From 20b63d12b533daf2e9b2936ffb03074861e1673e Mon Sep 17 00:00:00 2001 From: Lennart Poettering Date: Wed, 17 Dec 2014 21:54:00 +0100 Subject: [PATCH] util: in make_stdio() use dup2() rather than dup3() dup3() allows setting O_CLOEXEC which we are not interested in. However, it also fails if called with the same fd as input and output, which is something we don't want. Hence use dup2(). Also, we need to explicitly turn off O_CLOEXEC for the fds, in case the input fd was O_CLOEXEC and < 3. --- src/shared/util.c | 12 ++++++++---- 1 file changed, 8 insertions(+), 4 deletions(-) diff --git a/src/shared/util.c b/src/shared/util.c index ee95a4b6f..364f61885 100644 --- a/src/shared/util.c +++ b/src/shared/util.c @@ -2468,9 +2468,9 @@ int make_stdio(int fd) { assert(fd >= 0); - r = dup3(fd, STDIN_FILENO, 0); - s = dup3(fd, STDOUT_FILENO, 0); - t = dup3(fd, STDERR_FILENO, 0); + r = dup2(fd, STDIN_FILENO); + s = dup2(fd, STDOUT_FILENO); + t = dup2(fd, STDERR_FILENO); if (fd >= 3) safe_close(fd); @@ -2478,7 +2478,11 @@ int make_stdio(int fd) { if (r < 0 || s < 0 || t < 0) return -errno; - /* We rely here that the new fd has O_CLOEXEC not set */ + /* Explicitly unset O_CLOEXEC, since if fd was < 3, then + * dup2() was a NOP and the bit hence possibly set. */ + fd_cloexec(STDIN_FILENO, false); + fd_cloexec(STDOUT_FILENO, false); + fd_cloexec(STDERR_FILENO, false); return 0; } -- 2.30.2