feat(examples): Introduce DuckDB C example

examples/duckdb-0.9-c/.gitignore

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+/rootfs/
+/rootfs.cpio
+/run-qemu*
+/run-fc*
+/kraft-run-*
+/fc*.json

examples/duckdb-0.9-c/Dockerfile

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+FROM --platform=linux/x86_64 debian:bookworm AS build
+
+RUN set -xe; \
+    apt -yqq update; \
+    apt -yqq install \
+        wget \
+        ca-certificates \
+        build-essential \
+        unzip \
+    ;
+
+ARG DUCKDB_VERSION=0.9.1
+
+WORKDIR /src
+
+RUN set -xe; \
+    wget https://github.com/duckdb/duckdb/releases/download/v${DUCKDB_VERSION}/libduckdb-linux-amd64.zip; \
+    unzip -q libduckdb-linux-amd64.zip; \
+    mv libduckdb.so /usr/local/lib/; \
+    ldconfig /usr/local/lib/libduckdb.so \
+    ;
+
+COPY ./main.c /src/main.c
+
+RUN set -xe; \
+    gcc -Wall -I. -o /main /src/main.c -lduckdb
+
+FROM scratch
+
+COPY --from=build /main /main
+COPY --from=build /usr/local/lib/libduckdb.so /usr/local/lib/libduckdb.so
+COPY --from=build /lib/x86_64-linux-gnu/libc.so.6 /lib/x86_64-linux-gnu/libc.so.6
+COPY --from=build /lib/x86_64-linux-gnu/libgcc_s.so.1 /lib/x86_64-linux-gnu/libgcc_s.so.1
+COPY --from=build /lib/x86_64-linux-gnu/libpthread.so.0 /lib/x86_64-linux-gnu/libpthread.so.0
+COPY --from=build /lib/x86_64-linux-gnu/libdl.so.2 /lib/x86_64-linux-gnu/libdl.so.2
+COPY --from=build /lib/x86_64-linux-gnu/libstdc++.so.6 /lib/x86_64-linux-gnu/libstdc++.so.6
+COPY --from=build /lib/x86_64-linux-gnu/libm.so.6 /lib/x86_64-linux-gnu/libm.so.6
+COPY --from=build /lib64/ld-linux-x86-64.so.2 /lib64/ld-linux-x86-64.so.2
+COPY --from=build /etc/ld.so.cache /etc/ld.so.cache

examples/duckdb-0.9-c/Kraftfile

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+spec: v0.6
+
+name: duckdb-c
+
+runtime: index.unikraft.io/unikraft.org/base:latest
+
+rootfs: ./Dockerfile
+
+cmd: ["/main"]

examples/duckdb-0.9-c/Makefile

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+IMAGE_NAME = unikraft-duckdb-c
+
+include ../../utils/bincompat/docker.Makefile

examples/duckdb-0.9-c/README.md

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+# DuckDB C Example
+
+This directory contains a simple C example using the [DuckDB](https://duckdb.org) library running with Unikraft in binary compatibility mode.
+The C program is extracted from [DuckDB examples](https://github.com/duckdb/duckdb/blob/main/examples/embedded-c/main.c) and it creates and uses a test database.
+
+Follow the instructions in the common `../README.md` file to set up and configure the application.
+
+## Quick Run
+
+Use `kraft` to run the image:
+
+```console
+kraft run -M 128M
+```
+
+Once executed, it will print out information from the created database:
+
+```console
+```
+
+## Scripted Run
+
+Use the scripted runs, detailed in the common `../README.md`.
+Running the scripts will print out information ame as above.

examples/duckdb-0.9-c/config.yaml

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+networking: False
+accel: True
+memory: 256

examples/duckdb-0.9-c/main.c

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+/* https://github.com/duckdb/duckdb/blob/main/examples/embedded-c/main.c */
+
+#include "duckdb.h"
+#include <stdio.h>
+
+int main() {
+	duckdb_database db = NULL;
+	duckdb_connection con = NULL;
+	duckdb_result result;
+
+	if (duckdb_open(NULL, &db) == DuckDBError) {
+		fprintf(stderr, "Failed to open database\n");
+		goto cleanup;
+	}
+	if (duckdb_connect(db, &con) == DuckDBError) {
+		fprintf(stderr, "Failed to open connection\n");
+		goto cleanup;
+	}
+	if (duckdb_query(con, "CREATE TABLE integers(i INTEGER, j INTEGER);", NULL) == DuckDBError) {
+		fprintf(stderr, "Failed to query database\n");
+		goto cleanup;
+	}
+	if (duckdb_query(con, "INSERT INTO integers VALUES (3, 4), (5, 6), (7, NULL);", NULL) == DuckDBError) {
+		fprintf(stderr, "Failed to query database\n");
+		goto cleanup;
+	}
+	if (duckdb_query(con, "SELECT * FROM integers", &result) == DuckDBError) {
+		fprintf(stderr, "Failed to query database\n");
+		goto cleanup;
+	}
+	// print the names of the result
+	idx_t row_count = duckdb_row_count(&result);
+	idx_t column_count = duckdb_column_count(&result);
+	for (size_t i = 0; i < column_count; i++) {
+		printf("%s ", duckdb_column_name(&result, i));
+	}
+	printf("\n");
+	// print the data of the result
+	for (size_t row_idx = 0; row_idx < row_count; row_idx++) {
+		for (size_t col_idx = 0; col_idx < column_count; col_idx++) {
+			char *val = duckdb_value_varchar(&result, col_idx, row_idx);
+			printf("%s ", val);
+			duckdb_free(val);
+		}
+		printf("\n");
+	}
+	// duckdb_print_result(result);
+cleanup:
+	duckdb_destroy_result(&result);
+	duckdb_disconnect(&con);
+	duckdb_close(&db);
+}