[Spice-devel] [PATCH win-vdagent v2] Support file transfer for existing files

[Frediano Ziglio]

> 
> On Thu, 2017-04-27 at 15:20 -0500, Jonathon Jongsma wrote:
> > Previously, if the user attempted to transfer a file that had the
> > same
> > name as a file that already exists on the guest, we would just fail
> > the
> > transfer. This patch tries to match the behavior of the linux
> > vdagent
> > where we try to append an integer onto the name of the new file to
> > make
> > it unique. For example, if you tried to transfer 'file.doc' to the
> > guest
> > and that file already existed, it would try to create 'file (1).doc'
> > instead. If that also failed, it would attempt 'file (2).doc', etc,
> > up
> > to 63.
> > 
> > Resolves: rhbz#1410181
> > Signed-off-by: Jonathon Jongsma <jjongsma at redhat.com>
> > ---
> > Changes since v1:
> >  - change from "file.doc (1)" to "file (1).doc"
> >  - retain debug output for other CreateFile errors
> > 
> >  vdagent/file_xfer.cpp | 50
> > ++++++++++++++++++++++++++++++++++++++++++++------
> >  1 file changed, 44 insertions(+), 6 deletions(-)
> > 
> > diff --git a/vdagent/file_xfer.cpp b/vdagent/file_xfer.cpp
> > index f763ed3..24eb00a 100644
> > --- a/vdagent/file_xfer.cpp
> > +++ b/vdagent/file_xfer.cpp
> > @@ -61,6 +61,7 @@ void
> > FileXfer::handle_start(VDAgentFileXferStartMessage* start,
> >      HANDLE handle;
> >      AsUser as_user;
> >      int wlen;
> > +    int attempt = 0;
> >  
> >      status->id = start->id;
> >      status->result = VD_AGENT_FILE_XFER_STATUS_ERROR;
> > @@ -99,15 +100,52 @@ void
> > FileXfer::handle_start(VDAgentFileXferStartMessage* start,
> >  
> >      file_path[wlen++] = TEXT('\\');
> >      file_path[wlen] = TEXT('\0');
> > -    if((wlen = MultiByteToWideChar(CP_UTF8, 0, file_name, -1,
> > file_path + wlen, MAX_PATH - wlen)) == 0){
> > -        vd_printf("failed converting file_name:%s to WideChar",
> > file_name);
> > -        return;
> > +
> > +    const int MAX_ATTEMPTS = 64; // matches behavior of linux
> > vdagent
> > +    const size_t POSTFIX_LEN = 6; // up to 2 digits in parentheses
> > and final NULL: " (xx)"
> > +    size_t name_len = strlen(file_name);
> > +    char *extension = strrchr(file_name, '.');
> > +
> > +    for (attempt = 0; attempt < MAX_ATTEMPTS; attempt++) {
> > +        char dest_filename[MAX_PATH];
> > +        if (attempt == 0) {
> > +            strcpy(dest_filename, file_name);
> > +        } else {
> > +            if (name_len + POSTFIX_LEN > MAX_PATH) {
> > +                vd_printf("failed creating %ls. Postfix makes name
> > too long for the buffer.", file_path);
> > +                return;
> > +            }
> > +
> > +            int basename_len = (extension != NULL) ? (extension -
> > file_name) : name_len;
> > +            memcpy(dest_filename, file_name, basename_len);
> > +            // append postfix
> > +            int postfix_len = snprintf(dest_filename +
> > basename_len, POSTFIX_LEN, " (%d)", attempt);
> > +            if (extension != NULL) {
> > +                strcpy(dest_filename + basename_len + postfix_len,
> > extension);
> > +            }
> > +        }
> > +        if((MultiByteToWideChar(CP_UTF8, 0, dest_filename, -1,
> missing space^
> > file_path + wlen, MAX_PATH - wlen)) == 0){
>                                   and here ^
> > +            vd_printf("failed converting file_name:%s to WideChar",
> > dest_filename);
> > +            return;
> > +        }
> > +        handle = CreateFile(file_path, GENERIC_WRITE, 0, NULL,
> > CREATE_NEW, 0, NULL);
> > +        if (handle != INVALID_HANDLE_VALUE) {
> > +            break;
> > +        }
> > +
> > +        // If the file already exists, we can re-try with a new
> > filename. If
> > +        // it's a different error, there's not much we can do.
> > +        if (GetLastError() != ERROR_FILE_EXISTS) {
> > +            vd_printf("Failed creating %ls %lu", file_path,
> > GetLastError());
> > +            return;
> > +        }
> >      }
> > -    handle = CreateFile(file_path, GENERIC_WRITE, 0, NULL,
> > CREATE_NEW, 0, NULL);
> > -    if (handle == INVALID_HANDLE_VALUE) {
> > -        vd_printf("failed creating %ls %lu", file_path,
> > GetLastError());
> > +
> > +    if (attempt == MAX_ATTEMPTS) {
> > +        vd_printf("Failed creating %ls. More than 63 copies
> > exist?", file_path);
> >          return;
> >      }
> > +
> >      task = new FileXferTask(handle, file_size, file_path);
> >      _tasks[start->id] = task;
> >      status->result = VD_AGENT_FILE_XFER_STATUS_CAN_SEND_DATA;
> 
> looks good, ack
> 
> Pavel
> 

