diff options
Diffstat (limited to 'doc/new_chapters/io.t')
| -rw-r--r-- | doc/new_chapters/io.t | 79 |
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 |