usr.bin: Add 'nerve' program to poke ctlfs

The 'nerve' program allows users to poke at a ctlfs entry and write
their own data.

Signed-off-by: Ian Moffett <ian@osmora.org>

3 files changed, 281 insertions, 0 deletions

diff --git a/usr.bin/Makefile b/usr.bin/Makefile
index f30905e..802b773 100644
--- a/usr.bin/Makefile
+++ b/usr.bin/Makefile
@@ -21,3 +21,4 @@ all:
 	make -C login/ $(ARGS)
 	make -C sleep/ $(ARGS)
 	make -C kstat/ $(ARGS)
+	make -C nerve/ $(ARGS)
diff --git a/usr.bin/nerve/Makefile b/usr.bin/nerve/Makefile
new file mode 100644
index 0000000..cc0fd91
--- /dev/null
+++ b/usr.bin/nerve/Makefile
@@ -0,0 +1,6 @@
+include user.mk
+
+CFILES = $(shell find . -name "*.c")
+
+$(ROOT)/base/usr/bin/nerve:
+	gcc $(CFILES) -o $@ $(INTERNAL_CFLAGS)
diff --git a/usr.bin/nerve/nerve.c b/usr.bin/nerve/nerve.c
new file mode 100644
index 0000000..d79c4cb
--- /dev/null
+++ b/usr.bin/nerve/nerve.c
@@ -0,0 +1,274 @@
+/*
+ * Copyright (c) 2023-2025 Ian Marco Moffett and the Osmora Team.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright notice,
+ *    this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of Hyra nor the names of its
+ *    contributors may be used to endorse or promote products derived from
+ *    this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
+ * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
+ * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
+ * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
+ * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
+ * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
+ * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
+ * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
+ * POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/errno.h>
+#include <sys/console.h>
+#include <stdio.h>
+#include <string.h>
+#include <unistd.h>
+#include <fcntl.h>
+#include <stdint.h>
+
+/* Verb numeric defs (see string defs) */
+#define VERB_UNKNOWN    -1
+#define VERB_POKE       0x0000
+
+/* Verb string defs (see numeric defs) */
+#define SVERB_POKE "poke"
+
+/* Nerve numeric defs (see string defs) */
+#define NERVE_UNKNOWN  -1
+#define NERVE_CONSATTR 0x0000
+
+/* Nerve string defs (see numeric defs) */
+#define SNERVE_CONSATTR "consattr"
+
+/* Misc defines */
+#define NERVE_PACKET_LEN 16
+
+struct verb_handler;
+
+static int poke_nerve(const char *nerve, struct verb_handler *h);
+
+/*
+ * Contains verb handlers called when a verb
+ * (e.g., 'poke') is matched.
+ */
+struct verb_handler {
+    int(*run)(const char *nerve, struct verb_handler *h);
+    char **argv;
+    size_t argc;
+};
+
+/*
+ * Holds information that may be sent down
+ * my nerves.
+ *
+ * Example: nerve poke <x> 1 0 1
+ *                         * * *
+ *     +--------+         / / /
+ *     | meow   | <------+ / /
+ *     |--------|         / /
+ *     | foo    | <------+ /
+ *     |--------|         /
+ *     | foobar | <------+
+ *     +--------+
+ *       packet
+ */
+struct nerve_payload {
+    uint32_t packet[NERVE_PACKET_LEN];
+    uint16_t len;
+};
+
+/*
+ * Verb handler table, when a verb is matched,
+ * its respective handler is called.
+ */
+static struct verb_handler verbtab[] = {
+    { poke_nerve }
+};
+
+/*
+ * Print list of available options as well as
+ * information about the program.
+ */
+static void
+help(void)
+{
+    printf(
+        "nerve: usage: nerve <verb> [ .. data ..]\n"
+        "verb 'poke': Poke a control (/ctl) nerve\n"
+        "???????????????? NERVES ????????????????\n"
+        "consattr: Console attributes\n"
+    );
+}
+
+/*
