Simplify implementation of save_err_str()

Check return value of FormatMessageA() function and remove copy_string()
function as it is not needed.

1 files changed, 22 insertions, 26 deletions

diff --git a/dlfcn.c b/dlfcn.c
index 475b069..8687c51 100644
--- a/dlfcn.c
+++ b/dlfcn.c
@@ -133,45 +133,41 @@ static char error_buffer[65535];
 static char *current_error;

 static char dlerror_buffer[65536];

 

-static int copy_string( char *dest, int dest_size, const char *src )

-{

-    int i = 0;

-

-    /* gcc should optimize this out */

-    if( !src || !dest )

-        return 0;

-

-    for( i = 0 ; i < dest_size-1 ; i++ )

-    {

-        if( !src[i] )

-            break;

-        else

-            dest[i] = src[i];

-    }

-    dest[i] = '\0';

-

-    return i;

-}

-

 static void save_err_str( const char *str )

 {

     DWORD dwMessageId;

-    DWORD pos;

+    DWORD ret;

+    size_t pos, len;

 

     dwMessageId = GetLastError( );

 

     if( dwMessageId == 0 )

         return;

 

+    len = strlen( str );

+    if( len > sizeof( error_buffer ) - 5 )

+        len = sizeof( error_buffer ) - 5;

+

     /* Format error message to:

      * "<argument to function that failed>": <Windows localized error message>

       */

-    pos  = copy_string( error_buffer,     sizeof(error_buffer),     "\"" );

-    pos += copy_string( error_buffer+pos, sizeof(error_buffer)-pos, str );

-    pos += copy_string( error_buffer+pos, sizeof(error_buffer)-pos, "\": " );

-    pos += FormatMessageA( FORMAT_MESSAGE_FROM_SYSTEM, NULL, dwMessageId,

+    pos = 0;

+    error_buffer[pos++] = '"';

+    memcpy( error_buffer+pos, str, len );

+    pos += len;

+    error_buffer[pos++] = '"';

+    error_buffer[pos++] = ':';

+    error_buffer[pos++] = ' ';

+

+    ret = FormatMessageA( FORMAT_MESSAGE_FROM_SYSTEM, NULL, dwMessageId,

         MAKELANGID( LANG_NEUTRAL, SUBLANG_DEFAULT ),

-        error_buffer+pos, sizeof(error_buffer)-pos, NULL );

+        error_buffer+pos, (DWORD) (sizeof(error_buffer)-pos), NULL );

+    pos += ret;

+

+    /* When FormatMessageA() fails it returns zero and does not touch buffer

+     * so add trailing null byte */

+    if( ret == 0 )

+        error_buffer[pos] = '\0';

 

     if( pos > 1 )

     {