Backport from Tcl 8.6.

	* unix/tclUnixPipe.c (DefaultTempDir): [Bug 2933003]: Allow overriding
	of the back-stop default temporary file location at compile time by
	setting the TCL_TEMPORARY_FILE_DIRECTORY #def to a string containing
	the directory name (defaults to "/tmp" as that is the most common
	default).

1 files changed, 40 insertions, 2 deletions

diff --git a/unix/tclUnixPipe.c b/unix/tclUnixPipe.c
index 829a4a6..4540ae6 100644
--- a/unix/tclUnixPipe.c
+++ b/unix/tclUnixPipe.c
@@ -199,7 +199,7 @@ TclpCreateTempFile(contents)
      * We should also check against making more then TMP_MAX of these.
      */
 
-    strcpy(fileName, P_tmpdir);				/* INTL: Native. */
+    strcpy(fileName, DefaultTempDir());			/* INTL: Native. */
     if (fileName[strlen(fileName) - 1] != '/') {
 	strcat(fileName, "/");				/* INTL: Native. */
     }
@@ -251,7 +251,7 @@ TclpTempFileName()
      * We should also check against making more then TMP_MAX of these.
      */
 
-    strcpy(fileName, P_tmpdir);		/* INTL: Native. */
+    strcpy(fileName, DefaultTempDir());	/* INTL: Native. */
     if (fileName[strlen(fileName) - 1] != '/') {
 	strcat(fileName, "/");		/* INTL: Native. */
     }
@@ -271,6 +271,44 @@ TclpTempFileName()
 /*
  *----------------------------------------------------------------------
  *
+ * DefaultTempDir --
+ *
+ *	Helper that does *part* of what tempnam() does.
+ *
+ *----------------------------------------------------------------------
+ */
+
+static const char *
+DefaultTempDir(void)
+{
+    const char *dir;
+    struct stat buf;
+
+    dir = getenv("TMPDIR");
+    if (dir && dir[0] && stat(dir, &buf) == 0 && S_ISDIR(buf.st_mode)
+	    && access(dir, W_OK)) {
+	return dir;
+    }
+
+#ifdef P_tmpdir
+    dir = P_tmpdir;
+    if (stat(dir, &buf) == 0 && S_ISDIR(buf.st_mode) && access(dir, W_OK)) {
+	return dir;
+    }
+#endif
+
+    /*
+     * Assume that the default location ("/tmp" if not overridden) is always
+     * an existing writable directory; we've no recovery mechanism if it
+     * isn't.
+     */
+
+    return TCL_TEMPORARY_FILE_DIRECTORY;
+}
+
+/*
+ *----------------------------------------------------------------------
+ *
  * TclpCreatePipe --
  *
  *      Creates a pipe - simply calls the pipe() function.