fix line-buffered flush omission for odd usage of putc-family functions

as specified, the int argument providing the character to write is
converted to type unsigned char. for the actual write to buffer,
conversion happened implicitly via the assignment operator; however,
the logic to check whether the argument was a newline used the
original int value. thus usage such as putchar('\n'+0x100) failed to
produce a flush.

diff --git a/src/internal/stdio_impl.h b/src/internal/stdio_impl.h
index 0dd7fb5e41ef0ef839f433e6cf11901303d97460..7cdf729de8e7e8146e96bae75662ce4bac0c0cd0 100644 (file)
--- a/src/internal/stdio_impl.h
+++ b/src/internal/stdio_impl.h
@@ -86,7 +86,8 @@ void __ofl_unlock(void);
 #define getc_unlocked(f) \
        ( ((f)->rpos < (f)->rend) ? *(f)->rpos++ : __uflow((f)) )
 
-#define putc_unlocked(c, f) ( ((c)!=(f)->lbf && (f)->wpos<(f)->wend) \
+#define putc_unlocked(c, f) \
+       ( ((unsigned char)(c)!=(f)->lbf && (f)->wpos<(f)->wend) \
        ? *(f)->wpos++ = (c) : __overflow((f),(c)) )
 
 /* Caller-allocated FILE * operations */