kbuild: Fix compiler warning with assertion when calling 'fwrite'

Reinhard Tartler discovered a corner case of calling xfwrite() where the
length of the string is zero.

Arnaud Lacombe suggested to use assertion for the corner case, as
fwrite(3) is currently used:

 1) in comment printers. Empty comment are not allowed.
 2) in a callback passed to expr_print(), where the string printed is
    either NULL OR non-empty.
 3) in the lexer, auto-generated, and unused.

I feel using assertion is a good solution:

 1) It cleanly takes care of the above-mentioned corner case.
 2) It can be easily disabled by defining NDEBUG.
 3) It asserts xfwrite() is simply a wrapper for fwrite().

Reported-by: Reinhard Tartler <Reinhard.Tartler@informatik.uni-erlangen.de>
Signed-off-by: Arnaud Lacombe <lacombar@gmail.com>
Signed-off-by: Jean Sacren <sakiwit@gmail.com>
Signed-off-by: Michal Marek <mmarek@suse.cz>
This commit is contained in:
Arnaud Lacombe 2011-11-23 13:05:53 -05:00 committed by Michal Marek
parent e2aef4d33a
commit 37ae2d5998
2 changed files with 5 additions and 2 deletions

View File

@ -10,6 +10,7 @@
extern "C" {
#endif
#include <assert.h>
#include <stdio.h>
#ifndef __cplusplus
#include <stdbool.h>

View File

@ -90,8 +90,10 @@ struct conf_printer {
/* confdata.c and expr.c */
static inline void xfwrite(const void *str, size_t len, size_t count, FILE *out)
{
if (fwrite(str, len, count, out) < count)
fprintf(stderr, "\nError in writing or end of file.\n");
assert(len != 0);
if (fwrite(str, len, count, out) != count)
fprintf(stderr, "Error in writing or end of file.\n");
}
/* menu.c */