unix, win: consistently null-terminate buffers

libuv has multiple functions which return buffers. Make them consistent
with the following rules: the returned size *does not* include the null
byte, but the buffer *is* null terminated.

There is only one exception to the above: Linux abstract sockets,
because null bytes are not used as string terminators in those.

Refs: https://github.com/libuv/libuv/pull/674
PR-URL: https://github.com/libuv/libuv/pull/690
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>

src/fs-poll.c

@@ -138,13 +138,14 @@ int uv_fs_poll_getpath(uv_fs_poll_t* handle, char* buffer, size_t* size) {
   assert(ctx != NULL);
 
   required_len = strlen(ctx->path);
-  if (required_len > *size) {
+  if (required_len >= *size) {
     *size = required_len;
     return UV_ENOBUFS;
   }
 
   memcpy(buffer, ctx->path, required_len);
   *size = required_len;
+  buffer[required_len] = '\0';
 
   return 0;
 }

src/unix/pipe.c

@@ -234,7 +234,7 @@ static int uv__pipe_getsockpeername(const uv_pipe_t* handle,
     addrlen = strlen(sa.sun_path);
 
 
-  if (addrlen > *size) {
+  if (addrlen >= *size) {
     *size = addrlen;
     return UV_ENOBUFS;
   }
@@ -242,6 +242,10 @@ static int uv__pipe_getsockpeername(const uv_pipe_t* handle,
   memcpy(buffer, sa.sun_path, addrlen);
   *size = addrlen;
 
+  /* only null-terminate if it's not an abstract socket */
+  if (buffer[0] != '\0')
+    buffer[addrlen] = '\0';
+
   return 0;
 }
 

src/uv-common.c

@@ -451,13 +451,14 @@ int uv_fs_event_getpath(uv_fs_event_t* handle, char* buffer, size_t* size) {
   }
 
   required_len = strlen(handle->path);
-  if (required_len > *size) {
+  if (required_len >= *size) {
     *size = required_len;
     return UV_ENOBUFS;
   }
 
   memcpy(buffer, handle->path, required_len);
   *size = required_len;
+  buffer[required_len] = '\0';
 
   return 0;
 }

src/win/pipe.c

@@ -2038,7 +2038,7 @@ static int uv__pipe_getname(const uv_pipe_t* handle, char* buffer, size_t* size)
     *size = 0;
     err = uv_translate_sys_error(GetLastError());
     goto error;
-  } else if (pipe_prefix_len + addrlen > *size) {
+  } else if (pipe_prefix_len + addrlen >= *size) {
     /* "\\\\.\\pipe" + name */
     *size = pipe_prefix_len + addrlen;
     err = UV_ENOBUFS;
@@ -2062,6 +2062,7 @@ static int uv__pipe_getname(const uv_pipe_t* handle, char* buffer, size_t* size)
 
   addrlen += pipe_prefix_len;
   *size = addrlen;
+  buffer[addrlen] = '\0';
 
   err = 0;
   goto cleanup;

test/test-fs-event.c

@@ -819,6 +819,7 @@ TEST_IMPL(fs_event_getpath) {
   r = uv_fs_event_getpath(&fs_event, buf, &len);
   ASSERT(r == 0);
   ASSERT(buf[len - 1] != 0);
+  ASSERT(buf[len] == '\0');
   ASSERT(memcmp(buf, "watch_dir", len) == 0);
   r = uv_fs_event_stop(&fs_event);
   ASSERT(r == 0);

test/test-fs-poll.c

@@ -173,6 +173,7 @@ TEST_IMPL(fs_poll_getpath) {
   len = sizeof buf;
   ASSERT(0 == uv_fs_poll_getpath(&poll_handle, buf, &len));
   ASSERT(buf[len - 1] != 0);
+  ASSERT(buf[len] == '\0');
   ASSERT(0 == memcmp(buf, FIXTURE, len));
 
   uv_close((uv_handle_t*) &poll_handle, close_cb);

test/test-pipe-getsockname.c

@@ -114,6 +114,7 @@ TEST_IMPL(pipe_getsockname) {
   ASSERT(r == 0);
 
   ASSERT(buf[len - 1] != 0);
+  ASSERT(buf[len] == '\0');
   ASSERT(memcmp(buf, TEST_PIPENAME, len) == 0);
 
   len = sizeof buf;