/**
Generate a filename unique in an NFS namespace by creating a copy of str and
appending .{hostname}.{pid} to it. If gethostname() fails then a pseudo-
random string is substituted for {hostname} - the randomness of the string
should be strong enough across different machines. The main assumption
though is that gethostname will not fail and this is just a "safe enough"
fallback.
The memory returned should be freed using free().
*/
static std::string gen_unique_nfs_filename( const char *filename )
{
char hostname[HOST_NAME_MAX + 1];
char pid_str[256];
snprintf(pid_str, sizeof pid_str, "%ld", (long)getpid());
if ( gethostname( hostname, sizeof hostname ) != 0 )
{
sprint_rand_digits( hostname, HOST_NAME_MAX );
}
std::string newname(filename);
newname.push_back('.');
newname.append(hostname);
newname.push_back('.');
newname.append(pid_str);
return newname;
}
/**
Generate a filename unique in an NFS namespace by creating a copy of str and
appending .{hostname}.{pid} to it. If gethostname() fails then a pseudo-
random string is substituted for {hostname} - the randomness of the string
should be strong enough across different machines. The main assumption
though is that gethostname will not fail and this is just a "safe enough"
fallback.
The memory returned should be freed using free().
*/
static char *gen_unique_nfs_filename( const char *filename )
{
int pidlen, hnlen, orglen = strlen( filename );
char hostname[HOST_NAME_MAX + 1];
char *newname;
if ( gethostname( hostname, HOST_NAME_MAX + 1 ) == 0 )
{
hnlen = strlen( hostname );
}
else
{
hnlen = sprint_rand_digits( hostname, HOST_NAME_MAX );
hostname[hnlen] = '\0';
}
newname = malloc( orglen + 1 /* period */ + hnlen + 1 /* period */ +
/* max possible pid size: 0.31 ~= log(10)2 */
(int)(0.31 * sizeof(pid_t) * CHAR_BIT + 1)
+ 1 /* '\0' */ );
if ( newname == NULL )
{
debug( 1, L"gen_unique_nfs_filename: %s", strerror( errno ) );
return newname;
}
memcpy( newname, filename, orglen );
newname[orglen] = '.';
memcpy( newname + orglen + 1, hostname, hnlen );
newname[orglen + 1 + hnlen] = '.';
pidlen = sprint_pid_t( getpid(), newname + orglen + 1 + hnlen + 1 );
newname[orglen + 1 + hnlen + 1 + pidlen] = '\0';
/* debug( 1, L"gen_unique_nfs_filename returning with: newname = \"%s\"; "
L"HOST_NAME_MAX = %d; hnlen = %d; orglen = %d; "
L"sizeof(pid_t) = %d; maxpiddigits = %d; malloc'd size: %d",
newname, (int)HOST_NAME_MAX, hnlen, orglen,
(int)sizeof(pid_t),
(int)(0.31 * sizeof(pid_t) * CHAR_BIT + 1),
(int)(orglen + 1 + hnlen + 1 +
(int)(0.31 * sizeof(pid_t) * CHAR_BIT + 1) + 1) ); */
return newname;
}
