[flang-commits] [flang] ea5b205 - [flang][runtime] Don't crash after surviving internal output overflow

[Peter Klausler via flang-commits]

Author: Peter Klausler
Date: 2022-06-04T08:47:13-07:00
New Revision: ea5b205bb89508613ee0a57ccbfd6924c4a9586b

URL: https://github.com/llvm/llvm-project/commit/ea5b205bb89508613ee0a57ccbfd6924c4a9586b
DIFF: https://github.com/llvm/llvm-project/commit/ea5b205bb89508613ee0a57ccbfd6924c4a9586b.diff

LOG: [flang][runtime] Don't crash after surviving internal output overflow

After the program has survived its attempt to overflow the output buffer
with an internal WRITE using ERR=, IOSTAT=, &/or IOMSG=, don't crash
by accidentally blank-filling the next record that usually doesn't exist.

Differential Revision: https://reviews.llvm.org/D127024

Added: 
    

Modified: 
    flang/runtime/internal-unit.cpp

Removed: 
    


################################################################################
diff  --git a/flang/runtime/internal-unit.cpp b/flang/runtime/internal-unit.cpp
index 39a8e4b2c9c4..9f1d6c572c32 100644
--- a/flang/runtime/internal-unit.cpp
+++ b/flang/runtime/internal-unit.cpp
@@ -41,7 +41,9 @@ template <Direction DIR> void InternalDescriptorUnit<DIR>::EndIoStatement() {
   if constexpr (DIR == Direction::Output) {
     // Clear the remainder of the current record if anything was written
     // to it, or if it is the only record.
-    if (endfileRecordNumber.value_or(-1) == 2 || furthestPositionInRecord > 0) {
+    auto end{endfileRecordNumber.value_or(0)};
+    if (currentRecordNumber < end &&
+        (end == 2 || furthestPositionInRecord > 0)) {
       BlankFillOutputRecord();
     }
   }