Char array corrupted after passing through ONC RPC - c

Question

when calling a ONC-RPC-function that returns a char array I get (apparently) uninitialized memory on the first call. Subsequent calls give me the correct result.
This example showcases the issue:
ftp.x:
const BLOCKSIZE = 1024;
struct block {
char arr<BLOCKSIZE>;
};
program FILE_GET_BLOCK_PROG {
version FILE_GET_BLOCK_VERS {
block FILE_GET_BLOCK() = 1;
} = 1;
} = 0x42424243;
ftp_client.c:
#include "ftp.h"
#include <errno.h>
#include <string.h>
size_t
file_get_block_prog_1(char *host, char *buf)
{
CLIENT *clnt;
block *result_1;
#ifndef DEBUG
clnt = clnt_create (host, FILE_GET_BLOCK_PROG, FILE_GET_BLOCK_VERS, "udp");
if (clnt == NULL) {
clnt_pcreateerror (host);
exit (1);
}
#endif /* DEBUG */
result_1 = file_get_block_1(NULL, clnt);
if (result_1 == (block *) NULL) {
clnt_perror (clnt, "call failed");
}
#ifndef DEBUG
clnt_destroy (clnt);
#endif /* DEBUG */
memcpy(buf, result_1->arr.arr_val, result_1->arr.arr_len);
return result_1->arr.arr_len;
}
int
main (int argc, char *argv[])
{
char *host, *source_filename;
char buf[BLOCKSIZE+1];
int block_count;
size_t bytes_read;
if (argc < 2) {
printf ("usage: %s server_host\n", argv[0]);
exit (1);
}
host = argv[1];
bytes_read = file_get_block_prog_1 (host, buf);
buf[bytes_read] = '\0';
printf("%d bytes:\n%s\n", bytes_read, buf);
exit (0);
}
ftp_server.c:
#include "ftp.h"
#include <errno.h>
#include <string.h>
#include <sys/stat.h>
block *
file_get_block_1_svc(void *argp, struct svc_req *rqstp)
{
static block result;
static int request = 1;
char buf[BLOCKSIZE+1];
size_t bytes_read;
strcpy(buf, "This is just a simple test block. There is nothing relevant in here.");
result.arr.arr_len = strlen(buf);
result.arr.arr_val = buf;
printf("Request #%d:\n%s\n", request++, buf);
return &result;
}
When running the server and calling the client twice, this is my output:
client:
$ ./ftp_client localhost
68 bytes:
$ ./ftp_client localhost
68 bytes:
This is just a simple test bock. There is nothing relevant in here.
server:
Request #1:
This is just a simple test bock. There is nothing relevant in here.
Request #2:
This is just a simple test bock. There is nothing relevant in here.
Is there any initialization I missed that I need to do before the first request? What else would cause this behavior?