diff options
Diffstat (limited to 'libc/sysdeps/unix/sysv/linux/gethostid.c')
-rw-r--r-- | libc/sysdeps/unix/sysv/linux/gethostid.c | 121 |
1 files changed, 121 insertions, 0 deletions
diff --git a/libc/sysdeps/unix/sysv/linux/gethostid.c b/libc/sysdeps/unix/sysv/linux/gethostid.c new file mode 100644 index 000000000..de98fb3d7 --- /dev/null +++ b/libc/sysdeps/unix/sysv/linux/gethostid.c @@ -0,0 +1,121 @@ +/* Copyright (C) 1995,1996,1998-2001,2003,2004,2006 + 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, write to the Free + Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA + 02111-1307 USA. */ + +#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 (id) + 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_not_cancel (HOSTIDFILE, O_CREAT|O_WRONLY|O_TRUNC, 0644); + if (fd < 0) + return -1; + + written = write_not_cancel (fd, &id32, sizeof (id32)); + + close_not_cancel_no_status (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 () +{ + 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_not_cancel (HOSTIDFILE, O_RDONLY|O_LARGEFILE, 0); + if (fd >= 0) + { + ssize_t n = read_not_cancel (fd, &id, sizeof (id)); + + close_not_cancel_no_status (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 |