From 5a6e8d098abfef67028e6c3edbac39e0bbaf8bd8 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Wed, 10 Feb 2016 13:51:05 -0500 Subject: [PATCH] fix failed write reporting by fwrite in line-buffered mode when a write error occurred while flushing output due to a newline, fwrite falsely reported all bytes up to and including the newline as successfully written. in general, due to buffering such "spurious success" returns are acceptable for stdio; however for line-buffered mode it was subtly wrong. errors were still visible via ferror() or as a short-write return if there was more data past the newline that should have been written, but since the contract for line-buffered mode is that everything up through the newline be written out immediately, a discrepency was observable in the actual file contents. --- src/stdio/fwrite.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/src/stdio/fwrite.c b/src/stdio/fwrite.c index 81ec271e..fa30c0d3 100644 --- a/src/stdio/fwrite.c +++ b/src/stdio/fwrite.c @@ -13,8 +13,8 @@ size_t __fwritex(const unsigned char *restrict s, size_t l, FILE *restrict f) /* Match /^(.*\n|)/ */ for (i=l; i && s[i-1] != '\n'; i--); if (i) { - if (f->write(f, s, i) < i) - return i; + size_t n = f->write(f, s, i); + if (n < i) return n; s += i; l -= i; } -- 2.25.1