tools: add a xkbcli tool as entry point for the various tools we have

This is the base tool, no subtools are currently connected so you only get help
and version for now. The goal here is to have a git-like infrastructure where
/usr/bin/xkbcli is the main tool, anything else will hide in libexec.

The infrastructure for this is copied from libinput. Tools themselves will
will be installed in $prefix/libexec/xkbcommon and the xkbcli tool forks
off whatever argv[1] is after modifying the PATH to include the libexec dir.

libinput has additional code for checking whether we're running this from the
builddir but it's a bit iffy and it's usefulness is limited - if you're in the
builddir anyway you can just run ./builddir/xkbcli-<toolname> directly.
So for this code here, running ./builddir/xkbcli <toolname> will execute the
one in the prefix/libexecdir.

Since we want that tool available everywhere even where some of the subtools
aren't present, we need to ifdef the getopt handling.

man page generation is handled via ronn which is a ruby program but allows
markdown for the sources. It's hidden behind a meson option to disable where
downloading ronn isn't an option. The setup is generic enough that we can add
other man-pages by just appending to the array.

Signed-off-by: Peter Hutterer <peter.hutterer@who-t.net>

4 files changed, 187 insertions, 0 deletions

diff --git a/tools/tools-common.c b/tools/tools-common.c
index 6e397c2..0b42892 100644
--- a/tools/tools-common.c
+++ b/tools/tools-common.c
@@ -34,16 +34,22 @@
 
 #include <limits.h>
 #include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
 #include <sys/types.h>
 #include <sys/stat.h>
 #ifdef _MSC_VER
 #include <io.h>
 #include <windows.h>
+#ifndef PATH_MAX
+#define PATH_MAX MAX_PATH
+#endif
 #else
 #include <unistd.h>
 #include <termios.h>
 #endif
 
+#include "utils.h"
 #include "tools-common.h"
 
 void
@@ -197,4 +203,59 @@ tools_enable_stdin_echo(void)
         (void) tcsetattr(STDIN_FILENO, TCSADRAIN, &termios);
     }
 }
+
 #endif
+
+static inline bool
+tools_setup_path(void)
+{
+    const char *path = getenv("PATH");
+    const char *extra_path = LIBXKBCOMMON_TOOL_PATH;
+    char new_path[PATH_MAX];
+
+    if (snprintf_safe(new_path, sizeof(new_path), "%s:%s",
+                      extra_path, path ? path : "")) {
+        setenv("PATH", new_path, 1);
+        return true;
+    } else {
+        return false;
+    }
+}
+
+int
+tools_exec_command(const char *prefix, int real_argc, char **real_argv)
+{
+    char *argv[64] = {NULL};
+    char executable[128];
+    const char *command;
+
+    assert((size_t)real_argc < ARRAY_SIZE(argv));
+
+    command = real_argv[0];
+
+    if (!snprintf_safe(executable, sizeof(executable),
+                       "%s-%s", prefix, command)) {
+        fprintf(stderr, "Failed to assemble command\n");
+        return EXIT_FAILURE;
+    }
+
+    if (!tools_setup_path()) {
+        fprintf(stderr, "Failed to set PATH\n");
+        return EXIT_FAILURE;
+    }
+
+    argv[0] = executable;
+    for (int i = 1; i < real_argc; i++)
+        argv[i] = real_argv[i];
+
+    execvp(executable, argv);
+    if (errno == ENOENT) {
+        fprintf(stderr, "Command '%s' is not available\n", command);
+        return EXIT_INVALID_USAGE;
+    } else {
+        fprintf(stderr, "Failed to execute '%s' (%s)\n",
+                command, strerror(errno));
+    }
+
+    return EXIT_FAILURE;
+}
diff --git a/tools/tools-common.h b/tools/tools-common.h
index f0faa34..bc6fa38 100644
--- a/tools/tools-common.h
+++ b/tools/tools-common.h
@@ -49,6 +49,9 @@ tools_disable_stdin_echo(void);
 void
 tools_enable_stdin_echo(void);
 
+int
+tools_exec_command(const char *prefix, int argc, char **argv);
+
 #ifdef _MSC_VER
 #define setenv(varname, value, overwrite) _putenv_s((varname), (value))
 #define unsetenv(varname) _putenv_s(varname, "")
diff --git a/tools/xkbcli.1.ronn b/tools/xkbcli.1.ronn
new file mode 100644
index 0000000..8e2c338
--- /dev/null
+++ b/tools/xkbcli.1.ronn
@@ -0,0 +1,31 @@
+# xkbcli(1) - tool to interact with XKB keymaps
+
+## SYNOPSIS
+
+**xkbcli** [--help|--version] &lt;command&gt; [<args>]
+
+## DESCRIPTION
+
+**xkbcli** is a commandline tool to query, compile and test XKB keymaps,
+layouts and other elements.
+
+## OPTIONS
+
+  * `--help`:
+      Print help and exit
+
+  * `--version`:
+      Print the version and exit
+
+## EXIT STATUS
+
+  * 0:
+    exited successfully
+  * 1:
+    an error occured
+  * 2:
+    program was called with invalid arguments
+
+## SEE ALSO
+
+The libxkbcommon online documentation at <https://xkbcommon.org>
diff --git a/tools/xkbcli.c b/tools/xkbcli.c
new file mode 100644
index 0000000..fbab9dd
--- /dev/null
+++ b/tools/xkbcli.c
@@ -0,0 +1,92 @@
+/*
+ * Copyright © 2020 Red Hat, Inc.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the next
+ * paragraph) shall be included in all copies or substantial portions of the
+ * Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+#include "config.h"
+
+#include <getopt.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+#include "tools-common.h"
+
+static void
+usage(void)
+{
+    printf("Usage: xkbcli [--help|-h] [--version|-V] <command> [<args>]\n"
+           "\n"
+           "Global options:\n"
+           "  -h, --help ...... show this help and exit\n"
+           "  -V, --version ... show version information and exit\n"
+           "\n");
+}
+
+int
+main(int argc, char **argv)
+{
+    enum options {
+        OPT_HELP = 1,
+        OPT_VERSION,
+    };
+    int option_index = 0;
+
+    while (1) {
+        int c;
+#if HAVE_GETOPT_LONG
+        static struct option opts[] = {
+            { "help",    no_argument, 0, OPT_HELP },
+            { "version", no_argument, 0, OPT_VERSION },
+            { 0, 0, 0, 0}
+        };
+
+        c = getopt_long(argc, argv, "+hV", opts, &option_index);
+#else
+        c = getopt(argc, argv, "+hV");
+#endif
+        if (c == -1)
+            break;
+
+        switch(c) {
+            case 'h':
+            case OPT_HELP:
+                usage();
+                return EXIT_SUCCESS;
+            case 'V':
+            case OPT_VERSION:
+                printf("%s\n", LIBXKBCOMMON_VERSION);
+                return EXIT_SUCCESS;
+            default:
+                usage();
+                return EXIT_INVALID_USAGE;
+        }
+    }
+
+    if (optind >= argc) {
+        usage();
+        return EXIT_INVALID_USAGE;
+    }
+
+    argv += optind;
+    argc -= optind;
+
+    return tools_exec_command("xkbcli", argc, argv);
+}