Fix #1473: warn when fclose() is used as a while loop condition#8444
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francois-berder wants to merge 3 commits intocppcheck-opensource:mainfrom
Open
Fix #1473: warn when fclose() is used as a while loop condition#8444francois-berder wants to merge 3 commits intocppcheck-opensource:mainfrom
francois-berder wants to merge 3 commits intocppcheck-opensource:mainfrom
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…oop condition Using fclose() as a while loop condition closes the file on every iteration and operates on an already-closed file handle from the second iteration onward. Signed-off-by: Francois Berder <fberder@outlook.fr>
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danmar
reviewed
Apr 25, 2026
…while loop condition
…d as a while loop condition
danmar
reviewed
Apr 28, 2026
| const Token* bodyEnd = nullptr; | ||
| const Token* bodyStart = nullptr; | ||
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| if (Token::simpleMatch(loopTok->previous(), "}")) { // Handle do-while loops |
Collaborator
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it doesn't have to be a do-while when previous token is a "}".
| operation = Filepointer::Operation::CLOSE; | ||
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| // #1473 Check if fclose is in a while loop condition | ||
| if (fileTok) { |
Collaborator
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the old code does not use AST so it doesn't handle well when the parameter is some expression.
imagine:
while (i < 10 && fclose(f[i++]) {}
It is ugly code. I suggest you check that fileTok is just a simple variable token.
| } | ||
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| // Do not trigger a warning if the loop always exits or if the file is opened again in the loop. | ||
| if (!isReturnScope(bodyEnd, mSettings->library) && Token::findmatch(bodyStart, "%var% = fopen|freopen", bodyEnd, fileTok->varId()) == nullptr) |
Collaborator
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if there is any f = some_function(); in the loop we shouldn't warn. I suggest:
Suggested change
| if (!isReturnScope(bodyEnd, mSettings->library) && Token::findmatch(bodyStart, "%var% = fopen|freopen", bodyEnd, fileTok->varId()) == nullptr) | |
| if (!isReturnScope(bodyEnd, mSettings->library) && Token::findmatch(bodyStart, "%var% =", bodyEnd, fileTok->varId()) == nullptr) |
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Using fclose() as a while loop condition closes the file on every iteration and operates on an already-closed file handle from the second iteration onward.