Ticket #4258: wron subshell prompt parsing with fish 3.3.0.

Fish 3.3.0 sends \r while printing prompt and mc erases prompt buffer.
This change was introduced by
https://github.com/fish-shell/fish-shell/pull/8011.

(parse_subshell_prompt_string): modify subshell promt parsing.
First, skip trailing EOL (\n and \r). Then find previous EOL (if it
exists).
Get a part of subshell prompt between those EOLs and use it as
MC prompt.

Signed-off-by: Andrew Borodin <aborodin@vmail.ru>

configure.ac

@@ -722,6 +722,7 @@ tests/src/Makefile
 tests/src/filemanager/Makefile
 tests/src/editor/Makefile
 tests/src/editor/test-data.txt
+tests/src/subshell/Makefile
 tests/src/vfs/Makefile
 tests/src/vfs/extfs/Makefile
 tests/src/vfs/extfs/helpers-list/Makefile

src/subshell/common.c

@@ -717,11 +717,33 @@ parse_subshell_prompt_string (const char *buffer, int bytes)
         subshell_prompt_temp_buffer = g_string_sized_new (INITIAL_PROMPT_SIZE);
 
     /* Extract the prompt from the shell output */
-    for (i = 0; i < bytes; i++)
-        if (buffer[i] == '\n' || buffer[i] == '\r')
-            g_string_set_size (subshell_prompt_temp_buffer, 0);
-        else if (buffer[i] != '\0')
-            g_string_append_c (subshell_prompt_temp_buffer, buffer[i]);
+
+    /* Remove trailing '\n' and '\r' */
+    for (i = bytes - 1; (buffer[i] == '\n' || buffer[i] == '\r') && i >= 0; i--)
+        ;
+    if (i < 0)
+    {
+        g_string_set_size (subshell_prompt_temp_buffer, 0);
+        return;
+    }
+
+    /* New length */
+    bytes = i + 1;
+
+    /* Get a part of buffer between last '\n' and/or '\r' and penultimate ones */
+    for (; buffer[i] != '\n' && buffer[i] != '\r' && i >= 0; i--)
+        ;
+    if (i >= 0)
+    {
+        i++;
+        buffer += i;
+        bytes -= i;
+    }
+    g_string_overwrite_len (subshell_prompt_temp_buffer, 0, buffer, bytes);
+    /* Make string nul-terminated */
+    g_string_set_size (subshell_prompt_temp_buffer, bytes);
+
+    /* FIXME: can buffer contain '\0'? */
 }
 
 /* --------------------------------------------------------------------------------------------- */

tests/src/Makefile.am

@@ -6,6 +6,10 @@ if USE_INTERNAL_EDIT
 SUBDIRS += editor
 endif
 
+if ENABLE_SUBSHELL
+SUBDIRS += subshell
+endif
+
 AM_CPPFLAGS = \
 	$(GLIB_CFLAGS) \
 	-I$(top_srcdir) \

tests/src/subshell/Makefile.am

@@ -0,0 +1,26 @@
+PACKAGE_STRING = "/src/subshell"
+
+AM_CPPFLAGS = \
+	$(GLIB_CFLAGS) \
+	-I$(top_srcdir) \
+	@CHECK_CFLAGS@ \
+	@PCRE_CPPFLAGS@
+
+AM_LDFLAGS = @TESTS_LDFLAGS@
+
+LIBS = @CHECK_LIBS@ \
+	$(top_builddir)/src/libinternal.la \
+	$(top_builddir)/lib/libmc.la \
+	@PCRE_LIBS@
+
+if ENABLE_MCLIB
+LIBS += $(GLIB_LIBS)
+endif
+
+TESTS = \
+	parse_subshell_prompt_string
+
+check_PROGRAMS = $(TESTS)
+
+parse_subshell_prompt_string_SOURCES = \
+	parse_subshell_prompt_string.c

tests/src/subshell/parse_subshell_prompt_string.c

@@ -0,0 +1,135 @@
+/*
+   src/subshell - tests for parse_subshell_prompt_string() function
+
+   Copyright (C) 2021
+   Free Software Foundation, Inc.
+
+   Written by:
+   Andrew Borodin <aborodin@vmail.ru>, 2021
+
+   This file is part of the Midnight Commander.
+
+   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 <http://www.gnu.org/licenses/>.
+ */
+
+#define TEST_SUITE_NAME "/src/subshell"
+
+#include "tests/mctest.h"
+
+#include "src/subshell/common.c"
+
+/* --------------------------------------------------------------------------------------------- */
+
+/* @Before */
+static void
+setup (void)
+{
+    mc_global.mc_run_mode = MC_RUN_FULL;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/* @After */
+static void
+teardown (void)
+{
+    g_string_free (subshell_prompt, TRUE);
+    subshell_prompt = NULL;
+    g_string_free (subshell_prompt_temp_buffer, TRUE);
+    subshell_prompt_temp_buffer = NULL;
+}
+
+/* --------------------------------------------------------------------------------------------- */
+
+/* @DataSource("test_parse_subshell_prompt_string_ds") */
+/* *INDENT-OFF* */
+static const struct test_parse_subshell_prompt_string_ds
+{
+    const char *input_value;
+    const char *expected_result;
+} test_parse_subshell_prompt_string_ds[] =
+{
+    { /* 0 */
+        "blabla",
+        "blabla"
+    },
+    { /* 1 */
+        "blabla\r",
+        "blabla"
+    },
+    { /* 2 */
+        "blabla\n",
+        "blabla"
+    },
+    { /* 3 */
+        "blabla\r\n",
+        "blabla"
+    },
+    { /* 4 */
+        "\r\n",
+        ""
+    },
+    { /* 5 */
+        "\rblabla",
+        "blabla"
+    },
+    { /* 6 */
+        "\r\nblabla",
+        "blabla"
+    },
+    { /* 7 */
+        "\r\nblabla\r\n",
+        "blabla"
+    },
+    { /* 8 */
+        "bla1\r\nbla2\r\n",
+        "bla2"
+    }
+};
+/* *INDENT-ON* */
+
+/* @Test(dataSource = "test_parse_subshell_prompt_string_ds") */
+/* *INDENT-OFF* */
+START_PARAMETRIZED_TEST (test_parse_subshell_prompt_string, test_parse_subshell_prompt_string_ds)
+/* *INDENT-ON* */
+{
+    /* when */
+    parse_subshell_prompt_string (data->input_value, strlen (data->input_value));
+    /* then */
+    mctest_assert_str_eq (subshell_prompt_temp_buffer->str, data->expected_result);
+}
+/* *INDENT-OFF* */
+END_PARAMETRIZED_TEST
+/* *INDENT-ON* */
+
+/* --------------------------------------------------------------------------------------------- */
+
+int
+main (void)
+{
+    TCase *tc_core;
+
+    tc_core = tcase_create ("Core");
+
+    tcase_add_checked_fixture (tc_core, setup, teardown);
+
+    /* Add new tests here: *************** */
+    mctest_add_parameterized_test (tc_core, test_parse_subshell_prompt_string,
+                                   test_parse_subshell_prompt_string_ds);
+    /* *********************************** */
+
+    return mctest_run_all (tc_core);
+}
+
+/* --------------------------------------------------------------------------------------------- */