log.c

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/*
 * This file is part of the libsigrok project.
 *
 * Copyright (C) 2011-2012 Uwe Hermann <uwe@hermann-uwe.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation; either version 2 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, see <http://www.gnu.org/licenses/>.
 */

#include <config.h>
#include <stdarg.h>
#include <stdio.h>
#include <glib/gprintf.h>
#include <libsigrok/libsigrok.h>
#include "libsigrok-internal.h"

/** @cond PRIVATE */
#define LOG_PREFIX "log"
/** @endcond */

/**
 * @file
 *
 * Controlling the libsigrok message logging functionality.
 */

/**
 * @defgroup grp_logging Logging
 *
 * Controlling the libsigrok message logging functionality.
 *
 * @{
 */

/* Currently selected libsigrok loglevel. Default: SR_LOG_WARN. */
static int cur_loglevel = SR_LOG_WARN; /* Show errors+warnings per default. */

/* Function prototype. */
static int sr_logv(void *cb_data, int loglevel, const char *format,
                   va_list args);

/* Pointer to the currently selected log callback. Default: sr_logv(). */
static sr_log_callback sr_log_cb = sr_logv;

/*
 * Pointer to private data that can be passed to the log callback.
 * This can be used (for example) by C++ GUIs to pass a "this" pointer.
 */
static void *sr_log_cb_data = NULL;

/** @cond PRIVATE */
#define LOGLEVEL_TIMESTAMP SR_LOG_DBG
/** @endcond */
static int64_t sr_log_start_time = 0;

/**
 * Set the libsigrok loglevel.
 *
 * This influences the amount of log messages (debug messages, error messages,
 * and so on) libsigrok will output. Using SR_LOG_NONE disables all messages.
 *
 * Note that this function itself will also output log messages. After the
 * loglevel has changed, it will output a debug message with SR_LOG_DBG for
 * example. Whether this message is shown depends on the (new) loglevel.
 *
 * @param loglevel The loglevel to set (SR_LOG_NONE, SR_LOG_ERR, SR_LOG_WARN,
 *                 SR_LOG_INFO, SR_LOG_DBG, or SR_LOG_SPEW).
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid loglevel.
 *
 * @since 0.1.0
 */
SR_API int sr_log_loglevel_set(int loglevel)
{
        if (loglevel < SR_LOG_NONE || loglevel > SR_LOG_SPEW) {
                sr_err("Invalid loglevel %d.", loglevel);
                return SR_ERR_ARG;
        }
        /* Output time stamps relative to time at startup */
        if (loglevel >= LOGLEVEL_TIMESTAMP && sr_log_start_time == 0)
                sr_log_start_time = g_get_monotonic_time();

        cur_loglevel = loglevel;

        sr_dbg("libsigrok loglevel set to %d.", loglevel);

        return SR_OK;
}

/**
 * Get the libsigrok loglevel.
 *
 * @return The currently configured libsigrok loglevel.
 *
 * @since 0.1.0
 */
SR_API int sr_log_loglevel_get(void)
{
        return cur_loglevel;
}

/**
 * Set the libsigrok log callback to the specified function.
 *
 * @param cb Function pointer to the log callback function to use.
 *           Must not be NULL.
 * @param cb_data Pointer to private data to be passed on. This can be used by
 *                the caller to pass arbitrary data to the log functions. This
 *                pointer is only stored or passed on by libsigrok, and is
 *                never used or interpreted in any way. The pointer is allowed
 *                to be NULL if the caller doesn't need/want to pass any data.
 *
 * @return SR_OK upon success, SR_ERR_ARG upon invalid arguments.
 *
 * @since 0.3.0
 */
SR_API int sr_log_callback_set(sr_log_callback cb, void *cb_data)
{
        if (!cb) {
                sr_err("%s: cb was NULL", __func__);
                return SR_ERR_ARG;
        }

