add vsyslog() for systems without it.

lib/util/vsyslog.c

@@ -0,0 +1,68 @@
+/*
+ * Copyright (c) 2016 Todd C. Miller <Todd.Miller@courtesan.com>
+ *
+ * Permission to use, copy, modify, and distribute this software for any
+ * purpose with or without fee is hereby granted, provided that the above
+ * copyright notice and this permission notice appear in all copies.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+ * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+ * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+ * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+ * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+ * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+ * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include <config.h>
+
+#include <errno.h>
+#include <stdarg.h>
+#include <stdio.h>
+#include <stdlib.h>
+#ifdef HAVE_STRING_H
+# include <string.h>
+#endif /* HAVE_STRING_H */
+#ifdef HAVE_STRINGS_H
+# include <strings.h>
+#endif /* HAVE_STRINGS_H */
+#include <syslog.h>
+
+#include "sudo_compat.h"
+
+#ifndef HAVE_VSYSLOG
+void
+sudo_vsyslog(int pri, const char *fmt, va_list ap)
+{
+    int saved_errno = errno;
+    char *buf, *cp, *ep, new_fmt[1024];
+    size_t len;
+
+    /* Rewrite fmt, replacing %m with an errno string. */
+    for (cp = new_fmt, ep = new_fmt + sizeof(new_fmt); *fmt != '\0'; fmt++) {
+	if (fmt[0] == '%' && fmt[1] == 'm') {
+	    fmt++;
+	    len = strlcpy(cp, strerror(saved_errno), (ep - cp));
+	    if (len >= (size_t)(ep - cp))
+		len = (size_t)(ep - cp) - 1;
+	    cp += len;
+	    break;
+	} else {
+	    if (fmt[0] == '%' && fmt[1] == '%') {
+		    fmt++;
+		    if (cp < ep - 1)
+			*cp++ = '%';
+	    }
+	    if (cp < ep - 1)
+		*cp++ = *fmt;
+	}
+    }
+    *cp = '\0';
+
+    /* Format message and log it. */
+    if (vasprintf(&buf, new_fmt, ap) != -1) {
+	syslog(pri, "%s", buf);
+	free(buf);
+    }
+}
+#endif /* HAVE_VSYSLOG */