Align examples and remove reading from stdin

examples/parse_args.h

@@ -0,0 +1,213 @@
+//
+// Copyright (c) 2024 ZettaScale Technology
+//
+// This program and the accompanying materials are made available under the
+// terms of the Eclipse Public License 2.0 which is available at
+// http://www.eclipse.org/legal/epl-2.0, or the Apache License, Version 2.0
+// which is available at https://www.apache.org/licenses/LICENSE-2.0.
+//
+// SPDX-License-Identifier: EPL-2.0 OR Apache-2.0
+//
+// Contributors:
+//   ZettaScale Zenoh Team, <zenoh@zettascale.tech>
+//
+
+#pragma once
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#include "zenoh.h"
+
+#define COMMON_HELP \
+    "\
+        -c <CONFIG> (optional, string): The path to a configuration file for the session. If this option isn't passed, the default configuration will be used.\n\
+        -m <MODE> (optional, string, default='peer'): The zenoh session mode. [possible values: peer, client, router]\n\
+        -e <CONNECT> (optional, string): endpoint to connect to. Repeat option to pass multiple endpoints. If none are given, endpoints will be discovered through multicast-scouting if it is enabled.\n\
+        -l <LISTEN> (optional, string): locator to listen on. Repeat option to pass multiple locators. If none are given, the default configuration will be used.\n\
+        --no-multicast-scouting (optional): By default zenohd replies to multicast scouting messages for being discovered by peers and clients. This option disables this feature.\n\
+"
+
+/**
+ * Parse an option of format `-f`, `--flag`, `-f <value>` or `--flag <value>` from `argv`. If found, the option and its
+ * eventual value are each replaced by NULL in `argv`
+ * @param argc: argc passed from `main` function
+ * @param argv: argv passed from `main` function
+ * @param opt: option to parse (without `-` or `--` prefix)
+ * @param opt_has_value: if true, the option is of format `-f <value>` or `--flag <value>` and `value` will be returned
+ * if found, else an error message is printed and program will exit. If false, option has no value and a non-null
+ * pointer will be returned if option is found.
+ * @returns NULL if option was not found, else a non-null value depending on if `opt_has_value`.
+ */
+char* parse_opt(const int argc, char** argv, const char* opt, const bool opt_has_value) {
+    size_t optlen = strlen(opt);
+    for (int i = 1; i < argc; i++) {
+        if (argv[i] == NULL) {
+            continue;
+        }
+        size_t len = strlen(argv[i]);
+        if (len >= 2) {
+            if (optlen == 1) {
+                if (argv[i][0] == '-' && argv[i][1] == opt[0]) {
+                    argv[i] = NULL;
+                    if (!opt_has_value) {
+                        return (char*)opt;
+                    } else if (i + 1 < argc && argv[i + 1]) {
+                        char* value = argv[i + 1];
+                        argv[i + 1] = NULL;
+                        return value;
+                    } else {
+                        printf("Option -%s given without a value\n", opt);
+                        exit(-1);
+                    }
+                }
+            } else if (optlen > 1 && len > 3 && argv[i][0] == '-' && argv[i][1] == '-') {
+                // Note: support for '--arg=<value>' syntax can be added here
+                if (strcmp(argv[i] + 2, opt) == 0) {
+                    argv[i] = NULL;
+                    if (!opt_has_value) {
+                        return (char*)opt;
+                    } else if (i + 1 < argc && argv[i + 1]) {
+                        char* value = argv[i + 1];
+                        argv[i + 1] = NULL;
+                        return value;
+                    } else {
+                        printf("Option --%s given without a value\n", opt);
+                        exit(-1);
+                    }
+                }
+            }
+        }
+    }
+    return NULL;
+}
+
+/**
+ * Check if any options remains in `argv`. Must be called after all expected options are parsed
+ * @param argc
+ * @param argv
+ * @returns NULL if no option was found, else the first option string that was found
+ */
+char* check_unknown_opts(const int argc, char** argv) {
+    for (int i = 1; i < argc; i++) {
+        if (argv[i] && argv[i][0] == '-') {
+            return argv[i];
+        }
+    }
+    return NULL;
+}
+
+/**
+ * Parse positional arguments from `argv`. Must be called after all expected options are parsed, and after checking that
+ * no unknown options remain in `argv`
+ * @param argc
+ * @param argv
