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/* defaultkey.c - fetch the default secret key id
* Copyright (C) 1999 Michael Roth <mroth@gnupg.org>
*
* This file is part of pgpgpg.
*
* pgpgpg is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* pgpgpg is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA
*/
#include "includes.h"
#include "argvfactory.h"
/*****************************************************************************
*
* Function : get_defaultkey()
*
* Purpose : Runs GnuPG (Gnu Privacy Guard) to determine the first key in the
* secret keyring which is also known as the default key.
*
* Output : Returns the long GnuPG keyid of the default keyid.
*
* Errors : Returns Null if the defaultkey couldn't be determined.
*
*****************************************************************************/
char * get_defaultkey(void)
{
enum { buffer_size = 1024 };
char buffer[buffer_size];
ArgvFactory af;
pid_t child_pid;
int child_status;
int child_pipe[2];
int dev_null_fd;
FILE *in;
char *defaultid = NULL;
int err = 0;
argv_factory_init(&af);
argv_factory_add(&af, GPG_PATH);
argv_factory_add(&af, "--with-colons");
argv_factory_add(&af, "--batch");
argv_factory_add(&af, "--quiet");
argv_factory_add(&af, "--no-verbose");
argv_factory_add(&af, "--list-secret-keys");
if (pipe(child_pipe))
{
perror("Can't setup a pipe for gpg.");
return NULL;
}
if ((dev_null_fd = open("/dev/null", O_RDWR)) == -1)
{
perror("Can't open /dev/null for redirect");
return NULL;
}
switch ((child_pid = fork()))
{
case -1:
perror("Can't fork to execute gpg");
return NULL;
case 0: /* child */
err += close(0) == -1 ? 1 : 0;
err += close(1) == -1 ? 1 : 0;
err += close(2) == -1 ? 1 : 0;
err += dup2(dev_null_fd, 0) == -1 ? 1 : 0;
err += dup2(child_pipe[1], 1) == -1 ? 1 : 0;
err += dup2(dev_null_fd, 2) == -1 ? 1 : 0;
err += close(child_pipe[0]) == -1 ? 1 : 0;
err += close(child_pipe[1]) == -1 ? 1 : 0;
err += close(dev_null_fd) == -1 ? 1 : 0;
if (err)
{
fprintf(stderr, "Error in redirecting stdin, stdout and stderr. Can't execute gpg.");
return NULL;
}
execv(af.argv[0], af.argv);
perror("Can't execute gpg (execv failed).");
return NULL;
default: /* parent */
close(child_pipe[1]);
close(dev_null_fd);
if (!(in = fdopen(child_pipe[0], "r"))) /* much easier to use a FILE */
{
perror("Can't associate stream with pipe.");
return NULL;
}
while (fgets(buffer, buffer_size, in))
{
if (strncmp(buffer, "sec:", 4))
{
/* skip remaining line */
while (!strchr(buffer, '\n') && fgets(buffer, buffer_size, in));
}
else
{
/* the first secret key is the default key; skip 4 colon seperated fields */
int i;
defaultid = buffer;
for(i=0; i<4; ++i)
defaultid = defaultid ? strchr(defaultid+1, ':') : NULL;
if (defaultid)
{
char *end;
--defaultid;
defaultid[0] = '0';
defaultid[1] = 'x';
if (!(end = strchr(defaultid, ':')))
{
fprintf(stderr, "Wrong keylist format.\n");
defaultid = NULL;
break;
}
*end = 0;
defaultid = strdup(defaultid);
break;
}
else
{
fprintf(stderr, "Wrong keylist format.\n");
break;
}
}
}
fclose(in);
/* terminate child */
kill(child_pid, SIGINT);
waitpid(child_pid, &child_status, 0);
}
argv_factory_release(&af);
return defaultid;
}
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