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utils-std

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

echo.c (2338B)

    

  1. // utils-std: Collection of commonly available Unix tools
  2. // SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
  3. // SPDX-License-Identifier: MPL-2.0
  5. #define _POSIX_C_SOURCE 200809L
  6. #include <stdbool.h>
  7. #include <stdio.h>  // perror
  8. #include <string.h> // strlen
  9. #include <unistd.h> // write
  11. static void
  12. unescape(char *str, size_t *len)
  13. {
  14. 	char *start = str;
  15. 	char *store = str;
  17. 	for(; str < (start + *len); ++str, ++store)
  18. 	{
  19. 		if(*str != '\\')
  20. 		{
  21. 			*store = *str;
  22. 			continue;
  23. 		}
  25. 		switch(*++str)
  26. 		{
  27. 		case '\\': // POSIX
  28. 		default:
  29. 			*store = *str;
  30. 			break;
  31. 		case 'a':
  32. 			*store = '\a';
  33. 			break;
  34. 		case 'b':
  35. 			*store = '\b';
  36. 			break;
  37. 		case 'c':
  38. 			goto unescape_end;
  39. 		case 'f':
  40. 			*store = '\f';
  41. 			break;
  42. 		case 'n':
  43. 			*store = '\n';
  44. 			break;
  45. 		case 'r':
  46. 			*store = '\r';
  47. 			break;
  48. 		case 't':
  49. 			*store = '\t';
  50. 			break;
  51. 		case 'v':
  52. 			*store = '\v';
  53. 			break;
  54. 		case '0': /* \0 \0n \0nn \0nnn */
  55. 		{
  56. 			int value = 0;
  57. 			int i = 0;
  58. 			for(; i < 4 && str[i] >= '0' && str[i] <= '7'; i++)
  59. 			{
  60. 				value <<= 3;
  61. 				value += str[i] - '0';
  62. 			}
  63. 			str += (i - 1);
  64. 			*store = (char)value;
  65. 			break;
  66. 		}
  67. 		}
  68. 	}
  70. unescape_end:
  71. 	*store = '\0';
  72. 	*len = (size_t)(store - start);
  73. }
  75. int
  76. main(int argc, char *argv[])
  77. {
  78. 	size_t arg_len = 0;
  79. 	bool opt_n = false, opt_e = false;
  81. 	argc--;
  82. 	argv++;
  84. 	for(; argc > 0;)
  85. 	{
  86. 		if(argv[0][0] != '-') break;
  88. 		/* '-' and '--' needs to be passed as-is so no argc--,argv++ */
  89. 		if(argv[0][1] == '\0' || (argv[0][1] == '-' && argv[0][2] == '\0')) break;
  91. 		for(int i = 1; argv[0][i] != '\0'; i++)
  92. 		{
  93. 			switch(argv[0][i])
  94. 			{
  95. 			case 'n':
  96. 				opt_n = true;
  97. 				break;
  98. 			case 'e':
  99. 				opt_e = true;
  100. 				break;
  101. 			case 'E':
  102. 				opt_e = false;
  103. 				break;
  104. 			default:
  105. 				break;
  106. 			}
  107. 		}
  109. 		argc--;
  110. 		argv++;
  111. 	}
  113. 	for(int i = 0; i < argc; i++)
  114. 	{
  115. 		size_t len = strlen(argv[i]);
  116. 		argv[i][len] = ' ';
  117. 		arg_len += len + 1; // str + space
  118. 	}
  120. 	if(arg_len == 0)
  121. 	{
  122. 		if(opt_n) return 0;
  124. 		if(write(1, "\n", 1) < 1)
  125. 		{
  126. 			perror("echo: error: Failed writing");
  127. 			return 1;
  128. 		}
  130. 		return 0;
  131. 	}
  132. 	else
  133. 		argv[0][arg_len - 1] = '\n';
  135. 	if(opt_n) arg_len--; // no newline
  137. 	if(opt_e) unescape(*argv, &arg_len);
  139. 	ssize_t nwrite = write(1, *argv, arg_len);
  140. 	if(nwrite < (ssize_t)arg_len)
  141. 	{
  142. 		perror("echo: error: Failed writing");
  143. 		return 1;
  144. 	}
  146. 	return 0;
  147. }