Merge #850 'impl mkdtemp for windows, refactor vim_tempname'

1 files changed, 131 insertions, 0 deletions

diff --git a/src/nvim/tempfile.c b/src/nvim/tempfile.c
new file mode 100644
index 0000000000..41fc163936
--- /dev/null
+++ b/src/nvim/tempfile.c
@@ -0,0 +1,131 @@
+#include <inttypes.h>
+#include <stdbool.h>
+#include <stdlib.h>
+#include <stdio.h>
+
+#include "nvim/ascii.h"
+#include "nvim/memory.h"
+#include "nvim/misc1.h"
+#include "nvim/os/os.h"
+#include "nvim/os/os_defs.h"
+#include "nvim/path.h"
+#include "nvim/strings.h"
+#include "nvim/tempfile.h"
+
+#ifdef INCLUDE_GENERATED_DECLARATIONS
+# include "tempfile.c.generated.h"
+#endif
+
+/// Name of Vim's own temp dir. Ends in a slash.
+static char_u *vim_tempdir = NULL;
+
+/// Create a directory for private use by this instance of Neovim.
+/// This is done once, and the same directory is used for all temp files.
+/// This method avoids security problems because of symlink attacks et al.
+/// It's also a bit faster, because we only need to check for an existing
+/// file when creating the directory and not for each temp file.
+static void vim_maketempdir(void)
+{
+  static const char *temp_dirs[] = TEMP_DIR_NAMES;
+  // Try the entries in `TEMP_DIR_NAMES` to create the temp directory.
+  char_u itmp[TEMP_FILE_PATH_MAXLEN];
+  for (size_t i = 0; i < sizeof(temp_dirs) / sizeof(char *); ++i) {
+    // Expand environment variables, leave room for "/nvimXXXXXX/999999999"
+    expand_env((char_u *)temp_dirs[i], itmp, TEMP_FILE_PATH_MAXLEN - 22);
+    if (!os_isdir(itmp)) {  // directory doesn't exist
+      continue;
+    }
+
+    add_pathsep(itmp);
+    // Concatenate with temporary directory name pattern
+    STRCAT(itmp, "nvimXXXXXX");
+    if (!os_mkdtemp((char *)itmp)) {
+      continue;
+    }
+    if (vim_settempdir(itmp)) {
+      // Successfully created and set temporary directory so stop trying.
+      break;
+    } else {
+      // Couldn't set `vim_tempdir` to itmp so remove created directory.
+      os_rmdir((char *)itmp);
+    }
+  }
+}
+
+/// Delete the temp directory and all files it contains.
+void vim_deltempdir(void)
+{
+  if (vim_tempdir != NULL) {
+    snprintf((char *)NameBuff, MAXPATHL, "%s*", vim_tempdir);
+
+    char_u **files;
+    int file_count;
+    if (gen_expand_wildcards(1, &NameBuff, &file_count, &files,
+        EW_DIR|EW_FILE|EW_SILENT) == OK) {
+      for (int i = 0; i < file_count; ++i) {
+        os_remove((char *)files[i]);
+      }
+      FreeWild(file_count, files);
+    }
+    path_tail(NameBuff)[-1] = NUL;
+    os_rmdir((char *)NameBuff);
+
+    free(vim_tempdir);
+    vim_tempdir = NULL;
+  }
+}
+
+/// Get the name of temp directory. This directory would be created on the first
+/// call to this function.
+char_u *vim_gettempdir(void)
+{
+  if (vim_tempdir == NULL) {
+    vim_maketempdir();
+  }
+
+  return vim_tempdir;
+}
+
+/// Set Neovim own temporary directory name to `tempdir`. This directory should
+/// be already created. Expand this name to a full path and put it in
+/// `vim_tempdir`. This avoids that using `:cd` would confuse us.
+///
+/// @param tempdir must be no longer than MAXPATHL.
+///
+/// @return false if we run out of memory.
+static bool vim_settempdir(char_u *tempdir)
+{
+  char_u *buf = verbose_try_malloc((size_t)MAXPATHL + 2);
+  if (!buf) {
+    return false;
+  }
+  vim_FullName(tempdir, buf, MAXPATHL, false);
+  add_pathsep(buf);
+  vim_tempdir = vim_strsave(buf);
+  free(buf);
+  return true;
+}
+
+/// Return a unique name that can be used for a temp file.
+///
+/// @note The temp file is NOT created.
+///
+/// @return pointer to the temp file name or NULL if Neovim can't create
+///         temporary directory for its own temporary files.
+char_u *vim_tempname(void)
+{
+  // Temp filename counter.
+  static uint32_t temp_count;
+
+  char_u *tempdir = vim_gettempdir();
+  if (!tempdir) {
+    return NULL;
+  }
+
+  // There is no need to check if the file exists, because we own the directory
+  // and nobody else creates a file in it.
+  char_u itmp[TEMP_FILE_PATH_MAXLEN];
+  snprintf((char *)itmp, TEMP_FILE_PATH_MAXLEN,
+           "%s%" PRIu32, tempdir, temp_count++);
+  return vim_strsave(itmp);
+}