Changeset a65c28e in rtems

Timestamp:

09/30/98 15:42:46 (25 years ago)

Author:

Wade A Smith <warm38@…>

Branches:

4.10, 4.11, 4.8, 4.9, 5, master

Children:

c11f512

Parents:

9dd23877

Message:

Documented the fsync and fdatasync routines in this file.

File:

• doc/new_chapters/io.t (modified) (9 diffs)

doc/new_chapters/io.t

@@ -24 +24 @@
 @item @code{fcntl} - Manipulates an open file descriptor
 @item @code{lseek} - Reposition read/write file offset
-@item @code{fsync} - XXX
-@item @code{fdatasync} - XXX
+@item @code{fsync} - Synchronize a file's complete in-core state with that on disk
+@item @code{fdatasync} - synchronize a file's in-core data with that on disk
 @item @code{mount} - Mount a file system
 @item @code{umount} - Unmount file systems
@@ -92 +92 @@
 #include <unistd.h>
 
-int dup(int fildes
+int dup(
+  int fildes
 );
 @end example
@@ -178 +179 @@
 #include <unistd.h>
 
-int close(int fildes
+int close(
+  int fildes
 );
 @end example
@@ -235 +237 @@
 @table @b
 @item EAGAIN
-The
+The O_NONBLOCK flag is set for a file descriptor and the process
+would be delayed in the I/O operation.
 
 @item EBADF
@@ -311 +314 @@
 #include <unistd.h>
 
-int write(int         fildes,
-          const void *buf,
-          unsigned int nbytes
+int write(
+  int           fildes,
+  const void   *buf,
+  unsigned int  nbytes
 );
 @end example
@@ -332 +336 @@
 
 @item EFBIG
-The
+An attempt was made to write to a file that exceeds the maximum file 
+size
 
 @item EINTR
@@ -567 +572 @@
 
 @page
-@subsection fsync - 
+@subsection fsync - Synchronize a file's complete in-core state with that on disk
 
 @subheading CALLING SEQUENCE:
@@ -574 +579 @@
 @example
 int fsync(
-);
-@end example
-@end ifset
-
-@ifset is-Ada
-@end ifset
-
-@subheading STATUS CODES:
-
-@table @b
-@item E
-The
-
-@end table
-
-@subheading DESCRIPTION:
-
-@subheading NOTES:
-
-@page
-@subsection fdatasync - 
+  int fd
+);
+@end example
+@end ifset
+
+@ifset is-Ada
+@end ifset
+
+@subheading STATUS CODES:
+
+On success, zero is returned.  On error, -1 is returned, and @code{errno}
+is set appropriately.
+
+@table @b
+@item EBADF
+@code{fd} is not a valid descriptor open for writing
+
+@item EINVAL
+@code{fd} is bound to a special file which does not support support synchronization
+
+@item EROFS
+@code{fd} is bound to a special file which does not support support synchronization
+
+@item EIO
+An error occurred during synchronization
+
+@end table
+
+@subheading DESCRIPTION:
+
+@code{fsync} copies all in-core parts of a file to disk.
+
+@subheading NOTES:
+
+NONE
+
+@page
+@subsection fdatasync - synchronize a file's in-core data with that on disk. 
 
 @subheading CALLING SEQUENCE:
@@ -601 +623 @@
 @example
 int fdatasync(
-);
-@end example
-@end ifset
-
-@ifset is-Ada
-@end ifset
-
-@subheading STATUS CODES:
-
-@table @b
-@item E
-The
-
-@end table
-
-@subheading DESCRIPTION:
-
-@subheading NOTES:
+  int fd
+);
+@end example
+@end ifset
+
+@ifset is-Ada
+@end ifset
+
+@subheading STATUS CODES:
+
+On success, zeor is returned.  On error, -1 is returned, and @code{errno} is
+set appropriately.
+
+@table @b
+@item EBADF
+@code{fd} is not a valid file descriptor open for writing.
+
+@item EINVAL
+@code{fd} is bound to a special file which dows not support synchronization.
+
+@item EIO
+An error occurred during synchronization.
+
+@item EROFS
+@code{fd} is bound to a special file which dows not support synchronization.
+
+@end table
+
+@subheading DESCRIPTION:
+
+@code{fdatasync} flushes all data buffers of a file to disk (before the system call
+returns).  It resembles @code{fsync} but is not required to update the metadata such  
+as access time.
+
+Applications that access databases or log files often write a tiny data fragment
+(e.g., one line in a log file) and then call @code{fsync} immediately in order to  
+ensure that the written data is physically stored on the harddisk.  Unfortunately, 
+fsync will always initiate two write operations: one for the newly written data and 
+another one in order to update the modification time stored in the inode.  If the 
+modification time is not a part of the transaction concept @code{fdatasync} can be 
+used to avoid unnecessary inode disk write operations.
+
+@subheading NOTES:
+
+NONE
 
 @page