d686482d0
Denis Vlasenko
2008-02-25
Subject
actually add libbb/safe_gethostname.c
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libbb/safe_gethostname.c+53 -0
| @@ -0,0 +1,53 @@ | |
| + | /* vi: set sw=4 ts=4: */ |
| + | /* |
| + | * Safe gethostname implementation for busybox |
| + | * |
| + | * Copyright (C) 2008 Tito Ragusa <[email protected]> |
| + | * |
| + | * Licensed under GPLv2 or later, see file LICENSE in this tarball for details. |
| + | */ |
| + | |
| + | /* |
| + | * SUSv2 guarantees that "Host names are limited to 255 bytes" |
| + | * POSIX.1-2001 guarantees that "Host names (not including the terminating |
| + | * null byte) are limited to HOST_NAME_MAX bytes" (64 bytes on my box). |
| + | * |
| + | * RFC1123 says: |
| + | * |
| + | * The syntax of a legal Internet host name was specified in RFC-952 |
| + | * [DNS:4]. One aspect of host name syntax is hereby changed: the |
| + | * restriction on the first character is relaxed to allow either a |
| + | * letter or a digit. Host software MUST support this more liberal |
| + | * syntax. |
| + | * |
| + | * Host software MUST handle host names of up to 63 characters and |
| + | * SHOULD handle host names of up to 255 characters. |
| + | */ |
| + | |
| + | #include "libbb.h" |
| + | #include <sys/utsname.h> |
| + | |
| + | /* |
| + | * On success return the current malloced and NUL terminated hostname. |
| + | * On error return malloced and NUL terminated string "?". |
| + | * This is an illegal first character for a hostname. |
| + | * The returned malloced string must be freed by the caller. |
| + | */ |
| + | char *safe_gethostname(void) |
| + | { |
| + | struct utsname uts; |
| + | |
| + | /* The length of the arrays in a struct utsname is unspecified; |
| + | * the fields are terminated by a null byte. |
| + | * Note that there is no standard that says that the hostname |
| + | * set by sethostname(2) is the same string as the nodename field of the |
| + | * struct returned by uname (indeed, some systems allow a 256-byte host- |
| + | * name and an 8-byte nodename), but this is true on Linux. The same holds |
| + | * for setdomainname(2) and the domainname field. |
| + | */ |
| + | |
| + | /* Uname can fail only if you pass a bad pointer to it. */ |
| + | uname(&uts); |
| + | |
| + | return xstrndup(!*(uts.nodename) ? "?" : uts.nodename, sizeof(uts.nodename)); |
| + | } |