From 284e1b7a5c4b1b0b0f38d16ecb1507ea4ac964f4 Mon Sep 17 00:00:00 2001
From: Charles Cabergs <me@cacharle.xyz>
Date: Sat, 8 Aug 2020 16:22:55 +0200
Subject: Moved everything in root

---
 head.c | 166 +++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 166 insertions(+)
 create mode 100644 head.c

(limited to 'head.c')

diff --git a/head.c b/head.c
new file mode 100644
index 0000000..f2201b5
--- /dev/null
+++ b/head.c
@@ -0,0 +1,166 @@
+#include <unistd.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdbool.h>
+#include <string.h>
+#include <errno.h>
+#include <stdarg.h>
+
+typedef enum
+{
+	VLEVEL_QUIET,
+	VLEVEL_NORMAL,
+	VLEVEL_VERBOSE,
+}	t_verbose_level;
+
+typedef enum
+{
+	UNIT_LINE,
+	UNIT_BYTE,
+}	t_unit;
+
+char	*g_name = "head";
+
+#define UNIT_BYTE_BUFFER_SIZE 1028
+
+void	fatal_printf(const char *format, ...)
+{
+	va_list	ap;
+
+	va_start(ap, format);
+	fprintf(stderr, "%s: ", g_name);
+	vfprintf(stderr, format, ap);
+	va_end(ap);
+	exit(EXIT_FAILURE);
+}
+
+int	file_head(FILE *file,
+			  char *header, t_unit unit,
+			  unsigned long count, char line_delimiter)
+{
+	char	buf[UNIT_BYTE_BUFFER_SIZE] = {'\0'};
+	size_t	read_size;
+	size_t	write_size;
+	char	*line = NULL;
+	size_t	line_size = 0;
+	ssize_t	ret;
+
+	if (header != NULL)
+		printf("==> %s <==\n", header);
+	switch (unit)
+	{
+		case UNIT_BYTE:
+			while (count > 0)
+			{
+				read_size = count > UNIT_BYTE_BUFFER_SIZE ? UNIT_BYTE_BUFFER_SIZE : count;
+				write_size = fread(buf, 1, read_size, file);
+				fwrite(buf, 1, write_size, stdout);
+				if (write_size < read_size)
+					break;
+				count -= read_size;
+			}
+			break;
+
+		case UNIT_LINE:
+			for (; count > 0 && (ret = getdelim(&line, &line_size, line_delimiter, file)) != -1; count--)
+				fwrite(line, 1, ret, stdout);
+			free(line);
+			break;
+	}
+	return 0;
+}
+
+int	file_path_head(char *path,
+				   char *header, t_unit unit,
+				   unsigned long count, char line_delimiter)
+{
+	FILE *file;
+
+	if ((file = fopen(path, "r")) == NULL)
+	{
+		fprintf(stderr, "%s: cannot open '%s' for reading: %s\n", g_name, path, strerror(errno));
+		return -1;
+	}
+	file_head(file, header, unit, count, line_delimiter);
+	fclose(file);
+	return 0;
+}
+
+int main(int argc, char **argv)
+{
+	int				option;
+	t_verbose_level	verbose_level = VLEVEL_NORMAL;
+	t_unit			unit = UNIT_LINE;
+	unsigned long	count = 10;
+	char			line_delimiter = '\n';
+
+	g_name = argv[0];
+
+	while ((option = getopt(argc, argv, "c:n:qvz")) != -1)
+	{
+		switch (option)
+		{
+			case 'c':
+			case 'n':
+				if (strchr(optarg, '-') != NULL)
+					fatal_printf("invalid number of bytes: '%s'\n", optarg);
+				char	*endptr;
+				errno = 0;
+				// TODO '-' prefix result in tail
+				// TODO human readable size suffix
+				count = strtoul(optarg, &endptr, 10);
+				if (*endptr != '\0')
+					fatal_printf("invalid number of bytes: '%s'\n", optarg);
+				if (errno != 0 || *endptr != '\0')
+					fatal_printf("invalid number of bytes: '%s': %s\n", optarg, strerror(errno));
+				switch (option)
+				{
+					case 'c': unit = UNIT_BYTE; break;
+					case 'n': unit = UNIT_LINE; break;
+				}
+				break;
+
+			case 'q': verbose_level = VLEVEL_QUIET;   break;
+			case 'v': verbose_level = VLEVEL_VERBOSE; break;
+			case 'z': line_delimiter = '\0';          break;
+		}
+	}
+
+	if (argv[optind] == NULL)
+	{
+		file_head(
+			stdin, verbose_level == VLEVEL_VERBOSE ? "standard input" : NULL,
+			unit, count, line_delimiter);
+		return EXIT_SUCCESS;
+	}
+
+	if (argv[optind + 1] == NULL)
+	{
+		if (strcmp(argv[optind], "-") == 0)
+			file_head(
+				stdin, verbose_level == VLEVEL_VERBOSE ? "standard input" : NULL,
+				unit, count, line_delimiter);
+		else
+			file_path_head(
+				argv[optind], verbose_level == VLEVEL_VERBOSE ? argv[optind] : NULL,
+				unit, count, line_delimiter);
+		return EXIT_SUCCESS;
+	}
+
+	for (; optind < argc; optind++)
+	{
+		int	ret = 0;
+
+		if (strcmp(argv[optind], "-") == 0)
+			ret = file_head(
+				stdin, verbose_level != VLEVEL_QUIET ? "standard input" : NULL,
+				unit, count, line_delimiter);
+		else
+			ret = file_path_head(
+				argv[optind], verbose_level != VLEVEL_QUIET ? argv[optind] : NULL,
+				unit, count, line_delimiter);
+		if (argv[optind + 1] != NULL && ret != -1)
+			putchar('\n');
+	}
+	return EXIT_SUCCESS;
+}
-- 
cgit