+ * @param nb_args: number of expected positional arguments
+ * @returns NULL if found more positional arguments than `nb_args`. Else an array of found arguments in order, followed
+ * by NULL values if found less positional arguments than `nb_args`
+ * @note Returned pointer is dynamically allocated and must be freed
+ */
+char** parse_pos_args(const int argc, char** argv, const size_t nb_args) {
+    char** pos_argv = (char**)malloc(nb_args * sizeof(char*));
+    // Initialize pointers to NULL to detect when example is called with number of args < nb_args
+    for (int i = 0; i < nb_args; i++) {
+        pos_argv[i] = NULL;
+    }
+    size_t pos_argc = 0;
+    for (int i = 1; i < argc; i++) {
+        if (argv[i]) {
+            pos_argc++;
+            if (pos_argc > nb_args) {
+                free(pos_argv);
+                return NULL;
+            }
+            pos_argv[pos_argc - 1] = argv[i];
+        }
+    }
+    return pos_argv;
+}
+
+/**
+ * Parse zenoh options that require a JSON-serialized list (-e, -l from common args) and add them to
+ * `config`. Prints error message and exits if fails to insert parsed values
+ * @param argc
+ * @param argv
+ * @param opt: option to parse (without `-` or `--` prefix)
+ * @param config: address of an owned zenoh configuration
+ * @param config_key: zenoh configuration key under which the parsed values will be inserted
+ */
+void parse_zenoh_json_list_config(const int argc, char** argv, const char* opt, const char* config_key,
+                                  const z_owned_config_t* config) {
+    char buf[256] = "";
+    char* value = parse_opt(argc, argv, opt, true);
+    while (value) {
+        size_t len_format_value = strlen(value) + 4;  // value + quotes + comma + nullbyte
+        char* format_value = (char*)malloc(len_format_value);
+        snprintf(format_value, len_format_value, "'%s',", value);
+        strcat(buf, format_value);
+        free(format_value);
+        value = parse_opt(argc, argv, opt, true);
+    }
+    size_t buflen = strlen(buf);
+    if (buflen > 0) {
+        // remove trailing comma
+        buf[buflen - 1] = '\0';
+        buflen--;
+        // add list delimiters
+        size_t json_list_len = buflen + 3;  // buf + brackets + nullbyte
+        char* json_list = (char*)malloc(json_list_len);
+        snprintf(json_list, json_list_len, "[%s]", buf);
+        // insert in config
+        if (zc_config_insert_json(z_loan(*config), config_key, json_list) < 0) {
+            printf(
+                "Couldn't insert value `%s` in configuration at `%s`. This is likely because `%s` expects a "
+                "JSON-serialized list of strings\n",
+                json_list, config_key, config_key);
+            free(json_list);
+            exit(-1);
+        }
+        free(json_list);
+    }
+}
+
+/**
+ * Parse zenoh options that are common to all examples (-c, -m, -e, -l, --no-multicast-scouting) and add them to
+ * `config`
+ * @param argc
+ * @param argv
+ * @param config: address of an owned zenoh configuration
+ */
+void parse_zenoh_common_args(const int argc, char** argv, z_owned_config_t* config) {
+    // -c: A configuration file.
+    char* config_file = parse_opt(argc, argv, "c", true);
+    if (config_file) {
+        *config = zc_config_from_file(config_file);
+    }
+    // -m: The Zenoh session mode [default: peer].
+    char* mode = parse_opt(argc, argv, "m", true);
+    if (mode) {
+        size_t buflen = strlen(mode) + 3;  // mode + quotes + nullbyte
+        char* buf = (char*)malloc(buflen);
+        snprintf(buf, buflen, "'%s'", mode);
+        if (zc_config_insert_json(z_loan(*config), Z_CONFIG_MODE_KEY, buf) < 0) {
+            printf(
+                "Couldn't insert value `%s` in configuration at `%s`. Value must be one of: 'client', 'peer' or "
+                "'router'\n",
+                mode, Z_CONFIG_MODE_KEY);
+            free(buf);
+            exit(-1);
+        }
+        free(buf);
+    }
+    // -e: Endpoint to connect to. Can be repeated
+    parse_zenoh_json_list_config(argc, argv, "e", Z_CONFIG_CONNECT_KEY, config);
+    // -l: Endpoint to listen on. Can be repeated
+    parse_zenoh_json_list_config(argc, argv, "l", Z_CONFIG_LISTEN_KEY, config);
+    // --no-multicast-scrouting: Disable the multicast-based scouting mechanism.
+    char* no_multicast_scouting = parse_opt(argc, argv, "no-multicast-scouting", false);
+    if (no_multicast_scouting && zc_config_insert_json(z_loan(*config), Z_CONFIG_MULTICAST_SCOUTING_KEY, "false") < 0) {
+        printf("Couldn't disable multicast-scouting.\n");
+        exit(-1);
+    }
+}

