This introduces a new QEMU API qemu_close_range() that closes all
open file descriptors from first to last (included).
This API will try a more efficient call to close_range(), or walk
through of /proc/self/fd whenever these are possible, otherwise it
falls back to a plain close loop.
Co-developed-by: Zhangjin Wu <falcon@tinylab.org>
Signed-off-by: Bin Meng <bmeng@tinylab.org>
---
Changes in v3:
- fix win32 build failure
Changes in v2:
- new patch: "util/osdep: Introduce qemu_close_range()"
include/qemu/osdep.h | 1 +
util/osdep.c | 48 ++++++++++++++++++++++++++++++++++++++++++++
2 files changed, 49 insertions(+)
diff --git a/include/qemu/osdep.h b/include/qemu/osdep.h
index cc61b00ba9..e22434ce10 100644
--- a/include/qemu/osdep.h
+++ b/include/qemu/osdep.h
@@ -560,6 +560,7 @@ int qemu_open_old(const char *name, int flags, ...);
int qemu_open(const char *name, int flags, Error **errp);
int qemu_create(const char *name, int flags, mode_t mode, Error **errp);
int qemu_close(int fd);
+int qemu_close_range(unsigned int first, unsigned int last);
int qemu_unlink(const char *name);
#ifndef _WIN32
int qemu_dup_flags(int fd, int flags);
diff --git a/util/osdep.c b/util/osdep.c
index e996c4744a..91275e70f8 100644
--- a/util/osdep.c
+++ b/util/osdep.c
@@ -30,6 +30,7 @@
#include "qemu/mprotect.h"
#include "qemu/hw-version.h"
#include "monitor/monitor.h"
+#include <dirent.h>
static const char *hw_version = QEMU_HW_VERSION;
@@ -411,6 +412,53 @@ int qemu_close(int fd)
return close(fd);
}
+int qemu_close_range(unsigned int first, unsigned int last)
+{
+ DIR *dir = NULL;
+
+#ifdef CONFIG_CLOSE_RANGE
+ int r = close_range(first, last, 0);
+ if (!r) {
+ /* Success, no need to try other ways. */
+ return 0;
+ }
+#endif
+
+#ifdef __linux__
+ dir = opendir("/proc/self/fd");
+#endif
+ if (!dir) {
+ /*
+ * If /proc is not mounted or /proc/self/fd is not supported,
+ * try close() from first to last.
+ */
+ for (int i = first; i <= last; i++) {
+ close(i);