Merge pull request #761 'fix a few strncpy calls by using xstrlcpy'

src/nvim/api/private/helpers.c

@@ -67,7 +67,7 @@ bool try_end(Error *err)
                                              ET_ERROR,
                                              NULL,
                                              &should_free);
-    strncpy(err->msg, msg, sizeof(err->msg));
+    xstrlcpy(err->msg, msg, sizeof(err->msg));
     err->set = true;
     free_global_msglist();
 

src/nvim/api/private/helpers.h

@@ -5,10 +5,11 @@
 
 #include "nvim/api/private/defs.h"
 #include "nvim/vim.h"
+#include "nvim/memory.h"
 
 #define set_api_error(message, err)                \
   do {                                             \
-    strncpy(err->msg, message, sizeof(err->msg));  \
+    xstrlcpy(err->msg, message, sizeof(err->msg)); \
     err->set = true;                               \
   } while (0)
 

src/nvim/memory.c

@@ -183,6 +183,19 @@ char *xstpncpy(char *restrict dst, const char *restrict src, size_t maxlen)
     }
 }
 
+size_t xstrlcpy(char *restrict dst, const char *restrict src, size_t size)
+{
+    size_t ret = strlen(src);
+
+    if (size) {
+        size_t len = (ret >= size) ? size - 1 : ret;
+        memcpy(dst, src, len);
+        dst[len] = '\0';
+    }
+
+    return ret;
+}
+
 char *xstrdup(const char *str)
 {
   char *ret = strdup(str);

src/nvim/memory.h

@@ -125,6 +125,19 @@ char *xstpcpy(char *restrict dst, const char *restrict src);
 /// @param maxlen
 char *xstpncpy(char *restrict dst, const char *restrict src, size_t maxlen);
 
+/// xstrlcpy - Copy a %NUL terminated string into a sized buffer
+///
+/// Compatible with *BSD strlcpy: the result is always a valid
+/// NUL-terminated string that fits in the buffer (unless,
+/// of course, the buffer size is zero). It does not pad
+/// out the result like strncpy() does.
+///
+/// @param dst Where to copy the string to
+/// @param src Where to copy the string from
+/// @param size Size of destination buffer
+/// @return Length of the source string (i.e.: strlen(src))
+size_t xstrlcpy(char *restrict dst, const char *restrict src, size_t size);
+
 /// Duplicates a chunk of memory using xmalloc
 ///
 /// @see {xmalloc}

src/nvim/os/server.c

@@ -85,7 +85,11 @@ void server_start(char *endpoint, ChannelProtocol prot)
   char addr[ADDRESS_MAX_SIZE];
 
   // Trim to `ADDRESS_MAX_SIZE`
-  strncpy(addr, endpoint, sizeof(addr));
+  if (xstrlcpy(addr, endpoint, sizeof(addr)) >= sizeof(addr)) {
+      // TODO(aktau): since this is not what the user wanted, perhaps we
+      // should return an error here
+      EMSG2("Address was too long, truncated to %s", addr);
+  }
 
   // Check if the server already exists
   if (map_has(cstr_t)(servers, addr)) {
@@ -111,7 +115,7 @@ void server_start(char *endpoint, ChannelProtocol prot)
   }
 
   // Extract the address part
-  strncpy(ip, addr, addr_len);
+  xstrlcpy(ip, addr, addr_len);
 
   int port = NEOVIM_DEFAULT_TCP_PORT;
 
@@ -183,7 +187,7 @@ void server_stop(char *endpoint)
   char addr[ADDRESS_MAX_SIZE];
 
   // Trim to `ADDRESS_MAX_SIZE`
-  strncpy(addr, endpoint, sizeof(addr));
+  xstrlcpy(addr, endpoint, sizeof(addr));
 
   if ((server = map_get(cstr_t)(servers, addr)) == NULL) {
     EMSG2("Not listening on %s", addr);