01/04: [SDK] Do not use a NUL file while calculating format string length CORE-14342

[Mark Jansen]

https://git.reactos.org/?p=reactos.git;a=commitdiff;h=2f548599a4b9e33eeec79…

commit 2f548599a4b9e33eeec79b113e7d8bc511336b07
Author:     Mark Jansen <mark.jansen(a)reactos.org>
AuthorDate: Thu Mar 8 21:38:40 2018 +0100
Commit:     Mark Jansen <mark.jansen(a)reactos.org>
CommitDate: Sat Mar 10 00:04:57 2018 +0100

    [SDK] Do not use a NUL file while calculating format string length
    CORE-14342
---
 sdk/lib/crt/printf/_vscprintf.c  | 15 +++++----------
 sdk/lib/crt/printf/_vscwprintf.c | 14 +++++---------
 2 files changed, 10 insertions(+), 19 deletions(-)

diff --git a/sdk/lib/crt/printf/_vscprintf.c b/sdk/lib/crt/printf/_vscprintf.c
index 5db594f718..7b4e6b5f72 100644
--- a/sdk/lib/crt/printf/_vscprintf.c
+++ b/sdk/lib/crt/printf/_vscprintf.c
@@ -15,14 +15,9 @@ _vscprintf(
    const char *format,
    va_list argptr)
 {
-    int ret;
-    FILE* nulfile = fopen("nul", "w");
-    if(nulfile == NULL)
-    {
-        /* This should never happen... */
-        return -1;
-    }
-    ret = streamout(nulfile, format, argptr);
-    fclose(nulfile);
-    return ret;
+    FILE nulfile;
+    nulfile._tmpfname = nulfile._ptr = nulfile._base = NULL;
+    nulfile._bufsiz = nulfile._charbuf = nulfile._cnt = 0;
+    nulfile._flag = _IOSTRG | _IOWRT;
+    return streamout(&nulfile, format, argptr);
 }
diff --git a/sdk/lib/crt/printf/_vscwprintf.c b/sdk/lib/crt/printf/_vscwprintf.c
index f6b7e9d55d..5b01fc1db9 100644
--- a/sdk/lib/crt/printf/_vscwprintf.c
+++ b/sdk/lib/crt/printf/_vscwprintf.c
@@ -22,15 +22,11 @@ _vscwprintf(
 {
     int ret;
 #ifndef _LIBCNT_
-    FILE* nulfile;
-    nulfile = fopen("nul", "w");
-    if(nulfile == NULL)
-    {
-        /* This should never happen... */
-        return -1;
-    }
-    ret = wstreamout(nulfile, format, argptr);
-    fclose(nulfile);
+    FILE nulfile;
+    nulfile._tmpfname = nulfile._ptr = nulfile._base = NULL;
+    nulfile._bufsiz = nulfile._charbuf = nulfile._cnt = 0;
+    nulfile._flag = _IOSTRG | _IOWRT;
+    ret = wstreamout(&nulfile, format, argptr);
 #else
     ret = -1;
 #endif