test_zstd_too_small.c

// gcc -g -O0 -Ilib -Llib test.c lib/libzstd.a -o test &&  ./test aaaaaaaaaaaa
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <zstd.h>

int main(int argc, char **argv) {
    char *payload = argc > 1 ? argv[1] : "compress me";
    size_t payload_len = strlen(payload);

    size_t compressed_size = ZSTD_compressBound(payload_len);
    char *compressed = malloc(compressed_size);

    size_t compressed_size_rv = ZSTD_compress((void*)compressed, compressed_size, (void *)payload, payload_len, 1);

    size_t decompressed_size = 1; // ZSTD_getFrameContentSize(compressed, compressed_size);
    if (decompressed_size == ZSTD_CONTENTSIZE_ERROR
        || decompressed_size == ZSTD_CONTENTSIZE_UNKNOWN) {
        printf("ZSTD_CONTENTSIZE_ERROR or ZSTD_CONTENTSIZE_UNKNOWN\n");
        free(compressed);
        return 0;
    }

    char *decompressed = malloc(decompressed_size);
    size_t decompressed_size_rv = ZSTD_decompress((void*)decompressed, decompressed_size, (void*)compressed, compressed_size_rv);

    if (decompressed_size_rv != payload_len) {
        printf("ERR\n");
    } else {
        printf("OK\n");
    }

    free(compressed);
    free(decompressed);

    return 0;
}