fix some gcc warnings (#73) * tweak string size fix gcc8 warnings ``` svr-agentfwd.c: In function 'bindagent': svr-agentfwd.c:254:53: warning: '%s' directive output may be truncated writing up to 107 bytes into a region of size between 0 and 107 [-Wformat-truncation=] snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~ ~~~~~~~~ svr-agentfwd.c:254:2: note: 'snprintf' output between 2 and 216 bytes into a destination of size 108 snprintf(addr.sun_path, sizeof(addr.sun_path), "%s/%s", path, sockfile); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ ``` * cleanup signed/unsigned comparison fix gcc8 warnings ``` scp.c: In function 'do_local_cmd': scp.c:132:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < a->num; i++) ^ scpmisc.c: In function 'addargs': scpmisc.c:161:25: warning: comparison of integer expressions of different signedness: 'int' and 'u_int' {aka 'unsigned int'} [-Wsign-compare] } else if (args->num+2 >= nalloc) ^~ scpmisc.c: In function 'replacearg': scpmisc.c:183:12: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] if (which >= args->num) ^~ scpmisc.c: In function 'freeargs': scpmisc.c:196:17: warning: comparison of integer expressions of different signedness: 'u_int' {aka 'unsigned int'} and 'int' [-Wsign-compare] for (i = 0; i < args->num; i++) ^ ``` see https://cvsweb.openbsd.org/cgi-bin/cvsweb/src/usr.bin/ssh/misc.h.diff?r1=1.16&r2=1.17

/* LibTomCrypt, modular cryptographic library -- Tom St Denis
 *
 * LibTomCrypt is a library that provides various cryptographic
 * algorithms in a highly modular and flexible manner.
 *
 * The library is free for all purposes without any express
 * guarantee it works.
 */

#include "tomcrypt.h"

#ifdef LTC_CHACHA20POLY1305_MODE

/**
  Set IV + counter data (with RFC7905-magic) to the ChaCha20Poly1305 state and reset the context
  @param st     The ChaCha20Poly1305 state
  @param iv     The IV data to add
  @param ivlen  The length of the IV (must be 12 or 8)
  @param sequence_number   64bit sequence number which is incorporated into IV as described in RFC7905
  @return CRYPT_OK on success
 */
int chacha20poly1305_setiv_rfc7905(chacha20poly1305_state *st, const unsigned char *iv, unsigned long ivlen, ulong64 sequence_number)
{
   int i;
   unsigned char combined_iv[12] = { 0 };

   LTC_ARGCHK(st != NULL);
   LTC_ARGCHK(iv != NULL);
   LTC_ARGCHK(ivlen == 12);

   STORE64L(sequence_number, combined_iv + 4);
   for (i = 0; i < 12; i++) combined_iv[i] = iv[i] ^ combined_iv[i];
   return chacha20poly1305_setiv(st, combined_iv, 12);
}

#endif

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