Trim all zeros from input

If the buffer only contains zeros, return 0.

Author: abolz

include/rapidjson/internal/strtod.h

@@ -242,17 +242,21 @@ inline double StrtodFullPrecision(double d, int p, const char* decimals, size_t
     RAPIDJSON_ASSERT(dExp <= INT_MAX - dLen);
 
     // Trim leading zeros
-    while (*decimals == '0' && dLen > 1) {
+    while (dLen > 0 && *decimals == '0') {
         dLen--;
         decimals++;
     }
 
     // Trim trailing zeros
-    while (decimals[dLen - 1] == '0' && dLen > 1) {
+    while (dLen > 0 && decimals[dLen - 1] == '0') {
         dLen--;
         dExp++;
     }
 
+    if (dLen == 0) { // Buffer only contains zeros.
+        return 0.0;
+    }
+
     // Trim right-most digits
     const int kMaxDecimalDigit = 780;
     if (dLen > kMaxDecimalDigit) {