[PATCH] sparse: Make pre_buffer dynamically increasable

[Atsushi Nemoto <anemo@mba.ocn.ne.jp>]

I got this error when running sparse on mips kernel with gcc 4.3:

builtin:272:1: warning: Newline in string or character constant

The linux-mips kernel uses '$(CC) -dM -E' to generates arguments for
sparse.  With gcc 4.3, it generates lot of '-D' options and causes
pre_buffer overflow.  The linux-mips kernel can filter unused symbols
out to avoid overflow, but sparse should be fixed anyway.

This patch make pre_buffer dynamically increasable and add extra
checking for overflow instead of silently truncating.

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
---
diff --git a/lib.c b/lib.c
index 0abcc9a..6e8d09b 100644
--- a/lib.c
+++ b/lib.c
@@ -186,7 +186,8 @@ void die(const char *fmt, ...)
 }
 
 static unsigned int pre_buffer_size;
-static char pre_buffer[8192];
+static unsigned int pre_buffer_alloc_size;
+static char *pre_buffer;
 
 int Waddress_space = 1;
 int Wbitwise = 0;
@@ -232,12 +233,20 @@ void add_pre_buffer(const char *fmt, ...)
        unsigned int size;
 
        va_start(args, fmt);
+       if (pre_buffer_alloc_size < pre_buffer_size + getpagesize()) {
+               pre_buffer_alloc_size += getpagesize();
+               pre_buffer = realloc(pre_buffer, pre_buffer_alloc_size);
+               if (!pre_buffer)
+                       die("Unable to allocate more pre_buffer space");
+       }
        size = pre_buffer_size;
        size += vsnprintf(pre_buffer + size,
-               sizeof(pre_buffer) - size,
+               pre_buffer_alloc_size - size,
                fmt, args);
        pre_buffer_size = size;
        va_end(args);
+       if (pre_buffer_size >= pre_buffer_alloc_size - 1)
+               die("pre_buffer overflow");
 }
 
 static char **handle_switch_D(char *arg, char **next)