From 9659a127a34402d02637e0f52bfab9ee7543fb5b Mon Sep 17 00:00:00 2001 From: Chandler Carruth Date: Sat, 7 Jul 2018 02:46:12 +0000 Subject: [PATCH] [Support] Clear errno before calling the function in RetryAfterSignal. For certain APIs, the return value of the function does not distinguish between failure (which populates errno) and other non-error conditions (which do not set errno). For example, `fgets` returns `NULL` both when an error has occurred, or upon EOF. If `errno` is already `EINTR` for whatever reason, then ``` RetryAfterSignal(nullptr, fgets, ...); ``` on a stream that has reached EOF would infinite loop. Fix this by setting `errno` to `0` before each attempt in `RetryAfterSignal`. Patch by Ricky Zhou! Differential Revision: https://reviews.llvm.org/D48755 llvm-svn: 336479 --- llvm/include/llvm/Support/Errno.h | 5 +++-- llvm/unittests/Support/ErrnoTest.cpp | 3 +++ 2 files changed, 6 insertions(+), 2 deletions(-) diff --git a/llvm/include/llvm/Support/Errno.h b/llvm/include/llvm/Support/Errno.h index 35dc1ea..8069c36 100644 --- a/llvm/include/llvm/Support/Errno.h +++ b/llvm/include/llvm/Support/Errno.h @@ -34,9 +34,10 @@ template inline auto RetryAfterSignal(const FailT &Fail, const Fun &F, const Args &... As) -> decltype(F(As...)) { decltype(F(As...)) Res; - do + do { + errno = 0; Res = F(As...); - while (Res == Fail && errno == EINTR); + } while (Res == Fail && errno == EINTR); return Res; } diff --git a/llvm/unittests/Support/ErrnoTest.cpp b/llvm/unittests/Support/ErrnoTest.cpp index 67f834a..701ac96 100644 --- a/llvm/unittests/Support/ErrnoTest.cpp +++ b/llvm/unittests/Support/ErrnoTest.cpp @@ -33,4 +33,7 @@ TEST(ErrnoTest, RetryAfterSignal) { std::unique_ptr P(RetryAfterSignal(nullptr, [] { return new int(47); })); EXPECT_EQ(47, *P); + + errno = EINTR; + EXPECT_EQ(-1, RetryAfterSignal(-1, [] { return -1; })); } -- 2.7.4