cmd: devmem: rework for argp

This subcommand differs from the others a bit in regards of
sub-subcommands. `read` and `write` are being handled in
`parse_opt` directly instead of creating two new subcommands, mainly
because the overhead of creating two new subcommands would be too
much for the small amount of code that would be shared between them.

Signed-off-by: Tan Siewert <[email protected]>

src/cmd/devmem.c

@@ -1,26 +1,77 @@
 // SPDX-License-Identifier: Apache-2.0
 // Copyright (C) 2018,2021 IBM Corp.
+
+/* For program_invocation_short_name */
+#define _GNU_SOURCE
+
+#include <argp.h>
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
+#include <string.h>
 
 #include "ahb.h"
+#include "arg_helper.h"
 #include "ast.h"
 #include "bridge/devmem.h"
 #include "priv.h"
 
-int cmd_devmem(const char *name, int argc, char *argv[])
+struct cmd_devmem_args {
+    char *args[2];
+};
+
+static struct argp_option options[] = {
+    {0}
+};
+
+static error_t parse_opt(int key, char *arg, struct argp_state *state)
+{
+    switch (key) {
+        case ARGP_KEY_ARG:
+            if (state->arg_num == 0) {
+                if (strcmp("read", arg) && strcmp("write", arg))
+                    argp_usage(state);
+            }
+            break;
+        case ARGP_KEY_END:
+            if (!strcmp("write", state->argv[1])) {
+                if (state->argc != 4)
+                    argp_usage(state);
+            }
+            break;
+        default:
+            return ARGP_ERR_UNKNOWN;
+    }
+
+    return 0;
+}
+
+static struct argp argp_devmem = {
+    options,
+    parse_opt,
+    "read|write ADDRESS [VALUE]",
+    "/dev/mem stuff",
+    NULL,
+    NULL,
+    NULL
+};
+
+int cmd_devmem(struct argp_state* state)
 {
     struct devmem _devmem, *devmem = &_devmem;
     struct ahb *ahb;
     int cleanup;
     int rc;
 
+    struct subcommand devmem_cmd;
+    struct cmd_devmem_args arguments = {0};
+    parse_subcommand(&argp_devmem, "devmem", &arguments, state, &devmem_cmd);
+
     rc = devmem_init(devmem);
     if (rc < 0) {
         bool denied = (rc == -EACCES || rc == -EPERM);
         if (denied && !priv_am_root()) {
-            priv_print_unprivileged(name);
+            priv_print_unprivileged(program_invocation_short_name);
         } else {
             errno = -rc;
             perror("devmem_init");
@@ -29,7 +80,9 @@ int cmd_devmem(const char *name, int argc, char *argv[])
     }
 
     ahb = devmem_as_ahb(devmem);
-    rc = ast_ahb_access(name, argc, argv, ahb);
+    /* FIXME: argc + argv once all commands are migrated */
+    rc = ast_ahb_access(program_invocation_short_name,
+                        devmem_cmd.argc - 1, devmem_cmd.argv + 1, ahb);
     if (rc) {
         errno = -rc;
         perror("ast_ahb_access");

src/culvert.c

@@ -2,9 +2,6 @@
 // Copyright (C) 2018,2021 IBM Corp.
 // Copyright (C) 2021, Oracle and/or its affiliates.
 
-/* For program_invocation_short_name */
-#define _GNU_SOURCE
-
 #include <errno.h>
 #include <argp.h>
 #include <stdbool.h>
@@ -22,12 +19,12 @@
 /* Migrated to argp */
 int cmd_console(struct argp_state *state);
 int cmd_coprocessor(struct argp_state *state);
+int cmd_devmem(struct argp_state *state);
 
 /* Still using the old argument parser -> to be migrated */
 int cmd_ilpc(const char *name, int argc, char *argv[]);
 int cmd_p2a(const char *name, int argc, char *argv[]);
 int cmd_debug(const char *name, int argc, char *argv[]);
-int cmd_devmem(const char *name, int argc, char *argv[]);
 int cmd_read(const char *name, int argc, char *argv[]);
 int cmd_write(const char *name, int argc, char *argv[]);
 int cmd_replace(const char *name, int argc, char *argv[]);