diff --git a/dlls/msvcirt/msvcirt.c b/dlls/msvcirt/msvcirt.c
index 0b2fadfb1cb..cd0e7c57d1c 100644
--- a/dlls/msvcirt/msvcirt.c
+++ b/dlls/msvcirt/msvcirt.c
@@ -117,6 +117,12 @@ typedef struct {
     freeFunction f_free;
 } strstreambuf;
 
+/* class stdiobuf */
+typedef struct {
+    streambuf base;
+    FILE *file;
+} stdiobuf;
+
 /* class ios */
 struct _ostream;
 typedef struct {
@@ -153,6 +159,8 @@ extern const vtable_ptr MSVCP_streambuf_vtable;
 extern const vtable_ptr MSVCP_filebuf_vtable;
 /* ??_7strstreambuf@@6B@ */
 extern const vtable_ptr MSVCP_strstreambuf_vtable;
+/* ??_7stdiobuf@@6B@ */
+extern const vtable_ptr MSVCP_stdiobuf_vtable;
 /* ??_7ios@@6B@ */
 extern const vtable_ptr MSVCP_ios_vtable;
 
@@ -195,6 +203,18 @@ void __asm_dummy_vtables(void) {
             VTABLE_ADD_FUNC(strstreambuf_underflow)
             VTABLE_ADD_FUNC(streambuf_pbackfail)
             VTABLE_ADD_FUNC(strstreambuf_doallocate));
+    __ASM_VTABLE(stdiobuf,
+            VTABLE_ADD_FUNC(stdiobuf_vector_dtor)
+            VTABLE_ADD_FUNC(stdiobuf_sync)
+            VTABLE_ADD_FUNC(streambuf_setbuf)
+            VTABLE_ADD_FUNC(stdiobuf_seekoff)
+            VTABLE_ADD_FUNC(streambuf_seekpos)
+            VTABLE_ADD_FUNC(streambuf_xsputn)
+            VTABLE_ADD_FUNC(streambuf_xsgetn)
+            VTABLE_ADD_FUNC(stdiobuf_overflow)
+            VTABLE_ADD_FUNC(stdiobuf_underflow)
+            VTABLE_ADD_FUNC(stdiobuf_pbackfail)
+            VTABLE_ADD_FUNC(streambuf_doallocate));
     __ASM_VTABLE(ios,
             VTABLE_ADD_FUNC(ios_vector_dtor));
 #ifndef __GNUC__
@@ -204,6 +224,7 @@ void __asm_dummy_vtables(void) {
 DEFINE_RTTI_DATA0(streambuf, 0, ".?AVstreambuf@@")
 DEFINE_RTTI_DATA1(filebuf, 0, &streambuf_rtti_base_descriptor, ".?AVfilebuf@@")
 DEFINE_RTTI_DATA1(strstreambuf, 0, &streambuf_rtti_base_descriptor, ".?AVstrstreambuf@@")
+DEFINE_RTTI_DATA1(stdiobuf, 0, &streambuf_rtti_base_descriptor, ".?AVstdiobuf@@")
 DEFINE_RTTI_DATA0(ios, 0, ".?AVios@@")
 
 /* ??0streambuf@@IAE@PADH@Z */
@@ -1434,6 +1455,134 @@ int __thiscall strstreambuf_underflow(strstreambuf *this)
     return (this->base.gptr < this->base.egptr) ? *this->base.gptr : EOF;
 }
 
+/* ??0stdiobuf@@QAE@ABV0@@Z */
+/* ??0stdiobuf@@QEAA@AEBV0@@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_copy_ctor, 8)
+stdiobuf* __thiscall stdiobuf_copy_ctor(stdiobuf *this, const stdiobuf *copy)
+{
+    FIXME("(%p %p) stub\n", this, copy);
+    return this;
+}
+
+/* ??0stdiobuf@@QAE@PAU_iobuf@@@Z */
+/* ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_file_ctor, 8)
+stdiobuf* __thiscall stdiobuf_file_ctor(stdiobuf *this, FILE *file)
+{
+    FIXME("(%p %p) stub\n", this, file);
+    return this;
+}
+
+/* ??1stdiobuf@@UAE@XZ */
+/* ??1stdiobuf@@UEAA@XZ */
+DEFINE_THISCALL_WRAPPER(stdiobuf_dtor, 4)
+void __thiscall stdiobuf_dtor(stdiobuf *this)
+{
+    FIXME("(%p) stub\n", this);
+}
+
+/* ??4stdiobuf@@QAEAAV0@ABV0@@Z */
+/* ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_assign, 8)
+stdiobuf* __thiscall stdiobuf_assign(stdiobuf *this, const stdiobuf *rhs)
+{
+    stdiobuf_dtor(this);
+    return stdiobuf_copy_ctor(this, rhs);
+}
+
+/* ??_Estdiobuf@@UAEPAXI@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_vector_dtor, 8)
+stdiobuf* __thiscall stdiobuf_vector_dtor(stdiobuf *this, unsigned int flags)
+{
+    TRACE("(%p %x)\n", this, flags);
+    if (flags & 2) {
+        /* we have an array, with the number of elements stored before the first object */
+        INT_PTR i, *ptr = (INT_PTR *)this-1;
+
+        for (i = *ptr-1; i >= 0; i--)
+            stdiobuf_dtor(this+i);
+        MSVCRT_operator_delete(ptr);
+    } else {
+        stdiobuf_dtor(this);
+        if (flags & 1)
+            MSVCRT_operator_delete(this);
+    }
+    return this;
+}
+
+/* ??_Gstdiobuf@@UAEPAXI@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_scalar_dtor, 8)
+stdiobuf* __thiscall stdiobuf_scalar_dtor(stdiobuf *this, unsigned int flags)
+{
+    TRACE("(%p %x)\n", this, flags);
+    stdiobuf_dtor(this);
+    if (flags & 1) MSVCRT_operator_delete(this);
+    return this;
+}
+
+/* ?overflow@stdiobuf@@UAEHH@Z */
+/* ?overflow@stdiobuf@@UEAAHH@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_overflow, 8)
+int __thiscall stdiobuf_overflow(stdiobuf *this, int c)
+{
+    FIXME("(%p %d) stub\n", this, c);
+    return EOF;
+}
+
+/* ?pbackfail@stdiobuf@@UAEHH@Z */
+/* ?pbackfail@stdiobuf@@UEAAHH@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_pbackfail, 8)
+int __thiscall stdiobuf_pbackfail(stdiobuf *this, int c)
+{
+    FIXME("(%p %d) stub\n", this, c);
+    return EOF;