        /* Note: 'cb_data' is allowed to be NULL. */

        sr_log_cb = cb;
        sr_log_cb_data = cb_data;

        return SR_OK;
}

/**
 * Set the libsigrok log callback to the default built-in one.
 *
 * Additionally, the internal 'sr_log_cb_data' pointer is set to NULL.
 *
 * @return SR_OK upon success, a negative error code otherwise.
 *
 * @since 0.1.0
 */
SR_API int sr_log_callback_set_default(void)
{
        /*
         * Note: No log output in this function, as it should safely work
         * even if the currently set log callback is buggy/broken.
         */
        sr_log_cb = sr_logv;
        sr_log_cb_data = NULL;

        return SR_OK;
}

/**
 * Get the libsigrok log callback routine and callback data.
 *
 * @param[out] cb Pointer to a function pointer to receive the log callback
 *      function. Optional, can be NULL.
 * @param[out] cb_data Pointer to a void pointer to receive the log callback's
 *      additional arguments. Optional, can be NULL.
 *
 * @return SR_OK upon success.
 *
 * @since 0.6.0
 */
SR_API int sr_log_callback_get(sr_log_callback *cb, void **cb_data)
{
        if (cb)
                *cb = sr_log_cb;
        if (cb_data)
                *cb_data = sr_log_cb_data;

        return SR_OK;
}

static int sr_logv(void *cb_data, int loglevel, const char *format, va_list args)
{
        int ret;
        uint64_t elapsed_us, minutes;
        unsigned int rest_us, seconds, microseconds;
        char *raw_output, *output, c;
        ssize_t print_len;
        size_t raw_len;
        const char *raw_ptr;
        char *out_ptr;

        /* This specific log callback doesn't need the void pointer data. */
        (void)cb_data;

        (void)loglevel;

        /* Prefix with 'sr:'. Optionally prefix with timestamp. */
        ret = fputs("sr: ", stderr);
        if (ret < 0)
                return SR_ERR;
        if (cur_loglevel >= LOGLEVEL_TIMESTAMP) {
                elapsed_us = g_get_monotonic_time() - sr_log_start_time;

                minutes = elapsed_us / G_TIME_SPAN_MINUTE;
                rest_us = elapsed_us % G_TIME_SPAN_MINUTE;
                seconds = rest_us / G_TIME_SPAN_SECOND;
                microseconds = rest_us % G_TIME_SPAN_SECOND;

                ret = g_fprintf(stderr, "[%.2" PRIu64 ":%.2u.%.6u] ",
                                minutes, seconds, microseconds);
                if (ret < 0)
                        return SR_ERR;
        }

        /* Print the caller's message into a local buffer. */
        raw_output = NULL;
        print_len = g_vasprintf(&raw_output, format, args);
        if (print_len < 0) {
                g_free(raw_output);
                return SR_ERR;
        }
        raw_len = (size_t)print_len;

        /* Copy the string. Strip unwanted line breaks. */
        output = g_malloc(raw_len + 1);
        if (!output) {
                g_free(raw_output);
                return SR_ERR;
        }
        out_ptr = output;
        raw_ptr = raw_output;
        while (*raw_ptr) {
                c = *raw_ptr++;
                if (c == '\r' || c == '\n')
                        continue;
                *out_ptr++ = c;
        }
        *out_ptr = '\0';
        g_free(raw_output);

        /* Print the trimmed output text. */
        g_fprintf(stderr, "%s\n", output);
        fflush(stderr);
        g_free(output);

        return SR_OK;
}

/** @private */
SR_PRIV int sr_log(int loglevel, const char *format, ...)
{
        int ret;
        va_list args;

        /* Only output messages of at least the selected loglevel(s). */
        if (loglevel > cur_loglevel)
                return SR_OK;

        /* Silently succeed when no logging callback is registered. */
        if (!sr_log_cb)
                return SR_OK;

        va_start(args, format);
        ret = sr_log_cb(sr_log_cb_data, loglevel, format, args);
        va_end(args);

        return ret;
}

/** @} */