Add wxFile::{Get,Clear}LastError() functions.

Remember the errno of the last file operation instead of just remembering
whether there was an error or not.

See #12636.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66150 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

docs/changes.txt

@@ -408,6 +408,7 @@ All:
 - Added cwd and env arguments to wxExecute() (Emilien Kia).
 - Added "rest" argument to wxString::Before{First,Last}().
 - Added wxThread::OnKill() and OnDelete() callbacks.
+- Added wxFile::GetLastError() and ClearLastError() (ryazanov).
 
 All (GUI):
 

include/wx/file.h

@@ -49,11 +49,11 @@ public:
   // ctors
   // -----
     // def ctor
-  wxFile() { m_fd = fd_invalid; m_error = false; }
+  wxFile() { m_fd = fd_invalid; m_lasterror = 0; }
     // open specified file (may fail, use IsOpened())
   wxFile(const wxString& fileName, OpenMode mode = read);
     // attach to (already opened) file
-  wxFile(int lfd) { m_fd = lfd; m_error = false; }
+  wxFile(int lfd) { m_fd = lfd; m_lasterror = 0; }
 
   // open/close
     // create a new file (with the default value of bOverwrite, it will fail if
@@ -65,7 +65,7 @@ public:
   bool Close();  // Close is a NOP if not opened
 
   // assign an existing file descriptor and get it back from wxFile object
-  void Attach(int lfd) { Close(); m_fd = lfd; m_error = false; }
+  void Attach(int lfd) { Close(); m_fd = lfd; m_lasterror = 0; }
   void Detach()       { m_fd = fd_invalid;  }
   int  fd() const { return m_fd; }
 
@@ -95,10 +95,15 @@ public:
     // is end of file reached?
   bool Eof() const;
     // has an error occurred?
-  bool Error() const { return m_error; }
+  bool Error() const { return m_lasterror != 0; }
+    // get last errno
+  int GetLastError() const { return m_lasterror; }
+    // reset error state
+  void ClearLastError() { m_lasterror = 0; }
     // type such as disk or pipe
   wxFileKind GetKind() const { return wxGetFileKind(m_fd); }
 
+
   // dtor closes the file if opened
   ~wxFile() { Close(); }
 
@@ -109,8 +114,16 @@ private:
   wxFile(const wxFile&);
   wxFile& operator=(const wxFile&);
 
+  // Copy the value of errno into m_lasterror if rc == -1 and return true in
+  // this case (indicating that we've got an error). Otherwise return false.
+  //
+  // Notice that we use the possibly 64 bit wxFileOffset instead of int here so
+  // that it works for checking the result of functions such as tell() too.
+  bool CheckForError(wxFileOffset rc) const;
+
+
   int m_fd; // file descriptor or INVALID_FD if not opened
-  bool m_error; // error memory
+  int m_lasterror; // errno value of last error
 };
 
 // ----------------------------------------------------------------------------

interface/wx/file.h

@@ -231,6 +231,32 @@ public:
     */
     ~wxFile();
 
+    /**
+        Returns the error code for the last unsuccessful operation.
+
+        The error code is system-dependent and corresponds to the value of the
+        standard @c errno variable when the last error occurred.
+
+        Notice that only simple accessors such as IsOpened() and Eof() (and
+        this method itself) don't modify the last error value, all other
+        methods can potentially change it if an error occurs, including the
+        const ones such as Tell() or Length().
+
+        @since 2.9.2
+
+        @see ClearLastError()
+    */
+    int GetLastError() const;
+
+    /**
+        Resets the error code.
+
+        GetLastError() will return 0 until the next error occurs.
+
+        @since 2.9.2
+    */
+    void ClearLastError();
+
     /**
         This function verifies if we may access the given file in specified mode.
         Only values of @c wxFile::read or @c wxFile::write really make sense here.

src/common/file.cpp

@@ -88,6 +88,10 @@
 
 #include  <stdio.h>       // SEEK_xxx constants
 
+#ifndef __WXWINCE__
+    #include <errno.h>
+#endif
+
 // Windows compilers don't have these constants
 #ifndef W_OK
     enum
@@ -176,11 +180,27 @@ bool wxFile::Access(const wxString& name, OpenMode mode)
 wxFile::wxFile(const wxString& fileName, OpenMode mode)
 {
     m_fd = fd_invalid;
-    m_error = false;
+    m_lasterror = 0;
 