+}
+
+/* ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z */
+/* ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_seekoff, 16)
+streampos __thiscall stdiobuf_seekoff(stdiobuf *this, streamoff offset, ios_seek_dir dir, int mode)
+{
+    FIXME("(%p %d %d %d) stub\n", this, offset, dir, mode);
+    return EOF;
+}
+
+/* ?setrwbuf@stdiobuf@@QAEHHH@Z */
+/* ?setrwbuf@stdiobuf@@QEAAHHH@Z */
+DEFINE_THISCALL_WRAPPER(stdiobuf_setrwbuf, 12)
+int __thiscall stdiobuf_setrwbuf(stdiobuf *this, int read_size, int write_size)
+{
+    FIXME("(%p %d %d) stub\n", this, read_size, write_size);
+    return EOF;
+}
+
+/* ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ */
+/* ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ */
+DEFINE_THISCALL_WRAPPER(stdiobuf_stdiofile, 4)
+FILE* __thiscall stdiobuf_stdiofile(stdiobuf *this)
+{
+    FIXME("(%p) stub\n", this);
+    return NULL;
+}
+
+/* ?sync@stdiobuf@@UAEHXZ */
+/* ?sync@stdiobuf@@UEAAHXZ */
+DEFINE_THISCALL_WRAPPER(stdiobuf_sync, 4)
+int __thiscall stdiobuf_sync(stdiobuf *this)
+{
+    FIXME("(%p) stub\n", this);
+    return EOF;
+}
+
+/* ?underflow@stdiobuf@@UAEHXZ */
+/* ?underflow@stdiobuf@@UEAAHXZ */
+DEFINE_THISCALL_WRAPPER(stdiobuf_underflow, 4)
+int __thiscall stdiobuf_underflow(stdiobuf *this)
+{
+    FIXME("(%p) stub\n", this);
+    return EOF;
+}
+
 /* ??0ios@@IAE@ABV0@@Z */
 /* ??0ios@@IEAA@AEBV0@@Z */
 DEFINE_THISCALL_WRAPPER(ios_copy_ctor, 8)
@@ -2098,6 +2247,7 @@ static void init_io(void *base)
     init_streambuf_rtti(base);
     init_filebuf_rtti(base);
     init_strstreambuf_rtti(base);
+    init_stdiobuf_rtti(base);
     init_ios_rtti(base);
 #endif
 }
diff --git a/dlls/msvcirt/msvcirt.spec b/dlls/msvcirt/msvcirt.spec
index 4b448ba5d02..032667296e3 100644
--- a/dlls/msvcirt/msvcirt.spec
+++ b/dlls/msvcirt/msvcirt.spec
@@ -98,10 +98,10 @@
 @ stub -arch=win64 ??0ostrstream@@QEAA@PEADHH@Z
 @ thiscall -arch=win32 ??0ostrstream@@QAE@XZ(ptr long) MSVCIRT_ostrstream_ctor
 @ cdecl -arch=win64 ??0ostrstream@@QEAA@XZ(ptr long) MSVCIRT_ostrstream_ctor
-@ stub -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z  # __thiscall stdiobuf::stdiobuf(class stdiobuf const &)
-@ stub -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z
-@ stub -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z  # __thiscall stdiobuf::stdiobuf(struct _iobuf *)
-@ stub -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z(ptr ptr) stdiobuf_copy_ctor
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z(ptr ptr) stdiobuf_copy_ctor
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z(ptr ptr) stdiobuf_file_ctor
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z(ptr ptr) stdiobuf_file_ctor
 @ stub -arch=win32 ??0stdiostream@@QAE@ABV0@@Z  # __thiscall stdiostream::stdiostream(class stdiostream const &)
 @ stub -arch=win64 ??0stdiostream@@QEAA@AEBV0@@Z
 @ stub -arch=win32 ??0stdiostream@@QAE@PAU_iobuf@@@Z  # __thiscall stdiostream::stdiostream(struct _iobuf *)
@@ -160,8 +160,8 @@
 @ stub -arch=win64 ??1ostream_withassign@@UEAA@XZ
 @ thiscall -arch=win32 ??1ostrstream@@UAE@XZ(ptr) MSVCIRT_ostrstream_dtor
 @ cdecl -arch=win64 ??1ostrstream@@UEAA@XZ(ptr) MSVCIRT_ostrstream_dtor
-@ stub -arch=win32 ??1stdiobuf@@UAE@XZ  # virtual __thiscall stdiobuf::~stdiobuf(void)
-@ stub -arch=win64 ??1stdiobuf@@UEAA@XZ
+@ thiscall -arch=win32 ??1stdiobuf@@UAE@XZ(ptr) stdiobuf_dtor
+@ cdecl -arch=win64 ??1stdiobuf@@UEAA@XZ(ptr) stdiobuf_dtor
 @ stub -arch=win32 ??1stdiostream@@UAE@XZ  # virtual __thiscall stdiostream::~stdiostream(void)
 @ stub -arch=win64 ??1stdiostream@@UEAA@XZ
 @ thiscall -arch=win32 ??1streambuf@@UAE@XZ(ptr) streambuf_dtor
@@ -214,8 +214,8 @@
 @ stub -arch=win64 ??4ostream_withassign@@QEAAAEAVostream@@PEAVstreambuf@@@Z
 @ stub -arch=win32 ??4ostrstream@@QAEAAV0@ABV0@@Z  # class ostrstream & __thiscall ostrstream::operator=(class ostrstream const &)
 @ stub -arch=win64 ??4ostrstream@@QEAAAEAV0@AEBV0@@Z
-@ stub -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z  # class stdiobuf & __thiscall stdiobuf::operator=(class stdiobuf const &)
-@ stub -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z(ptr ptr) stdiobuf_assign
+@ cdecl -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z(ptr ptr) stdiobuf_assign
 @ stub -arch=win32 ??4stdiostream@@QAEAAV0@AAV0@@Z  # class stdiostream & __thiscall stdiostream::operator=(class stdiostream &)
 @ stub -arch=win64 ??4stdiostream@@QEAAAEAV0@AEAV0@@Z
 @ thiscall -arch=win32 ??4streambuf@@QAEAAV0@ABV0@@Z(ptr ptr) streambuf_assign
@@ -316,7 +316,7 @@
