unix,win: add uv_os_gethostname()

Fixes: https://github.com/libuv/libuv/issues/1315
PR-URL: https://github.com/libuv/libuv/pull/1342
Reviewed-By: Santiago Gimeno <santiago.gimeno@gmail.com>
Reviewed-By: Sam Roberts <vieuxtech@gmail.com>

Makefile.am

@@ -178,6 +178,7 @@ test_run_tests_SOURCES = test/blackhole-server.c \
                          test/test-get-memory.c \
                          test/test-get-passwd.c \
                          test/test-getaddrinfo.c \
+                         test/test-gethostname.c \
                          test/test-getnameinfo.c \
                          test/test-getsockname.c \
                          test/test-handle-fileno.c \

checksparse.sh

@@ -104,6 +104,7 @@ test/test-get-loadavg.c
 test/test-get-memory.c
 test/test-get-passwd.c
 test/test-getaddrinfo.c
+test/test-gethostname.c
 test/test-getsockname.c
 test/test-homedir.c
 test/test-hrtime.c

docs/src/misc.rst

@@ -429,3 +429,14 @@ API
         This function is not thread safe.
 
     .. versionadded:: 1.12.0
+
+.. c:function:: int uv_os_gethostname(char* buffer, size_t* size)
+
+    Returns the hostname as a null-terminated string in `buffer`, and sets
+    `size` to the string length of the hostname. When calling this function,
+    `size` must be set to the amount of storage available in `buffer`, including
+    the null terminator. If the hostname exceeds the storage available in
+    `buffer`, `UV_ENOBUFS` is returned, and `size` is set to the amount of
+    storage required to hold the value.
+
+    .. versionadded:: 1.12.0

include/uv.h

@@ -1078,6 +1078,8 @@ UV_EXTERN int uv_os_getenv(const char* name, char* buffer, size_t* size);
 UV_EXTERN int uv_os_setenv(const char* name, const char* value);
 UV_EXTERN int uv_os_unsetenv(const char* name);
 
+UV_EXTERN int uv_os_gethostname(char* buffer, size_t* size);
+
 
 typedef enum {
   UV_FS_UNKNOWN = -1,

src/unix/core.c

@@ -28,6 +28,7 @@
 #include <errno.h>
 #include <assert.h>
 #include <unistd.h>
+#include <sys/param.h> /* MAXHOSTNAMELEN on Linux and the BSDs */
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <fcntl.h>
@@ -42,6 +43,7 @@
 #include <pwd.h>
 
 #ifdef __sun
+# include <netdb.h> /* MAXHOSTNAMELEN on Solaris */
 # include <sys/filio.h>
 # include <sys/types.h>
 # include <sys/wait.h>
@@ -80,6 +82,11 @@
 #include <sys/ioctl.h>
 #endif
 
+/* Fallback for the maximum hostname length */
+#ifndef MAXHOSTNAMELEN
+# define MAXHOSTNAMELEN 256
+#endif
+
 static int uv__run_pending(uv_loop_t* loop);
 
 /* Verify that uv_buf_t is ABI-compatible with struct iovec. */
@@ -1285,3 +1292,33 @@ int uv_os_unsetenv(const char* name) {
 
   return 0;
 }
+
+
+int uv_os_gethostname(char* buffer, size_t* size) {
+  /*
+    On some platforms, if the input buffer is not large enough, gethostname()
+    succeeds, but truncates the result. libuv can detect this and return ENOBUFS
+    instead by creating a large enough buffer and comparing the hostname length
+    to the size input.
+  */
+  char buf[MAXHOSTNAMELEN + 1];
+  size_t len;
+
+  if (buffer == NULL || size == NULL || *size == 0)
+    return -EINVAL;
+
+  if (gethostname(buf, sizeof(buf)) != 0)
+    return -errno;
+
+  buf[sizeof(buf) - 1] = '\0'; /* Null terminate, just to be safe. */
+  len = strlen(buf);
+
+  if (len >= *size) {
+    *size = len + 1;
+    return -ENOBUFS;
+  }
+
+  memcpy(buffer, buf, len + 1);
+  *size = len;
+  return 0;
+}

src/win/util.c

@@ -59,6 +59,14 @@
 # define UNLEN 256
 #endif
 
+/*
+  Max hostname length. The Windows gethostname() documentation states that 256
+  bytes will always be large enough to hold the null-terminated hostname.
+*/
+#ifndef MAXHOSTNAMELEN
+# define MAXHOSTNAMELEN 256
+#endif
+
 /* Maximum environment variable size, including the terminating null */
 #define MAX_ENV_VAR_LENGTH 32767
 
