[Libsysio-commit] HEAD: libsysio/drivers/native fs_native.c

[Lee W. <lw...@us...>]

Update of /cvsroot/libsysio/libsysio/drivers/native
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv30430/drivers/native

Modified Files:
	fs_native.c 
Log Message:


New operation for the drivers to implement -- take note!

The drivers now need to implement inop_pos which takes an inode and
a _SYSIO_OFF_T and should return the resulting position as though it were
lseek(FD2INO(fd), off, SEEK_SET). As usual a negative return value
is the negated errno.

Lseek is altered to use this.

Changes in fs_native.c to utilize pread/pwrite whenever positioning
is required instead of an lseek/io-op pair of calls. This addresses a race
to yod.



Index: fs_native.c
===================================================================
RCS file: /cvsroot/libsysio/libsysio/drivers/native/fs_native.c,v
retrieving revision 1.34
retrieving revision 1.35
diff -u -w -b -B -p -r1.34 -r1.35
--- fs_native.c	14 Apr 2004 17:25:43 -0000	1.34
+++ fs_native.c	16 Apr 2004 20:38:34 -0000	1.35
@@ -247,6 +247,7 @@ static int native_inop_unlink(struct pno
 static int native_inop_rename(struct pnode *old, struct pnode *new);
 static int native_inop_read(struct inode *ino, struct ioctx *ioctx);
 static int native_inop_write(struct inode *ino, struct ioctx *ioctx);
+static _SYSIO_OFF_T native_inop_pos(struct inode *ino, _SYSIO_OFF_T off);
 static int native_inop_iodone(struct ioctx *ioctx);
 static int native_inop_fcntl(struct inode *ino, int cmd, va_list ap);
 static int native_inop_sync(struct inode *ino);
@@ -278,6 +279,7 @@ static struct inode_ops native_i_ops = {
 	native_inop_rename,
 	native_inop_read,
 	native_inop_write,
+	native_inop_pos,
 	native_inop_iodone,
 	native_inop_fcntl,
 	native_inop_sync,
@@ -1293,24 +1295,47 @@ out:
 static ssize_t
 dopio(void *buf, size_t count, _SYSIO_OFF_T off, struct native_io *nio)
 {
+#ifdef _LARGEFILE64_SOURCE
+#define _NATIVE_SYSCALL_PREAD SYS_pread64
+#define _NATIVE_SYSCALL_PWRITE SYS_pwrite64
+#else
+#define _NATIVE_SYSCALL_PREAD SYS_pread
+#define _NATIVE_SYSCALL_PWRITE SYS_pwrite
+#endif
+	ssize_t	cc;
+
+	if (!(off == nio->nio_nino->ni_fpos || nio->nio_nino->ni_seekok))
+		return -ESPIPE;
 
+	if (!nio->nio_nino->ni_seekok) {
+		if (off != nio->nio_nino->ni_fpos) {
 	/*
-	 * Avoid the reposition call if we're already at the right place.
-	 * Allows us to access pipes and fifos.
+			 * They've done a p{read,write} or somesuch. Can't
+			 * seek on this descriptor so we err out now.
 	 */
-	if (off != nio->nio_nino->ni_fpos) {
-		int	err;
-
-		err = native_pos(nio->nio_nino->ni_fd, &off, SEEK_SET);
-		if (err)
-			return err;
-		nio->nio_nino->ni_fpos = off;
+			errno = ESPIPE;
+			return -1;
 	}
-
-	return syscall(nio->nio_op == 'r' ? SYS_read : SYS_write,
+		cc =
+		    syscall(nio->nio_op == 'r' ? SYS_read : SYS_write,
 		       nio->nio_nino->ni_fd,
 		       buf,
 		       count);
+		if (cc > 0)
+			nio->nio_nino->ni_fpos += cc;
+	} else
+		cc =
+		    syscall((nio->nio_op == 'r'
+			       ? _NATIVE_SYSCALL_PREAD
+			       : _NATIVE_SYSCALL_PWRITE),
+			    nio->nio_nino->ni_fd,
+			    buf,
+			    count,
+			    off);
+
+	return cc;
+#undef _NATIVE_SYSCALL_PREAD
+#undef _NATIVE_SYSCALL_PWRITE
 }
 
 static ssize_t
@@ -1515,6 +1540,16 @@ native_inop_write(struct inode *ino __IS
 	return doio('w', ioctx);
 }
 
+static _SYSIO_OFF_T
+native_inop_pos(struct inode *ino, _SYSIO_OFF_T off)
+{
+	struct native_inode *nino = I2NI(ino);
+	int	err;
+
+	err = native_pos(nino->ni_fd, &off, SEEK_SET);
+	return err < 0 ? err : off;
+}
+
 static int
 native_inop_iodone(struct ioctx *ioctxp __IS_UNUSED)
 {