 # @ extern ??_7ostream@@6B@  # const ostream::`vftable'
 # @ extern ??_7ostream_withassign@@6B@  # const ostream_withassign::`vftable'
 # @ extern ??_7ostrstream@@6B@  # const ostrstream::`vftable'
-# @ extern ??_7stdiobuf@@6B@  # const stdiobuf::`vftable'
+@ extern ??_7stdiobuf@@6B@ MSVCP_stdiobuf_vtable
 # @ extern ??_7stdiostream@@6B@  # const stdiostream::`vftable'
 @ extern ??_7streambuf@@6B@ MSVCP_streambuf_vtable
 # @ extern ??_7strstream@@6B@  # const strstream::`vftable'
@@ -375,7 +375,7 @@
 @ stub -arch=win32 ??_Eostream@@UAEPAXI@Z  # virtual void * __thiscall ostream::`vector deleting destructor'(unsigned int)
 @ stub -arch=win32 ??_Eostream_withassign@@UAEPAXI@Z  # virtual void * __thiscall ostream_withassign::`vector deleting destructor'(unsigned int)
 @ stub -arch=win32 ??_Eostrstream@@UAEPAXI@Z  # virtual void * __thiscall ostrstream::`vector deleting destructor'(unsigned int)
-@ stub -arch=win32 ??_Estdiobuf@@UAEPAXI@Z  # virtual void * __thiscall stdiobuf::`vector deleting destructor'(unsigned int)
+@ thiscall -arch=win32 ??_Estdiobuf@@UAEPAXI@Z(ptr long) stdiobuf_vector_dtor
 @ stub -arch=win32 ??_Estdiostream@@UAEPAXI@Z  # virtual void * __thiscall stdiostream::`vector deleting destructor'(unsigned int)
 @ thiscall -arch=win32 ??_Estreambuf@@UAEPAXI@Z(ptr long) streambuf_vector_dtor
 @ stub -arch=win32 ??_Estrstream@@UAEPAXI@Z  # virtual void * __thiscall strstream::`vector deleting destructor'(unsigned int)
@@ -394,7 +394,7 @@
 @ stub -arch=win32 ??_Gostream@@UAEPAXI@Z  # virtual void * __thiscall ostream::`scalar deleting destructor'(unsigned int)
 @ stub -arch=win32 ??_Gostream_withassign@@UAEPAXI@Z  # virtual void * __thiscall ostream_withassign::`scalar deleting destructor'(unsigned int)
 @ stub -arch=win32 ??_Gostrstream@@UAEPAXI@Z  # virtual void * __thiscall ostrstream::`scalar deleting destructor'(unsigned int)
-@ stub -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z  # virtual void * __thiscall stdiobuf::`scalar deleting destructor'(unsigned int)
+@ thiscall -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z(ptr long) stdiobuf_scalar_dtor
 @ stub -arch=win32 ??_Gstdiostream@@UAEPAXI@Z  # virtual void * __thiscall stdiostream::`scalar deleting destructor'(unsigned int)
 @ thiscall -arch=win32 ??_Gstreambuf@@UAEPAXI@Z(ptr long) streambuf_scalar_dtor
 @ stub -arch=win32 ??_Gstrstream@@UAEPAXI@Z  # virtual void * __thiscall strstream::`scalar deleting destructor'(unsigned int)
@@ -579,12 +579,12 @@
 @ cdecl -arch=win64 ?out_waiting@streambuf@@QEBAHXZ(ptr) streambuf_out_waiting
 @ thiscall -arch=win32 ?overflow@filebuf@@UAEHH@Z(ptr long) filebuf_overflow
 @ cdecl -arch=win64 ?overflow@filebuf@@UEAAHH@Z(ptr long) filebuf_overflow
-@ stub -arch=win32 ?overflow@stdiobuf@@UAEHH@Z  # virtual int __thiscall stdiobuf::overflow(int)
-@ stub -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?overflow@stdiobuf@@UAEHH@Z(ptr long) stdiobuf_overflow
+@ cdecl -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z(ptr long) stdiobuf_overflow
 @ thiscall -arch=win32 ?overflow@strstreambuf@@UAEHH@Z(ptr long) strstreambuf_overflow
 @ cdecl -arch=win64 ?overflow@strstreambuf@@UEAAHH@Z(ptr long) strstreambuf_overflow
-@ stub -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z  # virtual int __thiscall stdiobuf::pbackfail(int)
-@ stub -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z(ptr long) stdiobuf_pbackfail
+@ cdecl -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z(ptr long) stdiobuf_pbackfail
 @ thiscall -arch=win32 ?pbackfail@streambuf@@UAEHH@Z(ptr long) streambuf_pbackfail
 @ cdecl -arch=win64 ?pbackfail@streambuf@@UEAAHH@Z(ptr long) streambuf_pbackfail
 @ thiscall -arch=win32 ?pbase@streambuf@@IBEPADXZ(ptr) streambuf_pbase
@@ -645,8 +645,8 @@
 @ stub -arch=win64 ?seekg@istream@@QEAAAEAV1@JW4seek_dir@ios@@@Z
 @ thiscall -arch=win32 ?seekoff@filebuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) filebuf_seekoff
 @ cdecl -arch=win64 ?seekoff@filebuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) filebuf_seekoff
-@ stub -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z  # virtual long __thiscall stdiobuf::seekoff(long,enum ios::seek_dir,int)
-@ stub -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z
+@ thiscall -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) stdiobuf_seekoff
+@ cdecl -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) stdiobuf_seekoff
 @ thiscall -arch=win32 ?seekoff@streambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) streambuf_seekoff
 @ cdecl -arch=win64 ?seekoff@streambuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) streambuf_seekoff
