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
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
|
/*++
/* NAME
/* msg_output 3
/* SUMMARY
/* diagnostics output management
/* SYNOPSIS
/* #include <msg_output.h>
/*
/* typedef void (*MSG_OUTPUT_FN)(int level, char *text)
/*
/* void msg_output(output_fn)
/* MSG_OUTPUT_FN output_fn;
/*
/* void msg_printf(level, format, ...)
/* int level;
/* const char *format;
/*
/* void msg_vprintf(level, format, ap)
/* int level;
/* const char *format;
/* va_list ap;
/* DESCRIPTION
/* This module implements low-level output management for the
/* msg(3) diagnostics interface.
/*
/* msg_output() registers an output handler for the diagnostics
/* interface. An application can register multiple output handlers.
/* Output handlers are called in the specified order.
/* An output handler takes as arguments a severity level (MSG_INFO,
/* MSG_WARN, MSG_ERROR, MSG_FATAL, MSG_PANIC, monotonically increasing
/* integer values ranging from 0 to MSG_LAST) and pre-formatted,
/* sanitized, text in the form of a null-terminated string.
/*
/* msg_printf() and msg_vprintf() format their arguments, sanitize the
/* result, and call the output handlers registered with msg_output().
/*
/* msg_text() copies a pre-formatted text, sanitizes the result, and
/* calls the output handlers registered with msg_output().
/* REENTRANCY
/* .ad
/* .fi
/* The above output routines are protected against ordinary
/* recursive calls and against re-entry by signal
/* handlers, with the following limitations:
/* .IP \(bu
/* The signal handlers must never return. In other words, the
/* signal handlers must do one or more of the following: call
/* _exit(), kill the process with a signal, and permanently
/* block the process.
/* .IP \(bu
/* The signal handlers must call the above output routines not
/* until after msg_output() completes initialization, and not
/* until after the first formatted output to a VSTRING or
/* VSTREAM.
/* .IP \(bu
/* Each msg_output() call-back function, and each Postfix or
/* system function called by that call-back function, either
/* must protect itself against recursive calls and re-entry
/* by a terminating signal handler, or it must be called
/* exclusively by functions in the msg_output(3) module.
/* .PP
/* When re-entrancy is detected, the requested output operation
/* is skipped. This prevents memory corruption of VSTREAM_ERR
/* data structures, and prevents deadlock on Linux releases
/* that use mutexes within system library routines such as
/* syslog(). This protection exists under the condition that
/* these specific resources are accessed exclusively via
/* msg_output() call-back functions.
/* 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
/*
/* Wietse Venema
/* Google, Inc.
/* 111 8th Avenue
/* New York, NY 10011, USA
/*--*/
/* System library. */
#include <sys_defs.h>
#include <stdarg.h>
#include <errno.h>
/* Utility library. */
#include <mymalloc.h>
#include <vstring.h>
#include <vstream.h>
#include <msg_vstream.h>
#include <stringops.h>
#include <percentm.h>
#include <msg_output.h>
/*
* Global scope, to discourage the compiler from doing smart things.
*/
volatile int msg_vprintf_level;
/*
* Private state. Allow one nested call, so that one logging error can be
* reported to stderr before bailing out.
*/
#define MSG_OUT_NESTING_LIMIT 2
static MSG_OUTPUT_FN *msg_output_fn = 0;
static int msg_output_fn_count = 0;
static VSTRING *msg_buffers[MSG_OUT_NESTING_LIMIT];
/* msg_output - specify output handler */
void msg_output(MSG_OUTPUT_FN output_fn)
{
int i;
/*
* Allocate all resources during initialization. This may result in a
* recursive call due to memory allocation error.
*/
if (msg_buffers[MSG_OUT_NESTING_LIMIT - 1] == 0) {
for (i = 0; i < MSG_OUT_NESTING_LIMIT; i++)
msg_buffers[i] = vstring_alloc(100);
}
/*
* We're not doing this often, so avoid complexity and allocate memory
* for an exact fit.
*/
if (msg_output_fn_count == 0)
msg_output_fn = (MSG_OUTPUT_FN *) mymalloc(sizeof(*msg_output_fn));
else
msg_output_fn = (MSG_OUTPUT_FN *) myrealloc((void *) msg_output_fn,
(msg_output_fn_count + 1) * sizeof(*msg_output_fn));
msg_output_fn[msg_output_fn_count++] = output_fn;
}
/* msg_printf - format text and log it */
void msg_printf(int level, const char *format,...)
{
va_list ap;
va_start(ap, format);
msg_vprintf(level, format, ap);
va_end(ap);
}
/* msg_vprintf - format text and log it */
void msg_vprintf(int level, const char *format, va_list ap)
{
int saved_errno = errno;
VSTRING *vp;
int i;
if (msg_vprintf_level < MSG_OUT_NESTING_LIMIT) {
msg_vprintf_level += 1;
/* On-the-fly initialization for test programs and startup errors. */
if (msg_output_fn_count == 0)
msg_vstream_init("unknown", VSTREAM_ERR);
vp = msg_buffers[msg_vprintf_level - 1];
/* OK if terminating signal handler hijacks control before next stmt. */
vstring_vsprintf(vp, percentm(format, errno), ap);
printable(vstring_str(vp), '?');
for (i = 0; i < msg_output_fn_count; i++)
msg_output_fn[i] (level, vstring_str(vp));
msg_vprintf_level -= 1;
}
errno = saved_errno;
}
|