examples/z_delete.c

@@ -14,23 +14,19 @@
 #include <stdio.h>
 #include <string.h>
 
+#include "parse_args.h"
 #include "zenoh.h"
 
-int main(int argc, char **argv) {
-    char *keyexpr = "demo/example/zenoh-c-put";
+#define DEFAULT_KEYEXPR "demo/example/zenoh-c-put"
 
-    if (argc > 1) keyexpr = argv[1];
+struct args_t {
+    char* keyexpr;  // -k
+};
+struct args_t parse_args(int argc, char** argv, z_owned_config_t* config);
 
+int main(int argc, char** argv) {
     z_owned_config_t config = z_config_default();
-    if (argc > 3) {
-        if (zc_config_insert_json(z_loan(config), Z_CONFIG_CONNECT_KEY, argv[3]) < 0) {
-            printf(
-                "Couldn't insert value `%s` in configuration at `%s`. This is likely because `%s` expects a "
-                "JSON-serialized list of strings\n",
-                argv[3], Z_CONFIG_CONNECT_KEY, Z_CONFIG_CONNECT_KEY);
-            exit(-1);
-        }
-    }
+    struct args_t args = parse_args(argc, argv, &config);
 
     printf("Opening session...\n");
     z_owned_session_t s = z_open(z_move(config));
@@ -39,13 +35,50 @@ int main(int argc, char **argv) {
         exit(-1);
     }
 
-    printf("Deleting resources matching '%s'...\n", keyexpr);
+    printf("Deleting resources matching '%s'...\n", args.keyexpr);
     z_delete_options_t options = z_delete_options_default();
-    int res = z_delete(z_loan(s), z_keyexpr(keyexpr), &options);
+    int res = z_delete(z_loan(s), z_keyexpr(args.keyexpr), &options);
     if (res < 0) {
         printf("Delete failed...\n");
     }
 
     z_close(z_move(s));
     return 0;
 }
+
+void print_help() {
+    printf(
+        "\
+    Usage: z_delete [OPTIONS]\n\n\
+    Options:\n\
+        -k <KEY> (optional, string, default='%s'): The key expression to write to\n",
+        DEFAULT_KEYEXPR);
+    printf(COMMON_HELP);
+    printf(
+        "\
+        -h: print help\n");
+}
+
+struct args_t parse_args(int argc, char** argv, z_owned_config_t* config) {
+    if (parse_opt(argc, argv, "h", false)) {
+        print_help();
+        exit(1);
+    }
+    char* keyexpr = parse_opt(argc, argv, "k", true);
+    if (!keyexpr) {
+        keyexpr = DEFAULT_KEYEXPR;
+    }
+    parse_zenoh_common_args(argc, argv, config);
+    char* arg = check_unknown_opts(argc, argv);
+    if (arg) {
+        printf("Unknown option %s\n", arg);
+        exit(-1);
+    }
+    char** pos_args = parse_pos_args(argc, argv, 1);
+    if (!pos_args || pos_args[0]) {
+        printf("Unexpected positional arguments\n");
+        free(pos_args);
+        exit(-1);
+    }
+    return (struct args_t){.keyexpr = keyexpr};
+}