Make sure temporary file handles are not inherited by child processes

When testing a merge driver which spawns a merge server (for future merges)
I got the following error:

    Rename from 'xxx/.git/index.lock' to 'xxx/.git/index' failed. Should I try again? (y/n)

Only after I stop the merge server the lock is released.
This is caused by windows handle inheritance.

Starting childs with bInheritHandles==FALSE does not work,
because no file handles would be inherited,
not even the hStdXxx handles in STARTUPINFO.

Opening every file with O_NOINHERIT does not work,
Since it is used by git-upload-pack for example,
which expects inherited handles.

This leaves us with only creating temp files with the O_NOINHERIT flag.
Which (currently) only used by lock_file which is exactly what we want.


Signed-off-by: Ben Wijen <[email protected]>

Author: bwijen

compat/mingw.h

@@ -67,6 +67,10 @@ typedef int pid_t;
 #define F_SETFD 2
 #define FD_CLOEXEC 0x1
 
+#if !defined O_CLOEXEC && defined O_NOINHERIT
+#define O_CLOEXEC	O_NOINHERIT
+#endif
+
 #ifndef EAFNOSUPPORT
 #define EAFNOSUPPORT WSAEAFNOSUPPORT
 #endif

tempfile.c

@@ -120,7 +120,7 @@ int create_tempfile(struct tempfile *tempfile, const char *path)
 	prepare_tempfile_object(tempfile);
 
 	strbuf_add_absolute_path(&tempfile->filename, path);
-	tempfile->fd = open(tempfile->filename.buf, O_RDWR | O_CREAT | O_EXCL, 0666);
+	tempfile->fd = open(tempfile->filename.buf, O_RDWR | O_CREAT | O_EXCL | O_CLOEXEC, 0666);
 	if (tempfile->fd < 0) {
 		strbuf_reset(&tempfile->filename);
 		return -1;