qemu/osdep: Move close_all_open_fds() to oslib-posix

Move close_all_open_fds() in oslib-posix, rename it
qemu_close_all_open_fds() and export it.

Signed-off-by: Clément Léger <cleger@rivosinc.com>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-ID: <20240802145423.3232974-2-cleger@rivosinc.com>
Signed-off-by: Richard Henderson <richard.henderson@linaro.org>

util/oslib-posix.c

@@ -807,3 +807,37 @@ int qemu_msync(void *addr, size_t length, int fd)
 
     return msync(addr, length, MS_SYNC);
 }
+
+/*
+ * Close all open file descriptors.
+ */
+void qemu_close_all_open_fd(void)
+{
+    struct dirent *de;
+    int fd, dfd;
+    DIR *dir;
+
+#ifdef CONFIG_CLOSE_RANGE
+    int r = close_range(0, ~0U, 0);
+    if (!r) {
+        /* Success, no need to try other ways. */
+        return;
+    }
+#endif
+
+    dir = opendir("/proc/self/fd");
+    if (!dir) {
+        /* If /proc is not mounted, there is nothing that can be done. */
+        return;
+    }
+    /* Avoid closing the directory. */
+    dfd = dirfd(dir);
+
+    for (de = readdir(dir); de; de = readdir(dir)) {
+        fd = atoi(de->d_name);
+        if (fd != dfd) {
+            close(fd);
+        }
+    }
+    closedir(dir);
+}