[PATCH] tmpdir: Add function to create a unique temp directory.

[John Darrington]

* lib/tmpdir.c (create_tmp_dir): New function definition.
* lib/tmpdir.h (create_tmp_dir): New function declaration.
---
 lib/tmpdir.c | 119 +++++++++++++++++++++++++++++++++++++++++++++++++++
 lib/tmpdir.h |  20 +++++++++
 2 files changed, 139 insertions(+)

diff --git a/lib/tmpdir.c b/lib/tmpdir.c
index 28ff99f58..b6cd3e526 100644
--- a/lib/tmpdir.c
+++ b/lib/tmpdir.c
@@ -163,3 +163,122 @@ path_search (char *tmpl, size_t tmpl_len, const char 
*dir, const char *pfx,
   sprintf (tmpl + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx);
   return 0;
 }
+
+
+/* Create a unique temporary directory and return its name.
+
+   If BASEDIR is non-null the directory will be a sub-directory of BASEDIR.
+   Otherwise, if TRY_TMPDIR is non-null the directory will be created in the
+   first of $TMPDIR,  P_tmpdir, /tmp that exists.  If none of those directories
+   exist,  the function will fail, and ENOENT will be set in errno.
+
+   TRY_TMPDIR is ignored if BASEDIR is non-null.
+
+   If PFX is non-null,  the first 5 bytes of it will be used as a prefix for
+   the directory name.    On failure, NULL will be returned and errno set
+   accordingly.
+
+   On success, a temporary directory will be created (using mkdtemp from
+   stdlib.h), and its  name returned.
+
+   The caller is responsible for freeing the return value (and removing the
+   directory if appropriate). */
+char *
+create_tmp_dir (const char *basedir, const char *pfx, bool try_tmpdir)
+{
+  char *dir = NULL;
+  bool add_slash;
+  size_t dlen = 0;
+  size_t plen = 0;
+
+  if (!pfx || !pfx[0])
+    {
+      pfx = "file";
+      plen = 4;
+    }
+  else
+    {
+      plen = strlen (pfx);
+      if (plen > 5)
+        plen = 5;
+    }
+
+  if (basedir != NULL)
+    {
+      dir = strdup (basedir);
+      if (dir == NULL)
+        {
+          return NULL;
+        }
+    }
+
+  if (dir == NULL)
+    {
+      if (try_tmpdir)
+        {
+          char *d = __libc_secure_getenv ("TMPDIR");
+          if (d != NULL && direxists (d))
+            dir = strdup (d);
+          else if (dir != NULL && direxists (dir))
+            /* nothing */ ;
+          else
+            dir = NULL;
+        }
+    }
+
+  if (dir == NULL)
+    {
+#if defined _WIN32 && ! defined __CYGWIN__
+      char dirbuf[PATH_MAX];
+      DWORD retval;
+
+      /* Find Windows temporary file directory.
+         We try this before P_tmpdir because Windows defines P_tmpdir to "\\"
+         and will therefore try to put all temporary files in the root
+         directory (unless $TMPDIR is set).  */
+      retval = GetTempPath (PATH_MAX, dirbuf);
+      if (retval > 0 && retval < PATH_MAX && direxists (dirbuf))
+        dir = strdup (dirbuf);
+      else
+#endif
+      if (direxists (P_tmpdir))
+        dir = strdup (P_tmpdir);
+      else if (strcmp (P_tmpdir, "/tmp") != 0 && direxists ("/tmp"))
+        dir = strdup ("/tmp");
+      else
+        {
+          __set_errno (ENOENT);
+          return NULL;
+        }
+    }
+
+  dlen = strlen (dir);
+#ifdef __VMS
+  add_slash = 0;
+#else
+  add_slash = dlen != 0 && !ISSLASH (dir[dlen - 1]);
+#endif
+
+  {
+    char *d = dir;
+    /* Make room for "${dir}/${pfx}XXXXXX\0" */
+    dir = realloc (d, dlen + add_slash + plen + 6 + 1);
+    if (dir == NULL)
+      {
+        int e = errno;
+        free (d);
+        __set_errno (e);
+        return NULL;
+      }
+  }
+
+  if (0 > sprintf (dir + dlen, &"/%.*sXXXXXX"[!add_slash], (int) plen, pfx))
+    {
+        int e = errno;
+        free (dir);
+        __set_errno (e);
+        return NULL;
+    }
+
+  return mkdtemp (dir);
+}
diff --git a/lib/tmpdir.h b/lib/tmpdir.h
index 4d694a3d9..ea71ef635 100644
--- a/lib/tmpdir.h
+++ b/lib/tmpdir.h
@@ -24,3 +24,23 @@
    doesn't exist, none of the searched dirs exists, or there's not
    enough space in TMPL. */
 extern int path_search (char *tmpl, size_t tmpl_len, const char *dir, const 
char *pfx, bool try_tmpdir);
+
+/* Create a unique temporary directory and return its name.
+
+   If BASEDIR is non-null the directory will be a sub-directory of BASEDIR.
+   Otherwise, if TRY_TMPDIR is non-null the directory will be created in the
+   first of $TMPDIR,  P_tmpdir, /tmp that exists.  If none of those directories
+   exist,  the function will fail, and ENOENT will be set in errno.
+
+   TRY_TMPDIR is ignored if BASEDIR is non-null.
+
+   If PFX is non-null,  the first 5 bytes of it will be used as a prefix for
+   the directory name.    On failure, NULL will be returned and errno set
+   accordingly.
+
+   On success, a temporary directory will be created (using mkdtemp from
+   stdlib.h), and its  name returned.
+
+   The caller is responsible for freeing the return value (and removing the
+   directory if appropriate). */
+char *create_tmp_dir (const char *basedir, const char *pfx, bool try_tmpdir);
-- 
2.20.1