Make FILE*s less usable after fclose(3).
BSD doesn't invalidate the fd stored in struct FILE, which can make
it possible (via fileno(3), for example), to perform operations on
an fd you didn't intend to (rather than just failing with EBADF).
Fixing this makes the code slightly simpler anyway, and might help
catch bad code before it ships.
Bug: http://stackoverflow.com/questions/10816837/fclose-works-differently-on-android-and-linux
Change-Id: I9db74584038229499197a2695c70b58ed0372a87
diff --git a/libc/Android.mk b/libc/Android.mk
index 04941f1..969b8ef 100644
--- a/libc/Android.mk
+++ b/libc/Android.mk
@@ -444,7 +444,6 @@
upstream-openbsd/lib/libc/stdio/asprintf.c \
upstream-openbsd/lib/libc/stdio/clrerr.c \
upstream-openbsd/lib/libc/stdio/dprintf.c \
- upstream-openbsd/lib/libc/stdio/fclose.c \
upstream-openbsd/lib/libc/stdio/fdopen.c \
upstream-openbsd/lib/libc/stdio/feof.c \
upstream-openbsd/lib/libc/stdio/ferror.c \
@@ -455,7 +454,6 @@
upstream-openbsd/lib/libc/stdio/fgets.c \
upstream-openbsd/lib/libc/stdio/fgetwc.c \
upstream-openbsd/lib/libc/stdio/fgetws.c \
- upstream-openbsd/lib/libc/stdio/fileno.c \
upstream-openbsd/lib/libc/stdio/flags.c \
upstream-openbsd/lib/libc/stdio/fmemopen.c \
upstream-openbsd/lib/libc/stdio/fopen.c \
@@ -1623,4 +1621,3 @@
LOCAL_SANITIZE := never
LOCAL_NATIVE_COVERAGE := $(bionic_coverage)
include $(BUILD_STATIC_LIBRARY)
-
diff --git a/libc/stdio/findfp.c b/libc/stdio/findfp.c
index 6e20562..2a6be15 100644
--- a/libc/stdio/findfp.c
+++ b/libc/stdio/findfp.c
@@ -157,3 +157,37 @@
/* (void) _fwalk(fclose); */
(void) _fwalk(__sflush); /* `cheating' */
}
+
+int fclose(FILE* fp) {
+ if (fp->_flags == 0) {
+ // Already freed!
+ errno = EBADF;
+ return EOF;
+ }
+
+ FLOCKFILE(fp);
+ WCIO_FREE(fp);
+ int r = fp->_flags & __SWR ? __sflush(fp) : 0;
+ if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0) {
+ r = EOF;
+ }
+ if (fp->_flags & __SMBF) free(fp->_bf._base);
+ if (HASUB(fp)) FREEUB(fp);
+ if (HASLB(fp)) FREELB(fp);
+
+ // Poison this FILE so accesses after fclose will be obvious.
+ fp->_file = -1;
+ fp->_r = fp->_w = 0;
+
+ // Release this FILE for reuse.
