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gmessages: Add colour output support to structured log messages

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If outputting to a terminal which supports coloured output (rather than,
for example, redirecting to a file). This is only enabled for structured
log messages, where colour output support can be tested. It is not
enabled for non-structured log messages.

https://bugzilla.gnome.org/show_bug.cgi?id=744456
This commit is contained in:
Philip Withnall 2016-03-15 10:47:39 +00:00 committed by Matthias Clasen
parent 052eaf24f7
commit 37ef301684
2 changed files with 108 additions and 18 deletions
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121
glib/gmessages.c
View File

@ -82,7 +82,7 @@
* its log writer function so that, for example, it can use the correct
* server connection to submit logs to, that user data can be passed as a
* zero-length #GLogField to g_log_structured_array().
* * Colour output needed to be supported on the terminal, to make reading
* * Color output needed to be supported on the terminal, to make reading
* through logs easier.
*/
@ -969,48 +969,58 @@ format_unsigned (gchar *buf,
/* these are filtered by G_MESSAGES_DEBUG by the default log handler */
#define INFO_LEVELS (G_LOG_LEVEL_INFO | G_LOG_LEVEL_DEBUG)
static const gchar *log_level_to_color (GLogLevelFlags log_level,
gboolean use_color);
static const gchar *color_reset (gboolean use_color);
static FILE *
mklevel_prefix (gchar level_prefix[STRING_BUFFER_SIZE],
GLogLevelFlags log_level)
GLogLevelFlags log_level,
gboolean use_color)
{
gboolean to_stdout = TRUE;
/* we may not call _any_ GLib functions here */
strcpy (level_prefix, log_level_to_color (log_level, use_color));
switch (log_level & G_LOG_LEVEL_MASK)
{
case G_LOG_LEVEL_ERROR:
strcpy (level_prefix, "ERROR");
strcat (level_prefix, "ERROR");
to_stdout = FALSE;
break;
case G_LOG_LEVEL_CRITICAL:
strcpy (level_prefix, "CRITICAL");
strcat (level_prefix, "CRITICAL");
to_stdout = FALSE;
break;
case G_LOG_LEVEL_WARNING:
strcpy (level_prefix, "WARNING");
strcat (level_prefix, "WARNING");
to_stdout = FALSE;
break;
case G_LOG_LEVEL_MESSAGE:
strcpy (level_prefix, "Message");
strcat (level_prefix, "Message");
to_stdout = FALSE;
break;
case G_LOG_LEVEL_INFO:
strcpy (level_prefix, "INFO");
strcat (level_prefix, "INFO");
break;
case G_LOG_LEVEL_DEBUG:
strcpy (level_prefix, "DEBUG");
strcat (level_prefix, "DEBUG");
break;
default:
if (log_level)
{
strcpy (level_prefix, "LOG-");
strcat (level_prefix, "LOG-");
format_unsigned (level_prefix + 4, log_level & G_LOG_LEVEL_MASK, 16);
}
else
strcpy (level_prefix, "LOG");
strcat (level_prefix, "LOG");
break;
}
strcat (level_prefix, color_reset (use_color));
if (log_level & G_LOG_FLAG_RECURSION)
strcat (level_prefix, " (recursed)");
if (log_level & ALERT_LEVELS)
@ -1097,7 +1107,7 @@ g_logv (const gchar *log_domain,
gchar level_prefix[STRING_BUFFER_SIZE];
gchar *expected_message;
mklevel_prefix (level_prefix, expected->log_level);
mklevel_prefix (level_prefix, expected->log_level, FALSE);
expected_message = g_strdup_printf ("Did not see expected message %s-%s: %s",
expected->log_domain ? expected->log_domain : "**",
level_prefix, expected->pattern);
@ -1242,6 +1252,43 @@ log_level_to_file (GLogLevelFlags log_level)
return stdout;
}
static const gchar *
log_level_to_color (GLogLevelFlags log_level,
gboolean use_color)
{
/* we may not call _any_ GLib functions here */
if (!use_color)
return "";
if (log_level & G_LOG_LEVEL_ERROR)
return "\033[1;31m";
else if (log_level & G_LOG_LEVEL_CRITICAL)
return "\033[1;35m";
else if (log_level & G_LOG_LEVEL_WARNING)
return "\033[1;33m";
else if (log_level & G_LOG_LEVEL_MESSAGE)
return "\033[1;32m";
else if (log_level & G_LOG_LEVEL_INFO)
return "\033[1;32m";
else if (log_level & G_LOG_LEVEL_DEBUG)
return "\033[1;32m";
/* No color for custom log levels. */
return "";
}
static const gchar *
color_reset (gboolean use_color)
{
/* we may not call _any_ GLib functions here */
if (!use_color)
return "";
return "\033[0m";
}
/**
* g_log_structured:
* @log_domain: log domain, usually %G_LOG_DOMAIN
@ -1505,6 +1552,39 @@ g_log_set_writer_func (GLogWriterFunc func,
g_mutex_unlock (&g_messages_lock);
}
/**
* g_log_writer_supports_color:
* @output_fd: output file descriptor to check
*
* Check whether the given @output_fd file descriptor supports ANSI color
