From ddcaa0c99bd73671a424650c70415b178144ea7f Mon Sep 17 00:00:00 2001
From: NIWA Naoya <naoya@go.tuat.ac.jp>
Date: Fri, 28 Nov 2025 11:03:52 +0900
Subject: [PATCH] CLI: Add support for mapping stdin to a host file in syscall
 emulation

---
 src/cli/main.cpp               | 13 +++++++++++++
 src/os_emulation/ossyscall.cpp | 19 +++++++++++++++++++
 src/os_emulation/ossyscall.h   |  9 +++++++++
 3 files changed, 41 insertions(+)

diff --git a/src/cli/main.cpp b/src/cli/main.cpp
index 7fa5e1b6..a97733af 100644
--- a/src/cli/main.cpp
+++ b/src/cli/main.cpp
@@ -96,6 +96,8 @@ void create_parser(QCommandLineParser &p) {
     p.addOption(
         { { "serial-out", "serout" }, "File connected to the serial port output.", "FNAME" });
     p.addOption({ { "os-emulation", "osemu" }, "Operating system emulation." });
+    p.addOption(
+        { { "std-in", "stdin" }, "File connected to the syscall standard input.", "FNAME" });
     p.addOption(
         { { "std-out", "stdout" }, "File connected to the syscall standard output.", "FNAME" });
     p.addOption(
@@ -419,8 +421,13 @@ void configure_serial_port(QCommandLineParser &p, SerialPort *ser_port) {
 
 void configure_osemu(QCommandLineParser &p, MachineConfig &config, Machine *machine) {
     CharIOHandler *std_out = nullptr;
+    QScopedPointer<QString> std_in_path;
     int siz;
 
+    siz = p.values("std-in").size();
+    if (siz >= 1) {
+        std_in_path.reset(new QString(p.values("std-in").at(siz - 1)));
+    }
     siz = p.values("std-out").size();
     if (siz >= 1) {
         auto *qf = new QFile(p.values("std-out").at(siz - 1));
@@ -438,6 +445,12 @@ void configure_osemu(QCommandLineParser &p, MachineConfig &config, Machine *mach
         auto *osemu_handler = new osemu::OsSyscallExceptionHandler(
             config.osemu_known_syscall_stop(), config.osemu_unknown_syscall_stop(),
             config.osemu_fs_root());
+        if (!std_in_path.isNull() && !std_in_path->isEmpty()) {
+            if (!osemu_handler->map_stdin_to_hostfile(*std_in_path)) {
+                fprintf(stderr, "Failed to map stdin to host file '%s'\n", std_in_path->toLatin1().data());
+                exit(EXIT_FAILURE);
+            }
+        }
         if (std_out) {
             machine::Machine::connect(
                 osemu_handler, &osemu::OsSyscallExceptionHandler::char_written, std_out,
diff --git a/src/os_emulation/ossyscall.cpp b/src/os_emulation/ossyscall.cpp
index 0ab96d76..b9f9bceb 100644
--- a/src/os_emulation/ossyscall.cpp
+++ b/src/os_emulation/ossyscall.cpp
@@ -623,6 +623,25 @@ bool OsSyscallExceptionHandler::handle_exception(
     return true;
 }
 
+bool OsSyscallExceptionHandler::map_stdin_to_hostfile(const QString &hostpath) {
+    if (hostpath.isEmpty()) return false;
+    int hostfd = open(hostpath.toLatin1().data(), O_RDONLY);
+    if (hostfd < 0) {
+        fprintf(stderr, "map_stdin_to_hostfile: failed to open host file '%s' errno=%d", hostpath.toLatin1().data(), errno);
+        return false;
+    }
+    if (fd_mapping.size() <= 0) {
+        fd_mapping.push_back(FD_UNUSED);
+    }
+    // If there is an existing host fd mapped at target fd 0, close it (but don't close FD_TERMINAL/FD_UNUSED/FD_INVALID)
+    int prev = fd_mapping[0];
+    if (prev >= 0 && prev != FD_TERMINAL && prev != FD_UNUSED && prev != FD_INVALID) {
+        close(prev);
+    }
+    fd_mapping[0] = hostfd;
+    return true;
+}
+
 int32_t OsSyscallExceptionHandler::write_mem(
     machine::FrontendMemory *mem,
     Address addr,
diff --git a/src/os_emulation/ossyscall.h b/src/os_emulation/ossyscall.h
index d20a00cf..0a87a71a 100644
--- a/src/os_emulation/ossyscall.h
+++ b/src/os_emulation/ossyscall.h
@@ -35,6 +35,15 @@ class OsSyscallExceptionHandler : public machine::ExceptionHandler {
         machine::Address next_addr,
         machine::Address jump_branch_pc,
         machine::Address mem_ref_addr) override;
+    /**
+     * Map target fd 0 (stdin) to a host file opened from @hostpath.
+     * Returns true on success (host file opened and mapped), false on error.
+     *
+     * Notes:
+     * - Existing mapping at target fd 0 is closed if it refers to a host fd.
+     * - Uses filepath_to_host() to resolve @hostpath into host file path respecting fs_root.
+     */
+    bool map_stdin_to_hostfile(const QString &hostpath);
     OSSYCALL_HANDLER_DECLARE(syscall_default_handler);
     OSSYCALL_HANDLER_DECLARE(do_sys_exit);
     OSSYCALL_HANDLER_DECLARE(do_sys_set_thread_area);