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As reported in bug 32140, freopen leaks the FILE object when it returns NULL: there is no valid use of the FILE * pointer (including passing to freopen again or to fclose) after such an error return, so the underlying object should be freed. Add code to free it. Note 1: while I think it's clear from the relevant standards that the object should be freed and the FILE * can't be used after the call in this case (the stream is closed, which ends the lifetime of the FILE), it's entirely possible that some existing code does in fact try to use the existing FILE * in some way and could be broken by this change. (Though the most common case for freopen may be stdin / stdout / stderr, which _IO_deallocate_file explicitly checks for and does not deallocate.) Note 2: the deallocation is only done in the _IO_IS_FILEBUF case. Other kinds of streams bypass all the freopen logic handling closing the file, meaning a call to _IO_deallocate_file would neither be safe (the FILE might still be linked into the list of all open FILEs) nor sufficient (other internal memory allocations associated with the file would not have been freed). I think the validity of freopen for any other kind of stream will need clarifying with the Austin Group, but if it is valid in any such case (where "valid" means "not undefined behavior so required to close the stream" rather than "required to successfully associate the stream with the new file in cases where fopen would work"), more significant changes would be needed to ensure the stream gets fully closed. Tested for x86_64. |
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This directory contains the sources of the GNU C Library. See the file "version.h" for what release version you have. The GNU C Library is the standard system C library for all GNU systems, and is an important part of what makes up a GNU system. It provides the system API for all programs written in C and C-compatible languages such as C++ and Objective C; the runtime facilities of other programming languages use the C library to access the underlying operating system. In GNU/Linux systems, the C library works with the Linux kernel to implement the operating system behavior seen by user applications. In GNU/Hurd systems, it works with a microkernel and Hurd servers. The GNU C Library implements much of the POSIX.1 functionality in the GNU/Hurd system, using configurations i[4567]86-*-gnu and x86_64-gnu. When working with Linux kernels, this version of the GNU C Library requires Linux kernel version 3.2 or later. Also note that the shared version of the libgcc_s library must be installed for the pthread library to work correctly. The GNU C Library supports these configurations for using Linux kernels: aarch64*-*-linux-gnu alpha*-*-linux-gnu arc*-*-linux-gnu arm-*-linux-gnueabi csky-*-linux-gnuabiv2 hppa-*-linux-gnu i[4567]86-*-linux-gnu x86_64-*-linux-gnu Can build either x86_64 or x32 loongarch64-*-linux-gnu Hardware floating point, LE only. m68k-*-linux-gnu microblaze*-*-linux-gnu mips-*-linux-gnu mips64-*-linux-gnu or1k-*-linux-gnu powerpc-*-linux-gnu Hardware or software floating point, BE only. powerpc64*-*-linux-gnu Big-endian and little-endian. s390-*-linux-gnu s390x-*-linux-gnu riscv32-*-linux-gnu riscv64-*-linux-gnu sh[34]-*-linux-gnu sparc*-*-linux-gnu sparc64*-*-linux-gnu If you are interested in doing a port, please contact the glibc maintainers; see https://www.gnu.org/software/libc/ for more information. See the file INSTALL to find out how to configure, build, and install the GNU C Library. You might also consider reading the WWW pages for the C library at https://www.gnu.org/software/libc/. The GNU C Library is (almost) completely documented by the Texinfo manual found in the `manual/' subdirectory. The manual is still being updated and contains some known errors and omissions; we regret that we do not have the resources to work on the manual as much as we would like. For corrections to the manual, please file a bug in the `manual' component, following the bug-reporting instructions below. Please be sure to check the manual in the current development sources to see if your problem has already been corrected. Please see https://www.gnu.org/software/libc/bugs.html for bug reporting information. We are now using the Bugzilla system to track all bug reports. This web page gives detailed information on how to report bugs properly. The GNU C Library is free software. See the file COPYING.LIB for copying conditions, and LICENSES for notices about a few contributions that require these additional notices to be distributed. License copyright years may be listed using range notation, e.g., 1996-2015, indicating that every year in the range, inclusive, is a copyrightable year that would otherwise be listed individually.