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 <fal...@tinylab.org> Signed-off-by: Bin Meng <bm...@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); + } + + return 0; + } + +#ifndef _WIN32 + /* Avoid closing the directory */ + int dfd = dirfd(dir); + + for (struct dirent *de = readdir(dir); de; de = readdir(dir)) { + int fd = atoi(de->d_name); + if (fd < first || fd > last) { + /* Exclude the fds outside the target range */ + continue; + } + if (fd != dfd) { + close(fd); + } + } + closedir(dir); +#endif /* _WIN32 */ + + return 0; +} + /* * Delete a file from the filesystem, unless the filename is /dev/fdset/... * -- 2.34.1