[main.c] Complete list functionality

arena.c

@@ -0,0 +1,207 @@
+/* This arena allocator implementation was created by Will Brown (WCBROW01).
+ * Orginal source can be found at: https://github.com/WCBROW01/arena-allocator
+ * Licensed under the MIT License (c) 2022-2024 Will Brown */
+
+#include <stddef.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdalign.h>
+#include <stdbool.h>
+#include <string.h>
+
+#include "arena.h"
+
+#define next_multiple(a, b) ((a) + (b) - (a) % (b))
+#define MEM_ALIGNMENT alignof(max_align_t)
+#define align(n) ((n) % MEM_ALIGNMENT == 0 ? (n) : next_multiple(n, MEM_ALIGNMENT))
+
+// The arena region itself is allocated after the contents of the struct.
+struct Arena {
+	size_t size;
+	size_t tmp_size;
+	void *last_block;
+	void *next_block;
+	Arena *next_region;
+	bool dynamic;
+};
+
+// Get the start address of the arena
+static inline void *Arena_start(Arena *arena) {
+	return arena + 1;
+}
+
+// Allocates a fixed-size arena. Accepts the size of the arena in bytes.
+Arena *Arena_new(size_t size) {
+	Arena *new_arena = malloc(sizeof(Arena) + size);
+
+	*new_arena = (Arena) {
+		.size = size,
+		.tmp_size = 0,
+		.last_block = NULL,
+		.next_block = Arena_start(new_arena),
+		.next_region = NULL,
+		.dynamic = false
+	};
+
+	return new_arena;
+}
+
+/* Allocates a dynamically-sized arena. Accepts the initial size of the arena in bytes.
+ * If there is not enough space in the arena for an allocation, a new region will be created. */
+Arena *Arena_new_dynamic(size_t size) {
+	Arena *new_arena = malloc(sizeof(Arena) + size);
+
+	*new_arena = (Arena) {
+		.size = size,
+		.tmp_size = 0,
+		.last_block = NULL,
+		.next_block = Arena_start(new_arena),
+		.next_region = NULL,
+		.dynamic = true
+	};
+
+	return new_arena;
+}
+
+// Frees the entire arena from memory.
+void Arena_delete(Arena *arena) {
+	if (arena->next_region != NULL) Arena_delete(arena->next_region);
+	free(arena);
+}
+
+#ifdef ENABLE_DIAG
+static void print_diagnostic(Arena *arena, size_t size) {
+	fprintf(stderr, "Diagnostic info:\n");
+	fprintf(stderr, "Arena size: %zu bytes\n", arena->size);
+	fprintf(stderr, "Amount currently allocated: %zu bytes\n", arena->next_block - Arena_start(arena));
+	fprintf(stderr, "New block size: %zu bytes\n", size);
+	fprintf(stderr, "New size upon success: %zu bytes\n", arena->next_block + align(size) - Arena_start(arena));
+}
+#endif
+
+static inline void *Arena_init_block(Arena *arena, size_t size) {
+	size_t blksize = align(size);
+	arena->tmp_size += blksize;
+	void *new_block = arena->next_block;
+	arena->last_block = new_block;
+	arena->next_block += blksize;
+	return new_block;
+}
+
+// Will return a null pointer if you've tried allocating too much memory.
+void *Arena_alloc(Arena *arena, size_t size) {
+	if (arena->next_block + align(size) > Arena_start(arena) + arena->size) {
+		if (arena->dynamic) {
+			if (arena->next_region == NULL) {
+				// If the size is too large for a region, make a special region for only that block.
+				size_t region_size = size > arena->size ? size : arena->size;
+				arena->next_region = Arena_new_dynamic(region_size);
+				return Arena_init_block(arena->next_region, size);
+			} else {
+				return Arena_alloc(arena->next_region, size);
+			}
+		} else {
+#ifdef ENABLE_DIAG
+			fprintf(stderr, "Allocation too large. You've attempted to allocate a block of memory past the end of the arena.\n");
+			print_diagnostic(arena, size);
+#endif
+			return NULL;
+		}
+	} else {
+		return Arena_init_block(arena, size);
+	}
+}
+
+// Identical to Arena_alloc but it zeros your memory
+void *Arena_allocz(Arena *arena, size_t size) {
+	return memset(Arena_alloc(arena, size), 0, size);
+}
+
+/* Copy a block of memory into an arena.
+ * Functionally equivalent to memcpy. */
+void *Arena_copy(Arena *arena, const void *src, size_t size) {
+	void *new_block = Arena_alloc(arena, size);
+	if (new_block == NULL) {
+		return NULL;
+	} else {
+		memcpy(new_block, src, size);
+		return new_block;
+	}
+}
+
+/* If the pointer is to the last allocation, it will be resized.
+ * Otherwise, a new allocation will be created.
+ * Be careful with this! A null pointer will be returned upon error.
+ * Using this with memory outside of the arena is undefined behavior. */
+void *Arena_realloc(Arena *arena, void *ptr, size_t size) {
+	if (ptr == arena->last_block) {
+		if (arena->last_block + align(size) > Arena_start(arena) + arena->size) {
+			if (arena->dynamic) {
+				return Arena_copy(arena, ptr, size);
+			} else {
+#ifdef ENABLE_DIAG
+				fprintf(stderr, "Allocation too large. You've attempted to allocate a block of memory past the end of the arena.\n");
+				print_diagnostic(arena, size - (arena->next_block - arena->last_block));
+#endif
+				return NULL;
+			}
+		} else {
+			arena->next_block = arena->last_block + align(size);
+			return ptr;
+		}
+	} else {
+		return Arena_copy(arena, ptr, size);
+	}
+}
+
+/* Marks the beginning of a temporary buffer that can be deallocated at any time.
+ * The state of the last one is saved in case you have multiple. */
+void Arena_tmp_begin(Arena *arena) {
+	size_t tmp_size = arena->tmp_size;
+	void *last_block = arena->last_block;
+	arena->tmp_size = 0;
+
+	void *state = Arena_alloc(arena, sizeof(size_t) + sizeof(void*));
+	if (state == NULL) return;
+	*(size_t*) state = tmp_size;
+	*(void**) (state + sizeof(void*)) = last_block;
+}
+
+static void tmp_rewind(Arena *arena, bool *complete) {
+	void *stateloc = arena->next_block - arena->tmp_size;
+	if (arena->next_region != NULL) {
+		tmp_rewind(arena->next_region, complete);
+		arena->next_region = NULL;
+	}
+
+	if (*complete) return;
+
+	if (stateloc == Arena_start(arena)) {
+		Arena_delete(arena);
+	} else {
+		arena->tmp_size = *(size_t*) stateloc;
+		arena->last_block = *(void**) (stateloc + sizeof(size_t));
+		arena->next_block = stateloc;
+		*complete = true;
+	}
+}
+
+/* Deallocates the last temporary buffer. If there is none,
+ * the entire arena will be deallocated. */
+void Arena_tmp_rewind(Arena *arena) {
+	bool complete = false;
+
+	if (arena->next_region != NULL) {
+		tmp_rewind(arena->next_region, &complete);
+		arena->next_region = NULL;
+	}
+
+	if (!complete) {
+		void *stateloc = arena->next_block - arena->tmp_size;
+		if (stateloc != Arena_start(arena)) {
+			arena->tmp_size = *(size_t*) stateloc;
+			arena->last_block = *(void**) (stateloc + sizeof(size_t));
+		}
+		arena->next_block = stateloc;
+	}
+}

