logo

utils-std

Collection of commonly available Unix tools

base64.c (6555B)

    

  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 <fcntl.h>  /* open(), O_RDONLY */
  11. #include <stdint.h> /* uint8_t */
  12. #include <stdio.h>  /* fprintf(), BUFSIZ */
  13. #include <stdlib.h> /* abort */
  14. #include <string.h> /* strerror(), strncmp() */
  15. #include <unistd.h> /* read(), write(), close(), getopt(), opt* */
  17. // 64(26+26+10+2)
  18. static char b64_encmap[64] = "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/";
  19. static size_t c_out = 0;
  20. // 76 is lowest of all base64 related RFCs
  21. static long wrap_nl = 76;
  23. static int
  24. xputc(int c, FILE *stream)
  25. {
  26. 	assert(errno == 0);
  27. 	if(fputc(c, stream) == EOF)
  28. 	{
  29. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  30. 		errno = 0;
  31. 		return 1;
  32. 	}
  34. 	assert(errno == 0);
  35. 	int err = ferror(stream);
  36. 	if(err != 0)
  37. 	{
  38. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  39. 		errno = 0;
  40. 		return 1;
  41. 	}
  43. 	return 0;
  44. }
  46. static inline uint8_t
  47. b64_get(uint8_t pos)
  48. {
  49. 	assert(pos <= 64);
  50. 	return b64_encmap[pos];
  51. }
  53. static void
  54. b64encode(uint8_t out[4], uint8_t in[3])
  55. {
  56. 	out[0] = b64_get(in[0] >> 2);
  57. 	out[1] = b64_get((uint8_t)(((in[0] & 0x03) << 4) | (in[1] >> 4)));
  58. 	out[2] = b64_get((uint8_t)(((in[1] & 0x0f) << 2) | (in[2] >> 6)));
  59. 	out[3] = b64_get(in[2] & 0x3f);
  60. }
  62. static int
  63. encode(FILE *fin, const char *name)
  64. {
  65. 	while(1)
  66. 	{
  67. 		uint8_t obuf[4] = "----";
  68. 		uint8_t ibuf[3] = {0, 0, 0};
  69. 		uint8_t pad = 0;
  71. 		size_t c = 0;
  72. 		for(; c < 3; c++)
  73. 		{
  74. 			int buf = getc(fin);
  75. 			if(buf == EOF)
  76. 			{
  77. 				break;
  78. 			}
  79. 			ibuf[c] = buf;
  80. 		}
  81. 		if(c == 0)
  82. 		{
  83. 			return 0;
  84. 		};
  85. 		assert(errno == 0);
  86. 		if(ferror(fin))
  87. 		{
  88. 			fprintf(stderr, "base64: Error reading ‘%s’: %s\n", name, strerror(errno));
  89. 			errno = 0;
  90. 			return 1;
  91. 		}
  92. 		for(; c < 3; pad++, c++)
  93. 		{
  94. 			ibuf[c] = 0;
  95. 		}
  96. 		assert(c == 3);
  97. 		assert(pad <= 3);
  99. 		b64encode(obuf, (uint8_t *)ibuf);
  101. 		for(; pad > 0; pad--)
  102. 		{
  103. 			obuf[4 - pad] = '=';
  104. 		}
  106. 		assert(errno == 0);
  107. 		fwrite((char *)obuf, 4, 1, stdout);
  108. 		if(errno != 0)
  109. 		{
  110. 			fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  111. 			errno = 0;
  112. 			return 1;
  113. 		}
  114. 		c_out += 4;
  116. 		if(wrap_nl != 0 && (c_out + 4) > wrap_nl)
  117. 		{
  118. 			c_out = 0;
  119. 			if(xputc('\n', stdout) != 0) return 1;
  120. 		}
  122. 		if(feof(fin))
  123. 		{
  124. 			assert(errno == 0);
  125. 			if(fflush(stdout))
  126. 			{
  127. 				fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  128. 				errno = 0;
  129. 				return 1;
  130. 			}
  131. 			int err = ferror(stdout);
  132. 			if(err != 0)
  133. 			{
  134. 				fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  135. 				return 1;
  136. 			}
  138. 			return 0;
  139. 		}
  140. 	}
  142. 	abort(); // unreachable
  143. }
  145. // This function is based on NetBSD's code, which contains the following notices:
  146. // Copyright (c) 2018 The NetBSD Foundation, Inc.
  147. //
  148. // This code is derived from software contributed to The NetBSD Foundation
  149. // by Christos Zoulas.
  150. static int
  151. decode(FILE *fin, const char *name)
  152. {
  153. 	int c = 0;
  154. 	uint8_t out = 0;
  155. 	int state = 0;
  157. 	while((c = getc(fin)) != EOF)
  158. 	{
  159. 		if(isspace(c)) continue;
  161. 		if(c == '=') break;
  163. 		const char *pos = strchr(b64_encmap, c);
  164. 		if(pos == NULL)
  165. 		{
  166. 			fprintf(stderr, "base64: Invalid character %c\n", c);
  167. 			return 1;
  168. 		}
  170. 		uint8_t b = (uint8_t)(pos - b64_encmap);
  171. 		assert(b <= 64);
