Added shuf

2 files changed, 246 insertions, 9 deletions

diff --git a/README.md b/README.md
index 74da1d2..e6a4a74 100644
--- a/README.md
+++ b/README.md
@@ -2,17 +2,18 @@
 
 Rewrite of some core utilities for educational purposes.
 
-| Name       | Description                                                     |
-|------------|-----------------------------------------------------------------|
-| `mkdir`    | make directories                                                |
-| `basename` | strip directory and suffix from filenames                       |
-| `rm`       | remove files or directories                                     |
-| `seq`      | print a sequence of numbers                                     |
-| `tee`      | read from standard input and write to standard output and files |
+| Name       | Description                                                      |
+|------------|----------------------------------------------------------------- |
+| `mkdir`    | make directories                                                 |
+| `basename` | strip directory and suffix from filenames                        |
+| `rm`       | remove files or directories                                      |
+| `seq`      | print a sequence of numbers                                      |
+| `tee`      | read from standard input and write to standard output and files  |
+| `shuf`     | generate random permutations                                     |
 
 # TODO
 
-| Name       | Description                                                     |
+| Name       | Description |
 |------------|-----------------------------------------------------------------|
 | `cut`      | remove sections from each line of files                         |
 | `cp`       | |
@@ -25,7 +26,6 @@ Rewrite of some core utilities for educational purposes.
 | `tail`     | |
 | `tr`       | |
 | `test`     | |
-| `shuf`     | |
 | `sort`     | |
 | `uniq`     | |
 | `dirname`  | |
diff --git a/shuf.c b/shuf.c
new file mode 100644
index 0000000..5b4808a
--- /dev/null
+++ b/shuf.c
@@ -0,0 +1,237 @@
+#define _POSIX_C_SOURCE 200809L
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <limits.h>
+
+#define NUMBER_LEN(x) strlen(#x);
+
+static char *g_name = "shuf";
+
+void fatal(const char *format, ...)
+{
+	va_list	ap;
+
+	va_start(ap, format);
+	fprintf(stderr, "%s: ", g_name);
+	vfprintf(stderr, format, ap);
+	fputc('\n', stderr);
+	va_end(ap);
+	exit(EXIT_FAILURE);
+}
+
+long parse_ulong(char *str, char *error_msg)
+{
+	char *end;
+	long ret;
+
+	errno = 0;
+	ret = strtol(str, &end, 10);
+	if (errno != 0 || ret < 0 || *end != '\0')
+		fatal("%s '%s'", error_msg, optarg);
+	return ret;
+}
+
+typedef struct
+{
+	char **data;
+	size_t len;
+	size_t cap;
+} t_lines;
+
+#define INITIAL_CAPACITY 64
+
+void lines_init(t_lines *lines)
+{
+	lines->len = 0;
+	lines->cap = INITIAL_CAPACITY;
+	lines->data = malloc(lines->cap * sizeof(char*));
+	if (lines->data == NULL)
+		fatal("%s", strerror(errno));
+}
+
+void lines_destroy(t_lines *lines)
+{
+	for (size_t i = 0; i < lines->len; i++)
+		free(lines->data[i]);
+	free(lines->data);
+}
+
+#define GROWTH_FACTOR 2
+
+void lines_push(t_lines *lines, char *line)
+{
+	if (lines->len >= lines->cap)
+	{
+		lines->cap *= GROWTH_FACTOR;
+		lines->data = realloc(lines->data, lines->cap * sizeof(char*));
+		if (lines->data == NULL)
+			fatal("%s", strerror(errno));
+	}
+	lines->data[lines->len] = line;
+	lines->len++;
+}
+
+#define RANDOM_FILEPATH "/dev/random"
+
+int main(int argc, char **argv)
+{
