diff options
| -rw-r--r-- | Distrib/PortingIssues.mdwn | 19 |
1 files changed, 13 insertions, 6 deletions
diff --git a/Distrib/PortingIssues.mdwn b/Distrib/PortingIssues.mdwn index fb66791f..ef832cc4 100644 --- a/Distrib/PortingIssues.mdwn +++ b/Distrib/PortingIssues.mdwn @@ -70,6 +70,7 @@ Fixed code: #ifdef MAXHOSTNAMELEN char localhost[MAXHOSTNAMELEN]; #else + char *localhost; #endif @@ -167,7 +168,7 @@ The following declaration: sockaddr_un sun = { AF_UNIX, "/path/to/socket" }; -won't work on GNU/Hurd. The Glibc API requires that the second parameter of a `sockaddr_un` struct is array of chars, but NOT pointer to array of chars. Glibc wants a nul-terminated string of chars there, so we have to copy them directly into the `sun_path` address. An example: +won't work on GNU/Hurd. The Glibc API requires that the second parameter of a `sockaddr_un` struct is array of chars, but NOT pointer to array of chars. So we have to copy them directly into the `sun_path` address. Glibc wants string of chars there that doesn't need to end in nul character _and_ correct size of `sockaddr_un` passed to socket functions. When calling socket functions one should always use `SUN_LEN (su)` for the sockaddr length argument. An example: sockaddr_un su; /* AF_LOCAL is the canonical flag in Glibc. @@ -176,14 +177,21 @@ won't work on GNU/Hurd. The Glibc API requires that the second parameter of a `s /* Copy the string into sun_path. It must be no longer than approximately 100 characters. */ strcpy (su.sun_path, "/path/to/socket"); - /* Use `SUN_LEN (su)' in socket functions. */ -If you have pointer to array of characters as file name, you'd better use the following code: +`SUN_LEN` macro is not defined in [The Single UNIX Specification Version 3](http://www.unix-systems.org/version3/online.html) (see [sys/un.h manpage](http://www.opengroup.org/onlinepubs/007904975/basedefs/sys/un.h.html)). You can use the following definition to handle this case (definition taken from NetBSD): + + #ifndef SUN_LEN + #define SUN_LEN(su) \ + (sizeof(*(su)) - sizeof((su)->sun_path) + \ + strlen((su)->sun_path)) + #endif + +If you have pointer to array of characters as file name, you'd better use the following code to set `sun_path`: strncpy (su.sun_path, filename, sizeof (su.sun_path)); - /* Use `sizeof (su)' in socket functions. */ + su.sun_path[sizeof (su.sun_path) - 1] = '\0'; -If you expect file name longer than approximately 100 characters, use the following code: +If you expect file name longer than approximately 100 characters, use the following code. This is the recommended code for GNU systems. You can include it whenever `__GLIBC__` is defined. /* `offsetof', `alloca' and `AF_LOCAL' may not be available everywhere. */ @@ -192,7 +200,6 @@ If you expect file name longer than approximately 100 characters, use the follow struct sockaddr_un *su = alloca (su_len); su->sun_family = AF_LOCAL; strcpy (su->sun_path, filename); - /* Use `SUN_LEN (su)' in socket functions. */ NOTE: the current API is subject to change, see the notes in Glibc's docs ("info libc" and search for `sockaddr_un`) and [Debian bug #187391](http://bugs.debian.org/187391). |