arena.h

@@ -0,0 +1,52 @@
+/* This arena allocator implementation was created by Will Brown (WCBROW01).
+ * Orginal source can be found at: https://github.com/WCBROW01/arena-allocator
+ * Licensed under the MIT License (c) 2022-2024 Will Brown */
+
+#ifndef ARENA_H
+#define ARENA_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+typedef struct Arena Arena;
+
+// Allocates a fixed-size arena. Accepts the size of the arena in bytes.
+Arena *Arena_new(size_t size);
+
+/* Allocates a dynamically-sized arena. Accepts the initial size of the arena in bytes.
+ * If there is not enough space in the arena for an allocation, a new region will be created. */
+Arena *Arena_new_dynamic(size_t size);
+
+// Frees the entire arena from memory.
+void Arena_delete(Arena *arena);
+
+// Will return a null pointer if you've tried allocating too much memory.
+void *Arena_alloc(Arena *arena, size_t size);
+
+// Identical to Arena_alloc but it zeros your memory
+void *Arena_allocz(Arena *arena, size_t size);
+
+/* Copy a block of memory into an arena.
+ * Functionally equivalent to memcpy. */
+void *Arena_copy(Arena *arena, const void *src, size_t size);
+
+/* If the pointer is to the last allocation, it will be resized.
+ * Otherwise, a new allocation will be created.
+ * Be careful with this! A null pointer will be returned upon error.
+ * Using this with memory outside of the arena is undefined behavior. */
+void *Arena_realloc(Arena *arena, void *ptr, size_t size);
+
+/* Marks the beginning of a temporary buffer that can be deallocated at any time.
+ * The state of the last one is saved in case you have multiple. */
+void Arena_tmp_begin(Arena *arena);
+
+/* Deallocates the last temporary buffer. If there is none,
+ * the entire arena will be deallocated. */
+void Arena_tmp_rewind(Arena *arena);
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif

main.c

@@ -1,3 +1,4 @@
+#include <assert.h>
 #include <stdio.h>
 #include <stdbool.h>
 #include <stdlib.h>
@@ -19,6 +20,7 @@
 
