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-rw-r--r--src/util/msg_output.c175
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diff --git a/src/util/msg_output.c b/src/util/msg_output.c
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+/*++
+/* 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;
+}