On Unix the idiom to use a pipe is as follows:
pipe(fd);
pid = fork();
if (!pid) {
dup2(fd[1], 1);
close(fd[1]);
close(fd[0]);
...
}
close(fd[1]);
i.e. the child process closes the both pipe ends after duplicating one
to the file descriptors where they are needed.
On Windows, which does not have fork(), we never have an opportunity to
(1) duplicate a pipe end in the child, (2) close unused pipe ends. Instead,
we must use this idiom:
save1 = dup(1);
pipe(fd);
dup2(fd[1], 1);
spawn(...);
dup2(save1, 1);
close(fd[1]);
i.e. save away the descriptor at the destination slot, replace by the pipe
end, spawn process, restore the saved file.
But there is a problem: Notice that the child did not only inherit the
dup2()ed descriptor, but also *both* original pipe ends. Although the one
end that was dup()ed could be closed before the spawn(), we cannot close
the other end - the child inherits it, no matter what.
The solution is to generate non-inheritable pipes. At the first glance,
this looks strange: The purpose of pipes is usually to be inherited to
child processes. But notice that in the course of actions as outlined
above, the pipe descriptor that we want to inherit to the child is
dup2()ed, and as it so happens, Windows's dup2() creates inheritable
duplicates.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
When an external git command is invoked, it can be a Bourne shell script.
This patch looks into the command file to see whether it is one.
In this case, the command line is rearranged to invoke the shell
with the proper arguments.
With this change, scripted git commands work. Command line arguments
to those scripts cannot be complex (contain spaces or double-quotes), yet.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
The timer is implemented using a thread that calls the signal handler
at regular intervals.
We also replace Windows's signal() function because we must intercept
that SIGALRM is set (which is used when a timer is canceled).
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Since GIT calls into Microsoft's MSVCRT.DLL, it must use the printf
format that this DLL uses for 64-bit integers, which is %I64u instead
of %llu.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
Windows's rename() is based on the MoveFile() API, which fails if the
destination exists. Here we work around the problem by using MoveFileEx().
Furthermore, the posixly correct error is returned if the destination is
a directory.
The implementation is still slightly incomplete, however, because of the
missing error code translation: We assume that the failure is due to
permissions.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
On Windows, read-only files cannot be deleted. To make sure that
deletion does not fail because of this, always call chmod() before
unlink().
Signed-off-by: Johannes Schindelin <Johannes.Schindelin@gmx.de>
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
The wrapper does two things:
- Requests to open /dev/null are redirected to open the nul pseudo file.
- A request to open a file that currently exists as a directory on
Windows fails with EACCES; this is changed to EISDIR.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
GIT's guts work with a forward slash as a path separators. We do not change
that. Rather we make sure that only "normalized" paths enter the depths
of the machinery.
We have to translate backslashes to forward slashes in the prefix and in
command line arguments. Fortunately, all of them are passed through
functions in setup.c.
A macro has_dos_drive_path() is defined that checks whether a path begins
with a drive letter+colon combination. This predicate is always false on
Unix. Another macro is_dir_sep() abstracts that a backslash is also a
directory separator on Windows.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
With this change GIT can be compiled and linked using MinGW. Builtins
that only read the repository such as the log family and grep already
work.
Simple stubs are provided for a number of functions that the Windows C
runtime does not offer. They will be completed in later patches.
However, a fix for the snprintf/vsnprintf replacement is applied here
to avoid buffer overflows.
Dmitry Kakurin pointed out that access(..., X_OK) would always fails on
Vista and suggested the -D__USE_MINGW_ACCESS workaround.
Signed-off-by: Johannes Sixt <johannes.sixt@telecom.at>