 @ thiscall -arch=win32 ?seekoff@strstreambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) strstreambuf_seekoff
@@ -691,8 +691,8 @@
 @ stub -arch=win64 ?setmode@ofstream@@QEAAHH@Z
 @ thiscall -arch=win32 ?setp@streambuf@@IAEXPAD0@Z(ptr ptr ptr) streambuf_setp
 @ cdecl -arch=win64 ?setp@streambuf@@IEAAXPEAD0@Z(ptr ptr ptr) streambuf_setp
-@ stub -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z  # int __thiscall stdiobuf::setrwbuf(int,int)
-@ stub -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z
+@ thiscall -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z(ptr long long) stdiobuf_setrwbuf
+@ cdecl -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z(ptr long long) stdiobuf_setrwbuf
 @ thiscall -arch=win32 ?sgetc@streambuf@@QAEHXZ(ptr) streambuf_sgetc
 @ cdecl -arch=win64 ?sgetc@streambuf@@QEAAHXZ(ptr) streambuf_sgetc
 @ thiscall -arch=win32 ?sgetn@streambuf@@QAEHPADH@Z(ptr ptr long) streambuf_sgetn
@@ -708,8 +708,8 @@
 @ cdecl -arch=win64 ?sputc@streambuf@@QEAAHH@Z(ptr long) streambuf_sputc
 @ thiscall -arch=win32 ?sputn@streambuf@@QAEHPBDH@Z(ptr str long) streambuf_sputn
 @ cdecl -arch=win64 ?sputn@streambuf@@QEAAHPEBDH@Z(ptr str long) streambuf_sputn
-@ stub -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ  # struct _iobuf * __thiscall stdiobuf::stdiofile(void)
-@ stub -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ
+@ thiscall -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ(ptr) stdiobuf_stdiofile
+@ cdecl -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ(ptr) stdiobuf_stdiofile
 @ thiscall -arch=win32 ?stossc@streambuf@@QAEXXZ(ptr) streambuf_stossc
 @ cdecl -arch=win64 ?stossc@streambuf@@QEAAXXZ(ptr) streambuf_stossc
 @ stub -arch=win32 ?str@istrstream@@QAEPADXZ  # char * __thiscall istrstream::str(void)
@@ -725,8 +725,8 @@
 @ cdecl -arch=win64 ?sync@filebuf@@UEAAHXZ(ptr) filebuf_sync
 @ stub -arch=win32 ?sync@istream@@QAEHXZ  # int __thiscall istream::sync(void)
 @ stub -arch=win64 ?sync@istream@@QEAAHXZ
-@ stub -arch=win32 ?sync@stdiobuf@@UAEHXZ  # virtual int __thiscall stdiobuf::sync(void)
-@ stub -arch=win64 ?sync@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?sync@stdiobuf@@UAEHXZ(ptr) stdiobuf_sync
+@ cdecl -arch=win64 ?sync@stdiobuf@@UEAAHXZ(ptr) stdiobuf_sync
 @ thiscall -arch=win32 ?sync@streambuf@@UAEHXZ(ptr) streambuf_sync
 @ cdecl -arch=win64 ?sync@streambuf@@UEAAHXZ(ptr) streambuf_sync
 @ thiscall -arch=win32 ?sync@strstreambuf@@UAEHXZ(ptr) strstreambuf_sync
@@ -747,8 +747,8 @@
 @ cdecl -arch=win64 ?unbuffered@streambuf@@IEBAHXZ(ptr) streambuf_unbuffered_get
 @ thiscall -arch=win32 ?underflow@filebuf@@UAEHXZ(ptr) filebuf_underflow
 @ cdecl -arch=win64 ?underflow@filebuf@@UEAAHXZ(ptr) filebuf_underflow
-@ stub -arch=win32 ?underflow@stdiobuf@@UAEHXZ  # virtual int __thiscall stdiobuf::underflow(void)
-@ stub -arch=win64 ?underflow@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?underflow@stdiobuf@@UAEHXZ(ptr) stdiobuf_underflow
+@ cdecl -arch=win64 ?underflow@stdiobuf@@UEAAHXZ(ptr) stdiobuf_underflow
 @ thiscall -arch=win32 ?underflow@strstreambuf@@UAEHXZ(ptr) strstreambuf_underflow
 @ cdecl -arch=win64 ?underflow@strstreambuf@@UEAAHXZ(ptr) strstreambuf_underflow
 @ cdecl -arch=win32 ?unlock@ios@@QAAXXZ(ptr) ios_unlock
diff --git a/dlls/msvcrt20/msvcrt20.spec b/dlls/msvcrt20/msvcrt20.spec
index 53ef34c7599..368e8a13723 100644
--- a/dlls/msvcrt20/msvcrt20.spec
+++ b/dlls/msvcrt20/msvcrt20.spec
@@ -88,10 +88,10 @@
 @ stub -arch=win64 ??0ostrstream@@QEAA@PEADHH@Z
 @ thiscall -arch=win32 ??0ostrstream@@QAE@XZ(ptr long) msvcirt.??0ostrstream@@QAE@XZ
 @ cdecl -arch=win64 ??0ostrstream@@QEAA@XZ(ptr long) msvcirt.??0ostrstream@@QEAA@XZ
-@ stub -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z
-@ stub -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z
-@ stub -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z
-@ stub -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z(ptr ptr) msvcirt.??0stdiobuf@@QAE@ABV0@@Z
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z(ptr ptr) msvcirt.??0stdiobuf@@QEAA@AEBV0@@Z
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z(ptr ptr) msvcirt.??0stdiobuf@@QAE@PAU_iobuf@@@Z
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z(ptr ptr) msvcirt.??0stdiobuf@@QEAA@PEAU_iobuf@@@Z
 @ stub -arch=win32 ??0stdiostream@@QAE@ABV0@@Z
 @ stub -arch=win64 ??0stdiostream@@QEAA@AEBV0@@Z
 @ stub -arch=win32 ??0stdiostream@@QAE@PAU_iobuf@@@Z
@@ -144,8 +144,8 @@
 @ stub -arch=win64 ??1ostream_withassign@@UEAA@XZ
 @ thiscall -arch=win32 ??1ostrstream@@UAE@XZ(ptr) msvcirt.??1ostrstream@@UAE@XZ
