From 3132cb397ad1b60cac548b35ad8bbd4c7183fde4 Mon Sep 17 00:00:00 2001 From: Gunnar Beutner Date: Fri, 29 Jul 2011 10:17:46 +0200 Subject: [PATCH] Use /dev/null for stdout/stderr in libzfs_run_process(). Simply closing the stdout and/or stderr file descriptors for the child process can have bad side effects if for example the child writes to stdout/stderr after open()ing a file. The open() call might have returned the same file descriptor one would usually expect for stdout/stderr (1 and 2), thereby causing mis-directed writes. Signed-off-by: Brian Behlendorf Issue #190 --- lib/libzfs/libzfs_util.c | 13 ++++++++++--- 1 file changed, 10 insertions(+), 3 deletions(-) diff --git a/lib/libzfs/libzfs_util.c b/lib/libzfs/libzfs_util.c index f55b658..5f6763c 100644 --- a/lib/libzfs/libzfs_util.c +++ b/lib/libzfs/libzfs_util.c @@ -635,15 +635,22 @@ int libzfs_run_process(const char *path, char *argv[], int flags) { pid_t pid; - int rc; + int rc, devnull_fd; pid = vfork(); if (pid == 0) { + devnull_fd = open("/dev/null", O_WRONLY); + + if (devnull_fd < 0) + _exit(-1); + if (!(flags & STDOUT_VERBOSE)) - close(STDOUT_FILENO); + (void) dup2(devnull_fd, STDOUT_FILENO); if (!(flags & STDERR_VERBOSE)) - close(STDERR_FILENO); + (void) dup2(devnull_fd, STDERR_FILENO); + + close(devnull_fd); (void) execvp(path, argv); _exit(-1); -- 1.8.3.1