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trace2: refactor to avoid gcc warning under -O3
Refactor tr2_dst_try_uds_connect() to avoid a gcc warning[1] that
appears under -O3 (but not -O2). This makes the build pass under
DEVELOPER=1 without needing a DEVOPTS=no-error.
This can be reproduced with GCC Debian 8.3.0-6, but not e.g. with
clang 7.0.1-8+deb10u2. We've had this warning since
ee4512ed48
(trace2: create new combined trace facility, 2019-02-22).
As noted in [2] this warning happens because the compiler doesn't
assume that errno must be non-zero after a failed syscall.
Let's work around by using the well-established "saved_errno" pattern,
along with returning -1 ourselves instead of "errno". The caller can
thus rely on our "errno" on failure.
See https://gcc.gnu.org/bugzilla/show_bug.cgi?id=61846 for a related
bug report against GCC.
1.
trace2/tr2_dst.c: In function ‘tr2_dst_get_trace_fd.part.5’:
trace2/tr2_dst.c:296:10: warning: ‘fd’ may be used uninitialized in this function [-Wmaybe-uninitialized]
dst->fd = fd;
~~~~~~~~^~~~
trace2/tr2_dst.c:229:6: note: ‘fd’ was declared here
int fd;
^~
2. https://lore.kernel.org/git/20200404142131.GA679473@coredump.intra.peff.net/
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
Signed-off-by: Jeff King <peff@peff.net>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
This commit is contained in:
parent
c753e2a7a8
commit
4e0a64a713
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@ -115,15 +115,16 @@ static int tr2_dst_try_uds_connect(const char *path, int sock_type, int *out_fd)
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fd = socket(AF_UNIX, sock_type, 0);
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fd = socket(AF_UNIX, sock_type, 0);
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if (fd == -1)
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if (fd == -1)
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return errno;
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return -1;
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sa.sun_family = AF_UNIX;
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sa.sun_family = AF_UNIX;
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strlcpy(sa.sun_path, path, sizeof(sa.sun_path));
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strlcpy(sa.sun_path, path, sizeof(sa.sun_path));
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if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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if (connect(fd, (struct sockaddr *)&sa, sizeof(sa)) == -1) {
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int e = errno;
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int saved_errno = errno;
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close(fd);
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close(fd);
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return e;
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errno = saved_errno;
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return -1;
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}
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}
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*out_fd = fd;
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*out_fd = fd;
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@ -138,7 +139,6 @@ static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,
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{
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{
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unsigned int uds_try = 0;
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unsigned int uds_try = 0;
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int fd;
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int fd;
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int e;
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const char *path = NULL;
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const char *path = NULL;
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/*
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/*
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@ -182,15 +182,13 @@ static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,
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}
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}
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if (uds_try & TR2_DST_UDS_TRY_STREAM) {
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if (uds_try & TR2_DST_UDS_TRY_STREAM) {
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e = tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd);
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if (!tr2_dst_try_uds_connect(path, SOCK_STREAM, &fd))
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if (!e)
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goto connected;
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goto connected;
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if (e != EPROTOTYPE)
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if (errno != EPROTOTYPE)
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goto error;
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goto error;
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}
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}
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if (uds_try & TR2_DST_UDS_TRY_DGRAM) {
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if (uds_try & TR2_DST_UDS_TRY_DGRAM) {
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e = tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd);
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if (!tr2_dst_try_uds_connect(path, SOCK_DGRAM, &fd))
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if (!e)
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goto connected;
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goto connected;
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}
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}
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@ -198,7 +196,7 @@ static int tr2_dst_try_unix_domain_socket(struct tr2_dst *dst,
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if (tr2_dst_want_warning())
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if (tr2_dst_want_warning())
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warning("trace2: could not connect to socket '%s' for '%s' tracing: %s",
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warning("trace2: could not connect to socket '%s' for '%s' tracing: %s",
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path, tr2_sysenv_display_name(dst->sysenv_var),
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path, tr2_sysenv_display_name(dst->sysenv_var),
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strerror(e));
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strerror(errno));
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tr2_dst_trace_disable(dst);
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tr2_dst_trace_disable(dst);
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return 0;
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return 0;
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