+	int  option;
+	long max_output       = -1;
+	char *output_filepath = NULL;
+	bool repeat           = false;
+	bool echo             = false;
+	char delimiter        = '\n';
+	long range_start      = -1;
+	long range_stop       = -1;
+
+	while ((option = getopt(argc, argv, "ei:n:o:rz")) != -1)
+	{
+
+		switch (option)
+		{
+			case 'e': echo            = true;   break;
+			case 'r': repeat          = true;   break;
+			case 'o': output_filepath = optarg; break;
+			case 'z': delimiter       = '\0';   break;
+
+			case 'i':
+			{
+				char *hyphen = strchr(optarg, '-');
+				if (hyphen == NULL)
+					fatal("invalid input range '%s'", optarg);
+				*hyphen = '\0';
+				range_start = parse_ulong(optarg, "invalid input range");
+				*hyphen = '-';
+				range_stop  = parse_ulong(hyphen + 1, "invalid input range");
+				if (range_start > range_stop)
+					fatal("invalid input range '%s'", optarg);
+				break;
+			}
+
+			case 'n':
+				max_output = parse_ulong(optarg, "invalid line count");
+				break;
+		}
+
+	}
+	if (range_start != -1 && echo)
+		fatal("cannot combine -e and -i options");
+	if (range_start != -1 && optind != argc)
+		fatal("extra operand '%s'", argv[optind]);
+	if (!echo && argc - optind > 1)
+		fatal("extra operand '%s'", argv[optind]);
+
+	unsigned int seed;
+	FILE *seed_file = fopen(RANDOM_FILEPATH, "r");
+	if (seed_file == NULL)
+		fatal("%s: %s", RANDOM_FILEPATH, strerror(errno));
+	fread(&seed, sizeof(seed), 1, seed_file);
+	srand(seed);
+
+	t_lines lines;
+	lines_init(&lines);
+
+	if (range_start != -1)
+	{
+		size_t buf_len = NUMBER_LEN(LONG_MAX);
+		for (; range_start <= range_stop; range_start++)
+		{
+			char *line = malloc(buf_len * sizeof(char));
+			if (line == NULL)
+				fatal("%s", strerror(errno));
+			sprintf(line, "%ld", range_start);
+			lines_push(&lines, line);
+		}
+	}
+	else if (echo)
+	{
+		for (; optind < argc; optind++)
+		{
+			char *line = strdup(argv[optind]);
+			if (line == NULL)
+				fatal("%s", strerror(errno));
+			lines_push(&lines, line);
+		}
+	}
+	else
+	{
+		FILE *input = stdin;
+		if (optind != argc)
+		{
+			input = fopen(argv[optind], "r");
+			if (input == NULL)
+				fatal("%s: %s", argv[optind], strerror(errno));
+		}
+
+		char   *line     = NULL;
+		size_t line_size = 0;
+		errno = 0;
+		while (getdelim(&line, &line_size, delimiter, input) != -1)
+		{
+			lines_push(&lines, line);
+			line = NULL;
+			line_size = 0;
+		}
+		if (errno != 0)
+		{
+			fclose(input);
+			fatal("%s: %s", argv[optind], strerror(errno));
+		}
+		fclose(input);
+	}
+
+	if (lines.len == 0)
+	{
+		lines_destroy(&lines);
+		return EXIT_SUCCESS;
+	}
+	for (size_t i = lines.len - 1; i > 0; i--)
+	{
+		size_t j = rand() % i;
+		char *tmp = lines.data[i];
+		lines.data[i] = lines.data[j];
+		lines.data[j] = tmp;
+	}
+
+	FILE *output = stdout;
+	if (output_filepath != NULL)
+	{
+		output = fopen(output_filepath, "w");
+		if (output == NULL)
+			fatal("%s: %s", output_filepath, strerror(errno));
+	}
+
+	if (repeat)
+	{
+		for (size_t i = 0; true; i = (i + 1) % lines.len)
+		{
+			if (fputs(lines.data[i], output) == EOF)
+				break;
+			if (echo || range_start != -1)
+				if (fputc('\n', output) == EOF)
+					break;
+		}
+	}
+	else
+	{
+		for (size_t i = 0;
+			 max_output == -1 ? (i < lines.len) : (i < (unsigned long)max_output);
+			 i++)
+		{
+			if (fputs(lines.data[i], output) == EOF)
+				break;
+			if (echo || range_start != -1)
+				if (fputc('\n', output) == EOF)
+					break;
+		}
+	}
+	fclose(output);
+
+	lines_destroy(&lines);
+	return EXIT_SUCCESS;
+}