From ff6f2bc009e50e601d4f631f7ab35174b175e6fa Mon Sep 17 00:00:00 2001 From: Xiang Xiao Date: Tue, 13 Oct 2020 15:53:19 +0800 Subject: [PATCH] Remove all fclose with stdin, stdout and stderr since it is wrong to close the builtin stream and specially note https://pubs.opengroup.org/onlinepubs/9699919799/functions/fclose.html: Since after the call to fclose() any use of stream results in undefined behavior, fclose() should not be used on stdin, stdout, or stderr except immediately before process termination (see XBD Process Termination), so as to avoid triggering undefined behavior in other standard interfaces that rely on these streams. If there are any atexit() handlers registered by the application, such a call to fclose() should not occur until the last handler is finishing. Once fclose() has been used to close stdin, stdout, or stderr, there is no standard way to reopen any of these streams. and it is also unnecessary because the stream always get flushed. Signed-off-by: Xiang Xiao --- examples/nxterm/nxterm_main.c | 3 --- graphics/nxwm/src/cnxterm.cxx | 12 ------------ graphics/twm4nx/apps/cnxterm.cxx | 12 ------------ nshlib/nsh_altconsole.c | 15 ++++----------- nshlib/nsh_usbconsole.c | 21 +++------------------ 5 files changed, 7 insertions(+), 56 deletions(-) diff --git a/examples/nxterm/nxterm_main.c b/examples/nxterm/nxterm_main.c index 491ee94b7..8c9678759 100644 --- a/examples/nxterm/nxterm_main.c +++ b/examples/nxterm/nxterm_main.c @@ -391,9 +391,6 @@ int main(int argc, FAR char *argv[]) fflush(stdout); fflush(stderr); - fclose(stdout); - fclose(stderr); - dup2(fd, 1); dup2(fd, 2); diff --git a/graphics/nxwm/src/cnxterm.cxx b/graphics/nxwm/src/cnxterm.cxx index 8273b69e5..38e825013 100644 --- a/graphics/nxwm/src/cnxterm.cxx +++ b/graphics/nxwm/src/cnxterm.cxx @@ -503,24 +503,12 @@ int CNxTerm::nxterm(int argc, char *argv[]) std::fflush(stdout); std::fflush(stderr); -#ifdef CONFIG_NXTERM_NXKBDIN - std::fclose(stdin); -#endif - std::fclose(stdout); - std::fclose(stderr); - #ifdef CONFIG_NXTERM_NXKBDIN std::dup2(fd, 0); #endif std::dup2(fd, 1); std::dup2(fd, 2); -#ifdef CONFIG_NXTERM_NXKBDIN - std::fdopen(0, "r"); -#endif - std::fdopen(1, "w"); - std::fdopen(2, "w"); - // And we can close our original driver file descriptor if (fd > 2) diff --git a/graphics/twm4nx/apps/cnxterm.cxx b/graphics/twm4nx/apps/cnxterm.cxx index d895c8172..f67fdd48e 100644 --- a/graphics/twm4nx/apps/cnxterm.cxx +++ b/graphics/twm4nx/apps/cnxterm.cxx @@ -417,24 +417,12 @@ int CNxTerm::nxterm(int argc, char *argv[]) std::fflush(stdout); std::fflush(stderr); -#ifdef CONFIG_NXTERM_NXKBDIN - std::fclose(stdin); -#endif - std::fclose(stdout); - std::fclose(stderr); - #ifdef CONFIG_NXTERM_NXKBDIN std::dup2(fd, 0); #endif std::dup2(fd, 1); std::dup2(fd, 2); -#ifdef CONFIG_NXTERM_NXKBDIN - std::fdopen(0, "r"); -#endif - std::fdopen(1, "w"); - std::fdopen(2, "w"); - // And we can close our original driver file descriptor if (fd > 2) diff --git a/nshlib/nsh_altconsole.c b/nshlib/nsh_altconsole.c index 88bf54098..1de430608 100644 --- a/nshlib/nsh_altconsole.c +++ b/nshlib/nsh_altconsole.c @@ -78,9 +78,9 @@ static int nsh_clone_console(FAR struct console_stdio_s *pstate) return -ENODEV; } - /* Close stderr: we only close stderr if we opened the alternative one */ + /* Flush stderr: we only flush stderr if we opened the alternative one */ - fclose(stderr); + fflush(stderr); /* Associate the new opened file descriptor to stderr */ @@ -101,9 +101,9 @@ static int nsh_clone_console(FAR struct console_stdio_s *pstate) return -ENODEV; } - /* Close stdout: we only close stdout if we opened the alternative one */ + /* Flush stdout: we only flush stdout if we opened the alternative one */ - fclose(stdout); + fflush(stdout); /* Associate the new opened file descriptor to stdout */ @@ -122,7 +122,6 @@ static int nsh_clone_console(FAR struct console_stdio_s *pstate) pstate->cn_errstream = fdopen(pstate->cn_errfd, "a"); if (!pstate->cn_errstream) { - close(pstate->cn_errfd); free(pstate); return -EIO; } @@ -133,7 +132,6 @@ static int nsh_clone_console(FAR struct console_stdio_s *pstate) pstate->cn_outstream = fdopen(pstate->cn_outfd, "a"); if (!pstate->cn_outstream) { - close(pstate->cn_outfd); free(pstate); return -EIO; } @@ -202,10 +200,6 @@ static int nsh_wait_inputdev(FAR struct console_stdio_s *pstate, } while (fd < 0); - /* Close stdin: we only closed stdin if we opened the alternative one */ - - fclose(stdin); - /* Okay.. we have successfully opened the input device. Did * we just re-open fd 0? */ @@ -225,7 +219,6 @@ static int nsh_wait_inputdev(FAR struct console_stdio_s *pstate, pstate->cn_constream = fdopen(pstate->cn_confd, "r+"); if (!pstate->cn_constream) { - close(pstate->cn_confd); free(pstate); return -EIO; } diff --git a/nshlib/nsh_usbconsole.c b/nshlib/nsh_usbconsole.c index d7069ddf7..c323f2893 100644 --- a/nshlib/nsh_usbconsole.c +++ b/nshlib/nsh_usbconsole.c @@ -77,31 +77,16 @@ static void nsh_configstdio(int fd) { - /* Make sure the stdin, stdout, and stderr are closed */ + /* Make sure the stdout, and stderr are flushed */ - fclose(stdin); - fclose(stdout); - fclose(stderr); + fflush(stdout); + fflush(stderr); /* Dup the fd to create standard fd 0-2 */ dup2(fd, 0); dup2(fd, 1); dup2(fd, 2); - - /* fdopen to get the stdin, stdout and stderr streams. The following logic - * depends on the fact that the library layer will allocate FILEs in order. - * And since we closed stdin, stdout, and stderr above, that is what we - * should get. - * - * fd = 0 is stdin (read-only) - * fd = 1 is stdout (write-only, append) - * fd = 2 is stderr (write-only, append) - */ - - fdopen(0, "r"); - fdopen(1, "a"); - fdopen(2, "a"); } /****************************************************************************