dcs: sort of implement DCS passthrough

We now store the passthrough characters in a buffer, and call
dcs_passthrough() on unhook.

However, dcs_passthrough() doesn't do anything.

dcs.c

@@ -0,0 +1,32 @@
+#include "dcs.h"
+
+#define LOG_MODULE "dcs"
+#define LOG_ENABLE_DBG 0
+#include "log.h"
+
+void
+dcs_passthrough(struct terminal *term)
+{
+    LOG_DBG("DCS passthrough: %.*s (%zu bytes)",
+            (int)term->vt.dcs.idx, term->vt.dcs.data, term->vt.dcs.idx);
+}
+
+bool
+dcs_ensure_size(struct terminal *term, size_t required_size)
+{
+    if (required_size <= term->vt.dcs.size)
+        return true;
+
+    size_t new_size = (required_size + 127) / 128 * 128;
+    assert(new_size > 0);
+
+    uint8_t *new_data = realloc(term->vt.dcs.data, new_size);
+    if (new_data == NULL) {
+        LOG_ERRNO("failed to increase size of DCS buffer");
+        return false;
+    }
+
+    term->vt.dcs.data = new_data;
+    term->vt.dcs.size = new_size;
+    return true;
+}

dcs.h

@@ -0,0 +1,7 @@
+#pragma once
+
+#include <stdbool.h>
+#include "terminal.h"
+
+void dcs_passthrough(struct terminal *term);
+bool dcs_ensure_size(struct terminal *term, size_t required_size);

main.c

@@ -819,6 +819,7 @@ out:
         xkb_context_unref(term.kbd.xkb);
 
     free(term.vt.osc.data);
+    free(term.vt.dcs.data);
     for (int row = 0; row < term.normal.num_rows; row++)
         grid_row_free(term.normal.rows[row]);
     free(term.normal.rows);

meson.build

@@ -62,6 +62,7 @@ executable(
   'config.c', 'config.h',
   'commands.c', 'commands.h',
   'csi.c', 'csi.h',
+  'dcs.c', 'dcs.h',
   'font.c', 'font.h',
   'grid.c', 'grid.h',
   'input.c', 'input.h',

terminal.h

@@ -129,6 +129,11 @@ struct vt {
         size_t size;
         size_t idx;
     } osc;
+    struct {
+        uint8_t *data;
+        size_t size;
+        size_t idx;
+    } dcs;
     struct {
         uint8_t data[4];
         size_t idx;

vt.c

@@ -9,8 +9,9 @@
 #define LOG_ENABLE_DBG 0
 #include "log.h"
 #include "csi.h"
-#include "osc.h"
+#include "dcs.h"
 #include "grid.h"
+#include "osc.h"
 
 /* https://vt100.net/emu/dec_ansi_parser */
 
@@ -923,10 +924,21 @@ action(struct terminal *term, enum action _action, uint8_t c)
         break;
 
     case ACTION_HOOK:
-    case ACTION_UNHOOK:
+        term->vt.dcs.idx = 0;
+        break;
+
     case ACTION_PUT:
-        LOG_ERR("unimplemented: action %s", action_names[_action]);
-        abort();
+        if (!dcs_ensure_size(term, term->vt.dcs.idx + 1))
+            break;
+        term->vt.dcs.data[term->vt.dcs.idx++] = c;
+        break;
+
+    case ACTION_UNHOOK:
+        if (!dcs_ensure_size(term, term->vt.dcs.idx + 1))
+            break;
+        term->vt.dcs.data[term->vt.dcs.idx] = '\0';
+        dcs_passthrough(term);
+        break;
 
     case ACTION_UTF8_2_ENTRY:
         term->vt.utf8.idx = 0;