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?

4 files changed, 52 insertions, 4 deletions

diff --git a/lib/libc_r/uthread/uthread_read.c b/lib/libc_r/uthread/uthread_read.c
index 358a620..6c4d211 100644
--- a/lib/libc_r/uthread/uthread_read.c
+++ b/lib/libc_r/uthread/uthread_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 &&
diff --git a/lib/libc_r/uthread/uthread_readv.c b/lib/libc_r/uthread/uthread_readv.c
index 0a19290b..819e20c 100644
--- a/lib/libc_r/uthread/uthread_readv.c
+++ b/lib/libc_r/uthread/uthread_readv.c
@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: uthread_readv.c,v 1.4 1998/04/29 09:59:11 jb Exp $
+ * $Id: uthread_readv.c,v 1.5 1998/06/09 23:20:54 jb Exp $
  *
  */
 #include <sys/types.h>
@@ -45,9 +45,21 @@ ssize_t
 readv(int fd, const struct iovec * iov, int iovcnt)
 {
 	int	ret;
+	int	type;
 
 	/* 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 readv syscall: */
 		while ((ret = _thread_sys_readv(fd, iov, iovcnt)) < 0) {
 			if ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0 &&
diff --git a/lib/libc_r/uthread/uthread_write.c b/lib/libc_r/uthread/uthread_write.c
index 78940e2..9732031 100644
--- a/lib/libc_r/uthread/uthread_write.c
+++ b/lib/libc_r/uthread/uthread_write.c
@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: uthread_write.c,v 1.6 1998/05/25 21:45:50 jb Exp $
+ * $Id: uthread_write.c,v 1.7 1998/06/09 23:21:04 jb Exp $
  *
  */
 #include <sys/types.h>
@@ -46,6 +46,7 @@ write(int fd, const void *buf, size_t nbytes)
 {
 	int	blocking;
 	int	status;
+	int	type;
 	ssize_t n;
 	ssize_t num = 0;
 	ssize_t	ret;
@@ -56,6 +57,17 @@ write(int fd, const void *buf, size_t nbytes)
 
 	/* Lock the file descriptor for write: */
 	if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) {
+		/* Get the read/write mode type: */
+		type = _thread_fd_table[fd]->flags & O_ACCMODE;
+
+		/* Check if the file is not open for write: */
+		if (type != O_WRONLY && type != O_RDWR) {
+			/* File is not open for write: */
+			errno = EBADF;
+			_FD_UNLOCK(fd, FD_WRITE);
+			return (-1);
+		}
+
 		/* Check if file operations are to block */
 		blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0);
 
diff --git a/lib/libc_r/uthread/uthread_writev.c b/lib/libc_r/uthread/uthread_writev.c
index 9810aca..f5cb788 100644
--- a/lib/libc_r/uthread/uthread_writev.c
+++ b/lib/libc_r/uthread/uthread_writev.c
@@ -29,7 +29,7 @@
  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  * SUCH DAMAGE.
  *
- * $Id: uthread_writev.c,v 1.7 1998/05/27 00:44:58 jb Exp $
+ * $Id: uthread_writev.c,v 1.8 1998/06/09 23:21:05 jb Exp $
  *
  */
 #include <sys/types.h>
@@ -48,6 +48,7 @@ writev(int fd, const struct iovec * iov, int iovcnt)
 {
 	int	blocking;
 	int	idx = 0;
+	int	type;
 	ssize_t cnt;
 	ssize_t n;
 	ssize_t num = 0;
@@ -71,6 +72,17 @@ writev(int fd, const struct iovec * iov, int iovcnt)
 
 	/* Lock the file descriptor for write: */
 	if ((ret = _FD_LOCK(fd, FD_WRITE, NULL)) == 0) {
+		/* Get the read/write mode type: */
+		type = _thread_fd_table[fd]->flags & O_ACCMODE;
+
+		/* Check if the file is not open for write: */
+		if (type != O_WRONLY && type != O_RDWR) {
+			/* File is not open for write: */
+			errno = EBADF;
+			_FD_UNLOCK(fd, FD_WRITE);
+			return (-1);
+		}
+
 		/* Check if file operations are to block */
 		blocking = ((_thread_fd_table[fd]->flags & O_NONBLOCK) == 0);