extract .zst-compressed plain text with libarchive

unzstd_libarchive.c

#include <archive.h>
#include <stdio.h>

int main(int argc, char **argv) {
    struct archive *a;
    struct archive_entry *ae;

    char buffer[10240];
    int rc;

    a = archive_read_new();

    rc = archive_read_support_filter_zstd(a);
    printf("filter %d\n", rc);
    printf("%s %d", archive_error_string(a), archive_errno(a));

    rc = archive_read_support_format_raw(a);
    printf("format raw %d\n", rc);
    printf("%s %d", archive_error_string(a), archive_errno(a));

    rc = archive_read_open_filename(a, "setup.py.zst", 10240);
    printf("open %d\n", rc);
    printf("%s %d", archive_error_string(a), archive_errno(a));

    rc = archive_read_next_header(a, &ae);
    printf("read header %d\n", rc);
    printf("%s %d", archive_error_string(a), archive_errno(a));

    rc = archive_read_data(a, buffer, 10240);
    printf("read %d\n", rc);
    printf("%s %d", archive_error_string(a), archive_errno(a));

    printf("buffer %s\n", buffer);
    archive_free(a);
    printf("%s %d", archive_error_string(a), archive_errno(a));
}