Fix num2str() output when modulo != -1U

[fio.git] / lib / num2str.c

diff --git a/lib/num2str.c b/lib/num2str.c
index 448d3ff88b00cbe41c3fcbeb21665d19496cf2f7..8d0884132fe4ce5a3f2aace08fe26ef9eb5b28bf 100644 (file)
--- a/lib/num2str.c
+++ b/lib/num2str.c
@@ -10,7 +10,7 @@
 /**
  * num2str() - Cheesy number->string conversion, complete with carry rounding error.
  * @num: quantity (e.g., number of blocks, bytes or bits)
- * @maxlen: max number of digits in the output string (not counting prefix and units)
+ * @maxlen: max number of digits in the output string (not counting prefix and units, but counting .)
  * @base: multiplier for num (e.g., if num represents Ki, use 1024)
  * @pow2: select unit prefix - 0=power-of-10 decimal SI, nonzero=power-of-2 binary IEC
  * @units: select units - N2S_* macros defined in num2str.h
@@ -23,9 +23,9 @@ char *num2str(uint64_t num, int maxlen, int base, int pow2, int units)
        const char **unitprefix;
        const char *unitstr[] = { "", "/s", "B", "bit", "B/s", "bit/s" };
        const unsigned int thousand[] = { 1000, 1024 };
-       unsigned int modulo, decimals;
+       unsigned int modulo;
        int unit_index = 0, post_index, carry = 0;
-       char tmp[32];
+       char tmp[32], fmt[32];
        char *buf;
 
        compiletime_assert(sizeof(sistr) == sizeof(iecstr), "unit prefix arrays must be identical sizes");
@@ -62,6 +62,9 @@ char *num2str(uint64_t num, int maxlen, int base, int pow2, int units)
                break;
        }
 
+       /*
+        * Divide by K/Ki until string length of num <= maxlen.
+        */
        modulo = -1U;
        while (post_index < sizeof(sistr)) {
                sprintf(tmp, "%llu", (unsigned long long) num);
@@ -74,6 +77,9 @@ char *num2str(uint64_t num, int maxlen, int base, int pow2, int units)
                post_index++;
        }
 
+       /*
+        * If no modulo, then we're done.
+        */
        if (modulo == -1U) {
 done:
                if (post_index >= ARRAY_SIZE(sistr))
@@ -84,23 +90,25 @@ done:
                return buf;
        }
 
+       /*
+        * If no room for decimals, then we're done.
+        */
        sprintf(tmp, "%llu", (unsigned long long) num);
-       decimals = maxlen - strlen(tmp);
-       if ((int)decimals <= 1) {
+       if ((int)(maxlen - strlen(tmp)) <= 1) {
                if (carry)
                        num++;
                goto done;
        }
 
-       do {
-               sprintf(tmp, "%u", modulo);
-               if (strlen(tmp) <= decimals - 1)
-                       break;
-
-               modulo = (modulo + 9) / 10;
-       } while (1);
+       /*
+        * Fill in everything and return the result.
+        */
+       assert(maxlen - strlen(tmp) - 1 > 0);
+       assert(modulo < thousand[!!pow2]);
+       sprintf(fmt, "%%.%df", (int)(maxlen - strlen(tmp) - 1));
+       sprintf(tmp, fmt, (double)modulo / (double)thousand[!!pow2]);
 
-       sprintf(buf, "%llu.%u%s%s", (unsigned long long) num, modulo,
+       sprintf(buf, "%llu.%s%s%s", (unsigned long long) num, &tmp[2],
                        unitprefix[post_index], unitstr[unit_index]);
        return buf;
 }