Initial Spring 2016 commit.

userland/lib/libc/stdlib/getenv.c

@@ -0,0 +1,78 @@
+/*
+ * Copyright (c) 2013
+ *	The President and Fellows of Harvard College.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <stdlib.h>
+#include <string.h>
+
+/*
+ * getenv(): ANSI C
+ *
+ * Get an environment variable.
+ */
+
+/*
+ * This is initialized by crt0, though it actually lives in errno.c
+ */
+extern char **__environ;
+
+/*
+ * This is what we use by default if the kernel didn't supply an
+ * environment.
+ */
+static const char *__default_environ[] = {
+	"PATH=/bin:/sbin:/testbin",
+	"SHELL=/bin/sh",
+	"TERM=vt220",
+	NULL
+};
+
+char *
+getenv(const char *var)
+{
+	size_t varlen, thislen;
+	char *s;
+	unsigned i;
+
+	if (__environ == NULL) {
+		__environ = (char **)__default_environ;
+	}
+	varlen = strlen(var);
+	for (i=0; __environ[i] != NULL; i++) {
+		s = strchr(__environ[i], '=');
+		if (s == NULL) {
+			/* ? */
+			continue;
+		}
+		thislen = s - __environ[i];
+		if (thislen == varlen && !memcmp(__environ[i], var, thislen)) {
+			return s + 1;
+		}
+	}
+	return NULL;
+}