Re: [PATCH v2 06/19] hw/9pfs: Add missing definitions for Windows

[Christian Schoenebeck <qemu_oss@crudebyte.com>]

On Friday, November 11, 2022 5:22:12 AM CET Bin Meng wrote:
> From: Guohuai Shi <guohuai.shi@windriver.com>
> 
> Some definitions currently used by the 9pfs codes are only available
> on POSIX platforms. Let's add our own ones in preparation to adding
> 9pfs support for Windows.
> 
> Signed-off-by: Guohuai Shi <guohuai.shi@windriver.com>
> Signed-off-by: Bin Meng <bin.meng@windriver.com>
> 
> ---
> 
> Changes in v2:
> - Add S_IFLNK related macros to support symbolic link
> 
>  fsdev/file-op-9p.h | 33 +++++++++++++++++++++++++++++++++
>  hw/9pfs/9p.h       | 33 +++++++++++++++++++++++++++++++++
>  2 files changed, 66 insertions(+)
> 
> diff --git a/fsdev/file-op-9p.h b/fsdev/file-op-9p.h
> index 4997677460..7d9a736b66 100644
> --- a/fsdev/file-op-9p.h
> +++ b/fsdev/file-op-9p.h
> @@ -27,6 +27,39 @@
>  # include <sys/mount.h>
>  #endif
>  
> +#ifdef CONFIG_WIN32
> +
> +/* POSIX structure not defined in Windows */
> +
> +typedef uint32_t uid_t;
> +typedef uint32_t gid_t;
> +
> +/* from http://man7.org/linux/man-pages/man2/statfs.2.html */
> +typedef uint32_t __fsword_t;
> +typedef uint32_t fsblkcnt_t;
> +typedef uint32_t fsfilcnt_t;
> +
> +/* from linux/include/uapi/asm-generic/posix_types.h */
> +typedef struct {
> +    long __val[2];
> +} fsid_t;
> +
> +struct statfs {
> +    __fsword_t f_type;
> +    __fsword_t f_bsize;
> +    fsblkcnt_t f_blocks;
> +    fsblkcnt_t f_bfree;
> +    fsblkcnt_t f_bavail;
> +    fsfilcnt_t f_files;
> +    fsfilcnt_t f_ffree;
> +    fsid_t f_fsid;
> +    __fsword_t f_namelen;
> +    __fsword_t f_frsize;
> +    __fsword_t f_flags;
> +};
> +

Does it make sense to define all of these, even though not being used?

> +#endif /* CONFIG_WIN32 */
> +
>  #define SM_LOCAL_MODE_BITS    0600
>  #define SM_LOCAL_DIR_MODE_BITS    0700
>  
> diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
> index 2fce4140d1..957a7e4ccc 100644
> --- a/hw/9pfs/9p.h
> +++ b/hw/9pfs/9p.h
> @@ -3,13 +3,46 @@
>  
>  #include <dirent.h>
>  #include <utime.h>
> +#ifndef CONFIG_WIN32
>  #include <sys/resource.h>
> +#endif
>  #include "fsdev/file-op-9p.h"
>  #include "fsdev/9p-iov-marshal.h"
>  #include "qemu/thread.h"
>  #include "qemu/coroutine.h"
>  #include "qemu/qht.h"
>  
> +#ifdef CONFIG_WIN32
> +
> +#define NAME_MAX            MAX_PATH

That's not quite the same. MAX_PATH on Windows corresponds to PATH_MAX on
POSIX, which is the max. length of an entire path (i.e. drive, multiple
directory names, filename, backslashes). AFAICS MAX_PATH is 260 on Windows.

The max. length of a single filename component OTOH is 255 on Windows by
default. I don't know if there is a macro for the latter, if not, maybe
just hard coding it here for now?

> +
> +/* macros required for build, values do not matter */
> +#define AT_SYMLINK_NOFOLLOW 0x100   /* Do not follow symbolic links */
> +#define AT_REMOVEDIR        0x200   /* Remove directory instead of file */
> +#define O_DIRECTORY         02000000
> +
> +#define makedev(major, minor)   \
> +        ((dev_t)((((major) & 0xfff) << 8) | ((minor) & 0xff)))
> +#define major(dev)  ((unsigned int)(((dev) >> 8) & 0xfff))
> +#define minor(dev)  ((unsigned int)(((dev) & 0xff)))
> +
> +#ifndef S_IFLNK
> +/*
> + * Currenlty Windows/MinGW does not provide the following flag macros,
> + * so define them here for 9p codes.
> + *
> + * Once Windows/MinGW provides them, remove the defines to prevent conflicts.
> + */
> +#define S_IFLNK         0xA000
> +#define S_ISUID         0x0800
> +#define S_ISGID         0x0400
> +#define S_ISVTX         0x0200
> +
> +#define S_ISLNK(mode)   ((mode & S_IFMT) == S_IFLNK)
> +#endif /* S_IFLNK */
> +
> +#endif /* CONFIG_WIN32 */
> +
>  enum {
>      P9_TLERROR = 6,
>      P9_RLERROR,
>