linux/sbrk is wrong

[Szabolcs Nagy <nsz@port70.net>]

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linux brk syscall returns the end pointer
so if it fails then the old one
if it succeeds then the new one

the current implementation of sbrk returns
the end of the allocated area instead of
the begining

i attached a patch that fixes brk and sbrk

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diff --git a/src/linux/brk.c b/src/linux/brk.c
index 9f63c5a..c261518 100644
--- a/src/linux/brk.c
+++ b/src/linux/brk.c
@@ -2,5 +2,5 @@
 
 int brk(void *end)
 {
-	return -(syscall(SYS_brk, end) == -1);
+	return -((void *)syscall(SYS_brk, end) != end);
 }
diff --git a/src/linux/sbrk.c b/src/linux/sbrk.c
index b2943a9..478a35e 100644
--- a/src/linux/sbrk.c
+++ b/src/linux/sbrk.c
@@ -3,5 +3,11 @@
 
 void *sbrk(ptrdiff_t inc)
 {
-	return (void *)syscall(SYS_brk, syscall(SYS_brk, 0)+inc);
+	void *p = (void *)syscall(SYS_brk, 0);
+
+	if (inc == 0)
+		return p;
+	if ((void *)syscall(SYS_brk, p+inc) == p+inc)
+		return p;
+	return (void *)-1;
 }