diff options
| author | jb <jb@FreeBSD.org> | 1998-06-10 22:28:45 +0000 |
|---|---|---|
| committer | jb <jb@FreeBSD.org> | 1998-06-10 22:28:45 +0000 |
| commit | e55019792fa382e1b255e9d7419dada0e1ae68a1 (patch) | |
| tree | fa8fa1d1f6c9de31fd9ef7fd3a337d7431c17c18 /lib/libpthread/thread/thr_read.c | |
| parent | 45e8efa5ea54d24c71d47a462ce63a3083abe08b (diff) | |
| download | FreeBSD-src-e55019792fa382e1b255e9d7419dada0e1ae68a1.zip FreeBSD-src-e55019792fa382e1b255e9d7419dada0e1ae68a1.tar.gz | |
Check the access mode in the flags before waiting on a read or a write
that might never be possible if the file was not opened in the corrent
mode. This prevents a hang for bad programs. Why do people code like that?
Diffstat (limited to 'lib/libpthread/thread/thr_read.c')
| -rw-r--r-- | lib/libpthread/thread/thr_read.c | 14 |
1 files changed, 13 insertions, 1 deletions
diff --git a/lib/libpthread/thread/thr_read.c b/lib/libpthread/thread/thr_read.c index 358a620..6c4d211 100644 --- a/lib/libpthread/thread/thr_read.c +++ b/lib/libpthread/thread/thr_read.c @@ -29,7 +29,7 @@ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * - * $Id: uthread_read.c,v 1.4 1998/04/29 09:59:10 jb Exp $ + * $Id: uthread_read.c,v 1.5 1998/06/09 23:20:53 jb Exp $ * */ #include <sys/types.h> @@ -45,6 +45,7 @@ ssize_t read(int fd, void *buf, size_t nbytes) { int ret; + int type; /* POSIX says to do just this: */ if (nbytes == 0) @@ -52,6 +53,17 @@ read(int fd, void *buf, size_t nbytes) /* Lock the file descriptor for read: */ if ((ret = _FD_LOCK(fd, FD_READ, NULL)) == 0) { + /* Get the read/write mode type: */ + type = _thread_fd_table[fd]->flags & O_ACCMODE; + + /* Check if the file is not open for read: */ + if (type != O_RDONLY && type != O_RDWR) { + /* File is not open for read: */ + errno = EBADF; + _FD_UNLOCK(fd, FD_READ); + return (-1); + } + /* Perform a non-blocking read syscall: */ while ((ret = _thread_sys_read(fd, buf, nbytes)) < 0) { if ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0 && |
