[GitHub] [incubator-doris] morningman opened a new issue #1018: FloatToBuffer may core in some case

[GitBox <gi...@apache.org>]

morningman opened a new issue #1018: FloatToBuffer may core in some case
URL: https://github.com/apache/incubator-doris/issues/1018
 
 
   **Describe the bug**
   in `src/gutil/strings/numbers.cc`
   
   ```
   1310 int FloatToBuffer(float value, int width, char *buffer) {
   1311   // FLT_DIG is 6 for IEEE-754 floats, which are used on almost all
   1312   // platforms these days.  Just in case some system exists where FLT_DIG
   1313   // is significantly larger -- and risks overflowing our buffer -- we have
   1314   // this assert.
   1315   COMPILE_ASSERT(FLT_DIG < 10, FLT_DIG_is_too_big);
   1316
   1317   int snprintf_result =
   1318     snprintf(buffer, width, "%.*g", FLT_DIG, value);
   1319
   1320   // The snprintf should never overflow because the buffer is significantly
   1321   // larger than the precision we asked for.
   1322   DCHECK(snprintf_result > 0 && snprintf_result < width);
   1323
   1324   float parsed_value;
   1325   if (!safe_strtof(buffer, &parsed_value) || parsed_value != value) {
   1326     snprintf_result =
   1327       snprintf(buffer, width, "%.*g", FLT_DIG+2, value);
   1328
   1329     // Should never overflow; see above.
   1330     DCHECK(snprintf_result > 0 && snprintf_result < width);
   1331   }
   1332
   1333   return snprintf_result;
   1334 }
   ```
   
   line 1325: `parsed_value != value` may return true even if 2 values are some(because they are float)
   
   after line 1327, the snprintf_result = 14, which equal to width, such causing DCHECK failed.
   
   In gutils, the width here is 24, far larger than 14. So we just increase the width value to avoid this problem
   

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