sendfile.2: Fix description of the out_fd

commit cc56f7de7f00d188c7c4da1e9861581853b9e92f made sendfile(2) can work with any output file.
Therefore the out_fd of sendfile(2) can refer to any file, but current manual (man-pages-3.32) has not been changed so far.

Signed-off-by Akira Fujita <a-fujita-cUW4a6blu5N8UrSeD/[email protected]>

---
 sendfile.2 |   16 +++++++++-------

 1 file changed, 9 insertions(+), 7 deletions(-)

man2/sendfile.2    2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2    2010-12-03 16:01:59.000000000 +0900 +0 -0

@@ -87,15 +87,17 @@ and the file offset will be updated by t

 .I count
 is the number of bytes to copy between the file descriptors.

-Presently (Linux 2.6.9):
-.IR in_fd ,
+.IR in_fd
 must correspond to a file which supports
 .BR mmap (2)-like
 operations
-(i.e., it cannot be a socket);

man2/sendfile.2    2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2    2010-12-03 16:01:59.000000000 +0900 +7 -3

-and
-.I out_fd
-must refer to a socket.
+(i.e., it cannot be a socket).
+
+.IR out_fd
+was required to be a socket, but since Linux 2.6.33 it can be
+any file. If it is a regular file, then
+.BR sendfile()
+changes its offset appropriately.

 Applications may wish to fall back to
 .BR read (2)/ write (2)

man2/sendfile.2    2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2    2010-12-03 16:01:59.000000000 +0900 +0 -0

@@ -165,7 +167,7 @@ to minimize the number of packets and to
 
  In Linux 2.4 and earlier,

 .I out_fd

man2/sendfile.2    2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2    2010-12-03 16:01:59.000000000 +0900 +1 -1

-could refer to a regular file, and
+could also refer to a regular file, and

 .BR sendfile ()
 changed the current offset of that file.

Hello Akira,

2011/3/9 Akira Fujita<a-fujita-cUW4a6blu5N8UrSeD/[email protected]>:

Quoted 4 lines

commit cc56f7de7f00d188c7c4da1e9861581853b9e92f made sendfile(2) can work with any output file.
Therefore the out_fd of sendfile(2) can refer to any file, but current manual (man-pages-3.32) has not been changed so far.

Thank you for this report! Some notes below.

Quoted 7 lines

Signed-off-by Akira Fujita<a-fujita-cUW4a6blu5N8UrSeD/[email protected]>

---
  sendfile.2 |   16 +++++++++-------
  1 file changed, 9 insertions(+), 7 deletions(-)

man2/sendfile.2 2011-03-09 10:34:53.000000000 +0900 and the file offset will be updated by t · line 95

Quoted 10 lines

man2/sendfile.2 2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2 2010-12-03 16:01:59.000000000 +0900 +1 -3

@@ -87,15 +87,17 @@ and the file offset will be updated by t
  .I count
  is the number of bytes to copy between the file descriptors.
 
-Presently (Linux 2.6.9):
-.IR in_fd ,
+.IR in_fd
  must correspond to a file which supports
  .BR mmap (2)-like
  operations
-(i.e., it cannot be a socket);

You removed that piece, but I believe nothing changed for 'in_fd', so I kept that piece.

Quoted 14 lines

man2/sendfile.2 2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2 2010-12-03 16:01:59.000000000 +0900 +7 -3

-and
-.I out_fd
-must refer to a socket.
+(i.e., it cannot be a socket).
+
+.IR out_fd
+was required to be a socket, but since Linux 2.6.33 it can be
+any file. If it is a regular file, then
+.BR sendfile()
+changes its offset appropriately.
 
  Applications may wish to fall back to
  .BR read (2)/ write (2)

man2/sendfile.2 2011-03-09 10:34:53.000000000 +0900 to minimize the number of packets and to · line 172

Quoted 7 lines

man2/sendfile.2 2011-03-09 10:34:53.000000000 +0900 renamed from man2/sendfile.2 2010-12-03 16:01:59.000000000 +0900 +1 -1

@@ -165,7 +167,7 @@ to minimize the number of packets and to
 
  In Linux 2.4 and earlier,
  .I out_fd
-could refer to a regular file, and
+could also refer to a regular file, and
  .BR sendfile ()
  changed the current offset of that file.

For 3.33 I applied a slightly modified version of you patch; see below.

Cheers,

Michael

man2/sendfile.2 +6 -2

@@ -92,10 +92,14 @@ The
  argument must correspond to a file which supports
  .BR mmap (2)-like
  operations
-(i.e., it cannot be a socket);
-and
+(i.e., it cannot be a socket).
+In Linux kernels before 2.6.33,
  .I out_fd
  must refer to a socket.
+Since Linux 2.6.33 it can be any file.
+If it is a regular file, then
+.BR sendfile()
+changes the file offset offset appropriately.
 
  Applications may wish to fall back to
  .BR read (2)/ write (2)

For 3.33 I applied a slightly modified version of you patch; see below.

Cheers,

Michael

man2/sendfile.2 +0 -0

@@ -92,10 +92,14 @@ The

 argument must correspond to a file which supports .BR mmap (2)-like
 operations

man2/sendfile.2 +2 -2

-(i.e., it cannot be a socket);
-and
+(i.e., it cannot be a socket).
+In Linux kernels before 2.6.33,

 .I out_fd
 must refer to a socket.

HI,

On Sun, Sep 11, 2011 at 7:00 PM, Michael Kerrisk <[email protected]> wrote:
[...]

Quoted 18 lines

For 3.33 I applied a slightly modified version of you patch; see below.

Cheers,

Michael

man2/sendfile.2 +0 -0

@@ -92,10 +92,14 @@ The

 argument must correspond to a file which supports .BR mmap (2)-like
 operations

man2/sendfile.2 +2 -2

-(i.e., it cannot be a socket);
-and
+(i.e., it cannot be a socket).
+In Linux kernels before 2.6.33,

 .I out_fd

man2/sendfile.2 The · line 102

Quoted 5 lines

 must refer to a socket.

man2/sendfile.2 +4 -0

+Since Linux 2.6.33 it can be any file.
+If it is a regular file, then
+.BR sendfile()
+changes the file offset offset appropriately.

You wrote 'offset' twice here, I guess it's a typo, unless I'm missing something...