shell/ash: add forkshell_* to transfer data via pipe

2 files changed, 129 insertions, 0 deletions

diff --git a/shell/ash_mingw.c b/shell/ash_mingw.c
index c52d8b45c..a412b7210 100644
--- a/shell/ash_mingw.c
+++ b/shell/ash_mingw.c
@@ -781,3 +781,115 @@ misc_recv(int fd)
         /* stackbase... */
         guard_recv1(fd, -1);
 }
+
+/* * * * * fork entries * * * * */
+struct forkpoint {
+        const char *name;
+        void (*func)(union node *,int);
+};
+
+/* entry names should not be too long */
+struct forkpoint forkpoints[] = {
+        { NULL, NULL },
+};
+
+/* * * * * fork emulation * * * * */
+static int
+forkshell_init(struct forkshell *fs)
+{
+        static char argv2[32];
+        static const char *argv[4] = { NULL, "sh", argv2, NULL };
+        int p[2];
+
+        if (_pipe(p, 0, 0) < 0)
+                ash_msg_and_raise_error("Unable to create pipe");
+
+        /*
+         * Do not use C file handle here because MinGW port
+         * uses a custom execvp version, which will not reconstruct
+         * filehandle table correctly (for msvcrt to read)
+         */
+        sprintf(argv2, "subash%lx:%s", _get_osfhandle(p[0]), fs->fp);
+
+        argv[0] = CONFIG_BUSYBOX_EXEC_PATH;
+        fs->cmd.argv = argv;
+        fs->fd = p[1];
+        return 0;
+}
+
+static void
+forkshell_transfer(struct forkshell *fs)
+{
+        tblentry_send(fs->fd);
+        vartab_send(fs->fd);
+        localvars_send(fs->fd);
+        optlist_send(fs->fd);
+        misc_send(fs->fd);
+
+        guard_send(fs->fd, SER_FORK);
+        node_send(fs->fd, fs->n);
+        int_send(fs->fd, fs->flags);
+}
+
+static void
+forkshell_transfer_done(struct forkshell *fs)
+{
+        guard_send(fs->fd, SER_DONE);
+        close(fs->fd);
+}
+
+static void
+forkshell_cleanup(struct forkshell *fs)
+{
+}
+
+static int
+forkshell(const char *fp, union node *n, int flags)
+{
+        struct forkshell fs;
+        int status;
+        memset(&fs, 0, sizeof(fs));
+        fs.fp = fp;
+        fs.n = n;
+        fs.flags = flags;
+        forkshell_init(&fs);
+        if (start_command(&fs.cmd))
+                ash_msg_and_raise_error("unable to spawn shell");
+        forkshell_transfer(&fs);
+        forkshell_transfer_done(&fs);
+        forkshell_cleanup(&fs);
+        set_exitstatus(finish_command(&fs.cmd), fs.cmd.argv, &status);
+        return status;
+}
+
+static void
+subshell_run()
+{
+        struct forkpoint *fp;
+        int fd = subash_fd;
+        union node *n;
+        int flags;
+
+        if (fd == -1)
+                return;
+
+        for (fp = forkpoints;fp->name && strcmp(fp->name, subash_entry);fp ++);
+
+        if (!fp->name)
+                die("ASH_SHELL_ENTRY invalid");
+
+        tblentry_recv(fd);
+        vartab_recv(fd);
+        localvars_recv(fd);
+        optlist_recv(fd);
+        misc_recv(fd);
+
+        guard_recv1(fd, SER_FORK);
+        n = node_recv(fd);
+        flags = int_recv(fd);
+        guard_recv1(fd, SER_DONE);
+
+        fp->func(n, flags);
+
+        die("subshell ended unexpectedly");
+}
diff --git a/shell/ash_mingw.h b/shell/ash_mingw.h
new file mode 100644
index 000000000..658c7dae2
--- /dev/null
+++ b/shell/ash_mingw.h
@@ -0,0 +1,17 @@
+struct forkshell {
+        const char *fp;
+        union node *n;
+        int flags;
+        struct child_process cmd;
+        int fd;
+};
+
+static int forkshell_init(struct forkshell *fs);
+static void forkshell_transfer(struct forkshell *fs);
+static void forkshell_transfer_done(struct forkshell *fs);
+static void forkshell_cleanup(struct forkshell *fs);
+static int forkshell(const char *fp, union node *n, int flags);
+static void subshell_run();
+
+static int subash_fd = -1;
+static char subash_entry[16];