src/walk/walk.c

/*
 * Copyright (c) 2024 DTB <trinity@trinity.moe>
 * SPDX-License-Identifier: AGPL-3.0-or-later
 *
 * This program is free software: you can redistribute it and/or modify it under
 * the terms of the GNU Affero General Public License as published by the Free
 * Software Foundation, either version 3 of the License, or (at your option) any
 * later version.
 * 
 * This program is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE. See the GNU Affero General Public License for more
 * details.
 *
 * You should have received a copy of the GNU Affero General Public License
 * along with this program. If not, see https://www.gnu.org/licenses/.
 *
 * This file incorporates work covered by the following copyright and permission
 * notice:
 *
 *     Copyright 2019 Google LLC
 *    
 *     Licensed under the Apache License, Version 2.0 (the "License");
 *     you may not use this file except in compliance with the License.
 *     You may obtain a copy of the License at
 *    
 *         https://www.apache.org/licenses/LICENSE-2.0
 *    
 *     Unless required by applicable law or agreed to in writing, software
 *     distributed under the License is distributed on an "AS IS" BASIS,
 *     WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *     See the License for the specific language governing permissions and
 *     limitations under the License.
 */

#include <errno.h> /* errno */
#include <stdio.h> /* fprintf(3), perror(3), stderr, stdout */
#include <stdlib.h> /* free(3), realloc(3) */
#include <string.h> /* stpcpy(3), strcmp(3), strerror(3), strlen(3) */
#if !defined EX_OK || !defined EX_INVALID || !defined EX_OSERR \
		 || !defined EX_USAGE
#	include <sysexits.h>
#endif
#include <unistd.h> /* getopt(3) */
#include <dirent.h> /* closedir(3), opendir(3), readdir(3), DIR,
                     * struct dirent */

static char *program_name = "<no argv[0]>";
static char *dot[] = {".", NULL}; /* default (argc<2) */

static char *nul_terminator = "\0";
static char *newl_terminator = "\n";
static char *asv_terminator = "\037"; /* ASCII UNIT_SEPARATOR */
static char *terminator;

static int
fnprint(char *fn){
	if(terminator == nul_terminator)
		return fprintf(stdout, "%s%c", fn, nul_terminator[0]);
	else
		return fprintf(stdout, "%s%s", fn, terminator);
}

/* Walks the directory named dirname, printing the names of all files it
 * contains (but not the name of the directory itself).
 * Returns something other than EX_OK with errno set if an error occurs. */
static int
walk(char *dirname, char *argv0){
	DIR *dir;
	struct dirent *f;
	struct { size_t a; char *s; } filename = { 0, NULL };
	size_t l;
	char *np;
	int retval;

	fnprint(dirname);

	if((dir = opendir(dirname)) == NULL)
		return EX_NOINPUT;

	errno = 0;

	while((f = readdir(dir)) != NULL){
		if(strcmp(f->d_name, ".") == 0 || strcmp(f->d_name, "..") == 0)
			continue;
		if((l = strlen(dirname) + 1 + strlen(f->d_name) + 1) > filename.a){
			if((np = realloc(filename.s, l)) == NULL){
				free(filename.s);
				return EX_OSERR;
			}
			filename.a = l;
			filename.s = np;
		}
		stpcpy(stpcpy(stpcpy(filename.s, dirname), "/"), f->d_name);
		/* TODO(bbaren@google.com): Emulate Plan 9's cleanname(3). */
		/* Walk the file if we can successfully open it as a
		 * directory. */
		if(f->d_type == DT_DIR || f->d_type == DT_UNKNOWN){
			if((retval = walk(filename.s, argv0)) != EX_OK){
				if(retval == EX_OSERR){
					free(filename.s);
					return retval;
				}
				else if(retval != EX_NOINPUT)
					fprintf(stderr, "%s: %s: %s\n",
						argv0, filename.s, strerror(errno));
			}
		}else
			fnprint(filename.s);
	}

	if(errno != 0 || closedir(dir) != 0)
		fprintf(stderr, "%s: %s: %s\n", argv0, dirname, strerror(errno));

	free(filename.s);
	return EX_OK;
}

int main(int argc, char *argv[]){
	char *argv0;
	int c;
	int retval;

	argv0 = argv[0] == NULL ? program_name : argv[0];
	terminator = asv_terminator;

	if(argc > 0){
		while((c = getopt(argc, argv, "0d:l:n")) != -1)
			switch(c){
			case '0': terminator = nul_terminator; break;
			case 'd': terminator = optarg; break;
			case 'l': /* TODO */ break;
			case 'n': terminator = newl_terminator; break;
			default:
				fprintf(stderr,
					"Usage: %s (-0n)"
					" (-d [delimiter]) (-l [max levels])"
					" (directories...)\n", argv[0]);
				return EX_USAGE;
			}
		argv += optind;
	}

	retval = 0;

	if(*argv == NULL)
		argv = dot;

	while(*argv != NULL)
		if((retval = walk(*(argv++), argv0)) != EX_OK)
			switch(retval){
			case EX_OSERR: perror(argv0); return retval;
			case EX_NOINPUT:
				fprintf(stderr, "%s: %s: %s\n",
					argv0, *(argv - 1), strerror(errno));
				break;
			}

	return EX_OK;
}