vim-patch:8.2.0711: temp directory might be cleared (#21614)

Problem:    With a long running Vim the temp directory might be cleared on
            some systems.
Solution:   Lock the temp directory. (closes vim/vim#6044)

https://github.com/vim/vim/commit/b2d0e51366dea6843f991f31a457f5456d162678

3 files changed, 63 insertions, 0 deletions

diff --git a/cmake.config/CMakeLists.txt b/cmake.config/CMakeLists.txt
index b11ee2d969..183954b889 100644
--- a/cmake.config/CMakeLists.txt
+++ b/cmake.config/CMakeLists.txt
@@ -46,6 +46,26 @@ check_function_exists(strcasecmp HAVE_STRCASECMP)
 check_function_exists(strncasecmp HAVE_STRNCASECMP)
 check_function_exists(strptime HAVE_STRPTIME)
 
+check_c_source_compiles("
+#include <sys/types.h>
+#include <dirent.h>
+int main(void)
+{
+  DIR *dir = opendir(\"dirname\");
+  dirfd(dir);
+  return 0;
+}
+" HAVE_DIRFD)
+
+check_c_source_compiles("
+#include <sys/file.h>
+int main(void)
+{
+  flock(10, LOCK_SH);
+  return 0;
+}
+" HAVE_FLOCK)
+
 if(CMAKE_SYSTEM_NAME STREQUAL "SunOS")
   check_c_source_compiles("
 #include <termios.h>
diff --git a/cmake.config/config.h.in b/cmake.config/config.h.in
index 283a1d0c47..f946fa6124 100644
--- a/cmake.config/config.h.in
+++ b/cmake.config/config.h.in
@@ -54,6 +54,8 @@
 #  undef HAVE_SYS_UIO_H
 # endif
 #endif
+#cmakedefine HAVE_DIRFD
+#cmakedefine HAVE_FLOCK
 #cmakedefine HAVE_FORKPTY
 
 #ifndef UNIT_TESTING
diff --git a/src/nvim/fileio.c b/src/nvim/fileio.c
index fdf1973719..6bad91e959 100644
--- a/src/nvim/fileio.c
+++ b/src/nvim/fileio.c
@@ -65,6 +65,11 @@
 #include "nvim/undo.h"
 #include "nvim/vim.h"
 
+#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+# include <dirent.h>
+# include <sys/file.h>
+#endif
+
 #ifdef OPEN_CHR_FILES
 # include "nvim/charset.h"
 #endif
@@ -5167,6 +5172,9 @@ void forward_slash(char_u *fname)
 
 /// Path to Nvim's own temp dir. Ends in a slash.
 static char *vim_tempdir = NULL;
+#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+DIR *vim_tempdir_dp = NULL;  ///< File descriptor of temp dir
+#endif
 
 /// Creates a directory for private use by this instance of Nvim, trying each of
 /// `TEMP_DIR_NAMES` until one succeeds.
@@ -5331,10 +5339,40 @@ int delete_recursive(const char *name)
   return result;
 }
 
+#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+/// Open temporary directory and take file lock to prevent
+/// to be auto-cleaned.
+static void vim_opentempdir(void)
+{
+  if (vim_tempdir_dp != NULL) {
+    return;
+  }
+
+  DIR *dp = opendir(vim_tempdir);
+
+  if (dp != NULL) {
+    vim_tempdir_dp = dp;
+    flock(dirfd(vim_tempdir_dp), LOCK_SH);
+  }
+}
+
+/// Close temporary directory - it automatically release file lock.
+static void vim_closetempdir(void)
+{
+  if (vim_tempdir_dp != NULL) {
+    closedir(vim_tempdir_dp);
+    vim_tempdir_dp = NULL;
+  }
+}
+#endif
+
 /// Delete the temp directory and all files it contains.
 void vim_deltempdir(void)
 {
   if (vim_tempdir != NULL) {
+#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+    vim_closetempdir();
+#endif
     // remove the trailing path separator
     path_tail(vim_tempdir)[-1] = NUL;
     delete_recursive(vim_tempdir);
@@ -5370,6 +5408,9 @@ static bool vim_settempdir(char *tempdir)
   vim_FullName(tempdir, buf, MAXPATHL, false);
   add_pathsep(buf);
   vim_tempdir = xstrdup(buf);
+#if defined(HAVE_FLOCK) && defined(HAVE_DIRFD)
+  vim_opentempdir();
+#endif
   xfree(buf);
   return true;
 }