I would propose a version like


diff --git a/vdagent/file_xfer.cpp b/vdagent/file_xfer.cpp
index f763ed3..de1aea1 100644
--- a/vdagent/file_xfer.cpp
+++ b/vdagent/file_xfer.cpp
@@ -28,6 +28,8 @@
 #endif // compiler specific definitions
 
 #include <stdio.h>
+#include <spice/macros.h>
+
 #include "file_xfer.h"
 #include "as_user.h"
 
@@ -99,13 +101,40 @@ void FileXfer::handle_start(VDAgentFileXferStartMessage* start,
 
     file_path[wlen++] = TEXT('\\');
     file_path[wlen] = TEXT('\0');
-    if((wlen = MultiByteToWideChar(CP_UTF8, 0, file_name, -1, file_path + wlen, MAX_PATH - wlen)) == 0){
-        vd_printf("failed converting file_name:%s to WideChar", file_name);
-        return;
+
+    const int MAX_ATTEMPTS = 64; // matches behavior of linux vdagent
+    const size_t POSTFIX_LEN = 6; // up to 2 digits in parentheses and final NULL: " (xx)"
+    char *extension = strrchr(file_name, '.');
+    if (!extension)
+        extension = strchr(file_name, 0);
+
+    for (int attempt = 0; attempt < MAX_ATTEMPTS; attempt++) {
+        char dest_filename[SPICE_N_ELEMENTS(file_name) + POSTFIX_LEN];
+        if (attempt == 0) {
+            strcpy(dest_filename, file_name);
+        } else {
+            sprintf(dest_filename, "%.*s (%d)%s", int(extension - file_name), file_name,
+                    attempt, extension);
+        }
+        if ((MultiByteToWideChar(CP_UTF8, 0, dest_filename, -1, file_path + wlen, MAX_PATH - wlen)) == 0) {
+            vd_printf("failed converting file_name:%s to WideChar", dest_filename);
+            return;
+        }
+        handle = CreateFile(file_path, GENERIC_WRITE, 0, NULL, CREATE_NEW, 0, NULL);
+        if (handle != INVALID_HANDLE_VALUE) {
+            break;
+        }
+
+        // If the file already exists, we can re-try with a new filename. If
+        // it's a different error, there's not much we can do.
+        if (GetLastError() != ERROR_FILE_EXISTS) {
+            vd_printf("Failed creating %ls %lu", file_path, GetLastError());
+            return;
+        }
     }
-    handle = CreateFile(file_path, GENERIC_WRITE, 0, NULL, CREATE_NEW, 0, NULL);
+
     if (handle == INVALID_HANDLE_VALUE) {
-        vd_printf("failed creating %ls %lu", file_path, GetLastError());
+        vd_printf("Failed creating %ls. More than 63 copies exist?", file_path);
         return;
     }
     task = new FileXferTask(handle, file_size, file_path);


is more similar to the way is proposed in Unix version of the agent

Frediano