date and time created 91/01/10 23:37:32 by mckusick

SCCS-vsn: sys/sys/filedesc.h 7.1

diff --git a/usr/src/sys/sys/filedesc.h b/usr/src/sys/sys/filedesc.h
new file mode 100644 (file)
index 0000000..acbc31b
--- /dev/null
+++ b/usr/src/sys/sys/filedesc.h
@@ -0,0 +1,74 @@
+/*
+ * Copyright (c) 1990 The Regents of the University of California.
+ * All rights reserved.
+ *
+ * %sccs.include.redist.c%
+ *
+ *     @(#)filedesc.h  7.1 (Berkeley) %G%
+ */
+
+#ifndef _FILEDESC_
+/*
+ * This structure is used for the management of descriptors.
+ * It may be shared by multiple threads.
+ *
+ * A process is initially started out with NDFILE worth of
+ * descriptors, selected to be enough for typical applications
+ * based on the historic limit of 20 open files. Additional
+ * descriptors may be allocated up to a system defined limit
+ * defined by the global variable nofile; the initial value
+ * of nofile is set to NOFILE. The initial expansion is set to
+ * NDEXTENT; each time it runs out it is doubled until nofile
+ * is reached. NDEXTENT should be selected to be the biggest
+ * multiple of OFILESIZE (see below) that will fit in a
+ * power-of-two sized piece of memory.
+ */
+#define NDFILE         20
+#define NDEXTENT       25
+
+struct filedesc {
+       struct  vnode *fd_cdir;         /* current directory */
+       struct  vnode *fd_rdir;         /* root directory */
+       u_short fd_cmask;               /* mask for file creation */
+       u_short fd_refcnt;              /* reference count */
+       short   fd_lastfile;            /* high-water mark of fd_ofile */
+       short   fd_maxfiles;            /* maximum number of open files */
+       struct  file *fd_ofile[NDFILE]; /* file structures for open files */
+       struct  file **fd_moreofiles;   /* the rest of the open files */
+       char    fd_ofileflags[NDFILE];  /* per-process open file flags */
+       char    *fd_moreofileflags;     /* the rest of the open file flags */
+       long    fd_spare;               /* unused to round up to power of two */
+};
+
+/*
+ * Per-process open flags.
+ */
+#define        UF_EXCLOSE      0x01            /* auto-close on exec */
+#define        UF_MAPPED       0x02            /* mapped from device */
+
+/*
+ * Data structure access macros.
+ */
+#if !defined(vax) && !defined(tahoe)
+#define OFILE(fd, indx) ((indx) < NDFILE ? \
+       (fd)->fd_ofile[indx] : \
+       (fd)->fd_moreofiles[(indx) - NDFILE])
+#define OFILEFLAGS(fd, indx) ((indx) < NDFILE ? \
+       (fd)->fd_ofileflags[indx] : \
+       (fd)->fd_moreofileflags[(indx) - NDFILE])
+#define OFILESIZE (sizeof(struct file *) + sizeof(char))
+#else
+/* PCC cannot handle above as lvalues */
+struct file **ofilefunc();
+char *ofileflagsfunc();
+#define OFILE(fd, indx) *ofilefunc(fd, indx)
+#define OFILEFLAGS(fd, indx) *ofileflagsfunc(fd, indx)
+#define OFILESIZE (sizeof(struct file *) + sizeof(char))
+#endif
+
+/*
+ * Kernel global variables and routines.
+ */
+extern struct filedesc *fddup();
+extern int nofile;
+#endif _FILEDESC_