From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jonathan Larmour <jlarmour@redhat.com>
To: jjtsai <jjtsai@itri.org.tw>
Cc: ecos-discuss@sources.redhat.com
Subject: Re: [ECOS] [eCos] a question about ROMFS
Date: Tue, 17 Jul 2001 13:09:00 -0000
Message-id: <3B549B75.660C8B1D@redhat.com>
References: <005701c10dcb$d2cc2180$8c78608c@ccl.itri.org.tw> <3B535619.9EAA2385@redhat.com> <000e01c10e90$031b8820$8c78608c@ccl.itri.org.tw>
X-SW-Source: 2001-07/msg00526.html

jjtsai wrote:
> > I'll see if I can work on a better patch.
> That would be great!

Can you try the attached patch for me please? I haven't even tried
compiling it yet nevermind testing it, but I was hoping you could do that
instead :-). Let me know how it goes. Then I'll check it in.

Jifl
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Index: include/stream.inl
===================================================================
RCS file: /home/cvs/ecc/ecc/language/c/libc/stdio/current/include/stream.inl,v
retrieving revision 1.3
diff -u -5 -p -r1.3 stream.inl
--- include/stream.inl	2001/03/15 20:30:22	1.3
+++ include/stream.inl	2001/07/17 20:05:43
@@ -361,19 +361,19 @@ Cyg_StdioStream::get_position( fpos_t *p
 
 // set absolute position
 inline Cyg_ErrNo
 Cyg_StdioStream::set_position( fpos_t pos, int whence )
 {
+    CYG_ASSERTCLASS( this, "Stream object is not a valid stream!" );
+    
 #ifndef CYGPKG_LIBC_STDIO_FILEIO    
     // this is currently a workaround until we have real files
     // this will be corrected when we decide the true filesystem interface
 
     Cyg_ErrNo err;
     cyg_uint8 c;
 
-    CYG_ASSERTCLASS( this, "Stream object is not a valid stream!" );
-    
     if ((whence != SEEK_CUR) || pos < 0)
         return ENOSYS;
 
     if (!lock_me())
         return EBADF; // assume file is now invalid
@@ -396,18 +396,46 @@ Cyg_StdioStream::set_position( fpos_t po
 
     return ENOERR;
     
 #else
 
-    Cyg_ErrNo err;
-    off_t newpos = pos;
-
-    CYG_ASSERTCLASS( this, "Stream object is not a valid stream!" );
-    
     if (!lock_me())
         return EBADF; // assume file is now invalid
 
+    if ( whence != SEEK_END ) {
+        cyg_ucount32 bytesavail = bytes_available_to_read();
+        off_t abspos = (whence == SEEK_CUR) ? position + pos : pos;
+        off_t posdiff = abspos - position;
+    
+        if ( bytesavail > posdiff ) {
+            // can just "seek" within the existing buffer
+#ifdef CYGFUN_LIBC_STDIO_ungetc
+            if (flags.unread_char_buf_in_use) {
+                flags.unread_char_buf_in_use = false;
+                posdiff--;
+            }
+#endif
+#ifdef CYGSEM_LIBC_STDIO_WANT_BUFFERED_IO
+            if (posdiff>0 && flags.buffering) {
+                io_buf.set_bytes_read(posdiff);
+                posdiff=0;
+            } else 
+#endif
+            if (posdiff>0 && flags.readbuf_char_in_use) {
+                flags.readbuf_char_in_use = false;
+                posdiff--;
+            }
+            CYG_ASSERT(posdiff==0, "Failed to seek within buffer correctly");
+
+            position = abspos;
+            unlock_me();
+            return ENOERR;
+        }
+    }
+
+    Cyg_ErrNo err;
+    off_t newpos = pos;
     err = cyg_stdio_lseek( my_device, &newpos, whence );
 
     if( err == ENOERR )
     {
         // Clean out the buffer. Flush output if any present,
@@ -420,14 +448,14 @@ Cyg_StdioStream::set_position( fpos_t po
         flags.unread_char_buf_in_use = false;
 #endif
 
         // Clear EOF indicator.
         flags.at_eof = false;
-    }
-    
-    if( err == ENOERR )
+        
+        // update stream pos
         position = newpos;
+    }
     
     unlock_me();
 
     return err;
 #endif