3 files changed, 81 insertions, 1 deletions
diff --git a/ChangeLog b/ChangeLog
index d9918c1f..0bfc6592 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,11 @@
+2015-03-10  Kaz Kylheku  <kaz@kylheku.com>
+
+	* sysif.c (mkdir_nothrow_exists): New static function.
+	(ensure_dir): New function.
+	(sysif_init): ensure_dir registered as intrinsic.
+
+	* txr.1: ensure_dir documented.
+
 2015-02-25  Kaz Kylheku  <kaz@kylheku.com>
 
 	* parser.c (open_txr_file, regex_parse, lisp_parse): Functions
diff --git a/sysif.c b/sysif.c
index c401b23a..04466896 100644
--- a/sysif.c
+++ b/sysif.c
@@ -58,6 +58,7 @@
 #include "signal.h"
 #include "utf8.h"
 #include "unwind.h"
+#include "gc.h"
 #include "eval.h"
 #include "sysif.h"
 
@@ -180,6 +181,68 @@ static val mkdir_wrap(val path, val mode)
 }
 #endif
 
+#if HAVE_MKDIR || HAVE_WINDOWS_H
+static val mkdir_nothrow_exists(val path, val mode)
+{
+  val ret = t;
+
+  uw_catch_begin(cons(file_error_s, nil), esym, eobj);
+
+  ret = mkdir_wrap(path, mode);
+
+  uw_catch (esym, eobj) {
+    switch (errno) {
+    case EACCES:
+    case EPERM:
+      ret = num(errno);
+      break;
+    case EEXIST:
+      break;
+    default:
+      uw_throw(esym, eobj);
+    }
+  }
+
+  uw_unwind;
+
+  uw_catch_end;
+
+  return ret;
+}
+
+static val ensure_dir(val path, val mode)
+{
+#if HAVE_WINDOWS_H
+  val sep = lit("\\");
+  val sep_set = lit("\\/");
+#else
+  val sep = lit("/");
+  val sep_set = lit("/");
+#endif
+  val split_path = split_str_set(path, sep_set);
+  val partial_path = pop(&split_path);
+  val ret = t;
+
+  for (;;) {
+    if (length(partial_path) != zero)
+      ret = mkdir_nothrow_exists(partial_path, mode);
+
+    if (!split_path)
+      break;
+
+    partial_path = format(nil, lit("~a~a~a"),
+                          partial_path, sep, pop(&split_path), nao);
+  }
+
+  if (ret != t)
+    uw_throwf(file_error_s,
+              lit("ensure-dir: ~a: ~a/~s"), path, ret,
+              string_utf8(strerror(c_num(ret))), nao);
+
+  return ret;
+}
+#endif
+
 #if HAVE_UNISTD_H
 static val chdir_wrap(val path)
 {
@@ -388,6 +451,7 @@ void sysif_init(void)
 
 #if HAVE_MKDIR || HAVE_WINDOWS_H
   reg_fun(intern(lit("mkdir"), user_package), func_n2o(mkdir_wrap, 1));
+  reg_fun(intern(lit("ensure-dir"), user_package), func_n2o(ensure_dir, 1));
 #endif
 
 #if HAVE_UNISTD_H
diff --git a/txr.1 b/txr.1
index 75794618..a8c10b07 100644
--- a/txr.1
+++ b/txr.1
@@ -23989,9 +23989,10 @@ of the system timer.  Actual sleep times may be rounded up to the nearest 10
 millisecond multiple on a system where timed suspensions are triggered by a 100
 Hz tick.
 
-.coNP Function @ mkdir
+.coNP Functions @ mkdir and @ ensure-dir
 .synb
 .mets (mkdir < path <> [ mode ])
+.mets (ensure-dir < path <> [ mode ])
 .syne
 .desc
 .code mkdir
@@ -24015,6 +24016,13 @@ for the newly created directory. If omitted, the requested permissions are
 are subject to the system
 .codn umask .
 
+The function
+.code ensure-dir
+is similar to
+.code mkdir
+except that it attempts to create all the missing parent directories
+as necessary, and does not throw an error if the directory exists.
+
 .coNP Function @ chdir
 .synb
 .mets (chdir << path )