Re: [PATCH 09/19] index-helper: add Windows support

[Duy Nguyen <pclouds@gmail.com>]

I think it's safe to drop this patch now. It's mostly to prove that it
could work on Windows. But I don't think it's tested a lot (even I
only occasionally test it under wine).

On Thu, Mar 10, 2016 at 1:36 AM, David Turner <dturner@twopensource.com> wrote:
> From: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
>
> Windows supports shared memory, but the semantics is a bit different
> than POSIX shm. The most noticeable thing is there's no way to get the
> shared memory's size by the reader, and wrapping fstat to do that
> would be hell. So the shm size is added near the end, hidden away from
> shm users (storing it in headers would cause more problems with munmap,
> storing it as a separate shm is even worse).
>
> PostMessage is used instead of UNIX signals for
> notification. Lightweight (at least code-wise) on the client side.
>
> Signed-off-by: Nguyễn Thái Ngọc Duy <pclouds@gmail.com>
> ---
>  config.mak.uname |  2 ++
>  index-helper.c   | 48 ++++++++++++++++++++++++++++
>  read-cache.c     | 13 ++++++++
>  shm.c            | 96 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
>  4 files changed, 159 insertions(+)
>
> diff --git a/config.mak.uname b/config.mak.uname
> index b5108e1..49320c7 100644
> --- a/config.mak.uname
> +++ b/config.mak.uname
> @@ -394,6 +394,7 @@ ifndef DEBUG
>  else
>         BASIC_CFLAGS += -Zi -MDd
>  endif
> +       PROGRAM_OBJS += index-helper.o
>         X = .exe
>  endif
>  ifeq ($(uname_S),Interix)
> @@ -574,6 +575,7 @@ else
>                 NO_CURL = YesPlease
>         endif
>  endif
> +       PROGRAM_OBJS += index-helper.o
>  endif
>  ifeq ($(uname_S),QNX)
>         COMPAT_CFLAGS += -DSA_RESTART=0
> diff --git a/index-helper.c b/index-helper.c
> index 4dd9656..cf26da7 100644
> --- a/index-helper.c
> +++ b/index-helper.c
> @@ -155,6 +155,51 @@ static void loop(const char *pid_file, int idle_in_seconds)
>                 ; /* do nothing, all is handled by signal handlers already */
>  }
>
> +#elif defined(GIT_WINDOWS_NATIVE)
> +
> +static void loop(const char *pid_file, int idle_in_seconds)
> +{
> +       HWND hwnd;
> +       UINT_PTR timer = 0;
> +       MSG msg;
> +       HINSTANCE hinst = GetModuleHandle(NULL);
> +       WNDCLASS wc;
> +
> +       /*
> +        * Emulate UNIX signals by sending WM_USER+x to a
> +        * window. Register window class and create a new window to
> +        * catch these messages.
> +        */
> +       memset(&wc, 0, sizeof(wc));
> +       wc.lpfnWndProc   = DefWindowProc;
> +       wc.hInstance     = hinst;
> +       wc.lpszClassName = "git-index-helper";
> +       if (!RegisterClass(&wc))
> +               die_errno(_("could not register new window class"));
> +
> +       hwnd = CreateWindow("git-index-helper", pid_file,
> +                           0, 0, 0, 1, 1, NULL, NULL, hinst, NULL);
> +       if (!hwnd)
> +               die_errno(_("could not register new window"));
> +
> +       refresh(0);
> +       while (1) {
> +               timer = SetTimer(hwnd, timer, idle_in_seconds * 1000, NULL);
> +               if (!timer)
> +                       die(_("no timer!"));
> +               if (!GetMessage(&msg, hwnd, 0, 0) || msg.message == WM_TIMER)
> +                       break;
> +               switch (msg.message) {
> +               case WM_USER:
> +                       refresh(0);
> +                       break;
> +               default:
> +                       /* just reset the timer */
> +                       break;
> +               }
> +       }
> +}
> +
>  #else
>
>  static void loop(const char *pid_file, int idle_in_seconds)
> @@ -198,6 +243,9 @@ int main(int argc, char **argv)
>         fd = hold_lock_file_for_update(&lock,
>                                        git_path("index-helper.pid"),
>                                        LOCK_DIE_ON_ERROR);
> +#ifdef GIT_WINDOWS_NATIVE
> +       strbuf_addstr(&sb, "HWND");
> +#endif
>         strbuf_addf(&sb, "%" PRIuMAX, (uintmax_t) getpid());
>         write_in_full(fd, sb.buf, sb.len);
>         commit_lock_file(&lock);
> diff --git a/read-cache.c b/read-cache.c
> index 1a0ab0c..16fbdf6 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -1546,6 +1546,18 @@ static void post_read_index_from(struct index_state *istate)
>         tweak_untracked_cache(istate);
>  }
>
> +#if defined(GIT_WINDOWS_NATIVE)