  173. 		//fprintf(stderr, "state: %d | c: %c (%d) | b: %d\n", state, c, c, b);
  175. 		switch(state)
  176. 		{
  177. 		case 0:
  178. 			out = (uint8_t)(b << 2);
  179. 			break;
  180. 		case 1:
  181. 			out |= b >> 4;
  182. 			if(xputc(out, stdout) != 0) return 1;
  183. 			out = (uint8_t)((b & 0xf) << 4);
  184. 			break;
  185. 		case 2:
  186. 			out |= b >> 2;
  187. 			if(xputc(out, stdout) != 0) return 1;
  188. 			out = (uint8_t)((b & 0x3) << 6);
  189. 			break;
  190. 		case 3:
  191. 			out |= b;
  192. 			if(xputc(out, stdout) != 0) return 1;
  193. 			out = 0;
  194. 			break;
  195. 		default:
  196. 			abort();
  197. 		}
  198. 		state = (state + 1) & 3;
  199. 	}
  201. 	//fprintf(stderr, "[outside] state: %d | c: %c (%d) | out: %d\n", state, c, c, out);
  203. 	if(c == '=')
  204. 	{
  205. 		switch(state)
  206. 		{
  207. 		case 0:
  208. 		case 1:
  209. 			fprintf(stderr, "base64: Invalid character %c (early '=')\n", c);
  210. 			return 1;
  211. 		case 2:
  212. 			while(isspace(c = getc(fin)))
  213. 				;
  215. 			if(c != '=')
  216. 			{
  217. 				fprintf(stderr, "base64: Invalid character %c (not '=')\n", c);
  218. 				return 1;
  219. 			}
  220. 			/* fallthrough */
  221. 		case 3:
  222. 			while(isspace(c = getc(fin)))
  223. 				;
  225. 			if(c != EOF)
  226. 			{
  227. 				fprintf(stderr, "base64: Invalid character %c (not EOF)\n", c);
  228. 				return 1;
  229. 			}
  230. 			return 0;
  231. 		default:
  232. 			abort();
  233. 		}
  234. 	}
  236. 	assert(c == EOF || state == 0);
  238. 	assert(errno == 0);
  239. 	if(fflush(stdout))
  240. 	{
  241. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(errno));
  242. 		errno = 0;
  243. 		return 1;
  244. 	}
  245. 	assert(errno == 0);
  246. 	int err = ferror(stdout);
  247. 	if(err != 0)
  248. 	{
  249. 		fprintf(stderr, "base64: Error writing: %s\n", strerror(err));
  250. 		errno = 0;
  251. 		return 1;
  252. 	}
  254. 	return 0;
  255. }
  257. int
  258. main(int argc, char *argv[])
  259. {
  260. 	int (*process)(FILE *, const char *) = &encode;
  262. 	int c = 0, ret = 0;
  264. 	while((c = getopt(argc, argv, ":dw:")) != -1)
  265. 	{
  266. 		switch(c)
  267. 		{
  268. 		case 'd':
  269. 			process = &decode;
  270. 			break;
  271. 		case 'w':
  272. 			errno = 0;
  273. 			char *e = "";
  274. 			wrap_nl = strtol(optarg, &e, 10);
  276. 			// extraneous characters is invalid
  277. 			if(*e != 0) errno = EINVAL;
  279. 			if(errno != 0)
  280. 			{
  281. 				fprintf(stderr, "base64: Option `-w %s`: %s\n", optarg, strerror(errno));
  282. 				return 1;
  283. 			}
  284. 			break;
  285. 		case ':':
  286. 			fprintf(stderr, "base64: Error: Missing operand for option: ‘-%c’\n", optopt);
  287. 			return 1;
  288. 		case '?':
  289. 			fprintf(stderr, "base64: Error: Unrecognised option: ‘-%c’\n", optopt);
  290. 			return 1;
  291. 		}
  292. 	}
  294. 	argc -= optind;
  295. 	argv += optind;
  297. 	if(argc <= 0)
  298. 	{
  299. 		ret = process(stdin, "<stdin>");
  300. 		goto end;
  301. 	}
  303. 	for(int argi = 0; argi < argc; argi++)
  304. 	{
  305. 		if(strncmp(argv[argi], "-", 2) == 0)
  306. 		{
  307. 			if(process(stdin, "<stdin>") != 0)
  308. 			{
  309. 				ret = 1;
  310. 				goto end;
  311. 			}
  312. 		}
  313. 		else if(strncmp(argv[argi], "--", 3) == 0)
  314. 		{
  315. 			continue;
  316. 		}
  317. 		else
  318. 		{
  319. 			FILE *fin = fopen(argv[argi], "r");
  320. 			if(fin == NULL || ferror(fin) != 0)
  321. 			{
  322. 				fprintf(stderr, "base64: Error opening ‘%s’: %s\n", argv[argi], strerror(errno));
  323. 				ret = 1;
  324. 				goto end;
  325. 			}
  327. 			if(process(fin, argv[argi]) != 0)
  328. 			{
  329. 				ret = 1;
  330. 				goto end;
  331. 			}
  333. 			if(fclose(fin) < 0)
  334. 			{
  335. 				fprintf(stderr, "base64: Error closing ‘%s’: %s\n", argv[argi], strerror(errno));
  336. 				ret = 1;
  337. 				goto end;
  338. 			}
  339. 		}
  340. 	}
  342. end:
  343. 	if(wrap_nl != 0 && c_out > 0)
  344. 	{
  345. 		printf("\n");
  346. 	}
  347. 	return ret;
  348. }