 @ cdecl -arch=win64 ??1ostrstream@@UEAA@XZ(ptr) msvcirt.??1ostrstream@@UEAA@XZ
-@ stub -arch=win32 ??1stdiobuf@@UAE@XZ
-@ stub -arch=win64 ??1stdiobuf@@UEAA@XZ
+@ thiscall -arch=win32 ??1stdiobuf@@UAE@XZ(ptr) msvcirt.??1stdiobuf@@UAE@XZ
+@ cdecl -arch=win64 ??1stdiobuf@@UEAA@XZ(ptr) msvcirt.??1stdiobuf@@UEAA@XZ
 @ stub -arch=win32 ??1stdiostream@@UAE@XZ
 @ stub -arch=win64 ??1stdiostream@@UEAA@XZ
 @ thiscall -arch=win32 ??1streambuf@@UAE@XZ(ptr) msvcirt.??1streambuf@@UAE@XZ
@@ -198,8 +198,8 @@
 @ stub -arch=win64 ??4ostream_withassign@@QEAAAEAVostream@@PEAVstreambuf@@@Z
 @ stub -arch=win32 ??4ostrstream@@QAEAAV0@ABV0@@Z
 @ stub -arch=win64 ??4ostrstream@@QEAAAEAV0@AEBV0@@Z
-@ stub -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z
-@ stub -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4stdiobuf@@QAEAAV0@ABV0@@Z
+@ cdecl -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcirt.??4stdiobuf@@QEAAAEAV0@AEBV0@@Z
 @ stub -arch=win32 ??4stdiostream@@QAEAAV0@AAV0@@Z
 @ stub -arch=win64 ??4stdiostream@@QEAAAEAV0@AEAV0@@Z
 @ thiscall -arch=win32 ??4streambuf@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4streambuf@@QAEAAV0@ABV0@@Z
@@ -298,7 +298,7 @@
 # @ extern ??_7ostream@@6B@
 # @ extern ??_7ostream_withassign@@6B@
 # @ extern ??_7ostrstream@@6B@
-# @ extern ??_7stdiobuf@@6B@
+@ extern ??_7stdiobuf@@6B@ msvcirt.??_7stdiobuf@@6B@
 # @ extern ??_7stdiostream@@6B@
 @ extern ??_7streambuf@@6B@ msvcirt.??_7streambuf@@6B@
 # @ extern ??_7strstream@@6B@
@@ -356,7 +356,7 @@
 @ stub -arch=win32 ??_Eostream@@UAEPAXI@Z
 @ stub -arch=win32 ??_Eostream_withassign@@UAEPAXI@Z
 @ stub -arch=win32 ??_Eostrstream@@UAEPAXI@Z
-@ stub -arch=win32 ??_Estdiobuf@@UAEPAXI@Z
+@ thiscall -arch=win32 ??_Estdiobuf@@UAEPAXI@Z(ptr long) msvcirt.??_Estdiobuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Estdiostream@@UAEPAXI@Z
 @ thiscall -arch=win32 ??_Estreambuf@@UAEPAXI@Z(ptr long) msvcirt.??_Estreambuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Estrstream@@UAEPAXI@Z
@@ -374,7 +374,7 @@
 @ stub -arch=win32 ??_Gostream@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gostream_withassign@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gostrstream@@UAEPAXI@Z
-@ stub -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z
+@ thiscall -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z(ptr long) msvcirt.??_Gstdiobuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gstdiostream@@UAEPAXI@Z
 @ thiscall -arch=win32 ??_Gstreambuf@@UAEPAXI@Z(ptr long) msvcirt.??_Gstreambuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gstrstream@@UAEPAXI@Z
@@ -565,12 +565,12 @@
 @ cdecl -arch=win64 ?out_waiting@streambuf@@QEBAHXZ(ptr) msvcirt.?out_waiting@streambuf@@QEBAHXZ
 @ thiscall -arch=win32 ?overflow@filebuf@@UAEHH@Z(ptr long) msvcirt.?overflow@filebuf@@UAEHH@Z
 @ cdecl -arch=win64 ?overflow@filebuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@filebuf@@UEAAHH@Z
-@ stub -arch=win32 ?overflow@stdiobuf@@UAEHH@Z
-@ stub -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?overflow@stdiobuf@@UAEHH@Z(ptr long) msvcirt.?overflow@stdiobuf@@UAEHH@Z
+@ cdecl -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@stdiobuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?overflow@strstreambuf@@UAEHH@Z(ptr long) msvcirt.?overflow@strstreambuf@@UAEHH@Z
 @ cdecl -arch=win64 ?overflow@strstreambuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@strstreambuf@@UEAAHH@Z
-@ stub -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z
-@ stub -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z(ptr long) msvcirt.?pbackfail@stdiobuf@@UAEHH@Z
+@ cdecl -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z(ptr long) msvcirt.?pbackfail@stdiobuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?pbackfail@streambuf@@UAEHH@Z(ptr long) msvcirt.?pbackfail@streambuf@@UAEHH@Z
 @ cdecl -arch=win64 ?pbackfail@streambuf@@UEAAHH@Z(ptr long) msvcirt.?pbackfail@streambuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?pbase@streambuf@@IBEPADXZ(ptr) msvcirt.?pbase@streambuf@@IBEPADXZ
@@ -631,8 +631,8 @@
 @ stub -arch=win64 ?seekg@istream@@QEAAAEAV1@JW4seek_dir@ios@@@Z
 @ thiscall -arch=win32 ?seekoff@filebuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@filebuf@@UAEJJW4seek_dir@ios@@H@Z
 @ cdecl -arch=win64 ?seekoff@filebuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@filebuf@@UEAAJJW4seek_dir@ios@@H@Z
-@ stub -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z
-@ stub -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z
+@ thiscall -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z