> +static void do_poke(struct strbuf *sb, int refresh_cache)
> +{
> +       HWND hwnd;
> +       if (!starts_with(sb->buf, "HWND"))
> +               return;
> +       hwnd = FindWindow("git-index-helper", sb->buf);
> +       if (!hwnd)
> +               return;
> +       PostMessage(hwnd, refresh_cache ? WM_USER : WM_USER + 1, 0, 0);
> +}
> +#else
>  static void do_poke(struct strbuf *sb, int refresh_cache)
>  {
>         char    *start = sb->buf;
> @@ -1555,6 +1567,7 @@ static void do_poke(struct strbuf *sb, int refresh_cache)
>                 return;
>         kill(pid, refresh_cache ? SIGHUP : SIGUSR1);
>  }
> +#endif
>
>  static void poke_daemon(struct index_state *istate,
>                         const struct stat *st, int refresh_cache)
> diff --git a/shm.c b/shm.c
> index 4ec1a00..04d8a35 100644
> --- a/shm.c
> +++ b/shm.c
> @@ -52,6 +52,102 @@ void git_shm_unlink(const char *fmt, ...)
>         shm_unlink(path);
>  }
>
> +#elif defined(GIT_WINDOWS_NATIVE)
> +
> +#define SHM_PATH_LEN 82        /* a little bit longer than POSIX because of "Local\\" */
> +
> +static ssize_t create_shm_map(int oflag, int perm, ssize_t length,
> +                             void **mmap, int prot, int flags,
> +                             const char *path, unsigned long page_size)
> +{
> +       size_t real_length;
> +       void *last_page;
> +       HANDLE h;
> +
> +       assert(perm   == 0700);
> +       assert(oflag  == (O_CREAT | O_EXCL | O_RDWR));
> +       assert(prot   == (PROT_READ | PROT_WRITE));
> +       assert(flags  == MAP_SHARED);
> +       assert(length >= 0);
> +
> +       real_length = length;
> +       if (real_length % page_size)
> +               real_length += page_size - (real_length % page_size);
> +       real_length += page_size;
> +       h = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0,
> +                             real_length, path);
> +       if (!h)
> +               return -1;
> +       *mmap = MapViewOfFile(h, FILE_MAP_ALL_ACCESS, 0, 0, real_length);
> +       CloseHandle(h);
> +       if (!*mmap)
> +               return -1;
> +       last_page = (unsigned char *)*mmap + real_length - page_size;
> +       *(unsigned long *)last_page = length;
> +       return length;
> +}
> +
> +static ssize_t open_shm_map(int oflag, int perm, ssize_t length, void **mmap,
> +                           int prot, int flags, const char *path,
> +                           unsigned long page_size)
> +{
> +       void *last_page;
> +       HANDLE h;
> +
> +       assert(perm   == 0700);
> +       assert(oflag  == O_RDONLY);
> +       assert(prot   == PROT_READ);
> +       assert(flags  == MAP_SHARED);
> +       assert(length <= 0);
> +
> +       h = OpenFileMapping(FILE_MAP_READ, FALSE, path);
> +       if (!h)
> +               return -1;
> +       *mmap = MapViewOfFile(h, FILE_MAP_READ, 0, 0, 0);
> +       CloseHandle(h);
> +       if (!*mmap)
> +               return -1;
> +       if (length < 0) {
> +               MEMORY_BASIC_INFORMATION mbi;
> +               if (!VirtualQuery(*mmap, &mbi, sizeof(mbi))) {
> +                       UnmapViewOfFile(*mmap);
> +                       return -1;
> +               }
> +               if (mbi.RegionSize % page_size)
> +                       die("expected size %lu to be %lu aligned",
> +                                   mbi.RegionSize, page_size);
> +               last_page = (unsigned char *)*mmap + mbi.RegionSize - page_size;
> +               length = *(unsigned long *)last_page;
> +       }
> +       return length;
> +}
> +
> +ssize_t git_shm_map(int oflag, int perm, ssize_t length, void **mmap,
> +                   int prot, int flags, const char *fmt, ...)
> +{
> +       SYSTEM_INFO si;
> +       va_list ap;
> +       char path[SHM_PATH_LEN];
> +
> +       GetSystemInfo(&si);
> +
> +       strcpy(path, "Local\\");
> +       va_start(ap, fmt);
> +       vsprintf(path + strlen(path), fmt, ap);
> +       va_end(ap);
> +
> +       if (oflag & O_CREAT)
> +               return create_shm_map(oflag, perm, length, mmap, prot,
> +                                     flags, path, si.dwPageSize);
> +       else
> +               return open_shm_map(oflag, perm, length, mmap, prot,
> +                                   flags, path, si.dwPageSize);
> +}
> +
> +void git_shm_unlink(const char *fmt, ...)
> +{
> +}
> +
>  #else
>
>  ssize_t git_shm_map(int oflag, int perm, ssize_t length, void **mmap,
> --
> 2.4.2.767.g62658d5-twtrsrc
>



-- 
Duy