add realpath() and fix setenv() to store the reallocated environ array

sources/nix20/extra/realpath.c

@@ -0,0 +1,44 @@
+#include <dos/dos.h>
+#include <proto/dos.h>
+#include <errno.h>
+#include <sys/param.h>
+#include <stdlib.h>
+
+extern void __seterrno(void);
+
+/* Resolve name to an absolute AmigaDOS path.  A NULL resolved buffer is
+ * allocated with malloc, as POSIX allows. */
+char *realpath(const char *name, char *resolved) {
+	BPTR lock;
+	char *buf;
+
+#ifdef IXPATHS
+	extern char *__amigapath(const char *path);
+	if ((name = __amigapath(name)) == NULL)
+		return NULL;
+#endif
+
+	lock = Lock((CONST_STRPTR)name, ACCESS_READ);
+	if (lock == 0) {
+		__seterrno();
+		return NULL;
+	}
+
+	buf = resolved ? resolved : malloc(MAXPATHLEN);
+	if (buf == NULL) {
+		UnLock(lock);
+		errno = ENOMEM;
+		return NULL;
+	}
+
+	if (!NameFromLock(lock, (STRPTR)buf, MAXPATHLEN)) {
+		__seterrno();
+		UnLock(lock);
+		if (buf != resolved)
+			free(buf);
+		return NULL;
+	}
+
+	UnLock(lock);
+	return buf;
+}

sources/nix20/stdlib/putenv.c

@@ -38,17 +38,20 @@ int setenv(const char *name, const char *value, int overwrite) {
 		// insert
 		char ** neu;
 		if (environ_ptr__data != __dummy_env)
-			neu = (char **)realloc(environ_ptr__data, (p - environ_ptr__data + 1) * sizeof(char *));
+			neu = (char **)realloc(environ_ptr__data, (p - environ_ptr__data + 2) * sizeof(char *));
 		else
 			neu = (char **)malloc(2 * sizeof(char *));
 
-		if (!neu)
-			return ENOMEM;
+		if (!neu) {
+			errno = ENOMEM;
+			return -1;
+		}
 
 		if (environ_ptr__data != __dummy_env)
 			p = neu + (p - environ_ptr__data);
 		else
 			p = neu;
+		environ_ptr__data = neu;
 
 		*p++ = concat(name, "=", value, 0);
 		*p = 0;