diff options
Diffstat (limited to 'newlib/libc/stdio/freopen.c')
| -rw-r--r-- | newlib/libc/stdio/freopen.c | 16 |
1 files changed, 9 insertions, 7 deletions
diff --git a/newlib/libc/stdio/freopen.c b/newlib/libc/stdio/freopen.c index d5582d4..ae3444b 100644 --- a/newlib/libc/stdio/freopen.c +++ b/newlib/libc/stdio/freopen.c @@ -56,10 +56,10 @@ it). <[file]> and <[mode]> are used just as in <<fopen>>. If <[file]> is <<NULL>>, the underlying stream is modified rather than -closed. The file cannot change access mode (for example, if it was -previously read-only, <[mode]> must be "r", "rb", or "rt"), but can -change status such as append or binary mode. If modification is not -possible, failure occurs. +closed. The file cannot be given a more permissive access mode (for +example, a <[mode]> of "w" will fail on a read-only file descriptor), +but can change status such as append or binary mode. If modification +is not possible, failure occurs. RETURNS If successful, the result is the same as the argument <[fp]>. If the @@ -148,12 +148,14 @@ _DEFUN(_freopen_r, (ptr, file, mode, fp), #ifdef HAVE_FCNTL int oldflags; /* - * Reuse the file descriptor, but only if the access mode is - * unchanged. F_SETFL correctly ignores creation flags. + * Reuse the file descriptor, but only if the new access mode is + * equal or less permissive than the old. F_SETFL correctly + * ignores creation flags. */ f = fp->_file; if ((oldflags = _fcntl_r (ptr, f, F_GETFL, 0)) == -1 - || ((oldflags ^ oflags) & O_ACCMODE) != 0 + || ! ((oldflags & O_ACCMODE) == O_RDWR + || ((oldflags ^ oflags) & O_ACCMODE) == 0) || _fcntl_r (ptr, f, F_SETFL, oflags) == -1) f = -1; #else |