+ * The user gets to send data down my nerves through
+ * a nerve payload. This function acquires the nerve
+ * payload. Please don't hurt me.
+ *
+ * @argc: Number of arguments within argv
+ * @argv: Argument vector
+ * @res: Where the payload goes
+ */
+static int
+get_nerve_payload(int argc, char *argv[], struct nerve_payload *res)
+{
+    char *payload_str;
+    uint8_t datum;
+
+    /* Do we have a nerve payload? */
+    if (argc < 4) {
+        printf("[!] missing nerve payload\n");
+        return -1;
+    }
+
+    /* Reset fields */
+    res->len = 0;
+    memset(res->packet, 0, sizeof(res->packet));
+
+    /* Start grabbing bytes */
+    for (int i = 3; i < argc; ++i) {
+        payload_str = argv[i];
+        datum = atoi(payload_str);
+        res->packet[res->len++] = datum;
+    }
+
+    return 0;
+}
+
+/*
+ * Poke a control nerve located in /ctl/
+ *
+ * @nerve: Name of the nerve (e.g., consattr)
+ * @h: Verb handler, instance of self
+ *
+ * Returns less than zero if the nerve does not
+ * match.
+ */
+static int
+poke_nerve(const char *nerve, struct verb_handler *h)
+{
+    struct nerve_payload payload;
+    int error, nerve_idx = -1;
+
+    if (nerve == NULL || h == NULL) {
+        return -EINVAL;
+    }
+
+    /*
+     * Now we need to parse the nerve string
+     * and see if it matches with anything
+     * that we know.
+     */
+    switch (*nerve) {
+    case 'c':
+        if (strcmp(nerve, SNERVE_CONSATTR) == 0) {
+            nerve_idx = NERVE_CONSATTR;
+            error = get_nerve_payload(h->argc, h->argv, &payload);
+
+            if (error < 0) {
+                printf("[!] nerve error\n");
+                return -1;
+            }
+        }
+    }
+
+    switch (nerve_idx) {
+    case NERVE_CONSATTR:
+        {
+            struct console_attr c;
+            int fd;
+
+            c.cursor_x = payload.packet[0];
+            c.cursor_y = payload.packet[1];
+
+            fd = open("/ctl/console/attr", O_WRONLY);
+            write(fd, payload.packet, sizeof(c));
+            close(fd);
+            break;
+        }
+    default:
+        printf("[&^]: This is not my nerve.\n");
+        break;
+    }
+
+    return -1;
+}
+
+/*
+ * Convert a string verb, passed in through the command
+ * line, into a numeric definition
+ *
+ * @verb: String verb
+ */
+static int
+verb_to_def(const char *verb)
+{
+    if (verb == NULL) {
+        return -EINVAL;
+    }
+
+    /*
+     * Parse the verb and try to match it against
+     * a constant.
+     *
+     * TODO: Add 'peek'
+     *
+     * XXX: Here we are first matching the first character
+     *      before we match the entire verb as that is more
+     *      efficient than scanning each entire string until
+     *      one matches.
+     */
+    switch (*verb) {
+    case 'p':
+        if (strcmp(verb, SVERB_POKE) == 0) {
+            return VERB_POKE;
+        }
+    default:
+        printf("[!] bad verb \"%s\"\n", verb);
+        return VERB_UNKNOWN;
+    }
+
+    return VERB_UNKNOWN;
+}
+
+int
+main(int argc, char **argv)
+{
+    struct verb_handler *verbd;
+    int verb;
+
+    if (argc < 2) {
+        help();
+        return -1;
+    }
+
+    verb = verb_to_def(argv[1]);
+    if (verb < 0) {
+        return -1;
+    }
+
+    /* Make sure the arguments match */
+    switch (verb) {
+    case VERB_POKE:
+        if (argc < 3) {
+            printf("[!] missing nerve name\n");
+            help();
+            return -1;
+        }
+        break;
+    }
+
+    verbd = &verbtab[verb];
+    verbd->argv = argv;
+    verbd->argc = argc;
+    return verbd->run(argv[2], verbd);
+}