From 84696f37ae92280ded0e6600074ad8bc518255fa Mon Sep 17 00:00:00 2001 From: Markus Metzger Date: Fri, 26 Jan 2018 13:57:48 +0100 Subject: [PATCH] common: add scoped_mmap Add a simple helper to automatically unmap a memory mapping. gdb/ * common/scoped_mmap.h: New. * unittests/scoped_mmap-selftest.c: New. * Makefile.in (SUBDIR_UNITTESTS_SRCS): Add unittests/scoped_mmap-selftest.c. --- gdb/ChangeLog | 7 ++ gdb/Makefile.in | 1 + gdb/common/scoped_mmap.h | 76 ++++++++++++++++++++++ gdb/unittests/scoped_mmap-selftests.c | 92 +++++++++++++++++++++++++++ 4 files changed, 176 insertions(+) create mode 100644 gdb/common/scoped_mmap.h create mode 100644 gdb/unittests/scoped_mmap-selftests.c diff --git a/gdb/ChangeLog b/gdb/ChangeLog index 25f9e46a0b8..d401ee88915 100644 --- a/gdb/ChangeLog +++ b/gdb/ChangeLog @@ -1,3 +1,10 @@ +2018-02-09 Markus Metzger + + * common/scoped_mmap.h: New. + * unittests/scoped_mmap-selftest.c: New. + * Makefile.in (SUBDIR_UNITTESTS_SRCS): Add + unittests/scoped_mmap-selftest.c. + 2018-02-09 Markus Metzger * common/scoped_fd.h: New. diff --git a/gdb/Makefile.in b/gdb/Makefile.in index a982cdf556e..957654c9bd0 100644 --- a/gdb/Makefile.in +++ b/gdb/Makefile.in @@ -425,6 +425,7 @@ SUBDIR_UNITTESTS_SRCS = \ unittests/ptid-selftests.c \ unittests/rsp-low-selftests.c \ unittests/scoped_fd-selftests.c \ + unittests/scoped_mmap-selftests.c \ unittests/scoped_restore-selftests.c \ unittests/xml-utils-selftests.c diff --git a/gdb/common/scoped_mmap.h b/gdb/common/scoped_mmap.h new file mode 100644 index 00000000000..739cc7044af --- /dev/null +++ b/gdb/common/scoped_mmap.h @@ -0,0 +1,76 @@ +/* scoped_mmap, automatically unmap files + + Copyright (C) 2018 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#ifndef SCOPED_MMAP_H +#define SCOPED_MMAP_H + +#include "config.h" + +#ifdef HAVE_SYS_MMAN_H + +#include + +/* A smart-pointer-like class to mmap() and automatically munmap() a memory + mapping. */ + +class scoped_mmap +{ +public: + scoped_mmap () noexcept : m_mem (MAP_FAILED), m_length (0) {} + scoped_mmap (void *addr, size_t length, int prot, int flags, int fd, + off_t offset) noexcept : m_length (length) + { + m_mem = mmap (addr, m_length, prot, flags, fd, offset); + } + ~scoped_mmap () + { + if (m_mem != MAP_FAILED) + munmap (m_mem, m_length); + } + + DISABLE_COPY_AND_ASSIGN (scoped_mmap); + + void *release () noexcept + { + void *mem = m_mem; + m_mem = MAP_FAILED; + m_length = 0; + return mem; + } + + void reset (void *addr, size_t length, int prot, int flags, int fd, + off_t offset) noexcept + { + if (m_mem != MAP_FAILED) + munmap (m_mem, m_length); + + m_length = length; + m_mem = mmap (addr, m_length, prot, flags, fd, offset); + } + + size_t size () const noexcept { return m_length; } + void *get () const noexcept { return m_mem; } + +private: + void *m_mem; + size_t m_length; +}; + +#endif /* HAVE_SYS_MMAN_H */ +#endif /* SCOPED_MMAP_H */ diff --git a/gdb/unittests/scoped_mmap-selftests.c b/gdb/unittests/scoped_mmap-selftests.c new file mode 100644 index 00000000000..ece3d7a18ac --- /dev/null +++ b/gdb/unittests/scoped_mmap-selftests.c @@ -0,0 +1,92 @@ +/* Self tests for scoped_mmap for GDB, the GNU debugger. + + Copyright (C) 2018 Free Software Foundation, Inc. + + This file is part of GDB. + + This program is free software; you can redistribute it and/or modify + it under the terms of the GNU General Public License as published by + the Free Software Foundation; either version 3 of the License, or + (at your option) any later version. + + This program 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 General Public License for more details. + + You should have received a copy of the GNU General Public License + along with this program. If not, see . */ + +#include "defs.h" + +#include "common/scoped_mmap.h" +#include "config.h" + +#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_UNISTD_H) + +#include "selftest.h" + +#include + +namespace selftests { +namespace scoped_mmap { + +/* Test that the file is unmapped. */ +static void +test_destroy () +{ + void *mem; + + errno = 0; + { + ::scoped_mmap smmap (nullptr, sysconf (_SC_PAGESIZE), PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); + + mem = smmap.get (); + SELF_CHECK (mem != nullptr); + } + + SELF_CHECK (msync (mem, sysconf (_SC_PAGESIZE), 0) == -1 && errno == ENOMEM); +} + +/* Test that the memory can be released. */ +static void +test_release () +{ + void *mem; + + errno = 0; + { + ::scoped_mmap smmap (nullptr, sysconf (_SC_PAGESIZE), PROT_WRITE, + MAP_ANONYMOUS | MAP_PRIVATE, 0, 0); + + mem = smmap.release (); + SELF_CHECK (mem != nullptr); + } + + SELF_CHECK (msync (mem, sysconf (_SC_PAGESIZE), 0) == 0 || errno != ENOMEM); + + munmap (mem, sysconf (_SC_PAGESIZE)); +} + +/* Run selftests. */ +static void +run_tests () +{ + test_destroy (); + test_release (); +} + +} /* namespace scoped_mmap */ +} /* namespace selftests */ + +#endif /* !defined(HAVE_SYS_MMAN_H) || !defined(HAVE_UNISTD_H) */ + +void +_initialize_scoped_mmap_selftests () +{ +#if defined(HAVE_SYS_MMAN_H) && defined(HAVE_UNISTD_H) + selftests::register_test ("scoped_mmap", + selftests::scoped_mmap::run_tests); +#endif +} -- 2.30.2