     Open(fileName, mode);
 }
 
+bool wxFile::CheckForError(wxFileOffset rc) const
+{
+    if ( rc != -1 )
+        return false;
+
+    const_cast<wxFile *>(this)->m_lasterror =
+#ifndef __WXWINCE__
+                                                errno
+#else
+                                                ::GetLastError()
+#endif
+                                                ;
+
+    return true;
+}
+
 // create the file, fail if it already exists and bOverwrite
 bool wxFile::Create(const wxString& fileName, bool bOverwrite, int accessMode)
 {
@@ -190,7 +210,7 @@ bool wxFile::Create(const wxString& fileName, bool bOverwrite, int accessMode)
                      O_BINARY | O_WRONLY | O_CREAT |
                      (bOverwrite ? O_TRUNC : O_EXCL),
                      accessMode );
-    if ( fd == -1 )
+    if ( CheckForError(fd) )
     {
         wxLogSysError(_("can't create file '%s'"), fileName);
         return false;
@@ -242,7 +262,7 @@ bool wxFile::Open(const wxString& fileName, OpenMode mode, int accessMode)
 
     int fd = wxOpen( fileName, flags, accessMode);
 
-    if ( fd == -1 )
+    if ( CheckForError(fd) )
     {
         wxLogSysError(_("can't open file '%s'"), fileName);
         return false;
@@ -256,7 +276,7 @@ bool wxFile::Open(const wxString& fileName, OpenMode mode, int accessMode)
 bool wxFile::Close()
 {
     if ( IsOpened() ) {
-        if (wxClose(m_fd) == -1)
+        if ( CheckForError(wxClose(m_fd)) )
         {
             wxLogSysError(_("can't close file descriptor %d"), m_fd);
             m_fd = fd_invalid;
@@ -280,7 +300,7 @@ ssize_t wxFile::Read(void *pBuf, size_t nCount)
 
     ssize_t iRc = wxRead(m_fd, pBuf, nCount);
 
-    if ( iRc == -1 )
+    if ( CheckForError(iRc) )
     {
         wxLogSysError(_("can't read from file descriptor %d"), m_fd);
         return wxInvalidOffset;
@@ -296,10 +316,9 @@ size_t wxFile::Write(const void *pBuf, size_t nCount)
 
     ssize_t iRc = wxWrite(m_fd, pBuf, nCount);
 
-    if ( iRc == -1 )
+    if ( CheckForError(iRc) )
     {
         wxLogSysError(_("can't write to file descriptor %d"), m_fd);
-        m_error = true;
         iRc = 0;
     }
 
@@ -329,7 +348,7 @@ bool wxFile::Flush()
     // call it then
     if ( IsOpened() && GetKind() == wxFILE_KIND_DISK )
     {
-        if ( wxFsync(m_fd) == -1 )
+        if ( CheckForError(wxFsync(m_fd)) )
         {
             wxLogSysError(_("can't flush file descriptor %d"), m_fd);
             return false;
@@ -371,7 +390,7 @@ wxFileOffset wxFile::Seek(wxFileOffset ofs, wxSeekMode mode)
     }
 
     wxFileOffset iRc = wxSeek(m_fd, ofs, origin);
-    if ( iRc == wxInvalidOffset )
+    if ( CheckForError(iRc) )
     {
         wxLogSysError(_("can't seek on file descriptor %d"), m_fd);
     }
@@ -385,7 +404,7 @@ wxFileOffset wxFile::Tell() const
     wxASSERT( IsOpened() );
 
     wxFileOffset iRc = wxTell(m_fd);
-    if ( iRc == wxInvalidOffset )
+    if ( CheckForError(iRc) )
     {
         wxLogSysError(_("can't get seek position on file descriptor %d"), m_fd);
     }
@@ -429,6 +448,7 @@ wxFileOffset wxFile::Length() const
 
     if ( iRc == wxInvalidOffset )
     {
+        // last error was already set by Tell()
         wxLogSysError(_("can't find length of file on file descriptor %d"), m_fd);
     }