mingw: implement syslog

Syslog does not usually exist on Windows, so implement our own using
Window's ReportEvent mechanism.

Strings containing "%1" gets expanded into them selves by ReportEvent,
resulting in an unreadable string. "%2" and above is not a problem.
Unfortunately, on Windows an IPv6 address can contain "%1", so expand
"%1" to "% 1" before reporting. "%%1" is also a problem for ReportEvent,
but that string cannot occur in an IPv6 address.

Signed-off-by: Mike Pape <dotzenlabs@gmail.com>
Signed-off-by: Erik Faye-Lund <kusmabite@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 72 insertions, 0 deletions

diff --git a/compat/win32/syslog.c b/compat/win32/syslog.c
new file mode 100644
index 0000000..42b95a9
--- /dev/null
+++ b/compat/win32/syslog.c
@@ -0,0 +1,72 @@
+#include "../../git-compat-util.h"
+#include "../../strbuf.h"
+
+static HANDLE ms_eventlog;
+
+void openlog(const char *ident, int logopt, int facility)
+{
+	if (ms_eventlog)
+		return;
+
+	ms_eventlog = RegisterEventSourceA(NULL, ident);
+
+	if (!ms_eventlog)
+		warning("RegisterEventSource() failed: %lu", GetLastError());
+}
+
+void syslog(int priority, const char *fmt, ...)
+{
+	struct strbuf sb = STRBUF_INIT;
+	struct strbuf_expand_dict_entry dict[] = {
+		{"1", "% 1"},
+		{NULL, NULL}
+	};
+	WORD logtype;
+	char *str;
+	int str_len;
+	va_list ap;
+
+	if (!ms_eventlog)
+		return;
+
+	va_start(ap, fmt);
+	str_len = vsnprintf(NULL, 0, fmt, ap);
+	va_end(ap);
+
+	if (str_len < 0) {
+		warning("vsnprintf failed: '%s'", strerror(errno));
+		return;
+	}
+
+	str = malloc(str_len + 1);
+	va_start(ap, fmt);
+	vsnprintf(str, str_len + 1, fmt, ap);
+	va_end(ap);
+	strbuf_expand(&sb, str, strbuf_expand_dict_cb, &dict);
+	free(str);
+
+	switch (priority) {
+	case LOG_EMERG:
+	case LOG_ALERT:
+	case LOG_CRIT:
+	case LOG_ERR:
+		logtype = EVENTLOG_ERROR_TYPE;
+		break;
+
+	case LOG_WARNING:
+		logtype = EVENTLOG_WARNING_TYPE;
+		break;
+
+	case LOG_NOTICE:
+	case LOG_INFO:
+	case LOG_DEBUG:
+	default:
+		logtype = EVENTLOG_INFORMATION_TYPE;
+		break;
+	}
+
+	ReportEventA(ms_eventlog, logtype, 0, 0, NULL, 1, 0,
+	    (const char **)&sb.buf, NULL);
+
+	strbuf_release(&sb);
+}