userspace: Implement `basename` utility

userspace/programs/CMakeLists.txt

@@ -1,5 +1,6 @@
 set(USERSPACE_PROGRAMS
 	bananfetch
+	basename
 	cat
 	cat-mmap
 	chmod

userspace/programs/basename/CMakeLists.txt

@@ -0,0 +1,8 @@
+set(SOURCES
+	main.cpp
+)
+
+add_executable(basename ${SOURCES})
+banan_link_library(basename libc)
+
+install(TARGETS basename OPTIONAL)

userspace/programs/basename/main.cpp

@@ -0,0 +1,30 @@
+#include <libgen.h>
+#include <stdio.h>
+#include <string.h>
+
+int usage(const char* argv0, int ret)
+{
+	FILE* fout = ret ? stderr : stdout;
+	fprintf(fout, "usage: %s STRING [SUFFIX]\n", argv0);
+	return ret;
+}
+
+int main(int argc, const char* argv[])
+{
+	if (argc != 2 && argc != 3)
+		return usage(argv[0], 1);
+
+	const char* result = basename(const_cast<char*>(argv[1]));
+	int result_len = strlen(result);
+
+	if (argc == 3)
+	{
+		int suffix_len = strlen(argv[2]);
+		if (result_len >= suffix_len && strcmp(result - suffix_len, argv[2]) == 0)
+			result_len -= suffix_len;
+	}
+
+	printf("%.*s\n", result_len, result);
+
+	return 0;
+}