diff options
authorRich Felker <>2017-11-20 14:23:49 -0500
committerRich Felker <>2017-11-20 16:21:25 -0500
commita90d9da1d1b14d81c4f93e1a6d1a686c3312e4ba (patch)
parent72656157f54c47277b01ec85a6ba7c4084fea6c8 (diff)
fix treatment by fgetws of encoding errors as eof
fgetwc does not set the stream's error indicator on encoding errors, making ferror insufficient to distinguish between error and eof conditions. feof is also insufficient, since it will return true if the file ended with a partial character encoding error. whether fgetwc should be setting the error indicator itself is a question with conflicting answers. the POSIX text for the function states it as a requirement, but the ISO C text seems to require that it not. this may be revisited in the future based on the outcome of Austin Group issue #1170.
1 files changed, 6 insertions, 1 deletions
diff --git a/src/stdio/fgetws.c b/src/stdio/fgetws.c
index 195cb435..b08b3049 100644
--- a/src/stdio/fgetws.c
+++ b/src/stdio/fgetws.c
@@ -1,5 +1,6 @@
#include "stdio_impl.h"
#include <wchar.h>
+#include <errno.h>
wint_t __fgetwc_unlocked(FILE *);
@@ -11,6 +12,10 @@ wchar_t *fgetws(wchar_t *restrict s, int n, FILE *restrict f)
+ /* Setup a dummy errno so we can detect EILSEQ. This is
+ * the only way to catch encoding errors in the form of a
+ * partial character just before EOF. */
+ errno = EAGAIN;
for (; n; n--) {
wint_t c = __fgetwc_unlocked(f);
if (c == WEOF) break;
@@ -18,7 +23,7 @@ wchar_t *fgetws(wchar_t *restrict s, int n, FILE *restrict f)
if (c == '\n') break;
*p = 0;
- if (ferror(f)) p = s;
+ if (ferror(f) || errno==EILSEQ) p = s;