utils-std

uniq.c (5129B)

// utils-std: Collection of commonly available Unix tools
// SPDX-FileCopyrightText: 2017 Haelwenn (lanodan) Monnier <contact+utils@hacktivis.me>
// SPDX-License-Identifier: MPL-2.0
#define _POSIX_C_SOURCE 200809L
#include <assert.h>
#include <ctype.h> // isblank
#include <errno.h>
#include <stdbool.h>
#include <stdio.h>  // getline
#include <stdlib.h> // atoi
#include <string.h> // strncmp
#include <unistd.h> // getopt
enum uniq_mode
{
	UNIQ, // default
	COUNT,
	ONLY_REPEAT,
	NO_REPEAT,
};
const char *argv0 = "uniq";
int
main(int argc, char *argv[])
{
	enum uniq_mode mode = UNIQ;
	unsigned long field = 0, shift = 0;
	char *endptr = NULL;
	int c = -1;
	while((c = getopt(argc, argv, ":cdf:s:u")) != -1)
	{
		switch(c)
		{
		case 'c':
			if(mode != UNIQ)
			{
				fprintf(stderr, "%s: error: can only pass one of [-c|-d|-u]\n", argv0);
				return 1;
			}
			mode = COUNT;
			break;
		case 'd':
			if(mode != UNIQ)
			{
				fprintf(stderr, "%s: error: can only pass one of [-c|-d|-u]\n", argv0);
				return 1;
			}
			mode = ONLY_REPEAT;
			break;
		case 'f':
			errno = 0;
			field = strtoul(optarg, &endptr, 0);
			if(errno != 0)
			{
				fprintf(stderr, "%s: error: Failed parsing '-f %s': %s\n", argv0, optarg, strerror(errno));
				return 1;
			}
			if(endptr != NULL && endptr[0] != 0)
			{
				fprintf(stderr,
				        "%s: error: Non-numeric characters passed to '-f %s': %s\n",
				        argv0,
				        optarg,
				        endptr);
				return 1;
			}
			break;
		case 's':
			errno = 0;
			shift = strtoul(optarg, &endptr, 0);
			if(errno != 0)
			{
				fprintf(stderr, "%s: error: Failed parsing '-f %s': %s\n", argv0, optarg, strerror(errno));
				return 1;
			}
			if(endptr != NULL && endptr[0] != 0)
			{
				fprintf(stderr,
				        "%s: error: Non-numeric characters passed to '-f %s': %s\n",
				        argv0,
				        optarg,
				        endptr);
				return 1;
			}
			break;
		case 'u':
			if(mode != UNIQ)
			{
				fprintf(stderr, "%s: error: can only pass one of [-c|-d|-u]\n", argv0);
				return 1;
			}
			mode = NO_REPEAT;
			break;
		case ':':
			fprintf(stderr, "%s: error: Option '-%c' requires an operand\n", argv0, optopt);
			return 1;
		case '?':
			fprintf(stderr, "%s: error: Unhandled option '-%c'\n", argv0, optopt);
			return 1;
		default:
			fprintf(stderr, "%s: error: Unhandled getopt case '%c'\n", argv0, c);
			abort();
		}
	}
	argc -= optind;
	argv += optind;
	assert(errno == 0);
	FILE *input = stdin;
	FILE *output = stdout;
	switch(argc)
	{
	case 0:
		break;
	case 1:
		input = fopen(argv[0], "r");
		if(input == NULL)
		{
			fprintf(
			    stderr, "uniq: error: Failed opening input file '%s': %s\n", argv[0], strerror(errno));
			return 1;
		}
		break;
	case 2:
		input = fopen(argv[0], "r");
		if(input == NULL)
		{
			fprintf(
			    stderr, "uniq: error: Failed opening input file '%s': %s\n", argv[0], strerror(errno));
			return 1;
		}
		output = fopen(argv[1], "w");
		if(output == NULL)
		{
			fprintf(
			    stderr, "uniq: error: Failed opening output file '%s': %s\n", argv[1], strerror(errno));
			return 1;
		}
		break;
	default:
		fprintf(stderr, "uniq: error: Invalid number of arguments (%d), expected [0..2]\n", argc);
		return 1;
	}
	assert(errno == 0);
	char *first = NULL;
	ssize_t first_len = 0;
	size_t first_shift = 0;
	unsigned counter = 1;
	errno = 0;
	while(true)
	{
		assert(errno == 0);
		char *cur = NULL;
		size_t cur_size = 0;
		ssize_t cur_len = getline(&cur, &cur_size, input);
		size_t cur_shift = shift;
		if(cur_len > 0 && cur[cur_len - 1] == '\n')
		{
			cur[cur_len - 1] = 0;
			cur_len--;
		}
		if(field != 0)
		{
			ssize_t field_shift = 0;
			for(unsigned long i = 0; i < field; i++)
			{
				while(field_shift < cur_len && isblank(cur[field_shift]))
					field_shift++;
				while(field_shift < cur_len && !isblank(cur[field_shift]))
					field_shift++;
			}
			cur_shift += field_shift;
		}
		if(cur_shift > cur_len)
		{
			free(cur);
			cur_size = 0;
			cur = NULL;
			break;
		}
		//fprintf(stderr, "[debug] {cur_shift:%d} <%s>\n", cur_shift, cur+cur_shift);
		if(first != NULL)
		{
			if(cur != NULL && (cur_len - cur_shift == first_len - first_shift) &&
			   strncmp(cur + cur_shift, first + first_shift, cur_len - cur_shift) == 0)
			{
				counter += 1;
			}
			else
			{
				switch(mode)
				{
				case UNIQ:
					fwrite(first, first_len, 1, output);
					fprintf(output, "\n");
					break;
				case ONLY_REPEAT:
					if(counter > 1)
					{
						fwrite(first, first_len, 1, output);
						fprintf(output, "\n");
					}
					break;
				case NO_REPEAT:
					if(counter == 1)
					{
						fwrite(first, first_len, 1, output);
						fprintf(output, "\n");
					}
					break;
				case COUNT:
					fprintf(output, "%d %s\n", counter, first);
					break;
				}
				counter = 1;
				free(first);
			}
		}
		if(cur_len < 0)
		{
			if(cur_size > 0) free(cur);
			break;
		}
		if(counter == 1)
		{
			first = cur;
			first_len = cur_len;
			first_shift = cur_shift;
		}
	}
	if(errno != 0)
	{
		fprintf(stderr, "uniq: error: Failed reading: %s\n", strerror(errno));
		return 1;
	}
	return 0;
}