lsindex: Fixed wrong errno code to be shown

* When we want to inspect errno after readdir() (or fs_read_index_dir(),
  which is the same), we need to reset errno beforehand as documented
  in the OpenGroup Base.
* Minor coding style, and license header fixes.
* This fixes the wrong error code from #16301, but not the underlying
  issue.

src/bin/lsindex.cpp

@@ -1,10 +1,13 @@
-//	lsindex - for Haiku
+/*
-//
+ * Copyright 2002-2020, Haiku, Inc. All Rights Reserved.
-//	authors, in order of contribution:
+ * Distributed under the terms of the MIT License.
-//	[email protected]
+ *
-//	[email protected]
+ * Authors:
-//	[email protected]
+ *		[email protected]
-//
+ *		[email protected]
+ *		Axel Dörfler, [email protected]
+ */
+
 
 #include <TypeConstants.h>
 #include <fs_info.h>
@@ -137,11 +140,13 @@ print_index_verbose_stat(const index_info &info, char *name)
 
 	// Created
 	char string[30];
-	strftime(string, sizeof(string), "%Y-%m-%d %H:%M", localtime(&info.creation_time)); 
+	strftime(string, sizeof(string), "%Y-%m-%d %H:%M",
+		localtime(&info.creation_time));
 	printf("%s  ", string);
 
 	// Modified
-	strftime(string, sizeof(string), "%Y-%m-%d %H:%M", localtime(&info.modification_time)); 
+	strftime(string, sizeof(string), "%Y-%m-%d %H:%M",
+		localtime(&info.modification_time));
 	printf("%s", string);
 
 	// User
@@ -166,20 +171,23 @@ main(int argc, char **argv)
 			if (!strcmp(argv[i], "--help")) {
 				print_help();
 				return 0;
-			} else if (!strcmp(argv[i], "--verbose") || !strcmp(argv[i], "-v"))
+			}
+			if (!strcmp(argv[i], "--verbose") || !strcmp(argv[i], "-v"))
 				verbose = true;
 			else if (!strcmp(argv[i], "--long") || !strcmp(argv[i], "-l"))
 				longListing = true;
 			else if (!strcmp(argv[i], "--mkindex"))
 				mkindexOutput = true;
 			else {
-				fprintf(stderr, "%s: option %s is not understood (use --help for help)\n", argv[0], argv[i]);
+				fprintf(stderr, "%s: option %s is not understood (use --help "
+					"for help)\n", argv[0], argv[i]);
 				return -1;
 			}
 		} else {
 			device = dev_for_path(argv[i]);
 			if (device < 0) {
-				fprintf(stderr, "%s: can't get information about volume: %s\n", argv[0], argv[i]);
+				fprintf(stderr, "%s: can't get information about volume: %s\n",
+					argv[0], argv[i]);
 				return -1;
 			}
 		}
@@ -198,10 +206,13 @@ main(int argc, char **argv)
 	}
 
 	while (1) {
+		// We have to reset errno before calling fs_read_index_dir().
+		errno = 0;
 		dirent *index = fs_read_index_dir(indices);
 		if (index == NULL) {
 			if (errno != B_ENTRY_NOT_FOUND && errno != B_OK) {
-				printf("%s: fs_read_index_dir: (%d) %s\n", argv[0], errno, strerror(errno));
+				printf("%s: fs_read_index_dir: (%d) %s\n", argv[0], errno,
+					strerror(errno));
 				return errno;
 			}
 			break;
@@ -211,7 +222,8 @@ main(int argc, char **argv)
 			index_info info;
 
 			if (fs_stat_index(device, index->d_name, &info) != B_OK) {
-				printf("%s: fs_stat_index(): (%d) %s\n", argv[0], errno, strerror(errno));
+				printf("%s: fs_stat_index(): (%d) %s\n", argv[0], errno,
+					strerror(errno));
 				return errno;
 			}
 
@@ -219,8 +231,11 @@ main(int argc, char **argv)
 				print_index_verbose_stat(info, index->d_name);
 			else if (longListing)
 				print_index_long_stat(info, index->d_name);
-			else /* mkindexOutput */
+			else {
-				printf("mkindex -t %s '%s'\n", print_index_type(info, true), index->d_name);
+				// mkindex output
+				printf("mkindex -t %s '%s'\n", print_index_type(info, true),
+					index->d_name);
+			}
 		} else
 			printf("%s\n", index->d_name);
 	}