Initial Spring 2016 commit.

kern/include/kern/limits.h

@@ -0,0 +1,109 @@
+/*
+ * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008
+ *	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.
+ */
+
+#ifndef _KERN_LIMITS_H_
+#define _KERN_LIMITS_H_
+
+/*
+ * Constants for libc's <limits.h> - system limits.
+ *
+ * The symbols are prefixed with __ here to avoid namespace pollution
+ * in libc. Use <limits.h> (in either userspace or the kernel) to get
+ * the proper names.
+ *
+ * These are Unix-style limits that Unix defines; you can change them
+ * around or add others as needed or as are appropriate to your system
+ * design.
+ *
+ * Likewise, the default values provided here are fairly reasonable,
+ * but you can change them around pretty freely and userspace code
+ * should adapt. Do change these as needed to match your
+ * implementation.
+ */
+
+
+/*
+ * Important, both as part of the system call API and for system behavior.
+ *
+ * 255 for NAME_MAX and 1024 for PATH_MAX are conventional. ARG_MAX
+ * should be at least 16K. In real systems it often runs to 256K or
+ * more.
+ */
+
+/* Longest filename (without directory) not including null terminator */
+#define __NAME_MAX      255
+
+/* Longest full path name */
+#define __PATH_MAX      1024
+
+/* Max bytes for an exec function (should be at least 16K) */
+#define __ARG_MAX       (64 * 1024)
+
+
+/*
+ * Important for system behavior, but not a big part of the API.
+ *
+ * Most modern systems don't have OPEN_MAX at all, and instead go by
+ * whatever limit is set with setrlimit().
+ */
+
+/* Min value for a process ID (that can be assigned to a user process) */
+#define __PID_MIN       2
+
+/* Max value for a process ID (change this to match your implementation) */
+#define __PID_MAX       32767
+
+/* Max open files per process */
+#define __OPEN_MAX      128
+
+/* Max bytes for atomic pipe I/O -- see description in the pipe() man page */
+#define __PIPE_BUF      512
+
+
+/*
+ * Not so important parts of the API. (Especially in OS/161 where we
+ * don't do credentials by default.)
+ */
+
+/* Max number of supplemental group IDs in process credentials */
+#define __NGROUPS_MAX   32
+
+/* Max login name size (for setlogin/getlogin), incl. null */
+#define __LOGIN_NAME_MAX 17
+
+
+/*
+ * Not very important at all.
+ */
+
+/* Max number of iovec structures at once for readv/writev/preadv/pwritev */
+#define __IOV_MAX       1024
+
+
+#endif /* _KERN_LIMITS_H_ */