+@ cdecl -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z
 @ thiscall -arch=win32 ?seekoff@streambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@streambuf@@UAEJJW4seek_dir@ios@@H@Z
 @ cdecl -arch=win64 ?seekoff@streambuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@streambuf@@UEAAJJW4seek_dir@ios@@H@Z
 @ thiscall -arch=win32 ?seekoff@strstreambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@strstreambuf@@UAEJJW4seek_dir@ios@@H@Z
@@ -679,8 +679,8 @@
 @ stub -arch=win64 ?setmode@ofstream@@QEAAHH@Z
 @ thiscall -arch=win32 ?setp@streambuf@@IAEXPAD0@Z(ptr ptr ptr) msvcirt.?setp@streambuf@@IAEXPAD0@Z
 @ cdecl -arch=win64 ?setp@streambuf@@IEAAXPEAD0@Z(ptr ptr ptr) msvcirt.?setp@streambuf@@IEAAXPEAD0@Z
-@ stub -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z
-@ stub -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z
+@ thiscall -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z(ptr long long) msvcirt.?setrwbuf@stdiobuf@@QAEHHH@Z
+@ cdecl -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z(ptr long long) msvcirt.?setrwbuf@stdiobuf@@QEAAHHH@Z
 @ thiscall -arch=win32 ?sgetc@streambuf@@QAEHXZ(ptr) msvcirt.?sgetc@streambuf@@QAEHXZ
 @ cdecl -arch=win64 ?sgetc@streambuf@@QEAAHXZ(ptr) msvcirt.?sgetc@streambuf@@QEAAHXZ
 @ thiscall -arch=win32 ?sgetn@streambuf@@QAEHPADH@Z(ptr ptr long) msvcirt.?sgetn@streambuf@@QAEHPADH@Z
@@ -696,8 +696,8 @@
 @ cdecl -arch=win64 ?sputc@streambuf@@QEAAHH@Z(ptr long) msvcirt.?sputc@streambuf@@QEAAHH@Z
 @ thiscall -arch=win32 ?sputn@streambuf@@QAEHPBDH@Z(ptr str long) msvcirt.?sputn@streambuf@@QAEHPBDH@Z
 @ cdecl -arch=win64 ?sputn@streambuf@@QEAAHPEBDH@Z(ptr str long) msvcirt.?sputn@streambuf@@QEAAHPEBDH@Z
-@ stub -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ
-@ stub -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ
+@ thiscall -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ(ptr) msvcirt.?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ
+@ cdecl -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ(ptr) msvcirt.?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ
 @ thiscall -arch=win32 ?stossc@streambuf@@QAEXXZ(ptr) msvcirt.?stossc@streambuf@@QAEXXZ
 @ cdecl -arch=win64 ?stossc@streambuf@@QEAAXXZ(ptr) msvcirt.?stossc@streambuf@@QEAAXXZ
 @ stub -arch=win32 ?str@istrstream@@QAEPADXZ
@@ -713,8 +713,8 @@
 @ cdecl -arch=win64 ?sync@filebuf@@UEAAHXZ(ptr) msvcirt.?sync@filebuf@@UEAAHXZ
 @ stub -arch=win32 ?sync@istream@@QAEHXZ
 @ stub -arch=win64 ?sync@istream@@QEAAHXZ
-@ stub -arch=win32 ?sync@stdiobuf@@UAEHXZ
-@ stub -arch=win64 ?sync@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?sync@stdiobuf@@UAEHXZ(ptr) msvcirt.?sync@stdiobuf@@UAEHXZ
+@ cdecl -arch=win64 ?sync@stdiobuf@@UEAAHXZ(ptr) msvcirt.?sync@stdiobuf@@UEAAHXZ
 @ thiscall -arch=win32 ?sync@streambuf@@UAEHXZ(ptr) msvcirt.?sync@streambuf@@UAEHXZ
 @ cdecl -arch=win64 ?sync@streambuf@@UEAAHXZ(ptr) msvcirt.?sync@streambuf@@UEAAHXZ
 @ thiscall -arch=win32 ?sync@strstreambuf@@UAEHXZ(ptr) msvcirt.?sync@strstreambuf@@UAEHXZ
@@ -736,8 +736,8 @@
 @ cdecl -arch=win64 ?unbuffered@streambuf@@IEBAHXZ(ptr) msvcirt.?unbuffered@streambuf@@IEBAHXZ
 @ thiscall -arch=win32 ?underflow@filebuf@@UAEHXZ(ptr) msvcirt.?underflow@filebuf@@UAEHXZ
 @ cdecl -arch=win64 ?underflow@filebuf@@UEAAHXZ(ptr) msvcirt.?underflow@filebuf@@UEAAHXZ
-@ stub -arch=win32 ?underflow@stdiobuf@@UAEHXZ
-@ stub -arch=win64 ?underflow@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?underflow@stdiobuf@@UAEHXZ(ptr) msvcirt.?underflow@stdiobuf@@UAEHXZ
+@ cdecl -arch=win64 ?underflow@stdiobuf@@UEAAHXZ(ptr) msvcirt.?underflow@stdiobuf@@UEAAHXZ
 @ thiscall -arch=win32 ?underflow@strstreambuf@@UAEHXZ(ptr) msvcirt.?underflow@strstreambuf@@UAEHXZ
 @ cdecl -arch=win64 ?underflow@strstreambuf@@UEAAHXZ(ptr) msvcirt.?underflow@strstreambuf@@UEAAHXZ
 @ cdecl ?unexpected@@YAXXZ() msvcrt.?unexpected@@YAXXZ
diff --git a/dlls/msvcrt40/msvcrt40.spec b/dlls/msvcrt40/msvcrt40.spec
index 4a220ba6071..828165ceff1 100644
--- a/dlls/msvcrt40/msvcrt40.spec
+++ b/dlls/msvcrt40/msvcrt40.spec
@@ -110,10 +110,10 @@
 @ stub -arch=win64 ??0ostrstream@@QEAA@PEADHH@Z
 @ thiscall -arch=win32 ??0ostrstream@@QAE@XZ(ptr long) msvcirt.??0ostrstream@@QAE@XZ
 @ cdecl -arch=win64 ??0ostrstream@@QEAA@XZ(ptr long) msvcirt.??0ostrstream@@QEAA@XZ
-@ stub -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z
-@ stub -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z
-@ stub -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z
-@ stub -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@ABV0@@Z(ptr ptr) msvcirt.??0stdiobuf@@QAE@ABV0@@Z
