Merge pull request #4663 from krobelus/kitty-protocol-subshell-switch-key

Fix kitty keyboard protocol parsing of ctrl-o

Author: zyv

lib/Makefile.am

@@ -26,6 +26,7 @@ SUBLIB_includes = \
 	widget.h
 
 SRC_mc_utils = \
+	terminal.c terminal.h \
 	utilunix.c \
 	unixcompat.h \
 	util.c util.h

lib/terminal.c

@@ -0,0 +1,318 @@
+/*
+   Terminal emulation.
+
+   Copyright (C) 2025
+   Free Software Foundation, Inc.
+
+   This file is part of the Midnight Commander.
+   Authors:
+   Miguel de Icaza, 1994, 1995, 1996
+   Johannes Altmanninger, 2025
+
+   The Midnight Commander is free software: you can redistribute it
+   and/or modify it under the terms of the GNU General Public License as
+   published by the Free Software Foundation, either version 3 of the License,
+   or (at your option) any later version.
+
+   The Midnight Commander is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+   GNU General Public License for more details.
+
+   You should have received a copy of the GNU General Public License
+   along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+/** \file terminal.c
+ *  \brief Source: terminal emulation.
+ *  \author Johannes Altmanninger
+ *  \date 2025
+ *
+ *  Subshells running inside Midnight Commander may assume they run inside
+ *  a terminal. This module helps us act like a real terminal in relevant
+ *  aspects.
+ */
+
+#include <config.h>
+
+#include "lib/util.h"
+#include "lib/strutil.h"
+
+#include "lib/terminal.h"
+
+/*** global variables ****************************************************************************/
+
+/*** file scope macro definitions ****************************************************************/
+
+/*** file scope type declarations ****************************************************************/
+
+/*** forward declarations (file scope functions) *************************************************/
+
+/* --------------------------------------------------------------------------------------------- */
+/*** file scope functions ************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+/* --------------------------------------------------------------------------------------------- */
+/*** public functions ****************************************************************************/
+/* --------------------------------------------------------------------------------------------- */
+
+/**
+ * Parse a CSI command, starting from the third byte (i.e. the first
+ * parameter byte, if any).
+ *
+ * On success, *sptr will point to one-past the end of the sequence.
+ * On failure, *sptr will point to the first invalid byte.
+ *
+ * Here's the format in a sort of pidgin BNF:
+ *
+ * CSI-command = Esc '[' parameters (intermediate-byte)* final-byte
+ * parameters = [0-9;:]+
+ *            | [<=>?] (parameter-byte)* # private mode
+ * parameter-byte = [\x30-\x3F]     # one of "0-9;:<=>?"
+ * intermediate-byte = [\x20–\x2F]  # one of " !\"#$%&'()*+,-./"
+ * final-byte = [\x40-\x7e]         # one of "@A–Z[\]^_`a–z{|}~"
+ */
+gboolean
+parse_csi (struct csi_command_t *out, const char **sptr, const char *end)
+{
+    gboolean ok = FALSE;
+
+    const char *s = *sptr;
+    if (s == end)
+        goto invalid_sequence;
+
+    char c = *s;
+
+#define NEXT_CHAR                                                                                  \
+    do                                                                                             \
+    {                                                                                              \
+        if (++s == end)                                                                            \
+            goto invalid_sequence;                                                                 \
+        c = *s;                                                                                    \
+    }                                                                                              \
+    while (0)
+
+    char private_mode = '\0';
+
+    if (c >= '<' && c <= '?')  // "<=>?"
+    {
+        private_mode = c;
+        NEXT_CHAR;
+    }
+
+    // parameter bytes
+    size_t param_count = 0;
+
+    if (private_mode != '\0')
+    {
+        while (c >= 0x30 && c <= 0x3F)
+            NEXT_CHAR;
+    }
+    else
+    {
+        if (out != NULL)
+            // N.B. empty parameter strings are allowed. For our current use,
+            // treating them as zeroes happens to work.
+            memset (out->params, 0, sizeof (out->params));
+
+        uint32_t tmp = 0;
+        size_t sub_index = 0;
+
+        while (c >= 0x30 && c <= 0x3F)
+        {
+            if (c >= '0' && c <= '9')
+            {
+                if (param_count == 0)
+                    param_count = 1;
+                if (tmp * 10 < tmp)
+                    goto invalid_sequence;  // overflow
+                tmp *= 10;
+                if (tmp + c - '0' < tmp)
+                    goto invalid_sequence;  // overflow
+                tmp += c - '0';
+                if (out != NULL)
+                    out->params[param_count - 1][sub_index] = tmp;
+            }
+            else if (c == ':' && ++sub_index < G_N_ELEMENTS (out->params[0]))
+                tmp = 0;
+            else if (c == ';' && ++param_count <= G_N_ELEMENTS (out->params))
+                tmp = 0, sub_index = 0;
+            else
+                goto invalid_sequence;
+            NEXT_CHAR;
+        }
+    }
+
+    while (c >= 0x20 && c <= 0x2F)  // intermediate bytes
+        NEXT_CHAR;
+#undef NEXT_CHAR
+
