Introduce memory options 'unit' and 'decimals'

Previously the format placeholders were auto-converted to the maximum possible
unit, e.g. /proc/meminfo reports MemTotal of 16307104kB which will get
converted to 15.6GiB. It is now possible to specifiy the target unit, e.g. Mi,
which will be used for the conversion - in the example it would lead to
15924.9MiB.

The resulting number can now be further formatted via the decimal option. It
allows to specify the number of decimals to use, e.g. 15.6GiB vs. 15GiB or
15924.9MiB vs. 15925MiB.

1 files changed, 12 insertions, 8 deletions

diff --git a/src/print_mem.c b/src/print_mem.c
index 413067e..c291497 100644
--- a/src/print_mem.c
+++ b/src/print_mem.c
@@ -22,15 +22,19 @@ static const char memoryfile_linux[] = "/proc/meminfo";
  * Prints the given amount of bytes in a human readable manner.
  *
  */
-static int print_bytes_human(char *outwalk, uint64_t bytes) {
+static int print_bytes_human(char *outwalk, uint64_t bytes, const char *unit, const int decimals) {
     double size = bytes;
     int exponent = 0;
     int bin_base = BINARY_BASE;
     while (size >= bin_base && exponent < MAX_EXPONENT) {
+        if (strcasecmp(unit, iec_symbols[exponent]) == 0) {
+            break;
+        }
+
         size /= bin_base;
         exponent += 1;
     }
-    return sprintf(outwalk, "%.1f %sB", size, iec_symbols[exponent]);
+    return sprintf(outwalk, "%.*f %sB", decimals, size, iec_symbols[exponent]);
 }
 #endif
 
@@ -80,7 +84,7 @@ static long memory_absolute(const long mem_total, const char *size) {
 }
 #endif
 
-void print_memory(yajl_gen json_gen, char *buffer, const char *format, const char *format_degraded, const char *threshold_degraded, const char *threshold_critical, const char *memory_used_method) {
+void print_memory(yajl_gen json_gen, char *buffer, const char *format, const char *format_degraded, const char *threshold_degraded, const char *threshold_critical, const char *memory_used_method, const char *unit, const int decimals) {
     char *outwalk = buffer;
 
 #if defined(linux)
@@ -169,23 +173,23 @@ void print_memory(yajl_gen json_gen, char *buffer, const char *format, const cha
             *(outwalk++) = *walk;
 
         } else if (BEGINS_WITH(walk + 1, "total")) {
-            outwalk += print_bytes_human(outwalk, ram_total);
+            outwalk += print_bytes_human(outwalk, ram_total, unit, decimals);
             walk += strlen("total");
 
         } else if (BEGINS_WITH(walk + 1, "used")) {
-            outwalk += print_bytes_human(outwalk, ram_used);
+            outwalk += print_bytes_human(outwalk, ram_used, unit, decimals);
             walk += strlen("used");
 
         } else if (BEGINS_WITH(walk + 1, "free")) {
-            outwalk += print_bytes_human(outwalk, ram_free);
+            outwalk += print_bytes_human(outwalk, ram_free, unit, decimals);
             walk += strlen("free");
 
         } else if (BEGINS_WITH(walk + 1, "available")) {
-            outwalk += print_bytes_human(outwalk, ram_available);
+            outwalk += print_bytes_human(outwalk, ram_available, unit, decimals);
             walk += strlen("available");
 
         } else if (BEGINS_WITH(walk + 1, "shared")) {
-            outwalk += print_bytes_human(outwalk, ram_shared);
+            outwalk += print_bytes_human(outwalk, ram_shared, unit, decimals);
             walk += strlen("shared");
 
         } else if (BEGINS_WITH(walk + 1, "percentage_free")) {