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@AEBV0@@Z(ptr ptr) msvcirt.??0stdiobuf@@QEAA@AEBV0@@Z
+@ thiscall -arch=win32 ??0stdiobuf@@QAE@PAU_iobuf@@@Z(ptr ptr) msvcirt.??0stdiobuf@@QAE@PAU_iobuf@@@Z
+@ cdecl -arch=win64 ??0stdiobuf@@QEAA@PEAU_iobuf@@@Z(ptr ptr) msvcirt.??0stdiobuf@@QEAA@PEAU_iobuf@@@Z
 @ stub -arch=win32 ??0stdiostream@@QAE@ABV0@@Z
 @ stub -arch=win64 ??0stdiostream@@QEAA@AEBV0@@Z
 @ stub -arch=win32 ??0stdiostream@@QAE@PAU_iobuf@@@Z
@@ -176,8 +176,8 @@
 @ stub -arch=win64 ??1ostream_withassign@@UEAA@XZ
 @ thiscall -arch=win32 ??1ostrstream@@UAE@XZ(ptr) msvcirt.??1ostrstream@@UAE@XZ
 @ cdecl -arch=win64 ??1ostrstream@@UEAA@XZ(ptr) msvcirt.??1ostrstream@@UEAA@XZ
-@ stub -arch=win32 ??1stdiobuf@@UAE@XZ
-@ stub -arch=win64 ??1stdiobuf@@UEAA@XZ
+@ thiscall -arch=win32 ??1stdiobuf@@UAE@XZ(ptr) msvcirt.??1stdiobuf@@UAE@XZ
+@ cdecl -arch=win64 ??1stdiobuf@@UEAA@XZ(ptr) msvcirt.??1stdiobuf@@UEAA@XZ
 @ stub -arch=win32 ??1stdiostream@@UAE@XZ
 @ stub -arch=win64 ??1stdiostream@@UEAA@XZ
 @ thiscall -arch=win32 ??1streambuf@@UAE@XZ(ptr) msvcirt.??1streambuf@@UAE@XZ
@@ -242,8 +242,8 @@
 @ stub -arch=win64 ??4ostream_withassign@@QEAAAEAVostream@@PEAVstreambuf@@@Z
 @ stub -arch=win32 ??4ostrstream@@QAEAAV0@ABV0@@Z
 @ stub -arch=win64 ??4ostrstream@@QEAAAEAV0@AEBV0@@Z
-@ stub -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z
-@ stub -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z
+@ thiscall -arch=win32 ??4stdiobuf@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4stdiobuf@@QAEAAV0@ABV0@@Z
+@ cdecl -arch=win64 ??4stdiobuf@@QEAAAEAV0@AEBV0@@Z(ptr ptr) msvcirt.??4stdiobuf@@QEAAAEAV0@AEBV0@@Z
 @ stub -arch=win32 ??4stdiostream@@QAEAAV0@AAV0@@Z
 @ stub -arch=win64 ??4stdiostream@@QEAAAEAV0@AEAV0@@Z
 @ thiscall -arch=win32 ??4streambuf@@QAEAAV0@ABV0@@Z(ptr ptr) msvcirt.??4streambuf@@QAEAAV0@ABV0@@Z
@@ -351,7 +351,7 @@
 # @ extern ??_7ostream@@6B@
 # @ extern ??_7ostream_withassign@@6B@
 # @ extern ??_7ostrstream@@6B@
-# @ extern ??_7stdiobuf@@6B@
+@ extern ??_7stdiobuf@@6B@ msvcirt.??_7stdiobuf@@6B@
 # @ extern ??_7stdiostream@@6B@
 @ extern ??_7streambuf@@6B@ msvcirt.??_7streambuf@@6B@
 # @ extern ??_7strstream@@6B@
@@ -414,7 +414,7 @@
 @ stub -arch=win32 ??_Eostream@@UAEPAXI@Z
 @ stub -arch=win32 ??_Eostream_withassign@@UAEPAXI@Z
 @ stub -arch=win32 ??_Eostrstream@@UAEPAXI@Z
-@ stub -arch=win32 ??_Estdiobuf@@UAEPAXI@Z
+@ thiscall -arch=win32 ??_Estdiobuf@@UAEPAXI@Z(ptr long) msvcirt.??_Estdiobuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Estdiostream@@UAEPAXI@Z
 @ thiscall -arch=win32 ??_Estreambuf@@UAEPAXI@Z(ptr long) msvcirt.??_Estreambuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Estrstream@@UAEPAXI@Z
@@ -437,7 +437,7 @@
 @ stub -arch=win32 ??_Gostream@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gostream_withassign@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gostrstream@@UAEPAXI@Z
-@ stub -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z
+@ thiscall -arch=win32 ??_Gstdiobuf@@UAEPAXI@Z(ptr long) msvcirt.??_Gstdiobuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gstdiostream@@UAEPAXI@Z
 @ thiscall -arch=win32 ??_Gstreambuf@@UAEPAXI@Z(ptr long) msvcirt.??_Gstreambuf@@UAEPAXI@Z
 @ stub -arch=win32 ??_Gstrstream@@UAEPAXI@Z
@@ -634,12 +634,12 @@
 @ cdecl -arch=win64 ?out_waiting@streambuf@@QEBAHXZ(ptr) msvcirt.?out_waiting@streambuf@@QEBAHXZ
 @ thiscall -arch=win32 ?overflow@filebuf@@UAEHH@Z(ptr long) msvcirt.?overflow@filebuf@@UAEHH@Z
 @ cdecl -arch=win64 ?overflow@filebuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@filebuf@@UEAAHH@Z
-@ stub -arch=win32 ?overflow@stdiobuf@@UAEHH@Z
-@ stub -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?overflow@stdiobuf@@UAEHH@Z(ptr long) msvcirt.?overflow@stdiobuf@@UAEHH@Z
+@ cdecl -arch=win64 ?overflow@stdiobuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@stdiobuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?overflow@strstreambuf@@UAEHH@Z(ptr long) msvcirt.?overflow@strstreambuf@@UAEHH@Z
 @ cdecl -arch=win64 ?overflow@strstreambuf@@UEAAHH@Z(ptr long) msvcirt.?overflow@strstreambuf@@UEAAHH@Z
-@ stub -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z
-@ stub -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z
+@ thiscall -arch=win32 ?pbackfail@stdiobuf@@UAEHH@Z(ptr long) msvcirt.?pbackfail@stdiobuf@@UAEHH@Z
+@ cdecl -arch=win64 ?pbackfail@stdiobuf@@UEAAHH@Z(ptr long) msvcirt.?pbackfail@stdiobuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?pbackfail@streambuf@@UAEHH@Z(ptr long) msvcirt.?pbackfail@streambuf@@UAEHH@Z
 @ cdecl -arch=win64 ?pbackfail@streambuf@@UEAAHH@Z(ptr long) msvcirt.?pbackfail@streambuf@@UEAAHH@Z