+    if (c < 0x40 || c > 0x7E)  // final byte
+        goto invalid_sequence;
+
+    ++s;
+    ok = TRUE;
+
+    if (out != NULL)
+    {
+        out->private_mode = private_mode;
+        out->param_count = param_count;
+    }
+
+invalid_sequence:
+    *sptr = s;
+    return ok;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Remove all control sequences (CSI, OSC) from the argument string.
+ *
+ * The 256-color and true-color escape sequences should allow either ';' or ':' inside as
+ * separator, actually, ':' is the more correct according to ECMA-48. Some terminal emulators
+ * (e.g. xterm, gnome-terminal) support this.
+ *
+ * Non-printable characters are also removed.
+ */
+
+char *
+strip_ctrl_codes (char *s)
+{
+    char *w;        // Current position where the stripped data is written
+    const char *r;  // Current position where the original data is read
+
+    if (s == NULL)
+        return NULL;
+
+    const char *end = s + strlen (s);
+
+    for (w = s, r = s; *r != '\0';)
+    {
+        if (*r == ESC_CHAR)
+        {
+            // Skip the control sequence's arguments
+            // '(' need to avoid strange 'B' letter in *Suse (if mc runs under root user)
+            if (*(++r) == '[' || *r == '(')
+            {
+                ++r;
+                parse_csi (NULL, &r, end);
+                // We're already past the sequence, no need to increment.
+                continue;
+            }
+            if (*r == ']')
+            {
+                /*
+                 * Skip xterm's OSC (Operating System Command)
+                 * https://www.xfree86.org/current/ctlseqs.html
+                 * OSC P s ; P t ST
+                 * OSC P s ; P t BEL
+                 */
+                const char *new_r;
+
+                for (new_r = r; *new_r != '\0'; new_r++)
+                {
+                    switch (*new_r)
+                    {
+                        // BEL
+                    case '\a':
+                        r = new_r;
+                        goto osc_out;
+                    case ESC_CHAR:
+                        // ST
+                        if (new_r[1] == '\\')
+                        {
+                            r = new_r + 1;
+                            goto osc_out;
+                        }
+                        break;
+                    default:
+                        break;
+                    }
+                }
+            osc_out:;
+            }
+
+            /*
+             * Now we are at the last character of the sequence.
+             * Skip it unless it's binary 0.
+             */
+            if (*r != '\0')
+                r++;
+        }
+        else
+        {
+            const char *n;
+
+            n = str_cget_next_char (r);
+            if (str_isprint (r))
+            {
+                memmove (w, r, n - r);
+                w += n - r;
+            }
+            r = n;
+        }
+    }
+
+    *w = '\0';
+    return s;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+/**
+ * Convert "\E" -> esc character and ^x to control-x key and ^^ to ^ key
+ *
+ * @param p pointer to string
+ *
+ * @return newly allocated string
+ */
+
+char *
+convert_controls (const char *p)
+{
+    char *valcopy;
+    char *q;
+
+    valcopy = g_strdup (p);
+
+    // Parse the escape special character
+    for (q = valcopy; *p != '\0';)
+        switch (*p)
+        {
+        case '\\':
+            p++;
+
+            if (*p == 'e' || *p == 'E')
+            {
+                p++;
+                *q++ = ESC_CHAR;
+            }
+            break;
+
+        case '^':
+            p++;
+            if (*p == '^')
+                *q++ = *p++;
+            else
+            {
+                char c;
+
+                c = *p | 0x20;
+                if (c >= 'a' && c <= 'z')
+                {
+                    *q++ = c - 'a' + 1;
+                    p++;
+                }
+                else if (*p != '\0')
+                    p++;
+            }
+            break;
+
+        default:
+            *q++ = *p++;
+        }
+
+    *q = '\0';
+    return valcopy;
+}
+
+/* --------------------------------------------------------------------------------------------- */

lib/terminal.h

@@ -0,0 +1,41 @@
+/** \file terminal.h
+ *  \brief Header: terminal emulation logic.
+ */
+
+#ifndef MC_TERMINAL_H
+#define MC_TERMINAL_H
+
+#include <sys/types.h>
+#include <inttypes.h>  // uint32_t
+
+#include "lib/global.h"  // include <glib.h>
+
+/*** typedefs(not structures) and defined constants **********************************************/
+
+/*** enums ***************************************************************************************/
+
+/*** structures declarations (and typedefs of structures)*****************************************/
+
+struct csi_command_t
+{
+    char private_mode;
+    uint32_t params[16][4];
+    size_t param_count;
+};
+
+/*** global variables defined in .c file *********************************************************/
+
+/*** declarations of public functions ************************************************************/
+
+gboolean parse_csi (struct csi_command_t *out, const char **sptr, const char *end);
+
+char *strip_ctrl_codes (char *s);
+
+/* Replaces "\\E" and "\\e" with "\033". Replaces "^" + [a-z] with
+ * ((char) 1 + (c - 'a')). The same goes for "^" + [A-Z].
+ * Returns a newly allocated string. */
+char *convert_controls (const char *s);
+
+/*** inline functions ****************************************************************************/
+
+#endif