+ fp->_flags = 0;
+ FUNLOCKFILE(fp);
+ return (r);
+}
+
+int fileno(FILE* fp) {
+ FLOCKFILE(fp);
+ int result = fileno_unlocked(fp);
+ FUNLOCKFILE(fp);
+ return result;
+}
diff --git a/libc/stdio/local.h b/libc/stdio/local.h
index 6dcd3ae..a15bddf 100644
--- a/libc/stdio/local.h
+++ b/libc/stdio/local.h
@@ -215,7 +215,6 @@
#define __sfeof(p) (((p)->_flags & __SEOF) != 0)
#define __sferror(p) (((p)->_flags & __SERR) != 0)
#define __sclearerr(p) ((void)((p)->_flags &= ~(__SERR|__SEOF)))
-#define __sfileno(p) ((p)->_file)
#if !defined(__cplusplus)
#define __sgetc(p) (--(p)->_r < 0 ? __srget(p) : (int)(*(p)->_p++))
static __inline int __sputc(int _c, FILE* _p) {
diff --git a/libc/stdio/stdio_ext.cpp b/libc/stdio/stdio_ext.cpp
index f273d45..88e5951 100644
--- a/libc/stdio/stdio_ext.cpp
+++ b/libc/stdio/stdio_ext.cpp
@@ -27,6 +27,8 @@
*/
#include <stdio_ext.h>
+
+#include <errno.h>
#include <stdlib.h>
#include "local.h"
@@ -101,5 +103,10 @@
}
int fileno_unlocked(FILE* fp) {
- return __sfileno(fp);
+ int fd = fp->_file;
+ if (fd == -1) {
+ errno = EBADF;
+ return -1;
+ }
+ return fd;
}
diff --git a/libc/upstream-openbsd/lib/libc/stdio/fclose.c b/libc/upstream-openbsd/lib/libc/stdio/fclose.c
deleted file mode 100644
index c72af54..0000000
--- a/libc/upstream-openbsd/lib/libc/stdio/fclose.c
+++ /dev/null
@@ -1,63 +0,0 @@
-/* $OpenBSD: fclose.c,v 1.9 2009/11/09 00:18:27 kurt Exp $ */
-/*-
- * Copyright (c) 1990, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <errno.h>
-#include <stdio.h>
-#include <stdlib.h>
-#include "local.h"
-
-int
-fclose(FILE *fp)
-{
- int r;
-
- if (fp->_flags == 0) { /* not open! */
- errno = EBADF;
- return (EOF);
- }
- FLOCKFILE(fp);
- WCIO_FREE(fp);
- r = fp->_flags & __SWR ? __sflush(fp) : 0;
- if (fp->_close != NULL && (*fp->_close)(fp->_cookie) < 0)
- r = EOF;
- if (fp->_flags & __SMBF)
- free((char *)fp->_bf._base);
- if (HASUB(fp))
- FREEUB(fp);
- if (HASLB(fp))
- FREELB(fp);
- fp->_r = fp->_w = 0; /* Mess up if reaccessed. */
- fp->_flags = 0; /* Release this FILE for reuse. */
- FUNLOCKFILE(fp);
- return (r);
-}
diff --git a/libc/upstream-openbsd/lib/libc/stdio/fileno.c b/libc/upstream-openbsd/lib/libc/stdio/fileno.c
deleted file mode 100644
index 58628da..0000000
--- a/libc/upstream-openbsd/lib/libc/stdio/fileno.c
+++ /dev/null
@@ -1,51 +0,0 @@
-/* $OpenBSD: fileno.c,v 1.8 2009/11/09 00:18:27 kurt Exp $ */
-/*-
- * Copyright (c) 1990, 1993
- * The Regents of the University of California. All rights reserved.
- *
- * This code is derived from software contributed to Berkeley by
- * Chris Torek.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- * notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- * notice, this list of conditions and the following disclaimer in the
- * documentation and/or other materials provided with the distribution.
- * 3. Neither the name of the University nor the names of its contributors
- * may be used to endorse or promote products derived from this software
- * without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- */
-
-#include <stdio.h>
-#include "local.h"
-
-/*
- * A subroutine version of the macro fileno.
- */
-#undef fileno
-
-int
-fileno(FILE *fp)
-{
- int ret;
-
- FLOCKFILE(fp);
- ret = __sfileno(fp);
- FUNLOCKFILE(fp);
- return (ret);
-}
diff --git a/tests/stdio_test.cpp b/tests/stdio_test.cpp
index 58109a9..d054bf5 100644
--- a/tests/stdio_test.cpp
+++ b/tests/stdio_test.cpp
@@ -1054,3 +1054,17 @@
fclose(fr);
fclose(fw);
}
+
+TEST(STDIO_TEST, fclose_invalidates_fd) {
+ // The typical error we're trying to help people catch involves accessing
+ // memory after it's been freed. But we know that stdin/stdout/stderr are
+ // special and don't get deallocated, so this test uses stdin.
+ ASSERT_EQ(0, fclose(stdin));
+
+ // Even though using a FILE* after close is undefined behavior, I've closed
+ // this bug as "WAI" too many times. We shouldn't hand out stale fds,
+ // especially because they might actually correspond to a real stream.
+ errno = 0;
+ ASSERT_EQ(-1, fileno(stdin));
+ ASSERT_EQ(EBADF, errno);
+}
