cpp: fix memory corruption due to input buffer relocation

the dynamic input buffer resize code (fillbuf()) is broken as
the calling code assumes that memory wont relocate. instead
of trying to work out all the cases where this happens, i'm
getting rid of fillbuf() and just read the whole file into
memory in setsource().

the bug could be reproduced with something as simple as:

@{for(i in `{seq 1 10000}){echo $i ', \'; }} | cpp

1 files changed, 0 insertions, 3 deletions

diff --git a/sys/src/cmd/cpp/cpp.h b/sys/src/cmd/cpp/cpp.h
index 8299614a7..2f70ffcfe 100644
--- a/sys/src/cmd/cpp/cpp.h
+++ b/sys/src/cmd/cpp/cpp.h
@@ -29,7 +29,6 @@ enum kwtype { KIF, KIFDEF, KIFNDEF, KELIF, KELSE, KENDIF, KINCLUDE, KDEFINE,
 #define	ISMAC		010	/* builtin macro, e.g. __LINE__ */
 #define	ISVARMAC	020	/* variadic macro */
 
-#define	EOB	0xFE		/* sentinel for end of input buffer */
 #define	EOFC	0xFD		/* sentinel for end of input file */
 #define	XPWS	1		/* token flag: white space to assure token sep. */
 
@@ -58,7 +57,6 @@ typedef struct source {
 	uchar	*inb;		/* input buffer */
 	uchar	*inp;		/* input pointer */
 	uchar	*inl;		/* end of input */
-	int 	ins;		/* input buffer size */
 	int	fd;		/* input source */
 	int	ifdepth;	/* conditional nesting in include */
 	struct	source *next;	/* stack for #include */
@@ -102,7 +100,6 @@ void	*domalloc(int);
 void	dofree(void *);
 void	error(enum errtype, char *, ...);
 void	flushout(void);
-int	fillbuf(Source *);
 int	trigraph(Source *);
 int	foldline(Source *);
 Nlist	*lookup(Token *, int);