add example for reading packages, fix functions return pointers to copy on stack

example/Makefile

@@ -10,7 +10,7 @@ export SERVICEPOINT_HEADER_OUT := $(REPO_ROOT)/include
 override CFG_MUSL := $(if $(CFG_MUSL),$(CFG_MUSL),$(if $(MUSL),$(MUSL),0))
 override CFG_PROFILE := $(if $(CFG_PROFILE),$(CFG_PROFILE),$(if $(PROFILE),$(PROFILE),release))
 
-CCFLAGS += -Wall -fwhole-program -fPIE -pie
+CCFLAGS += -Wall -Wextra -pedantic -fwhole-program -fPIE -pie
 
 STRIPFLAGS := -s --strip-unneeded -R .comment -R .gnu.version -R .note -R .note.gnu.build-id -R .note.ABI-tag
 

example/src/header_logger.c

@@ -0,0 +1,76 @@
+#include <stdio.h>
+#include <sys/socket.h>
+#include <netinet/in.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <arpa/inet.h>
+#include <string.h>
+#include "servicepoint.h"
+
+#define DEFAULT_LISTEN_IP "127.0.0.1"
+
+void handle_error(const char *msg) {
+    perror(msg);
+    exit(EXIT_FAILURE);
+}
+
+int main(int argc, char **argv) {
+    init_env_logger();
+
+    int udp_socket = socket(AF_INET, SOCK_DGRAM, 0);
+    if (udp_socket == -1)
+        handle_error("socket could not be created\n");
+
+    char *listen_addr_arg;
+    if (argc > 1) {
+        listen_addr_arg = argv[1];
+    } else {
+        listen_addr_arg = DEFAULT_LISTEN_IP;
+    }
+
+    struct in_addr addr;
+    if (inet_aton(listen_addr_arg, &addr) == 0)
+        handle_error("listen ip could not be parsed\n");
+
+    struct sockaddr_in sockaddrIn = {
+            .sin_addr = addr,
+            .sin_family = AF_INET,
+            .sin_port = htons(2342),
+    };
+    memset(sockaddrIn.sin_zero, 0, sizeof(sockaddrIn.sin_zero));
+
+    if (bind(udp_socket, (struct sockaddr *) &sockaddrIn, sizeof(sockaddrIn)) == -1)
+        handle_error("could not bind socket\n");
+
+    printf("socket ready to receive on %s\n", listen_addr_arg);
+
+    uint8_t buffer[10000];
+    bool done = false;
+    while (!done) {
+        memset(buffer, 0, sizeof(buffer));
+
+        ssize_t num_bytes = recv(udp_socket, (void *) buffer, sizeof(buffer), 0);
+        if (num_bytes == -1)
+            handle_error("could not read from client");
+
+        Packet *packet = sp_packet_try_load((ByteSlice) {
+                .start = buffer,
+                .length = num_bytes,
+        });
+        if (packet == NULL) {
+            printf("received invalid packet\n");
+            continue;
+        }
+
+        struct Header *header = sp_packet_get_header(packet);
+        ByteSlice payload = sp_packet_get_payload(packet);
+        printf("Received packet: cc=%d, a=%d, b=%d, c=%d, d=%d, payload=%p (len %zu)\n",
+               header->command_code, header->a, header->b, header->c, header->d,
+               payload.start, payload.length);
+
+        done = header->command_code == COMMAND_CODE_HARD_RESET;
+        sp_packet_free(packet);
+    }
+
+    exit(EXIT_SUCCESS);
+}

example/src/moving_line.c

@@ -1,15 +1,15 @@
 #include "servicepoint.h"
 #include "helpers.h"
 
-int main() {
+int main(void) {
     sock_init();
 
     int result = 0;
     Bitmap *bitmap = sp_bitmap_new_max_sized();
-    for (int x = 0; x < sp_bitmap_width(bitmap); x++) {
+    for (size_t x = 0; x < sp_bitmap_width(bitmap); x++) {
         sp_bitmap_fill(bitmap, false);
 
-        for (int y = 0; y < sp_bitmap_height(bitmap); y++) {
+        for (size_t y = 0; y < sp_bitmap_height(bitmap); y++) {
             sp_bitmap_set(bitmap, (y + x) % PIXEL_WIDTH, y, true);
         }
 

src/commands/bitvec_command.rs

@@ -65,7 +65,7 @@ pub unsafe extern "C" fn sp_cmd_bitvec_free(command: NonNull<BitVecCommand>) {
 pub unsafe extern "C" fn sp_cmd_bitvec_get(
     mut command: NonNull<BitVecCommand>,
 ) -> *mut DisplayBitVec {
-    &mut unsafe { command.as_mut() }.bitvec
+    unsafe { &mut command.as_mut().bitvec }
 }
 
 /// Moves the provided [BitVec] to be contained in the [BitVecCommand].

src/commands/brightness_grid_command.rs

@@ -76,7 +76,7 @@ pub unsafe extern "C" fn sp_cmd_brightness_grid_set(
 pub unsafe extern "C" fn sp_cmd_brightness_grid_get(
     mut command: NonNull<BrightnessGridCommand>,
 ) -> *mut BrightnessGrid {
-    &mut unsafe { command.as_mut() }.grid
+    unsafe { &mut command.as_mut().grid }
 }
 
 /// Overwrites the origin field of the [BrightnessGridCommand].

src/commands/char_grid_command.rs

@@ -74,7 +74,7 @@ pub unsafe extern "C" fn sp_cmd_char_grid_set(
 pub unsafe extern "C" fn sp_cmd_char_grid_get(
     mut command: NonNull<CharGridCommand>,
 ) -> *mut CharGrid {
-    &mut unsafe { command.as_mut() }.grid
+    unsafe { &mut command.as_mut().grid }
 }
 
 /// Reads the origin field of the [CharGridCommand].

src/commands/cp437_grid_command.rs

@@ -83,7 +83,7 @@ pub unsafe extern "C" fn sp_cmd_cp437_grid_set(
 pub unsafe extern "C" fn sp_cmd_cp437_grid_get(
     mut command: NonNull<Cp437GridCommand>,
 ) -> *mut Cp437Grid {
-    &mut unsafe { command.as_mut() }.grid
+    unsafe { &mut command.as_mut().grid }
 }
 
 /// Gets the origin field of the [Cp437GridCommand].

src/commands/global_brightness_command.rs

@@ -53,5 +53,5 @@ pub unsafe extern "C" fn sp_cmd_brightness_global_set(
 pub unsafe extern "C" fn sp_cmd_brightness_global_get(
     mut command: NonNull<GlobalBrightnessCommand>,
 ) -> *mut Brightness {
-    &mut unsafe { command.as_mut() }.brightness
+    unsafe { &mut command.as_mut().brightness }
 }

src/packet.rs

@@ -38,7 +38,7 @@ pub unsafe extern "C" fn sp_packet_from_parts(
 pub unsafe extern "C" fn sp_packet_get_header(
     packet: NonNull<Packet>,
 ) -> NonNull<Header> {
-    NonNull::from(&mut unsafe { (*packet.as_ptr()).header })
+    NonNull::from(unsafe { &mut (*packet.as_ptr()).header })
 }
 
 /// Returns a pointer to the current payload of the provided packet.