add which

userspace/core/which.c

@@ -0,0 +1,63 @@
+/* This file is part of ToaruOS and is released under the terms
+ * of the NCSA / University of Illinois License - see LICENSE.md
+ * Copyright (C) 2013-2014 Kevin Lange
+ *
+ * which
+ *
+ * Searches through PATH to find an executable.
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#define DEFAULT_PATH ".:/bin:/usr/bin"
+
+int main(int argc, char * argv[]) {
+
+	if (argc < 2) {
+		return 1;
+	}
+
+	if (strstr(argv[1], "/")) {
+		struct stat t;
+		if (!stat(argv[1], &t)) {
+			if ((t.st_mode & 0111)) {
+				printf("%s\n", argv[1]);
+				return 0;
+			}
+		}
+	} else {
+		char * file = argv[1];
+		char * path = getenv("PATH");
+		if (!path) {
+			path = DEFAULT_PATH;
+		}
+
+		char * xpath = strdup(path);
+		int found = 0;
+		char * p, * tokens[10], * last;
+		int i = 0;
+		for ((p = strtok_r(xpath, ":", &last)); p; p = strtok_r(NULL, ":", &last)) {
+			int r;
+			struct stat stat_buf;
+			char * exe = malloc(strlen(p) + strlen(file) + 2);
+			strcpy(exe, p);
+			strcat(exe, "/");
+			strcat(exe, file);
+
+			r = stat(exe, &stat_buf);
+			if (r != 0) {
+				continue;
+			}
+			if (!(stat_buf.st_mode & 0111)) {
+				continue; /* XXX not technically correct; need to test perms */
+			}
+			printf("%s\n", exe);
+			return 0;
+		}
+		free(xpath);
+		return 1;
+	}
+	return 1;
+}