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Diffstat (limited to '')
| -rw-r--r-- | src/util/msg_output.c | 175 |
1 files changed, 175 insertions, 0 deletions
diff --git a/src/util/msg_output.c b/src/util/msg_output.c new file mode 100644 index 0000000..7031089 --- /dev/null +++ b/src/util/msg_output.c @@ -0,0 +1,175 @@ +/*++ +/* 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; +} |