 #include "config.h"
 #include "feed_info.h"
+#include "arena.h"
 
 // Function pointer type for commands
 typedef void (*command_func)(struct discord *, const struct discord_interaction *);
@@ -263,48 +265,142 @@ static void bot_command_remove(struct discord *client, const struct discord_inte
 	discord_create_interaction_response(client, event->id, event->token, &res, NULL);
 }
 
+#define LIST_PAGE_SIZE 5
+
+// The arena everything gets allocated to will be returned in the arena pointer
+static struct discord_interaction_callback_data *list_data_create(u64snowflake channel_id, int page_number, Arena **arena) {
+	assert(arena && "No arena provided"); // this is programmer error
+	// clamp page number
+	page_number = page_number < 1 ? 1 : page_number;
+	
+	*arena = Arena_new(8192); // this should be more than enough
+	struct discord_interaction_callback_data *data = Arena_allocz(*arena, sizeof(*data));
+	
+	int64_t count;
+	zblock_feed_info_err error = zblock_feed_info_count_channel(database_conn, channel_id, &count);
+	if (error) {
+		char *msg = Arena_alloc(*arena, sizeof(DISCORD_MAX_MESSAGE_LEN));
+		snprintf(msg, DISCORD_MAX_MESSAGE_LEN, "Error creating list: %s", zblock_feed_info_strerror(error));
+		data->content = msg;
+		return data;
+	}
+	
+	int last_page_number = count ? count % LIST_PAGE_SIZE ? count / LIST_PAGE_SIZE + 1 : count / LIST_PAGE_SIZE : 1;
+	
+	zblock_feed_info feeds[LIST_PAGE_SIZE];
+	int num_retrieved;
+	error = zblock_feed_info_retrieve_chunk_channel(database_conn, channel_id, (page_number - 1) * LIST_PAGE_SIZE, LIST_PAGE_SIZE, feeds, &num_retrieved);
+	if (error) {
+		char *msg = Arena_alloc(*arena, sizeof(DISCORD_MAX_MESSAGE_LEN));
+		snprintf(msg, DISCORD_MAX_MESSAGE_LEN, "Error creating list: %s", zblock_feed_info_strerror(error));
+		data->content = msg;
+		return data;
+	}
+	
+	// create our components starting with the action row
+	data->components = Arena_alloc(*arena, sizeof(*data->components));
+	data->components->size = 1;
+	data->components->array = Arena_allocz(*arena, data->components->size * sizeof(*data->components->array));
+	struct discord_component *action_row = data->components->array;
+	action_row->type = DISCORD_COMPONENT_ACTION_ROW;
+	// create buttons
+	action_row->components = Arena_alloc(*arena, sizeof(*action_row->components));
+	action_row->components->size = 2;
+	action_row->components->array = Arena_allocz(*arena, action_row->components->size * sizeof(*action_row->components->array));
+	struct discord_component *buttons = action_row->components->array;
+	// create emojis
+	struct discord_emoji *back_arrow = Arena_allocz(*arena, sizeof(*back_arrow));
+	back_arrow->name = "◀️";
+	struct discord_emoji *next_arrow = Arena_allocz(*arena, sizeof(*next_arrow));
+	next_arrow->name = "▶️";
+	// create button ids
+	int back_id_size = snprintf(NULL, 0, "list_page%d", page_number - 1) + 1;
+	char *back_id = Arena_alloc(*arena, back_id_size);
+	snprintf(back_id, back_id_size, "list_page%d", page_number - 1);
+	int next_id_size = snprintf(NULL, 0, "list_page%d", page_number + 1) + 1;
+	char *next_id = Arena_alloc(*arena, next_id_size);
+	snprintf(next_id, next_id_size, "list_page%d", page_number + 1);
+	// populate buttons
+	buttons[0] = (struct discord_component) {
+		.type = DISCORD_COMPONENT_BUTTON,
+		.disabled = page_number == 1,
+		.style = DISCORD_BUTTON_SECONDARY,
+		.custom_id = back_id,
+		.label = "Back",
+		.emoji = back_arrow
+	};
+	buttons[1] = (struct discord_component) {
+		.type = DISCORD_COMPONENT_BUTTON,
+		.disabled = page_number == last_page_number,
+		.style = DISCORD_BUTTON_SECONDARY,
+		.custom_id = next_id,
+		.label = "Next",
+		.emoji = next_arrow
+	};
+	
+	// create embed
+	data->embeds = Arena_alloc(*arena, sizeof(*data->embeds));
