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Filename : io.c
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/* -*- linux-c -*- 
 * I/O for printing warnings, errors and debug messages
 * Copyright (C) 2012 Red Hat Inc.
 *
 * This file is part of systemtap, and is free software.  You can
 * redistribute it and/or modify it under the terms of the GNU General
 * Public License (GPL); either version 2, or (at your option) any
 * later version.
 */

#ifndef _STAPDYN_IO_C_
#define _STAPDYN_IO_C_

#include <sys/param.h>
#include "transport.h"
#include "vsprintf.h"
#include "print.h"

#define WARN_STRING "WARNING: "
#define ERR_STRING "ERROR: "

enum code { INFO=0, WARN, ERROR, DBUG };

static void _stp_vlog (enum code type, const char *func, int line,
		       const char *fmt, va_list args)
	__attribute ((format (printf, 4, 0)));

static void _stp_vlog (enum code type, const char *func, int line,
		       const char *fmt, va_list args)
{
	size_t start = 0;
	size_t num;
	char local_buffer[STP_LOG_BUF_LEN];
	char *buf;

	/* If we're writing a debug message, just use the temporary
	 * buffer. These messages end up going through the normal
	 * transport path, not the OOB data path. */
	if (type == DBUG) {
		buf = local_buffer;
	}
	else {
		/* If we can't get a buffer, the transport must be not
		 * up yet.  Instead use our temporary buffer. */
		buf = _stp_dyninst_transport_log_buffer();
		if (buf == NULL)
			buf = local_buffer;
	}

	if (type == DBUG) {
		start = snprintf(buf, STP_LOG_BUF_LEN, "%s:%d: ", func, line);
	}
	else if (type == WARN) {
		/* This strcpy() is OK, since we know STP_LOG_BUF_LEN
		 * is > sizeof(WARN_STRING). */
		strcpy(buf, WARN_STRING);
		start = sizeof(WARN_STRING)- 1;
	}
	else if (type == ERROR) {
		/* This strcpy() is OK, since we know STP_LOG_BUF_LEN
		 * is > sizeof(ERR_STRING) (which is <
		 * sizeof(WARN_STRING). */
		strcpy(buf, ERR_STRING);
		start = sizeof(ERR_STRING) - 1;
	}

	/* Note that if the message is too long it will just get truncated. */
	num = vsnprintf(buf + start, STP_LOG_BUF_LEN - start - 1, fmt, args);
	if ((num + start) == 0)
		return;

	/* Mimic vscnprintf's length computation.  */
	if (num >= STP_LOG_BUF_LEN - start - 1)
		num = STP_LOG_BUF_LEN - start - 2;

	/* If the last character is not a newline, then add one. */
	if (buf[num + start - 1] != '\n') {
		buf[num + start] = '\n';
		num++;
		buf[num + start] = '\0';
	}

	if (buf != local_buffer) {
		/* If we successfully got log space, send it as OOB now.
		 * NB: don't explicitly send the \0 terminator. */
		_stp_dyninst_transport_write_oob_data(buf, num + start);
	}
	else if (type == DBUG && _stp_runtime_get_context() != NULL) {
                /* Debug messages go over the normal data path if we have a
                 * context for transport.  */
		_stp_print(buf);
		_stp_print_flush();
	}
	else {
		/* Fallback to local stderr as a last resort.  */
		fprintf(stderr, "%s", buf);
	}
}

/** Prints warning.
 * This function sends a warning message immediately to staprun. It
 * will also be sent over the bulk transport (relayfs) if it is
 * being used. If the last character is not a newline, then one 
 * is added. 
 * @param fmt A variable number of args.
 */
static void _stp_warn (const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	_stp_vlog (WARN, NULL, 0, fmt, args);
	va_end(args);
}


/** Prints error message and exits.
 * This function sends an error message immediately to staprun. It
 * will also be sent over the bulk transport (relayfs) if it is
 * being used. If the last character is not a newline, then one 
 * is added. 
 *
 * After the error message is displayed, the module will be unloaded.
 * @param fmt A variable number of args.
 * @sa _stp_exit().
 */
static void _stp_error (const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	_stp_vlog (ERROR, NULL, 0, fmt, args);
	va_end(args);
// FIXME: need to exit here...
//	_stp_exit();
}


/** Prints error message.
 * This function sends an error message immediately to staprun. It
 * will also be sent over the bulk transport (relayfs) if it is
 * being used. If the last character is not a newline, then one 
 * is added. 
 *
 * @param fmt A variable number of args.
 * @sa _stp_error
 */
static void _stp_softerror (const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	_stp_vlog (ERROR, NULL, 0, fmt, args);
	va_end(args);
}


static void _stp_dbug (const char *func, int line, const char *fmt, ...)
{
	va_list args;
	va_start(args, fmt);
	_stp_vlog (DBUG, func, line, fmt, args);
	va_end(args);
}

static void _stp_exit (void)
{
	_stp_dyninst_transport_request_exit();
}

#endif /* _STAPDYN_IO_C_ */