From 95e6d2685eec83a144f533a447ffd355fadf9d79 Mon Sep 17 00:00:00 2001 From: Mathieu Desnoyers Date: Mon, 12 Sep 2016 12:04:13 -0400 Subject: [PATCH] Implement liblttng-ust-fd This library overrides close() and closeall() libc functions, and uses lttng_ust_safe_close_fd() to check whether the application can interact with the file descriptor or if it should be left to lttng-ust. This takes care of bugs caused by applications doing bulk close() or closefrom() of file descriptors soon after forking. Fixes: #253 Fixes: #626 CC: Aravind HT Signed-off-by: Mathieu Desnoyers --- Makefile.am | 1 + configure.ac | 1 + liblttng-ust-fd/Makefile.am | 17 +++++++++ liblttng-ust-fd/lttng-ust-fd.c | 67 ++++++++++++++++++++++++++++++++++ 4 files changed, 86 insertions(+) create mode 100644 liblttng-ust-fd/Makefile.am create mode 100644 liblttng-ust-fd/lttng-ust-fd.c diff --git a/Makefile.am b/Makefile.am index e4987195..232acd11 100644 --- a/Makefile.am +++ b/Makefile.am @@ -3,6 +3,7 @@ ACLOCAL_AMFLAGS = -I config SUBDIRS = . include snprintf libringbuffer liblttng-ust-comm \ liblttng-ust \ liblttng-ust-ctl \ + liblttng-ust-fd \ liblttng-ust-fork \ liblttng-ust-libc-wrapper \ liblttng-ust-cyg-profile \ diff --git a/configure.ac b/configure.ac index 4256f665..a59758e8 100644 --- a/configure.ac +++ b/configure.ac @@ -451,6 +451,7 @@ AC_CONFIG_FILES([ liblttng-ust-ctl/Makefile liblttng-ust-fork/Makefile liblttng-ust-dl/Makefile + liblttng-ust-fd/Makefile liblttng-ust-java/Makefile liblttng-ust-java-agent/Makefile liblttng-ust-java-agent/java/Makefile diff --git a/liblttng-ust-fd/Makefile.am b/liblttng-ust-fd/Makefile.am new file mode 100644 index 00000000..52f897d6 --- /dev/null +++ b/liblttng-ust-fd/Makefile.am @@ -0,0 +1,17 @@ +AM_CPPFLAGS = -I$(top_srcdir)/include -I$(top_builddir)/include +AM_CFLAGS = -fno-strict-aliasing + +lib_LTLIBRARIES = liblttng-ust-fd.la +liblttng_ust_fd_la_SOURCES = \ + lttng-ust-fd.c +liblttng_ust_fd_la_LIBADD = \ + $(top_builddir)/liblttng-ust-comm/liblttng-ust-comm.la + +if LTTNG_UST_BUILD_WITH_LIBDL +liblttng_ust_fd_la_LIBADD += -ldl +endif +if LTTNG_UST_BUILD_WITH_LIBC_DL +liblttng_ust_fd_la_LIBADD += -lc +endif + +liblttng_ust_fd_la_CFLAGS = -DUST_COMPONENT=liblttng-ust-fd -fno-strict-aliasing diff --git a/liblttng-ust-fd/lttng-ust-fd.c b/liblttng-ust-fd/lttng-ust-fd.c new file mode 100644 index 00000000..6a095db6 --- /dev/null +++ b/liblttng-ust-fd/lttng-ust-fd.c @@ -0,0 +1,67 @@ +/* + * Copyright (C) 2016 Mathieu Desnoyers + * + * This library is free software; you can redistribute it and/or + * modify it under the terms of the GNU Lesser General Public + * License as published by the Free Software Foundation; version 2.1 of + * the License. + * + * This library is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU + * Lesser General Public License for more details. + * + * You should have received a copy of the GNU Lesser General Public + * License along with this library; if not, write to the Free Software + * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA + */ + +#define _GNU_SOURCE +#define _LGPL_SOURCE +#include +#include +#include +#include +#include +#include + +#include +#include "usterr-signal-safe.h" + +volatile enum ust_loglevel ust_loglevel; + +static int (*__lttng_ust_fd_plibc_close)(int fd); + +static +int _lttng_ust_fd_libc_close(int fd) +{ + if (!__lttng_ust_fd_plibc_close) { + __lttng_ust_fd_plibc_close = dlsym(RTLD_NEXT, "close"); + if (!__lttng_ust_fd_plibc_close) { + fprintf(stderr, "%s\n", dlerror()); + return -1; + } + } + return lttng_ust_safe_close_fd(fd, __lttng_ust_fd_plibc_close); +} + +int close(int fd) +{ + return _lttng_ust_fd_libc_close(fd); +} + +#if defined(__sun__) || defined(__FreeBSD__) +/* Solaris and FreeBSD. */ +void closefrom(int lowfd) +{ + (void) lttng_ust_safe_closefrom(lowfd, __lttng_ust_fd_plibc_close); +} +#elif defined(__NetBSD__) || defined(__OpenBSD__) +/* NetBSD and OpenBSD. */ +int closefrom(int lowfd) +{ + return lttng_ust_safe_closefrom(lowfd, __lttng_ust_fd_plibc_close); +} +#else +/* As far as we know, this OS does not implement closefrom. */ +#endif -- 2.34.1