From 52f0deb96975401d9f13334dc37f907630224af7 Mon Sep 17 00:00:00 2001 From: Rich Felker Date: Sun, 9 Jan 2022 00:33:56 -0500 Subject: make fseek detect and produce an error for invalid whence arguments this is a POSIX requirement. we previously relied on the underlying fd (or other backend) seek operation to produce the error, but since linux lseek now supports other seek modes (SEEK_DATA and SEEK_HOLE) which do not interact well with stdio buffering, this is insufficient. instead, explicitly check whence before performing any operations. --- src/stdio/fseek.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/src/stdio/fseek.c b/src/stdio/fseek.c index 439308f7..c07f7e95 100644 --- a/src/stdio/fseek.c +++ b/src/stdio/fseek.c @@ -1,7 +1,14 @@ #include "stdio_impl.h" +#include int __fseeko_unlocked(FILE *f, off_t off, int whence) { + /* Fail immediately for invalid whence argument. */ + if (whence != SEEK_CUR && whence != SEEK_SET && whence != SEEK_END) { + errno = EINVAL; + return -1; + } + /* Adjust relative offset for unread data in buffer, if any. */ if (whence == SEEK_CUR && f->rend) off -= f->rend - f->rpos; -- cgit 1.4.1