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Christian Grothoff
fdfd5dc80f
Hi,
gcc10 complains with two warnings when compiling libmicrohttpd using
#define NDEBUG 1
#define DAUTH_SUPPORT 1
so, "release build" with enabled "digest authentication":
../digestauth.c: In function 'MHD_digest_auth_check_digest2':
../digestauth.c:1287:9: warning: 'da.digest_size' may be used uninitialized in this function [-Wmaybe-uninitialized]
1287 | if (da.digest_size != digest_size)
| ~~^~~~~~~~~~~~
../digestauth.c: In function 'MHD_queue_auth_fail_response2':
../digestauth.c:1361:55: warning: 'da.digest_size' may be used uninitialized in this function [-Wmaybe-uninitialized]
1361 | char nonce[NONCE_STD_LEN (VLA_ARRAY_LEN_DIGEST (da.digest_size)) + 1];
|
This is a minor issue, without any practical effect, unless when calling the MHD API with an invalid value for the MHD_DigestAuthAlgorithm enum.
However, gcc is still right that there is a potential code path with undefined behaviour: the default-case in the switch statement in SETUP_DA does not set "da.digest_size".
Two functions later still always read this value. And the "mhd_assert" has no effect, since it's disabled when NDEBUG is set.
Trivial patch attached to silence the compiler warnings by also initializing "da.digest_size" in the default case of the switch statement:
About ===== GNU libmicrohttpd is a GNU package offering a C library that provides a compact API and implementation of an HTTP 1.1 web server (HTTP 1.0 is also supported). GNU libmicrohttpd only implements the HTTP 1.1 protocol. The main application must still provide the application logic to generate the content. GNU libmicrohttpd is dual-licensed under the GNU Lesser General Public License (LGPLv2.1+) and the eCos License. See COPYING for details. Joining GNU =========== This is a GNU program, developed by the GNU Project and part of the GNU Operating System. If you are the author of an awesome program and want to join us in writing Free Software, please consider making it an official GNU program and become a GNU maintainer. You can find instructions on how to do so at http://www.gnu.org/help/evaluation. We are looking forward to hacking with you! Installation ============ See INSTALL for generic installation instructions. If you are using Git, run "autoreconf -fi" to create configure. In order to run the testcases, you need a recent version of libcurl. libcurl is not required if you just want to install the library. Especially for development, do use the MHD_USE_ERROR_LOG option to get error messages. Configure options ================= If you are concerned about space, you should set "CFLAGS" to "-Os -fomit-frame-pointer" to have gcc generate tight code. You can use the following options to disable certain MHD features: --disable-https: no HTTPS / TLS / SSL support (significant reduction) --disable-messages: no error messages (they take space!) --disable-postprocessor: no MHD_PostProcessor API --disable-dauth: no digest authentication API --disable-epoll: no support for epoll, even on Linux The resulting binary should be about 30-40k depending on the platform. Portability =========== The latest version of libmicrohttpd will try to avoid SIGPIPE on its sockets. This should work on OS X, Linux and recent BSD systems (at least). On other systems that may trigger a SIGPIPE on send/recv, the main application should install a signal handler to handle SIGPIPE. libmicrohttpd should work well on GNU/Linux, W32, FreeBSD, Darwin, NetBSD, OpenBSD, Solaris/OpenIndiana, and z/OS. Note that HTTPS is not supported on z/OS (yet). We also have reports of users using it on vxWorks. Development Status ================== This is a beta release for libmicrohttpd. Before declaring the library stable, we should have testcases for the following features: - HTTP/1.1 pipelining (need to figure out how to ensure curl pipelines -- and it seems libcurl has issues with pipelining, see http://curl.haxx.se/mail/lib-2007-12/0248.html) - resource limit enforcement - client queuing early response, suppressing 100 CONTINUE - chunked encoding to validate handling of footers - more testing for SSL support - MHD basic and digest authentication In particular, the following functions are not covered by 'make check': - mhd_panic_std (daemon.c); special case (abort) - parse_options (daemon.c) - MHD_set_panic_func (daemon.c) - MHD_get_version (daemon.c) Note that the working library is in src/microhttpd/ with the API in src/include/microhttpd.h. An *experimental* (read: not yet working at all) newer implementation is in src/lib/, with the new API in src/include/microhttpd2.h. The experimental code will need MUCH more testing and development, you are strongly advised to stick to microhttpd.h unless you are a MHD developer!