1/*++
2/* NAME
3/*	dir_forest 3
4/* SUMMARY
5/*	file name to directory forest
6/* SYNOPSIS
7/*	#include <dir_forest.h>
8/*
9/*	char	*dir_forest(buf, path, depth)
10/*	VSTRING *buf;
11/*	const char *path;
12/*	int	depth;
13/* DESCRIPTION
14/*	This module implements support for directory forests: a file
15/*	organization that introduces one or more levels of intermediate
16/*	subdirectories in order to reduce the number of files per directory.
17/*
18/*	dir_forest() maps a file basename to a directory forest and
19/*	returns the resulting string: file name "abcd" becomes "a/b/"
20/*	and so on. The number of subdirectory levels is adjustable.
21/*
22/*	Arguments:
23/* .IP buf
24/*	A buffer that is overwritten with the result. The result
25/*	ends in "/" and is null terminated. If a null pointer is
26/*	specified, the result is written to a private buffer that
27/*	is overwritten upon each call.
28/* .IP path
29/*	A null-terminated string of printable characters. Characters
30/*	special to the file system are not permitted.
31/*	The first subdirectory is named after the first character
32/*	in \fIpath\fR, and so on. When the path is shorter than the
33/*	desired number of subdirectory levels, directory names
34/*	of '_' (underscore) are used as replacement.
35/* .IP depth
36/*	The desired number of subdirectory levels.
37/* DIAGNOSTICS
38/*	Panic: interface violations. Fatal error: out of memory.
39/* LICENSE
40/* .ad
41/* .fi
42/*	The Secure Mailer license must be distributed with this software.
43/* AUTHOR(S)
44/*	Wietse Venema
45/*	IBM T.J. Watson Research
46/*	P.O. Box 704
47/*	Yorktown Heights, NY 10598, USA
48/*--*/
49
50/* System library. */
51
52#include <sys_defs.h>
53#include <ctype.h>
54
55/* Utility library. */
56
57#include "msg.h"
58#include "dir_forest.h"
59
60/* dir_forest - translate base name to directory forest */
61
62char   *dir_forest(VSTRING *buf, const char *path, int depth)
63{
64    const char *myname = "dir_forest";
65    static VSTRING *private_buf = 0;
66    int     n;
67    const char *cp;
68    int     ch;
69
70    /*
71     * Sanity checks.
72     */
73    if (*path == 0)
74	msg_panic("%s: empty path", myname);
75    if (depth < 1)
76	msg_panic("%s: depth %d", myname, depth);
77
78    /*
79     * Your buffer or mine?
80     */
81    if (buf == 0) {
82	if (private_buf == 0)
83	    private_buf = vstring_alloc(1);
84	buf = private_buf;
85    }
86
87    /*
88     * Generate one or more subdirectory levels, depending on the pathname
89     * contents. When the pathname is short, use underscores instead.
90     * Disallow non-printable characters or characters that are special to
91     * the file system.
92     */
93    VSTRING_RESET(buf);
94    for (cp = path, n = 0; n < depth; n++) {
95	if ((ch = *cp) == 0) {
96	    ch = '_';
97	} else {
98	    if (!ISPRINT(ch) || ch == '.' || ch == '/')
99		msg_panic("%s: invalid pathname: %s", myname, path);
100	    cp++;
101	}
102	VSTRING_ADDCH(buf, ch);
103	VSTRING_ADDCH(buf, '/');
104    }
105    VSTRING_TERMINATE(buf);
106
107    if (msg_verbose > 1)
108	msg_info("%s: %s -> %s", myname, path, vstring_str(buf));
109    return (vstring_str(buf));
110}
111