bug#1043: emacs does not compile when using uClibc

bug#1043: emacs does not compile when using uClibc

[Dan Nicolaescu]

uClibc is an alternative libc, emacs does not work on such systems at
the moment.
The patch bellow fixes this.  Not sure if this is a bug fix, or it's
adding a new feature, so just record it here in case it's the latter.


Index: src/gmalloc.c
===================================================================
RCS file: /cvsroot/emacs/emacs/src/gmalloc.c,v
retrieving revision 1.28
diff -u -3 -p -r1.28 gmalloc.c
--- src/gmalloc.c	23 May 2008 04:39:57 -0000	1.28
+++ src/gmalloc.c	28 Sep 2008 07:08:54 -0000
@@ -1706,17 +1706,17 @@ MA 02110-1301, USA.  */
 #include <malloc.h>
 #endif
 
-#ifndef	__GNU_LIBRARY__
+/* uClibc defines __GNU_LIBRARY__, but it is not completely
+   compatible.  */
+#if !defined(__GNU_LIBRARY__) || defined(__UCLIBC__)
 #define	__sbrk	sbrk
-#endif
-
-#ifdef __GNU_LIBRARY__
+#else /* __GNU_LIBRARY__ && ! defined (__UCLIBC__) */
 /* It is best not to declare this and cast its result on foreign operating
    systems with potentially hostile include files.  */
 
 #include <stddef.h>
 extern __ptr_t __sbrk PP ((ptrdiff_t increment));
-#endif
+#endif /* __GNU_LIBRARY__ && ! defined (__UCLIBC__) */
 
 #ifndef NULL
 #define NULL 0
Index: src/s/gnu-linux.h
===================================================================
RCS file: /cvsroot/emacs/emacs/src/s/gnu-linux.h,v
retrieving revision 1.113
diff -u -3 -p -r1.113 gnu-linux.h
--- src/s/gnu-linux.h	2 Aug 2008 16:19:03 -0000	1.113
+++ src/s/gnu-linux.h	28 Sep 2008 07:08:54 -0000
@@ -156,11 +156,15 @@ along with GNU Emacs.  If not, see <http
 /* new C libio names */
 #define GNU_LIBRARY_PENDING_OUTPUT_COUNT(FILE) \
   ((FILE)->_IO_write_ptr - (FILE)->_IO_write_base)
-#else /* !_IO_STDIO_H */
+#elif defined (__UCLIBC__)
+/* using the uClibc library */
+#define GNU_LIBRARY_PENDING_OUTPUT_COUNT(FILE) \
+  ((FILE)->__bufpos - (FILE)->__bufstart)
+#else /* !_IO_STDIO_H && ! __UCLIBC__ */
 /* old C++ iostream names */
 #define GNU_LIBRARY_PENDING_OUTPUT_COUNT(FILE) \
   ((FILE)->_pptr - (FILE)->_pbase)
-#endif /* !_IO_STDIO_H */
+#endif /* !_IO_STDIO_H && ! __UCLIBC__ */
 #endif /* emacs */
 
 /* Ask GCC where to find libgcc.a.  */

bug#1043: emacs does not compile when using uClibc

[Stefan Monnier]

> uClibc is an alternative libc, emacs does not work on such systems at
> the moment.  The patch bellow fixes this.  Not sure if this is a bug
> fix, or it's adding a new feature, so just record it here in case it's
> the latter.

It looks safe enough.  But let's just note for the future that
PENDING_OUTPUT_COUNT should die.


        Stefan

bug#1043: emacs does not compile when using uClibc

[Richard M. Stallman]

    It looks safe enough.  But let's just note for the future that
    PENDING_OUTPUT_COUNT should die.

That feature used to be important for making output preemption really
work on remote logins.  Please do not get rid of it!

bug#1043: emacs does not compile when using uClibc

[Stefan Monnier]

>     It looks safe enough.  But let's just note for the future that
>     PENDING_OUTPUT_COUNT should die.

> That feature used to be important for making output preemption really
> work on remote logins.  Please do not get rid of it!

I do not understand:
1- PENDING_OUTPUT_COUNT is not a feature, but an internal
   implementation trick.  Not sure what is the corresponding feature.
2- Why/how is it related to remote logins?
3- Why/how is it related to output preemption?


        Stefan

bug#1043: emacs does not compile when using uClibc

[Richard M. Stallman]

    1- PENDING_OUTPUT_COUNT is not a feature, but an internal
       implementation trick.  Not sure what is the corresponding feature.

If you type a character during redisplay, it preempts output.
But all the characters that are buffered have to come out on the terminal
before it really succeeds in preempting.

The feature which PENDING_OUTPUT_COUNT is used for
is to limit the amount of output that gets buffered,
so that preemption is snappy.