Do not let isatty mess up errno

diff --git a/libc/stdio/stdio.c b/libc/stdio/stdio.c
index 9a7afbc..0d4708d 100644 (file)
--- a/libc/stdio/stdio.c
+++ b/libc/stdio/stdio.c
@@ -1953,9 +1953,11 @@ void _stdio_term(void)
 void _stdio_init(void)
 {
 #ifdef __STDIO_BUFFERS
+       int old_errno = errno;
        /* stdin and stdout uses line buffering when connected to a tty. */
        _stdio_streams[0].modeflags ^= (1-isatty(0)) * __FLAG_LBF;
        _stdio_streams[1].modeflags ^= (1-isatty(1)) * __FLAG_LBF;
+       __set_errno(old_errno);
 #endif /* __STDIO_BUFFERS */
 #ifndef __UCLIBC__
 /* __stdio_term is automatically when exiting if stdio is used.
@@ -2404,10 +2406,16 @@ FILE *_stdio_fopen(const char * __restrict filename,
                return NULL;
        }
 
-       stream->modeflags |=
 #ifdef __STDIO_BUFFERS
-               (isatty(stream->filedes) * __FLAG_LBF) |
-#endif /* __STDIO_BUFFERS */
+       {
+           /* Do not let isatty mess up errno */
+           int old_errno = errno;
+           stream->modeflags |= (isatty(stream->filedes) * __FLAG_LBF);
+           __set_errno(old_errno);
+       }
+#endif
+
+       stream->modeflags |=
 #if (O_APPEND == __FLAG_APPEND) \
 && ((O_LARGEFILE == __FLAG_LARGEFILE) || (O_LARGEFILE == 0))
                (open_mode & (O_APPEND|O_LARGEFILE)) | /* i386 linux and elks */