int c = 0, ret = 0;
  267. 	while((c = getopt(argc, argv, ":dw:")) != -1)
  268. 	{
  269. 		switch(c)
  270. 		{
  271. 		case 'd':
  272. 			process = &decode;
  273. 			break;
  274. 		case 'w':
  275. 			errno = 0;
  276. 			char *e = NULL;
  277. 			wrap_nl = strtol(optarg, &e, 10);
  279. 			// extraneous characters is invalid
  280. 			if(e && *e != 0) errno = EINVAL;
  282. 			if(errno != 0)
  283. 			{
  284. 				fprintf(stderr, "base64: Option `-w %s`: %s\n", optarg, strerror(errno));
  285. 				return 1;
  286. 			}
  287. 			break;
  288. 		case ':':
  289. 			fprintf(stderr, "base64: Error: Missing operand for option: ‘-%c’\n", optopt);
  290. 			return 1;
  291. 		case '?':
  292. 			fprintf(stderr, "base64: Error: Unrecognised option: ‘-%c’\n", optopt);
  293. 			return 1;
  294. 		}
  295. 	}
  297. 	argc -= optind;
  298. 	argv += optind;
  300. 	if(argc <= 0)
  301. 	{
  302. 		ret = process(stdin, "<stdin>");
  303. 		goto end;
  304. 	}
  306. 	for(int argi = 0; argi < argc; argi++)
  307. 	{
  308. 		if(strncmp(argv[argi], "-", 2) == 0)
  309. 		{
  310. 			if(process(stdin, "<stdin>") != 0)
  311. 			{
  312. 				ret = 1;
  313. 				goto end;
  314. 			}
  315. 		}
  316. 		else if(strncmp(argv[argi], "--", 3) == 0)
  317. 		{
  318. 			continue;
  319. 		}
  320. 		else
  321. 		{
  322. 			FILE *fin = fopen(argv[argi], "r");
  323. 			if(fin == NULL || ferror(fin) != 0)
  324. 			{
  325. 				fprintf(stderr, "base64: Error opening ‘%s’: %s\n", argv[argi], strerror(errno));
  326. 				ret = 1;
  327. 				goto end;
  328. 			}
  330. 			if(process(fin, argv[argi]) != 0)
  331. 			{
  332. 				ret = 1;
  333. 				goto end;
  334. 			}
  336. 			if(fclose(fin) < 0)
  337. 			{
  338. 				fprintf(stderr, "base64: Error closing ‘%s’: %s\n", argv[argi], strerror(errno));
  339. 				ret = 1;
  340. 				goto end;
  341. 			}
  342. 		}
  343. 	}
  345. end:
  346. 	if(wrap_nl != 0 && c_out > 0)
  347. 	{
  348. 		printf("\n");
  349. 	}
  351. 	if(fclose(stdin) != 0)
  352. 	{
  353. 		fprintf(stderr, "base64: Error closing <stdin>: %s\n", strerror(errno));
  354. 		ret = 1;
  355. 	}
  357. 	if(fclose(stdout) != 0)
  358. 	{
  359. 		fprintf(stderr, "base64: Error closing <stdout>: %s\n", strerror(errno));
  360. 		ret = 1;
  361. 	}
  363. 	return ret;
  364. }