* escape sequences. If so, they can safely be used when formatting log
* messages.
*
* Returns: %TRUE if ANSI color escapes are supported, %FALSE otherwise
* Since: 2.50
*/
gboolean
g_log_writer_supports_color (gint output_fd)
{
g_return_val_if_fail (output_fd >= 0, FALSE);
/* FIXME: This check could easily be expanded in future to be more robust
* against different types of terminal, which still vary in their color
* support. cmd.exe on Windows, for example, does not support ANSI colors;
* but bash on Windows does.
*
* On UNIX systems, we probably want to use the functions from terminfo to
* work out whether colors are supported.
*
* Some examples:
* - https://github.com/chalk/supports-color/blob/9434c93918301a6b47faa01999482adfbf1b715c/index.js#L61
* - http://stackoverflow.com/questions/16755142/how-to-make-win32-console-recognize-ansi-vt100-escape-sequences
* - http://blog.mmediasys.com/2010/11/24/we-all-love-colors/
* - http://unix.stackexchange.com/questions/198794/where-does-the-term-environment-variable-default-get-set
*/
return isatty (output_fd);
}
/**
* g_log_writer_is_journald:
* @output_fd: output file descriptor to check
@ -1563,6 +1643,8 @@ static void escape_string (GString *string);
* @fields: (array length=n_fields): key–value pairs of structured data forming
* the log message
* @n_fields: number of elements in the @fields array
* @use_color: %TRUE to use ANSI color escape sequences when formatting the
* message, %FALSE to not
*
* Format a structured log message as a string suitable for outputting to the
* terminal (or elsewhere). This will include the values of all fields it knows
@ -1581,7 +1663,8 @@ static void escape_string (GString *string);
gchar *
g_log_writer_format_fields (GLogLevelFlags log_level,
const GLogField *fields,
gsize n_fields)
gsize n_fields,
gboolean use_color)
{
gsize i;
const gchar *message = NULL;
@ -1601,7 +1684,7 @@ g_log_writer_format_fields (GLogLevelFlags log_level,
}
/* Format things. */
mklevel_prefix (level_prefix, log_level);
mklevel_prefix (level_prefix, log_level, use_color);
gstring = g_string_new (NULL);
if (log_level & ALERT_LEVELS)
@ -1751,6 +1834,9 @@ g_log_writer_journald (GLogLevelFlags log_level,
* which are understood by this function are included in the formatted string
* which is printed.
*
* If the output stream supports ANSI color escape sequences, they will be used
* in the output.
*
* A trailing new-line character is added to the log message when it is printed.
*
* This is suitable for use as a #GLogWriterFunc.
@ -1771,7 +1857,8 @@ g_log_writer_standard_streams (GLogLevelFlags log_level,
g_return_val_if_fail (n_fields > 0, G_LOG_WRITER_UNHANDLED);
stream = log_level_to_file (log_level);
out = g_log_writer_format_fields (log_level, fields, n_fields);
out = g_log_writer_format_fields (log_level, fields, n_fields,
g_log_writer_supports_color (fileno (stream)));
_g_fprintf (stream, "%s\n", out);
g_free (out);
@ -2081,7 +2168,7 @@ g_test_assert_expected_messages_internal (const char *domain,
expected = expected_messages->data;
mklevel_prefix (level_prefix, expected->log_level);
mklevel_prefix (level_prefix, expected->log_level, FALSE);
message = g_strdup_printf ("Did not see expected message %s-%s: %s",
expected->log_domain ? expected->log_domain : "**",
level_prefix, expected->pattern);
@ -2121,7 +2208,7 @@ _g_log_fallback_handler (const gchar *log_domain,
* the process ID unconditionally however.
*/
stream = mklevel_prefix (level_prefix, log_level);
stream = mklevel_prefix (level_prefix, log_level, FALSE);
if (!message)
message = "(NULL) message";
@ -2269,7 +2356,7 @@ g_log_default_handler (const gchar *log_domain,
return;
}
stream = mklevel_prefix (level_prefix, log_level);
stream = mklevel_prefix (level_prefix, log_level, FALSE);
gstring = g_string_new (NULL);
if (log_level & ALERT_LEVELS)

5
glib/gmessages.h
View File

@ -204,13 +204,16 @@ void g_log_set_writer_func (GLogWriterFunc func,
gpointer user_data,
GDestroyNotify user_data_free);
GLIB_AVAILABLE_IN_2_50
gboolean g_log_writer_supports_color (gint output_fd);
GLIB_AVAILABLE_IN_2_50
gboolean g_log_writer_is_journald (gint output_fd);
GLIB_AVAILABLE_IN_2_50
gchar *g_log_writer_format_fields (GLogLevelFlags log_level,
const GLogField *fields,
gsize n_fields);
gsize n_fields,
gboolean use_color);
GLIB_AVAILABLE_IN_2_50
GLogWriterOutput g_log_writer_journald (GLogLevelFlags log_level,