 @ thiscall -arch=win32 ?pbase@streambuf@@IBEPADXZ(ptr) msvcirt.?pbase@streambuf@@IBEPADXZ
@@ -702,8 +702,8 @@
 @ stub -arch=win64 ?seekg@istream@@QEAAAEAV1@JW4seek_dir@ios@@@Z
 @ thiscall -arch=win32 ?seekoff@filebuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@filebuf@@UAEJJW4seek_dir@ios@@H@Z
 @ cdecl -arch=win64 ?seekoff@filebuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@filebuf@@UEAAJJW4seek_dir@ios@@H@Z
-@ stub -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z
-@ stub -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z
+@ thiscall -arch=win32 ?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@stdiobuf@@UAEJJW4seek_dir@ios@@H@Z
+@ cdecl -arch=win64 ?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@stdiobuf@@UEAAJJW4seek_dir@ios@@H@Z
 @ thiscall -arch=win32 ?seekoff@streambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@streambuf@@UAEJJW4seek_dir@ios@@H@Z
 @ cdecl -arch=win64 ?seekoff@streambuf@@UEAAJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@streambuf@@UEAAJJW4seek_dir@ios@@H@Z
 @ thiscall -arch=win32 ?seekoff@strstreambuf@@UAEJJW4seek_dir@ios@@H@Z(ptr long long long) msvcirt.?seekoff@strstreambuf@@UAEJJW4seek_dir@ios@@H@Z
@@ -751,8 +751,8 @@
 @ stub -arch=win64 ?setmode@ofstream@@QEAAHH@Z
 @ thiscall -arch=win32 ?setp@streambuf@@IAEXPAD0@Z(ptr ptr ptr) msvcirt.?setp@streambuf@@IAEXPAD0@Z
 @ cdecl -arch=win64 ?setp@streambuf@@IEAAXPEAD0@Z(ptr ptr ptr) msvcirt.?setp@streambuf@@IEAAXPEAD0@Z
-@ stub -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z
-@ stub -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z
+@ thiscall -arch=win32 ?setrwbuf@stdiobuf@@QAEHHH@Z(ptr long long) msvcirt.?setrwbuf@stdiobuf@@QAEHHH@Z
+@ cdecl -arch=win64 ?setrwbuf@stdiobuf@@QEAAHHH@Z(ptr long long) msvcirt.?setrwbuf@stdiobuf@@QEAAHHH@Z
 @ thiscall -arch=win32 ?sgetc@streambuf@@QAEHXZ(ptr) msvcirt.?sgetc@streambuf@@QAEHXZ
 @ cdecl -arch=win64 ?sgetc@streambuf@@QEAAHXZ(ptr) msvcirt.?sgetc@streambuf@@QEAAHXZ
 @ thiscall -arch=win32 ?sgetn@streambuf@@QAEHPADH@Z(ptr ptr long) msvcirt.?sgetn@streambuf@@QAEHPADH@Z
@@ -768,8 +768,8 @@
 @ cdecl -arch=win64 ?sputc@streambuf@@QEAAHH@Z(ptr long) msvcirt.?sputc@streambuf@@QEAAHH@Z
 @ thiscall -arch=win32 ?sputn@streambuf@@QAEHPBDH@Z(ptr str long) msvcirt.?sputn@streambuf@@QAEHPBDH@Z
 @ cdecl -arch=win64 ?sputn@streambuf@@QEAAHPEBDH@Z(ptr str long) msvcirt.?sputn@streambuf@@QEAAHPEBDH@Z
-@ stub -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ
-@ stub -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ
+@ thiscall -arch=win32 ?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ(ptr) msvcirt.?stdiofile@stdiobuf@@QAEPAU_iobuf@@XZ
+@ cdecl -arch=win64 ?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ(ptr) msvcirt.?stdiofile@stdiobuf@@QEAAPEAU_iobuf@@XZ
 @ thiscall -arch=win32 ?stossc@streambuf@@QAEXXZ(ptr) msvcirt.?stossc@streambuf@@QAEXXZ
 @ cdecl -arch=win64 ?stossc@streambuf@@QEAAXXZ(ptr) msvcirt.?stossc@streambuf@@QEAAXXZ
 @ stub -arch=win32 ?str@istrstream@@QAEPADXZ
@@ -785,8 +785,8 @@
 @ cdecl -arch=win64 ?sync@filebuf@@UEAAHXZ(ptr) msvcirt.?sync@filebuf@@UEAAHXZ
 @ stub -arch=win32 ?sync@istream@@QAEHXZ
 @ stub -arch=win64 ?sync@istream@@QEAAHXZ
-@ stub -arch=win32 ?sync@stdiobuf@@UAEHXZ
-@ stub -arch=win64 ?sync@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?sync@stdiobuf@@UAEHXZ(ptr) msvcirt.?sync@stdiobuf@@UAEHXZ
+@ cdecl -arch=win64 ?sync@stdiobuf@@UEAAHXZ(ptr) msvcirt.?sync@stdiobuf@@UEAAHXZ
 @ thiscall -arch=win32 ?sync@streambuf@@UAEHXZ(ptr) msvcirt.?sync@streambuf@@UAEHXZ
 @ cdecl -arch=win64 ?sync@streambuf@@UEAAHXZ(ptr) msvcirt.?sync@streambuf@@UEAAHXZ
 @ thiscall -arch=win32 ?sync@strstreambuf@@UAEHXZ(ptr) msvcirt.?sync@strstreambuf@@UAEHXZ
@@ -808,8 +808,8 @@
 @ cdecl -arch=win64 ?unbuffered@streambuf@@IEBAHXZ(ptr) msvcirt.?unbuffered@streambuf@@IEBAHXZ
 @ thiscall -arch=win32 ?underflow@filebuf@@UAEHXZ(ptr) msvcirt.?underflow@filebuf@@UAEHXZ
 @ cdecl -arch=win64 ?underflow@filebuf@@UEAAHXZ(ptr) msvcirt.?underflow@filebuf@@UEAAHXZ
-@ stub -arch=win32 ?underflow@stdiobuf@@UAEHXZ
-@ stub -arch=win64 ?underflow@stdiobuf@@UEAAHXZ
+@ thiscall -arch=win32 ?underflow@stdiobuf@@UAEHXZ(ptr) msvcirt.?underflow@stdiobuf@@UAEHXZ
+@ cdecl -arch=win64 ?underflow@stdiobuf@@UEAAHXZ(ptr) msvcirt.?underflow@stdiobuf@@UEAAHXZ
 @ thiscall -arch=win32 ?underflow@strstreambuf@@UAEHXZ(ptr) msvcirt.?underflow@strstreambuf@@UAEHXZ
 @ cdecl -arch=win64 ?underflow@strstreambuf@@UEAAHXZ(ptr) msvcirt.?underflow@strstreambuf@@UEAAHXZ
 @ cdecl ?unexpected@@YAXXZ() msvcrt.?unexpected@@YAXXZ