summaryrefslogtreecommitdiffstats
path: root/doc/new_chapters
diff options
context:
space:
mode:
authorWade A Smith <warm38@juno.com>1998-09-30 15:42:46 +0000
committerWade A Smith <warm38@juno.com>1998-09-30 15:42:46 +0000
commita65c28e78594ff5f37f264bf264391c2f43a987f (patch)
tree1b088c8356658b3896f8a992019fde4894b0c048 /doc/new_chapters
parent9dd238772fa28013e6ea13b000d1c595e1f78ed1 (diff)
downloadrtems-a65c28e78594ff5f37f264bf264391c2f43a987f.tar.bz2
Documented the fsync and fdatasync routines in this file.
Diffstat (limited to 'doc/new_chapters')
-rw-r--r--doc/new_chapters/io.t79
1 files changed, 64 insertions, 15 deletions
diff --git a/doc/new_chapters/io.t b/doc/new_chapters/io.t
index 0345206593..6f777702e1 100644
--- a/doc/new_chapters/io.t
+++ b/doc/new_chapters/io.t
@@ -23,8 +23,8 @@ The directives provided by the input and output primitives manager are:
@item @code{write} - Writes to a file
@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
@item @code{aio_read} - YYY
@@ -91,7 +91,8 @@ in a future version.
@example
#include <unistd.h>
-int dup(int fildes
+int dup(
+ int fildes
);
@end example
@end ifset
@@ -177,7 +178,8 @@ NONE
@example
#include <unistd.h>
-int close(int fildes
+int close(
+ int fildes
);
@end example
@end ifset
@@ -234,7 +236,8 @@ the following:
@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
Invalid file descriptor
@@ -310,9 +313,10 @@ NONE
@example
#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
@end ifset
@@ -331,7 +335,8 @@ would be delayed in the I/O operation.
Invalid file descriptor
@item EFBIG
-The
+An attempt was made to write to a file that exceeds the maximum file
+size
@item EINTR
The function was interrupted by a signal.
@@ -566,13 +571,14 @@ ciated with such a device is undefined.
NONE
@page
-@subsection fsync -
+@subsection fsync - Synchronize a file's complete in-core state with that on disk
@subheading CALLING SEQUENCE:
@ifset is-C
@example
int fsync(
+ int fd
);
@end example
@end ifset
@@ -582,24 +588,41 @@ int fsync(
@subheading STATUS CODES:
+On success, zero is returned. On error, -1 is returned, and @code{errno}
+is set appropriately.
+
@table @b
-@item E
-The
+@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 -
+@subsection fdatasync - synchronize a file's in-core data with that on disk.
@subheading CALLING SEQUENCE:
@ifset is-C
@example
int fdatasync(
+ int fd
);
@end example
@end ifset
@@ -609,16 +632,42 @@ int fdatasync(
@subheading STATUS CODES:
+On success, zeor is returned. On error, -1 is returned, and @code{errno} is
+set appropriately.
+
@table @b
-@item E
-The
+@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
@subsection mount - Mount a file system