os: log: add syslog support

Add support for logging to syslog.

Signed-off-by: Enrico Weigelt, metux IT consult <info@metux.net>

hw/xnest/Init.c

@@ -24,6 +24,7 @@ is" without express or implied warranty.
 #include "mi/mi_priv.h"
 #include "miext/extinit_priv.h"
 #include "os/ddx_priv.h"
+#include "os/log_priv.h"
 #include "os/osdep.h"
 
 #include "screenint.h"

os/log.c

@@ -88,6 +88,10 @@ OR PERFORMANCE OF THIS SOFTWARE.
 #include <X11/Xfuncproto.h>
 #include <X11/Xos.h>
 
+#ifdef CONFIG_SYSLOG
+#include <syslog.h>
+#endif
+
 #include "dix/dix_priv.h"
 #include "dix/input_priv.h"
 #include "os/audit.h"
@@ -110,11 +114,16 @@ OR PERFORMANCE OF THIS SOFTWARE.
 /* Default logging parameters. */
 #define DEFAULT_LOG_VERBOSITY		0
 #define DEFAULT_LOG_FILE_VERBOSITY	3
+#define DEFAULT_SYSLOG_VERBOSITY	0
 
 static int logFileFd = -1;
 Bool xorgLogSync = FALSE;
 int xorgLogVerbosity = DEFAULT_LOG_VERBOSITY;
 int xorgLogFileVerbosity = DEFAULT_LOG_FILE_VERBOSITY;
+#ifdef CONFIG_SYSLOG
+int xorgSyslogVerbosity = DEFAULT_SYSLOG_VERBOSITY;
+const char *xorgSyslogIdent = "X";
+#endif
 
 /* Buffer to information logged before the log file is opened. */
 static char *saveBuffer = NULL;
@@ -206,6 +215,18 @@ static inline void doLogSync(void) {
 #endif
 }
 
+static void initSyslog(void) {
+#ifdef CONFIG_SYSLOG
+    char buffer[4096];
+    strcpy(buffer, xorgSyslogIdent);
+
+    snprintf(buffer, sizeof(buffer), "%s :%s", xorgSyslogIdent, (display ? display : "<>"));
+
+    /* initialize syslog */
+    openlog(buffer, LOG_PID, LOG_LOCAL1);
+#endif
+}
+
 /*
  * LogInit is called to start logging to a file.  It is also called (with
  * NULL arguments) when logging to a file is not wanted.  It must always be
@@ -263,6 +284,7 @@ LogInit(const char *fname, const char *backup)
     }
     needBuffer = FALSE;
 
+    initSyslog();
     return logFileName;
 }
 
@@ -294,6 +316,7 @@ LogSetDisplay(void)
         free(saved_log_fname);
         free(saved_log_backup);
     }
+    initSyslog();
 }
 
 void
@@ -528,6 +551,19 @@ vpnprintf(char *string, int size_in, const char *f, va_list args)
     return s_idx;
 }
 
+static void
+LogSyslogWrite(int verb, const char *buf, size_t len, Bool end_line) {
+#ifdef CONFIG_SYSLOG
+    if (inSignalContext) // syslog() ins't signal-safe yet :(
+        return;          // shall we try syslog(2) syscall instead ?
+
+    if (verb >= 0 && xorgSyslogVerbosity < verb)
+        return;
+
+    syslog(LOG_PID, "%.*s", (int)len, buf);
+#endif
+}
+
 /* This function does the actual log message writes. It must be signal safe.
  * When attempting to call non-signal-safe functions, guard them with a check
  * of the inSignalContext global variable. */
@@ -537,6 +573,8 @@ LogSWrite(int verb, const char *buf, size_t len, Bool end_line)
     static Bool newline = TRUE;
     int ret;
 
+    LogSyslogWrite(verb, buf, len, end_line);
+
     if (verb < 0 || xorgLogVerbosity >= verb)
         ret = write(2, buf, len);
 

os/log_priv.h

@@ -72,4 +72,21 @@ extern int xorgLogFileVerbosity;
  */
 extern Bool xorgLogSync;
 
+/**
+ * @brief syslog verbosity
+ *
+ * The verbosity level of logging to syslog. All messages with
+ * verbosity level below this one will be sent to local syslog daemon.
+ */
+extern int xorgSyslogVerbosity;
+
+/**
+ * @brief syslog identifier
+ *
+ * The identifier prefix used for syslog logging.
+ * Per default will be filled with basename(argv[0]). DDX'es can override
+ * this before calling LogInit()
+ */
+extern const char *xorgSyslogIdent;
+
 #endif /* __XORG_OS_LOGGING_H */

os/meson.build

@@ -23,6 +23,8 @@ srcs_os = [
     'log.c',
 ]
 
+conf_data.set('CONFIG_SYSLOG', cc.has_header('syslog.h') ? '1' : false)
+
 # Wrapper code for missing C library functions. Note that conf_data contains either '1' or false.
 srcs_libc = []
 if conf_data.get('HAVE_REALLOCARRAY').to_int() == 0

os/utils.c

@@ -67,6 +67,8 @@ OR PERFORMANCE OF THIS SOFTWARE.
 #define TRANS_REOPEN
 #include <X11/Xtrans/Xtrans.h>
 
+#include <libgen.h>
+
 #include "input.h"
 #include "dixfont.h"
 #include <X11/fonts/libxfont2.h>
@@ -420,6 +422,12 @@ ProcessCommandLine(int argc, char *argv[])
     }
     SeatId = getenv("XDG_SEAT");
 
+#ifdef CONFIG_SYSLOG
+    xorgSyslogIdent = getenv("SYSLOG_IDENT");
+    if (!xorgSyslogIdent)
+        xorgSyslogIdent = strdup(basename(argv[0]));
+#endif
+
     for (i = 1; i < argc; i++) {
         /* call ddx first, so it can peek/override if it wants */
         if ((skip = ddxProcessArgument(argc, argv, i))) {
@@ -756,6 +764,9 @@ ProcessCommandLine(int argc, char *argv[])
             else
                 UseMsg();
         }
+#ifdef CONFIG_SYSLOG
+        else if (ProcessCmdLineMultiInt(argc, argv, &i, "-syslogverbose", &xorgSyslogVerbosity));
+#endif
         else {
             ErrorF("Unrecognized option: %s\n", argv[i]);
             UseMsg();