linux-user: add open() hijack infrastructure
There are a number of files in /proc that expose host information
to the guest program. This patch adds infrastructure to override
the open() syscall for guest programs to enable us to on the fly
generate guest sensible files.
Signed-off-by: Alexander Graf <agraf@suse.de>
Signed-off-by: Riku Voipio <riku.voipio@linaro.org>
diff --git a/linux-user/syscall.c b/linux-user/syscall.c
index 2bf9e7e..e100025 100644
--- a/linux-user/syscall.c
+++ b/linux-user/syscall.c
@@ -4600,6 +4600,52 @@
return osversion;
}
+static int do_open(void *cpu_env, const char *pathname, int flags, mode_t mode)
+{
+ struct fake_open {
+ const char *filename;
+ int (*fill)(void *cpu_env, int fd);
+ };
+ const struct fake_open *fake_open;
+ static const struct fake_open fakes[] = {
+ { NULL, NULL }
+ };
+
+ for (fake_open = fakes; fake_open->filename; fake_open++) {
+ if (!strncmp(pathname, fake_open->filename,
+ strlen(fake_open->filename))) {
+ break;
+ }
+ }
+
+ if (fake_open->filename) {
+ const char *tmpdir;
+ char filename[PATH_MAX];
+ int fd, r;
+
+ /* create temporary file to map stat to */
+ tmpdir = getenv("TMPDIR");
+ if (!tmpdir)
+ tmpdir = "/tmp";
+ snprintf(filename, sizeof(filename), "%s/qemu-open.XXXXXX", tmpdir);
+ fd = mkstemp(filename);
+ if (fd < 0) {
+ return fd;
+ }
+ unlink(filename);
+
+ if ((r = fake_open->fill(cpu_env, fd))) {
+ close(fd);
+ return r;
+ }
+ lseek(fd, 0, SEEK_SET);
+
+ return fd;
+ }
+
+ return get_errno(open(path(pathname), flags, mode));
+}
+
/* do_syscall() should always have a single exit point at the end so
that actions, such as logging of syscall results, can be performed.
All errnos that do_syscall() returns must be -TARGET_<errcode>. */
@@ -4685,9 +4731,9 @@
case TARGET_NR_open:
if (!(p = lock_user_string(arg1)))
goto efault;
- ret = get_errno(open(path(p),
- target_to_host_bitmask(arg2, fcntl_flags_tbl),
- arg3));
+ ret = get_errno(do_open(cpu_env, p,
+ target_to_host_bitmask(arg2, fcntl_flags_tbl),
+ arg3));
unlock_user(p, arg1, 0);
break;
#if defined(TARGET_NR_openat) && defined(__NR_openat)
