1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
|
#ifndef _VBUF_H_INCLUDED_
#define _VBUF_H_INCLUDED_
/*++
/* NAME
/* vbuf 3h
/* SUMMARY
/* generic buffer
/* SYNOPSIS
/* #include <vbuf.h>
/* DESCRIPTION
/* .nf
/*
* The VBUF buffer is defined by 1) its structure, by 2) the VBUF_GET() and
* 3) VBUF_PUT() operations that automatically handle buffer empty and
* buffer full conditions, and 4) by the VBUF_SPACE() operation that allows
* the user to reserve buffer space ahead of time, to allow for situations
* where calling VBUF_PUT() is not possible or desirable.
*
* The VBUF buffer does not specify primitives for memory allocation or
* deallocation. The purpose is to allow different applications to have
* different strategies: a memory-resident buffer; a memory-mapped file; or
* a stdio-like window to an open file. Each application provides its own
* get(), put() and space() methods that perform the necessary magic.
*
* This interface is pretty normal. With one exception: the number of bytes
* left to read is negated. This is done so that we can change direction
* between reading and writing on the fly. The alternative would be to use
* separate read and write counters per buffer.
*/
typedef struct VBUF VBUF;
typedef int (*VBUF_GET_READY_FN) (VBUF *);
typedef int (*VBUF_PUT_READY_FN) (VBUF *);
typedef int (*VBUF_SPACE_FN) (VBUF *, ssize_t);
struct VBUF {
int flags; /* status, see below */
unsigned char *data; /* variable-length buffer */
ssize_t len; /* buffer length */
ssize_t cnt; /* bytes left to read/write */
unsigned char *ptr; /* read/write position */
VBUF_GET_READY_FN get_ready; /* read buffer empty action */
VBUF_PUT_READY_FN put_ready; /* write buffer full action */
VBUF_SPACE_FN space; /* request for buffer space */
};
/*
* Typically, an application will embed a VBUF structure into a larger
* structure that also contains application-specific members. This approach
* gives us the best of both worlds. The application can still use the
* generic VBUF primitives for reading and writing VBUFs. The macro below
* transforms a pointer from VBUF structure to the structure that contains
* it.
*/
#define VBUF_TO_APPL(vbuf_ptr,app_type,vbuf_member) \
((app_type *) (((char *) (vbuf_ptr)) - offsetof(app_type,vbuf_member)))
/*
* Buffer status management.
*/
#define VBUF_FLAG_RD_ERR (1<<0) /* read error */
#define VBUF_FLAG_WR_ERR (1<<1) /* write error */
#define VBUF_FLAG_ERR (VBUF_FLAG_RD_ERR | VBUF_FLAG_WR_ERR)
#define VBUF_FLAG_EOF (1<<2) /* end of data */
#define VBUF_FLAG_RD_TIMEOUT (1<<3) /* read timeout */
#define VBUF_FLAG_WR_TIMEOUT (1<<4) /* write timeout */
#define VBUF_FLAG_TIMEOUT (VBUF_FLAG_RD_TIMEOUT | VBUF_FLAG_WR_TIMEOUT)
#define VBUF_FLAG_BAD (VBUF_FLAG_ERR | VBUF_FLAG_EOF | VBUF_FLAG_TIMEOUT)
#define VBUF_FLAG_FIXED (1<<5) /* fixed-size buffer */
#define vbuf_rd_error(v) ((v)->flags & (VBUF_FLAG_RD_ERR | VBUF_FLAG_RD_TIMEOUT))
#define vbuf_wr_error(v) ((v)->flags & (VBUF_FLAG_WR_ERR | VBUF_FLAG_WR_TIMEOUT))
#define vbuf_rd_timeout(v) ((v)->flags & VBUF_FLAG_RD_TIMEOUT)
#define vbuf_wr_timeout(v) ((v)->flags & VBUF_FLAG_WR_TIMEOUT)
#define vbuf_error(v) ((v)->flags & (VBUF_FLAG_ERR | VBUF_FLAG_TIMEOUT))
#define vbuf_eof(v) ((v)->flags & VBUF_FLAG_EOF)
#define vbuf_timeout(v) ((v)->flags & VBUF_FLAG_TIMEOUT)
#define vbuf_clearerr(v) ((v)->flags &= ~VBUF_FLAG_BAD)
/*
* Buffer I/O-like operations and results.
*/
#define VBUF_GET(v) ((v)->cnt < 0 ? ++(v)->cnt, \
(int) *(v)->ptr++ : vbuf_get(v))
#define VBUF_PUT(v,c) ((v)->cnt > 0 ? --(v)->cnt, \
(int) (*(v)->ptr++ = (c)) : vbuf_put((v),(c)))
#define VBUF_SPACE(v,n) ((v)->space((v),(n)))
#define VBUF_EOF (-1) /* no more space or data */
extern int vbuf_get(VBUF *);
extern int vbuf_put(VBUF *, int);
extern int vbuf_unget(VBUF *, int);
extern ssize_t vbuf_read(VBUF *, void *, ssize_t);
extern ssize_t vbuf_write(VBUF *, const void *, ssize_t);
/* LICENSE
/* .ad
/* .fi
/* The Secure Mailer license must be distributed with this software.
/* AUTHOR(S)
/* Wietse Venema
/* IBM T.J. Watson Research
/* P.O. Box 704
/* Yorktown Heights, NY 10598, USA
/*--*/
#endif
|
