ash: allow HISTFILE=/dev/null to work as intended

It was noted that setting HISTFILE=/dev/null in upstream BusyBox
prevented shell history from being saved to a history file.  This
failed in busybox-w32 with an error from lseek(2).

The lseek(2) wrapper was rather conservative in the file types it
accepted.  Allowing FILE_TYPE_CHAR makes it possible to seek on
/dev/null, thus avoiding the issue with HISTFILE.

In addition, the wrapper for open(2) now converts the Unix-style
mode argument to Windows-style.

(GitHub issue #425)

1 files changed, 8 insertions, 3 deletions

diff --git a/win32/mingw.c b/win32/mingw.c
index 98254fdbe..4398f5462 100644
--- a/win32/mingw.c
+++ b/win32/mingw.c
@@ -225,7 +225,7 @@ static int mingw_is_directory(const char *path);
 int mingw_open (const char *filename, int oflags, ...)
 {
         va_list args;
-        unsigned mode;
+        int pmode, mode = 0666;
         int fd;
         int special = (oflags & O_SPECIAL);
         int dev = get_dev_type(filename);
@@ -243,7 +243,10 @@ int mingw_open (const char *filename, int oflags, ...)
         mode = va_arg(args, int);
         va_end(args);
 
-        fd = open(filename, oflags&~O_SPECIAL, mode);
+        pmode = ((mode & S_IWUSR) ? _S_IWRITE : 0) |
+                                        ((mode & S_IRUSR) ? _S_IREAD : 0);
+
+        fd = open(filename, oflags&~O_SPECIAL, pmode);
         if (fd >= 0) {
                 update_special_fd(dev, fd);
         }
@@ -2189,12 +2192,14 @@ size_t FAST_FUNC remove_cr(char *p, size_t len)
 
 off_t mingw_lseek(int fd, off_t offset, int whence)
 {
+        DWORD ftype;
         HANDLE h = (HANDLE)_get_osfhandle(fd);
         if (h == INVALID_HANDLE_VALUE) {
                 errno = EBADF;
                 return -1;
         }
-        if (GetFileType(h) != FILE_TYPE_DISK) {
+        ftype = GetFileType(h);
+        if (ftype != FILE_TYPE_DISK && ftype != FILE_TYPE_CHAR) {
                 errno = ESPIPE;
                 return -1;
         }