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

.TH dropbearconvert 1
.SH NAME
dropbearconvert \- convert between Dropbear and OpenSSH private key formats
.SH SYNOPSIS
.B dropbearconvert
.I input_type
.I output_type
.I input_file
.I output_file
.SH DESCRIPTION
.B Dropbear
and 
.B OpenSSH
SSH implementations have different private key formats.
.B dropbearconvert
can convert between the two.
.P
Dropbear uses the same SSH public key format as OpenSSH, it can be extracted
from a private key by using
.B dropbearkey \-y
.P
Encrypted private keys are not supported, use ssh-keygen(1) to decrypt them
first.
.SH ARGUMENTS
.TP
.I input_type
Either 
.I dropbear
or 
.I openssh
.TP
.I output_type
Either 
.I dropbear
or 
.I openssh
.TP
.I input_file
An existing Dropbear or OpenSSH private key file
.TP
.I output_file
The path to write the converted private key file. For client authentication ~/.ssh/id_dropbear is loaded by default
.SH EXAMPLE
 # dropbearconvert openssh dropbear ~/.ssh/id_rsa ~/.ssh/id_dropbear
.SH AUTHOR
Matt Johnston ([email protected]).
.SH SEE ALSO
 dropbearkey(1), ssh-keygen(1)
.P
https://matt.ucc.asn.au/dropbear/dropbear.html