Currently, the win32 port of QEMU Guest Agent does not properly handle Unicode
paths. The JSON decoder produces a valid UTF-8 path string, but this is passed
directly to CreateFileA, which is expecting an ANSI string and not UTF-8. This
leads to mangled filenames.

This patch follows the example of qmp_guest_set_user_password() and uses
g_utf8_to_utf16() to convert the string to UTF-16 and calls CreateFileW()
explicitly.

Signed-off-by: Jonathon Reinhart <jreinhart@cc-sw.com>
---
 qga/commands-win32.c | 24 +++++++++++++++++++-----
 1 file changed, 19 insertions(+), 5 deletions(-)

diff --git a/qga/commands-win32.c b/qga/commands-win32.c
index 98d9735389..416343b97b 100644
--- a/qga/commands-win32.c
+++ b/qga/commands-win32.c
@@ -160,13 +160,15 @@ static void handle_set_nonblocking(HANDLE fh)
 int64_t qmp_guest_file_open(const char *path, bool has_mode,
                             const char *mode, Error **errp)
 {
-    int64_t fd;
+    int64_t fd = -1;
     HANDLE fh;
     HANDLE templ_file = NULL;
     DWORD share_mode = FILE_SHARE_READ;
     DWORD flags_and_attr = FILE_ATTRIBUTE_NORMAL;
     LPSECURITY_ATTRIBUTES sa_attr = NULL;
     OpenFlags *guest_flags;
+    GError *gerr = NULL;
+    wchar_t *w_path = NULL;

     if (!has_mode) {
         mode = "r";
@@ -175,16 +177,21 @@ int64_t qmp_guest_file_open(const char *path,
bool has_mode,
     guest_flags = find_open_flag(mode);
     if (guest_flags == NULL) {
         error_setg(errp, "invalid file open mode");
-        return -1;
+        goto done;
+    }
+
+    w_path = g_utf8_to_utf16(path, -1, NULL, NULL, &gerr);
+    if (!w_path) {
+        goto done;
     }

-    fh = CreateFile(path, guest_flags->desired_access, share_mode, sa_attr,
+    fh = CreateFileW(w_path, guest_flags->desired_access, share_mode, sa_attr,
                     guest_flags->creation_disposition, flags_and_attr,
                     templ_file);
     if (fh == INVALID_HANDLE_VALUE) {
         error_setg_win32(errp, GetLastError(), "failed to open file '%s'",
                          path);
-        return -1;
+        goto done;
     }

     /* set fd non-blocking to avoid common use cases (like reading from a
@@ -196,10 +203,17 @@ int64_t qmp_guest_file_open(const char *path,
bool has_mode,
     if (fd < 0) {
         CloseHandle(fh);
         error_setg(errp, "failed to add handle to qmp handle table");
-        return -1;
+        goto done;
     }

     slog("guest-file-open, handle: % " PRId64, fd);
+
+done:
+    if (gerr) {
+        error_setg(errp, QERR_QGA_COMMAND_FAILED, gerr->message);
+        g_error_free(gerr);
+    }
+    g_free(w_path);
     return fd;
 }

-- 
2.11.0

Quoting Jonathon Reinhart (2018-08-01 18:10:59)
> Currently, the win32 port of QEMU Guest Agent does not properly handle Unicode
> paths. The JSON decoder produces a valid UTF-8 path string, but this is passed
> directly to CreateFileA, which is expecting an ANSI string and not UTF-8. This
> leads to mangled filenames.
> 
> This patch follows the example of qmp_guest_set_user_password() and uses
> g_utf8_to_utf16() to convert the string to UTF-16 and calls CreateFileW()
> explicitly.
> 
> Signed-off-by: Jonathon Reinhart <jreinhart@cc-sw.com>
> ---
>  qga/commands-win32.c | 24 +++++++++++++++++++-----
>  1 file changed, 19 insertions(+), 5 deletions(-)
> 
> diff --git a/qga/commands-win32.c b/qga/commands-win32.c
> index 98d9735389..416343b97b 100644
> --- a/qga/commands-win32.c
> +++ b/qga/commands-win32.c
> @@ -160,13 +160,15 @@ static void handle_set_nonblocking(HANDLE fh)
>  int64_t qmp_guest_file_open(const char *path, bool has_mode,
>                              const char *mode, Error **errp)
>  {
> -    int64_t fd;
> +    int64_t fd = -1;
>      HANDLE fh;
>      HANDLE templ_file = NULL;
>      DWORD share_mode = FILE_SHARE_READ;
>      DWORD flags_and_attr = FILE_ATTRIBUTE_NORMAL;
>      LPSECURITY_ATTRIBUTES sa_attr = NULL;
>      OpenFlags *guest_flags;
> +    GError *gerr = NULL;
> +    wchar_t *w_path = NULL;
> 
>      if (!has_mode) {
>          mode = "r";
> @@ -175,16 +177,21 @@ int64_t qmp_guest_file_open(const char *path,
> bool has_mode,

It looks like your mail client might be wrapping patches at 80 char,
which makes them not apply on my end. I've fixed this one up and
applied it though:

  https://github.com/mdroth/qemu/commits/qga

>      guest_flags = find_open_flag(mode);
>      if (guest_flags == NULL) {
>          error_setg(errp, "invalid file open mode");
> -        return -1;
> +        goto done;
> +    }
> +
> +    w_path = g_utf8_to_utf16(path, -1, NULL, NULL, &gerr);
> +    if (!w_path) {
> +        goto done;
>      }
> 
> -    fh = CreateFile(path, guest_flags->desired_access, share_mode, sa_attr,
> +    fh = CreateFileW(w_path, guest_flags->desired_access, share_mode, sa_attr,
>                      guest_flags->creation_disposition, flags_and_attr,
>                      templ_file);
>      if (fh == INVALID_HANDLE_VALUE) {
>          error_setg_win32(errp, GetLastError(), "failed to open file '%s'",
>                           path);
> -        return -1;
> +        goto done;
>      }
> 
>      /* set fd non-blocking to avoid common use cases (like reading from a
> @@ -196,10 +203,17 @@ int64_t qmp_guest_file_open(const char *path,
> bool has_mode,
>      if (fd < 0) {
>          CloseHandle(fh);
>          error_setg(errp, "failed to add handle to qmp handle table");
> -        return -1;
> +        goto done;
>      }
> 
>      slog("guest-file-open, handle: % " PRId64, fd);
> +
> +done:
> +    if (gerr) {
> +        error_setg(errp, QERR_QGA_COMMAND_FAILED, gerr->message);
> +        g_error_free(gerr);
> +    }
> +    g_free(w_path);
>      return fd;
>  }
> 
> -- 
> 2.11.0
>