Define HOST_NAME_MAX for NaCl and RTEMS (#876)
These OS's don't always have HOST_NAME_MAX defined, resulting in
build errors.
A few related changes as well:
* Only define HOST_NAME_MAX if it's not already defined. There are
some cases where this is already defined, e.g. with NaCl if
__USE_POSIX is set. To avoid all of these, only define it if it's
not already defined.
* Default HOST_NAME_MAX to 64 and issue a #warning. Having the wrong
max length is pretty harmless. The name just ends up getting
truncated and this is only for printing debug info. Because we're
constructing a std::string from a char[] (so defined length), we
don't need to worry about gethostname's undefined behavior for
whether the truncation is null-terminated when the hostname
doesn't fit in HOST_NAME_MAX. Of course, this doesn't help people
who have -Werror set, since they'll still get a warning.
diff --git a/src/sysinfo.cc b/src/sysinfo.cc
index 2812647..b5f99c7 100644
--- a/src/sysinfo.cc
+++ b/src/sysinfo.cc
@@ -429,11 +429,20 @@
#endif
return str;
#else // defined(BENCHMARK_OS_WINDOWS)
+#ifndef HOST_NAME_MAX
#ifdef BENCHMARK_HAS_SYSCTL // BSD/Mac Doesnt have HOST_NAME_MAX defined
#define HOST_NAME_MAX 64
+#elif defined(BENCHMARK_OS_NACL)
+#define HOST_NAME_MAX 64
#elif defined(BENCHMARK_OS_QNX)
#define HOST_NAME_MAX 154
+#elif defined(BENCHMARK_OS_RTEMS)
+#define HOST_NAME_MAX 256
+#else
+#warning "HOST_NAME_MAX not defined. using 64"
+#define HOST_NAME_MAX 64
#endif
+#endif // def HOST_NAME_MAX
char hostname[HOST_NAME_MAX];
int retVal = gethostname(hostname, HOST_NAME_MAX);
if (retVal != 0) return std::string("");