+	data->embeds->size = 1;
+	data->embeds->array = Arena_allocz(*arena, data->embeds->size * sizeof(*data->embeds->array));
+	struct discord_embed *embed = data->embeds->array;
+	int embed_title_size = snprintf(NULL, 0, "Feed List (Page %d of %d)", page_number, last_page_number) + 1;
+	char *embed_title = Arena_alloc(*arena, embed_title_size);
+	snprintf(embed_title, embed_title_size, "Feed List (Page %d of %d)", page_number, last_page_number);
+	
+	// write the description
+	char *embed_description;
+	if (count) {
+		embed_description = Arena_alloc(*arena, 4096); // the current max size of embed descriptions
+		int embed_description_size = 0;
+		for (int i = 0; i < num_retrieved; ++i) {
+			// in case somebody has maliciously long text in their feed
+			if (embed_description_size < 4096) {
+				embed_description_size += snprintf(embed_description + embed_description_size, 4096 - embed_description_size,
+					"### %d. %s\n" // feed title
+					"Link: %s\n" // feed url
+					"Last updated: %s\n", // last_pubDate
+					(page_number - 1) * LIST_PAGE_SIZE + i + 1, feeds[i].title,
+					feeds[i].url,
+					feeds[i].last_pubDate
+				);
+			}
+		}
+	} else {
+		embed_description = "There are no feeds in this channel.";
+	}
+	
+	*embed = (struct discord_embed) {
+		.title = embed_title,
+		.type = "rich",
+		.description = embed_description
+	};
+	
+	return data;
+}
+
 static void bot_command_list(struct discord *client, const struct discord_interaction *event) {
+	Arena *arena;
 	struct discord_interaction_response res = {
 		.type = DISCORD_INTERACTION_CHANNEL_MESSAGE_WITH_SOURCE,
-		.data = &(struct discord_interaction_callback_data) {
-			.components = CREATE_COMPONENTS({
-				{				
-					.type = DISCORD_COMPONENT_ACTION_ROW,
-					.components = CREATE_COMPONENTS({
-						{
-							.type = DISCORD_COMPONENT_BUTTON,
-							.disabled = false,
-							.style = DISCORD_BUTTON_SECONDARY,
-							.custom_id = "page_back",
-							.label = "Back",
-							.emoji = &(struct discord_emoji) {
-								.name = "◀️"
-							}
-						},
-						{
-							.type = DISCORD_COMPONENT_BUTTON,
-							.disabled = false,
-							.style = DISCORD_BUTTON_SECONDARY,
-							.custom_id = "page_next",
-							.label = "Next",
-							.emoji = &(struct discord_emoji) {
-								.name = "▶️"
-							}
-						}
-					})
-				}
-			}),
-			.embeds = CREATE_EMBEDS({
-				{
-					.title = "Feed List",
-					.type = "rich",
-					.description = "List functionality has not been fully implemented yet."
-				}
-			})
-		}
+		.data = list_data_create(event->channel_id, 1, &arena)
 	};
 
 	discord_create_interaction_response(client, event->id, event->token, &res, NULL);
+	Arena_delete(arena);
+}
+
+static void list_update(struct discord *client, const struct discord_interaction *event) {
+	int page_number;
+	sscanf(event->data->custom_id, "list_page%d", &page_number);
+
+	Arena *arena;
+	struct discord_interaction_response res = {
+		.type = DISCORD_INTERACTION_UPDATE_MESSAGE,
+		.data = list_data_create(event->channel_id, page_number, &arena)
+	};
+
+	discord_create_interaction_response(client, event->id, event->token, &res, NULL);
+	Arena_delete(arena);
 }
 
 static void bot_command_help(struct discord *client, const struct discord_interaction *event) {
@@ -409,8 +505,8 @@ static void on_interaction(struct discord *client, const struct discord_interact
 			};
 			discord_create_interaction_response(client, event->id, event->token, &res, NULL);		
 		} break;
-		case DISCORD_INTERACTION_MESSAGE_COMPONENT: {
-			// nothing yet
+		case DISCORD_INTERACTION_MESSAGE_COMPONENT: { // only the list command is used here so far
+			list_update(client, event);
 		} break;
 		default: // nothing
 	}