Mail Archives: djgpp-workers/1998/02/20/17:10:08
Hi All:
Here are the second try for the needed patchs to open.c, fcntl.h, open.txh
and fopen.txh to add the __djgpp_share_flags feature.
As we discussed with Eli the new feature doesn't change anything if you
don't indicate a value in __djgpp_share_flags. And follows the same mechanism
used by other variables in libc.
Even if you indicate a value in __djgpp_share_flags and you call open with
some share flag the values passed in the call will be used.
DJ: Please check my additions to the docs, my english is very bad.
Eli: you too.
SET
P.S. The diffs are from the djgpp root, with -c3 and using /.
------------------> Start of dif cut here <----------------------------------
*** src/libc/posix/fcntl/~open.c Sun Nov 16 14:05:00 1997
--- src/libc/posix/fcntl/open.c Tue Feb 17 18:43:52 1998
***************
*** 16,22 ****
int
open(const char* filename, int oflag, ...)
{
! int fd, dmode, bintext;
/* Check this up front, to reduce cost and minimize effect */
if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
--- 16,22 ----
int
open(const char* filename, int oflag, ...)
{
! int fd, dmode, bintext, dont_have_share;
/* Check this up front, to reduce cost and minimize effect */
if ((oflag & (O_CREAT | O_EXCL)) == (O_CREAT | O_EXCL))
***************
*** 39,52 ****
dmode = (*((&oflag)+1) & S_IWUSR) ? 0 : 1;
fd = _open(filename, oflag);
/* Under multi-taskers, such as Windows, our file might be open
by some other program with DENY-NONE sharing bit, which fails
the `_open' call above. Try again with DENY-NONE bit set,
unless some sharing bits were already set in the initial call. */
! if (fd == -1
! && ((oflag & (SH_DENYNO | SH_DENYRW | SH_DENYRD | SH_DENYWR)) == 0))
fd = _open(filename, oflag | SH_DENYNO);
if (fd == -1 && oflag & O_CREAT)
fd = _creat(filename, dmode);
--- 39,60 ----
dmode = (*((&oflag)+1) & S_IWUSR) ? 0 : 1;
+ /* Merge the share flags if they are specified */
+ dont_have_share = ((oflag &
+ (SH_DENYNO | SH_DENYRW | SH_DENYRD | SH_DENYWR)) == 0);
+ if (dont_have_share && __djgpp_share_flags)
+ {
+ dont_have_share=0;
+ oflag|=__djgpp_share_flags;
+ }
+
fd = _open(filename, oflag);
/* Under multi-taskers, such as Windows, our file might be open
by some other program with DENY-NONE sharing bit, which fails
the `_open' call above. Try again with DENY-NONE bit set,
unless some sharing bits were already set in the initial call. */
! if (fd == -1 && dont_have_share)
fd = _open(filename, oflag | SH_DENYNO);
if (fd == -1 && oflag & O_CREAT)
fd = _creat(filename, dmode);
*** src/libc/posix/fcntl/~open.txh Fri Apr 26 21:10:04 1996
--- src/libc/posix/fcntl/open.txh Tue Feb 17 18:42:44 1998
***************
*** 82,87 ****
--- 82,91 ----
Other @code{S_I*} values may be included, but they will be ignored.
+ You can specify the share flags (a DOS specific feature) in @var{mode}.
+ And you can indicate default values for the share flags in
+ @code{__djgpp_share_flags}. @xref{__djgpp_share_flags}.
+
@subheading Return Value
If successful, the file descriptor is returned. On error, a negative
***************
*** 92,95 ****
--- 96,161 ----
@example
int q = open("/tmp/foo.dat", O_RDONLY|O_BINARY);
@end example
+
+ @c
---------------------------------------------------------------------------
+ @node __djgpp_share_flags, io
+
+ @subheading Syntax
+
+ @example
+ #include <fcntl.h>
+
+ int __djgpp_share_flags = ...;
+ @end example
+
+ @subheading Description
+
+ This variable controls the share flags used by @code{open} (and hence
+ @code{fopen}) when opening a file.
+
+ If you assign any value different than 0 to this variable libc will
+ merge this value with the flags passed to @code{open}. But if you specify
+ any share flag in the @code{open} call then these flags will remain
+ untouched. In this way @code{__djgpp_share_flags} acts just like a default
+ and by default is 0 ensuring maximun compatibility with older versions of
+ djgpp.
+
+ If you don't know how the share flags act consult any DOS reference. They
+ allow to share or protect a file when it's opened more than ones by the
+ same task or by two or more tasks. The exact behavior depends on the exact
+ case. One interesting thing is that when the file is openen by two tasks
+ under Windows the results are different if you use Windows 3.1 or Windows 95.
+ To add even more complexity Windows 3.1 is affected by @code{SHARE.EXE}.
+
+ The available flags are:
+
+ @table @code
+
+ @item SH_COMPAT 0x0000
+
+ That's the compatible mode.
+
+ @item SH_DENYRW 0x0010
+
+ Deny read and deny write.
+
+ @item SH_DENYWR 0x0020
+
+ Deny write.
+
+ @item SH_DENYRD 0x0030
+
+ Deny read.
+
+ @item SH_DENYNO 0x0040
+
+ No deny.
+
+ @end table
+
+ Of course these flags are DOS specific and doesn't exist under other OSs;
+ and as you can imagine @code{__djgpp_share_flags} is djgpp specific.
+
+ @xref{open}.
+ @xref{fopen}.
*** src/libc/ansi/stdio/~fopen.txh Sun Aug 31 16:13:18 1997
--- src/libc/ansi/stdio/fopen.txh Tue Feb 17 18:42:44 1998
***************
*** 68,73 ****
--- 68,76 ----
If @code{b} or @code{t} is not specified in @var{mode}, the file type is
chosen by the value of @code{fmode} (@pxref{_fmode}).
+ If you need to specify the DOS share flags use the
@code{__djgpp_share_flags}.
+ @xref{__djgpp_share_flags}.
+
@subheading Return Value
A pointer to the @code{FILE} object, or @code{NULL} if there was an
*** include/~fcntl.h Thu Sep 26 22:23:32 1996
--- include/fcntl.h Tue Feb 17 18:42:44 1998
***************
*** 71,76 ****
--- 71,78 ----
#define _SH_DENYRD SH_DENYRD
#define _SH_DENYNO SH_DENYNO
+ extern int __djgpp_share_flags;
+
#define S_IREAD S_IRUSR
#define S_IWRITE S_IWUSR
#define S_IEXEC S_IXUSR
-------------------> End of diff cut here <----------------------------------
Here is the file with the variable, I don't know what's the rigth directory
for it because even when is used by open is far from POSIX.
------------------> Start of djshare.c <-------------------------------------
/* Copyright (C) 1998 DJ Delorie, see COPYING.DJ for details */
/* Extra share flags that can be indicated by the user */
int __djgpp_share_flags = 0;
------------------> End of djshare.c <---------------------------------------
------------------------------------ 0 --------------------------------
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Salvador Eduardo Tropea (SET). (Electronics Engineer)
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