These non-standard (former is Linux and FreeBSD, latter Solaris and
*BSD) functions are useful to avoid leaking unintended file descriptors
(i.e. those opened without O_CLOEXEC by negligence rather than
intentionally) to children on exec*(). Without them, one either has to
blindly call close() on integers up to _SC_OPEN_MAX (which can be very
large), or look up open file descriptors from /proc/self/fd (which
cannot be done safely after fork, since opendir() is not
async-signal-safe, not to mention this approach is Linux-specific).
The functions will be used in the following commit.
---
compat/Makefile.local | 4 ++++
compat/closefrom.c | 25 +++++++++++++++++++++++++
compat/have_close_range.c | 8 ++++++++
compat/have_closefrom.c | 8 ++++++++
configure | 32 ++++++++++++++++++++++++++++++++
5 files changed, 77 insertions(+)
create mode 100644 compat/closefrom.c
create mode 100644 compat/have_close_range.c
create mode 100644 compat/have_closefrom.c
diff --git a/compat/Makefile.local b/compat/Makefile.local
index c58ca746..70448be9 100644
--- a/compat/Makefile.local
+++ b/compat/Makefile.local
@@ -5,6 +5,10 @@ extra_cflags += -I$(srcdir)/$(dir)
notmuch_compat_srcs :=
+ifeq ($(HAVE_CLOSE_RANGE)$(HAVE_CLOSEFROM),00)
+notmuch_compat_srcs += $(dir)/closefrom.c
+endif
+
ifneq ($(HAVE_GETLINE),1)
notmuch_compat_srcs += $(dir)/getline.c $(dir)/getdelim.c
endif
diff --git a/compat/closefrom.c b/compat/closefrom.c
new file mode 100644
index 00000000..6e9cc12d
--- /dev/null
+++ b/compat/closefrom.c
@@ -0,0 +1,25 @@
+/* closefrom.c --- Implementation of replacement closefrom function.
+ *
+ * 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, 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, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA
+ * 02110-1301, USA. */
+
+#include <unistd.h>
+
+void
+closefrom (int lowfd)
+{
+ for (int i = lowfd; i < 1024; i++)
+ close (i);
+}
diff --git a/compat/have_close_range.c b/compat/have_close_range.c
new file mode 100644
index 00000000..4a1a947f
--- /dev/null
+++ b/compat/have_close_range.c
@@ -0,0 +1,8 @@
+#define _GNU_SOURCE
+#include <unistd.h>
+
+int
+main ()
+{
+ return close_range (0, ~0U, 0);
+}
diff --git a/compat/have_closefrom.c b/compat/have_closefrom.c
new file mode 100644
index 00000000..438dd7b1
--- /dev/null
+++ b/compat/have_closefrom.c
@@ -0,0 +1,8 @@
+#include <unistd.h>
+
+int
+main ()
+{
+ closefrom (0);
+ return 0;
+}
diff --git a/configure b/configure
index 7afd08c7..ae1939d9 100755
--- a/configure
+++ b/configure
@@ -1184,6 +1184,28 @@ else
fi
rm -f compat/have_timegm
+printf "Checking for close_range... "
+have_close_range="0"
+have_closefrom="0"
+if ${CC} -o compat/have_close_range "$srcdir"/compat/have_close_range.c >
/dev/null 2>&1
+then
+ printf "Yes.\n"
+ have_close_range="1"
+else
+ printf "No (will try closefrom).\n"
+
+ printf "Checking for closefrom... "
+ if ${CC} -o compat/have_closefrom "$srcdir"/compat/have_closefrom.c >
/dev/null 2>&1
+ then
+ printf "Yes.\n"
+ have_closefrom="1"
+ else
+ printf "No (will use our own instead).\n"
+ fi
+ rm -f compat/have_closefrom
+fi
+rm -f compat/have_close_range
+
cat <<EOF > _time_t.c
#include <time.h>
#include <assert.h>
@@ -1473,6 +1495,14 @@ HAVE_STRSEP = ${have_strsep}
# build its own version)
HAVE_TIMEGM = ${have_timegm}
+# Whether the close_range function is available (if not, then notmuch will
+# use closefrom)
+HAVE_CLOSE_RANGE = ${have_close_range}
+
+# Whether the closefrom function is available (if not, then notmuch will
+# use its own version)
+HAVE_CLOSEFROM = ${have_closefrom}
+
# Whether struct dirent has d_type (if not, then notmuch will use stat)
HAVE_D_TYPE = ${have_d_type}
@@ -1558,6 +1588,8 @@ COMMON_CONFIGURE_CFLAGS = \\
-DHAVE_STRCASESTR=\$(HAVE_STRCASESTR) \\
-DHAVE_STRSEP=\$(HAVE_STRSEP) \\
-DHAVE_TIMEGM=\$(HAVE_TIMEGM) \\
+ -DHAVE_CLOSE_RANGE=\$(HAVE_CLOSE_RANGE) \\
+ -DHAVE_CLOSEFROM=\$(HAVE_CLOSEFROM) \\
-DHAVE_D_TYPE=\$(HAVE_D_TYPE) \\
-DSTD_GETPWUID=\$(STD_GETPWUID) \\
-DSTD_ASCTIME=\$(STD_ASCTIME) \\
--
2.47.3
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