client: add CSV output mode

Add a new option (-c) to chronyc to enable printing of reports in a
column-separated values (CSV) format. IP addresses will not be resolved
to hostnames, time will be printed as number of seconds since the epoch
and values in seconds will not be converted to other units.

client.c

@@ -70,6 +70,8 @@ static int on_terminal = 0;
 
 static int no_dns = 0;
 
+static int csv_mode = 0;
+
 /* ================================================== */
 /* Log a message. This is a minimalistic replacement of the logging.c
    implementation to avoid linking with it and other modules. */
@@ -1667,6 +1669,9 @@ print_header(const char *header)
 {
   int len;
 
+  if (csv_mode)
+    return;
+
   printf("%s\n", header);
 
   len = strlen(header);
@@ -1687,7 +1692,7 @@ print_report(const char *format, ...)
 {
   char buf[256];
   va_list ap;
-  int i, sign, width, prec, spec;
+  int i, field, sign, width, prec, spec;
   const char *string;
   unsigned long long_uinteger;
   unsigned int uinteger;
@@ -1698,7 +1703,9 @@ print_report(const char *format, ...)
 
   va_start(ap, format);
 
-  while (1) {
+  for (field = 0; ; field++) {
+    /* Search for text between format specifiers and print it
+       if not in the CSV mode */
     for (i = 0; i < sizeof (buf) && format[i] != '%' && format[i] != '\0'; i++)
       buf[i] = format[i];
 
@@ -1706,7 +1713,9 @@ print_report(const char *format, ...)
       break;
 
     buf[i] = '\0';
-    printf("%s", buf);
+
+    if (!csv_mode)
+      printf("%s", buf);
 
     if (format[i] == '\0' || format[i + 1] == '\0')
       break;
@@ -1738,6 +1747,36 @@ print_report(const char *format, ...)
     spec = *format;
     format++;
 
+    /* Disable human-readable formatting in the CSV mode */
+    if (csv_mode) {
+      sign = width = 0;
+
+      if (field > 0)
+        printf(",");
+
+      switch (spec) {
+        case 'C':
+          spec = 'd';
+          break;
+        case 'F':
+        case 'P':
+          prec = 3;
+          spec = 'f';
+          break;
+        case 'O':
+        case 'S':
+          prec = 9;
+          spec = 'f';
+          break;
+        case 'I':
+          spec = 'U';
+          break;
+        case 'T':
+          spec = 'V';
+          break;
+      }
+    }
+
     switch (spec) {
       case 'C': /* clientlog interval */
         integer = va_arg(ap, int);
@@ -1826,6 +1865,9 @@ print_report(const char *format, ...)
     assert(0);
 
   va_end(ap);
+
+  if (csv_mode)
+    printf("\n");
 }
 
 /* ================================================== */
@@ -1835,6 +1877,9 @@ print_info_field(const char *format, ...)
 {
   va_list ap;
 
+  if (csv_mode)
+    return;
+
   va_start(ap, format);
   vprintf(format, ap);
   va_end(ap);
@@ -1848,7 +1893,7 @@ format_name(char *buf, int size, int trunc_dns, int ref, uint32_t ref_id,
 {
   if (ref) {
     snprintf(buf, size, "%s", UTI_RefidToString(ref_id));
-  } else if (no_dns) {
+  } else if (no_dns || csv_mode) {
     snprintf(buf, size, "%s", UTI_IPToString(ip_addr));
   } else {
     DNS_IPAddress2Name(ip_addr, buf, size);
@@ -2885,6 +2930,8 @@ main(int argc, char **argv)
       /* For compatibility */
     } else if (!strcmp(*argv, "-a")) {
       /* For compatibility */
+    } else if (!strcmp(*argv, "-c")) {
+      csv_mode = 1;
     } else if (!strcmp(*argv, "-d")) {
       log_debug_enabled = 1;
     } else if (!strcmp(*argv, "-m")) {
@@ -2900,7 +2947,7 @@ main(int argc, char **argv)
       return 0;
     } else if (!strncmp(*argv, "-", 1)) {
       LOG(LOGS_ERR, LOGF_Client,
-          "Usage: %s [-h HOST] [-p PORT] [-n] [-d] [-4|-6] [-m] [COMMAND]",
+          "Usage: %s [-h HOST] [-p PORT] [-n] [-c] [-d] [-4|-6] [-m] [COMMAND]",
           progname);
       return 1;
     } else {