Add `basename` implementation

2 files changed, 95 insertions, 1 deletions

diff --git a/src/basename.c b/src/basename.c
new file mode 100644
index 0000000..1785754
--- /dev/null
+++ b/src/basename.c
@@ -0,0 +1,92 @@
+#include <getopt.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+
+#define BASENAME_USAGE "Usage: basename NAME [SUFFIX]\n"
+#define BASENAME_USE "Return non-directory portion of a pathname\n"
+
+static char *remove_trailing_slashes(char *pathname) {
+	size_t j = strlen(pathname);
+	char *last_char = pathname + j - 1;
+	for (;last_char > pathname; last_char--) {
+		if (*last_char != '/') {
+			break;
+		}
+		*last_char = '\0';
+	}
+
+	return last_char;
+}
+
+int basename_main(int argc, char *argv[]) {
+	char *result = NULL;
+	char *suffix = NULL;
+	char *last_slash = NULL;
+	char *last_char = NULL;
+	char *suffix_end = NULL;
+	bool suffix_match = true;
+	size_t suffix_len = 0;
+	char *cursor = NULL;
+
+
+	if (getopt(argc, argv, "") != -1) {
+		fputs(BASENAME_USAGE, stderr);
+		return EXIT_FAILURE;
+	}
+
+	if (argc < 2 || argc > 3) {
+		fprintf(stderr, "%s%s", BASENAME_USAGE, BASENAME_USE);
+		return EXIT_FAILURE;
+	}
+
+	result = argv[1];
+	suffix = argc == 3 ? argv[2] : NULL;
+	
+	/* Return empty string on empty input string */
+	if (result[0] == '\0') {
+		puts("");
+		return EXIT_SUCCESS;
+	}
+	
+	/* Remove trailing whitespace and return "/" if the path was all slashes */
+	last_char = remove_trailing_slashes(result);
+	if (last_char == result) {
+		puts("/");
+		return EXIT_SUCCESS;
+	}
+
+	/* Keep only the last node */
+	last_slash = strrchr(result, '/'); 
+	result = last_slash == NULL ? result : last_slash + 1;
+
+
+	/* Remove suffix or return it as is if it's equal to last_node */
+	if (suffix == NULL) {
+		puts(result);
+		return EXIT_SUCCESS;
+	}
+
+	suffix_len = strlen(suffix);
+	if (suffix_len > strlen(result)) {
+		puts(result);
+		return EXIT_SUCCESS;
+	}
+
+	cursor = last_char;
+	for (suffix_end = suffix + suffix_len - 1; suffix_end > suffix; suffix_end--) {
+		if (*cursor != *suffix_end) {
+			suffix_match = false;
+			break;	
+		}
+		cursor--;
+	}
+
+	if (suffix_match && cursor != result) {
+		*cursor = '\0';
+	}
+
+	puts(result);
+	return EXIT_SUCCESS;
+}
diff --git a/src/main.c b/src/main.c
index 64da70f..cf2e30a 100644
--- a/src/main.c
+++ b/src/main.c
@@ -7,6 +7,7 @@ typedef int util_main(int, char **);
 
 extern util_main true_main;
 extern util_main false_main;
+extern util_main basename_main;
 
 typedef struct futiles_util futiles_util_t;
 struct futiles_util {
@@ -18,7 +19,8 @@ int display_utils(int, char **);
 const futiles_util_t utils[] = {
 	{ .name = "futiles", .main = display_utils },
 	{ .name = "true", .main = true_main },
-	{ .name = "false", .main = false_main }
+	{ .name = "false", .main = false_main },
+	{ .name = "basename", .main = basename_main }
 };
 #define UTILS_NB (sizeof(utils) / sizeof(futiles_util_t))