@@ -1540,3 +1548,29 @@ int uv_os_unsetenv(const char* name) {
 
   return 0;
 }
+
+
+int uv_os_gethostname(char* buffer, size_t* size) {
+  char buf[MAXHOSTNAMELEN + 1];
+  size_t len;
+
+  if (buffer == NULL || size == NULL || *size == 0)
+    return UV_EINVAL;
+
+  uv__once_init(); /* Initialize winsock */
+
+  if (gethostname(buf, sizeof(buf)) != 0)
+    return uv_translate_sys_error(WSAGetLastError());
+
+  buf[sizeof(buf) - 1] = '\0'; /* Null terminate, just to be safe. */
+  len = strlen(buf);
+
+  if (len >= *size) {
+    *size = len + 1;
+    return UV_ENOBUFS;
+  }
+
+  memcpy(buffer, buf, len + 1);
+  *size = len;
+  return 0;
+}

test/test-gethostname.c

@@ -0,0 +1,62 @@
+/* Copyright libuv contributors. All rights reserved.
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to
+ * deal in the Software without restriction, including without limitation the
+ * rights to use, copy, modify, merge, publish, distribute, sublicense, and/or
+ * sell copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS
+ * IN THE SOFTWARE.
+ */
+
+#include "uv.h"
+#include "task.h"
+#include <string.h>
+
+#ifndef MAXHOSTNAMELEN
+# define MAXHOSTNAMELEN 256
+#endif
+
+TEST_IMPL(gethostname) {
+  char buf[MAXHOSTNAMELEN + 1];
+  size_t size;
+  size_t enobufs_size;
+  int r;
+
+  /* Reject invalid inputs */
+  size = 1;
+  r = uv_os_gethostname(NULL, &size);
+  ASSERT(r == UV_EINVAL);
+  r = uv_os_gethostname(buf, NULL);
+  ASSERT(r == UV_EINVAL);
+  size = 0;
+  r = uv_os_gethostname(buf, &size);
+  ASSERT(r == UV_EINVAL);
+
+  /* Return UV_ENOBUFS if the buffer cannot hold the hostname */
+  enobufs_size = 1;
+  buf[0] = '\0';
+  r = uv_os_gethostname(buf, &enobufs_size);
+  ASSERT(r == UV_ENOBUFS);
+  ASSERT(buf[0] == '\0');
+  ASSERT(enobufs_size > 1);
+
+  /* Successfully get the hostname */
+  size = MAXHOSTNAMELEN + 1;
+  r = uv_os_gethostname(buf, &size);
+  ASSERT(r == 0);
+  ASSERT(size > 1 && size == strlen(buf));
+  ASSERT(size + 1 == enobufs_size);
+
+  return 0;
+}

test/test-list.h

@@ -220,6 +220,7 @@ TEST_DECLARE   (getaddrinfo_fail_sync)
 TEST_DECLARE   (getaddrinfo_basic)
 TEST_DECLARE   (getaddrinfo_basic_sync)
 TEST_DECLARE   (getaddrinfo_concurrent)
+TEST_DECLARE   (gethostname)
 TEST_DECLARE   (getnameinfo_basic_ip4)
 TEST_DECLARE   (getnameinfo_basic_ip4_sync)
 TEST_DECLARE   (getnameinfo_basic_ip6)
@@ -655,6 +656,8 @@ TASK_LIST_START
   TEST_ENTRY  (getaddrinfo_basic_sync)
   TEST_ENTRY  (getaddrinfo_concurrent)
 
+  TEST_ENTRY  (gethostname)
+
   TEST_ENTRY  (getnameinfo_basic_ip4)
   TEST_ENTRY  (getnameinfo_basic_ip4_sync)
   TEST_ENTRY  (getnameinfo_basic_ip6)

uv.gyp

@@ -357,6 +357,7 @@
         'test/test-get-memory.c',
         'test/test-get-passwd.c',
         'test/test-getaddrinfo.c',
+        'test/test-gethostname.c',
         'test/test-getnameinfo.c',
         'test/test-getsockname.c',
         'test/test-handle-fileno.c',