| /* Copyright (C) 1995-2018 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library 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 |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <alloca.h> |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <unistd.h> |
| #include <netdb.h> |
| #include <not-cancel.h> |
| |
| #define HOSTIDFILE "/etc/hostid" |
| |
| #ifdef SET_PROCEDURE |
| int |
| sethostid (long int id) |
| { |
| int fd; |
| ssize_t written; |
| int32_t id32 = id; |
| |
| /* Test for appropriate rights to set host ID. */ |
| if (__libc_enable_secure) |
| { |
| __set_errno (EPERM); |
| return -1; |
| } |
| |
| /* Make sure the ID is not too large. Needed for bi-arch support. */ |
| if (id32 != id) |
| { |
| __set_errno (EOVERFLOW); |
| return -1; |
| } |
| |
| /* Open file for writing. Everybody is allowed to read this file. */ |
| fd = __open_nocancel (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644); |
| if (fd < 0) |
| return -1; |
| |
| written = __write_nocancel (fd, &id32, sizeof (id32)); |
| |
| __close_nocancel_nostatus (fd); |
| |
| return written != sizeof (id32) ? -1 : 0; |
| } |
| |
| #else |
| # include <string.h> |
| # include <sys/param.h> |
| # include <resolv/netdb.h> |
| # include <netinet/in.h> |
| |
| long int |
| gethostid (void) |
| { |
| char hostname[MAXHOSTNAMELEN + 1]; |
| size_t buflen; |
| char *buffer; |
| struct hostent hostbuf, *hp; |
| int32_t id; |
| struct in_addr in; |
| int herr; |
| int fd; |
| |
| /* First try to get the ID from a former invocation of sethostid. */ |
| fd = __open_nocancel (HOSTIDFILE, O_RDONLY|O_LARGEFILE, 0); |
| if (fd >= 0) |
| { |
| ssize_t n = __read_nocancel (fd, &id, sizeof (id)); |
| |
| __close_nocancel_nostatus (fd); |
| |
| if (n == sizeof (id)) |
| return id; |
| } |
| |
| /* Getting from the file was not successful. An intelligent guess for |
| a unique number of a host is its IP address. Return this. */ |
| if (__gethostname (hostname, MAXHOSTNAMELEN) < 0 || hostname[0] == '\0') |
| /* This also fails. Return and arbitrary value. */ |
| return 0; |
| |
| buflen = 1024; |
| buffer = __alloca (buflen); |
| |
| /* To get the IP address we need to know the host name. */ |
| while (__gethostbyname_r (hostname, &hostbuf, buffer, buflen, &hp, &herr) |
| != 0 |
| || hp == NULL) |
| if (herr != NETDB_INTERNAL || errno != ERANGE) |
| return 0; |
| else |
| /* Enlarge buffer. */ |
| buffer = extend_alloca (buffer, buflen, 2 * buflen); |
| |
| in.s_addr = 0; |
| memcpy (&in, hp->h_addr, |
| (int) sizeof (in) < hp->h_length ? (int) sizeof (in) : hp->h_length); |
| |
| /* For the return value to be not exactly the IP address we do some |
| bit fiddling. */ |
| return (int32_t) (in.s_addr << 16 | in.s_addr >> 16); |
| } |
| #endif |