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[2.83.63.152]) by smtp.gmail.com with ESMTPSA id o3-20020a05600c510300b004065d67c3c9sm4577047wms.8.2023.10.15.06.18.05 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 15 Oct 2023 06:18:05 -0700 (PDT) Date: Sun, 15 Oct 2023 14:18:04 +0100 From: Stanislav Maslovski To: GFortran mailing list Subject: Segfaults in SIGINT signal handler Message-ID: Mail-Followup-To: GFortran mailing list MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline X-Spam-Status: No, score=-0.8 required=5.0 tests=BAYES_00,DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF,FREEMAIL_FROM,KAM_ASCII_DIVIDERS,RCVD_IN_DNSWL_NONE,SPF_HELO_NONE,SPF_PASS,TXREP autolearn=no autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on server2.sourceware.org List-Id: Hi, First of all, many thanks to everyone involved in developing and maintaining gfortran! I have been trying to use gfortran's function signal() to add a SIGINT signal handler to my program. Gfortran's documentation for this function says that, when the signal handler is called, it is given an argument of integer type. However, when I try to access this argument in the signal handler, my program segfaults. Here are two examples: ================= this code segfaults =================== program test_signal implicit none integer, parameter :: SIGINT = 2, SIG_ERR = -1 logical :: sig_received = .false. common /signal/ sig_received external sig_handler if (signal(SIGINT, sig_handler) /= SIG_ERR) then print *, "Signal handler installed" else print *, "Error in signal()" endif do while (.true.) print *, "Waiting for signal..." do while (.not. sig_received) continue enddo print *, "Signal received!" sig_received = .false. enddo end program subroutine sig_handler(s) implicit none integer, parameter :: SIGINT = 2 integer, intent(in) :: s logical sig_received common /signal/ sig_received if (s == SIGINT) sig_received = .true. end subroutine ========================================================= $ gfortran test_signal.f90 $ ./a.out Signal handler installed Waiting for signal... ^C Program received signal SIGSEGV: Segmentation fault - invalid memory reference. Backtrace for this error: #0 0x7f9c312218c2 in ??? #1 0x7f9c31220a55 in ??? #2 0x7f9c3105afcf in ??? at ./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0 #3 0x562929f153bc in ??? #4 0x7f9c3105afcf in ??? at ./signal/../sysdeps/unix/sysv/linux/x86_64/libc_sigaction.c:0 #5 0x562929f152f4 in ??? #6 0x562929f153a8 in ??? #7 0x7f9c310461c9 in __libc_start_call_main at ../sysdeps/nptl/libc_start_call_main.h:58 #8 0x7f9c31046284 in __libc_start_main_impl at ../csu/libc-start.c:360 #9 0x562929f150c0 in ??? #10 0xffffffffffffffff in ??? zsh: segmentation fault ./a.out ============= this code does not segfault =============== program test_signal implicit none integer, parameter :: SIGINT = 2, SIG_ERR = -1 logical :: sig_received = .false. common /signal/ sig_received external sig_handler if (signal(SIGINT, sig_handler) /= SIG_ERR) then print *, "Signal handler installed" else print *, "Error in signal()" endif do while (.true.) print *, "Waiting for signal..." do while (.not. sig_received) continue enddo print *, "Signal received!" sig_received = .false. enddo end program subroutine sig_handler(s) implicit none integer, intent(in) :: s logical sig_received common /signal/ sig_received sig_received = .true. end subroutine ========================================================= What am I doing wrong? With best regards, -- Stanislav Maslovski