Move mkdir_recursive to common/filestuff.c

This moves mkdir_recursive from dwarf-index-cache.c to
common/filestuff.c, and also changes it to return a boolean that says
whether or not it worked.

gdb/ChangeLog
2018-10-27  Tom Tromey  <tom@tromey.com>

	* unittests/mkdir-recursive-selftests.c: New file.
	* Makefile.in (SUBDIR_UNITTESTS_SRCS): Add
	unittests/mkdir-recursive-selftests.c.
	* dwarf-index-cache.c (mkdir_recursive): Move to
	common/filestuff.c.
	(index_cache::store): Check return value of mkdir_recursive.
	(create_dir_and_check, test_mkdir_recursive): Move to new file.
	(_initialize_index_cache): Don't register test.
	* common/filestuff.h (mkdir_recursive): Declare.
	* common/filestuff.c (mkdir_recursive): Move from
	dwarf-index-cache.c.  Return bool.

2 files changed, 55 insertions, 0 deletions

diff --git a/gdb/common/filestuff.c b/gdb/common/filestuff.c
index dfd86f9..d4bd1a8 100644
--- a/gdb/common/filestuff.c
+++ b/gdb/common/filestuff.c
@@ -447,3 +447,48 @@ is_regular_file (const char *name, int *errno_ptr)
     *errno_ptr = EINVAL;
   return false;
 }
+
+/* See common/filestuff.h.  */
+
+bool
+mkdir_recursive (const char *dir)
+{
+  gdb::unique_xmalloc_ptr<char> holder (xstrdup (dir));
+  char * const start = holder.get ();
+  char *component_start = start;
+  char *component_end = start;
+
+  while (1)
+    {
+      /* Find the beginning of the next component.  */
+      while (*component_start == '/')
+	component_start++;
+
+      /* Are we done?  */
+      if (*component_start == '\0')
+	return true;
+
+      /* Find the slash or null-terminator after this component.  */
+      component_end = component_start;
+      while (*component_end != '/' && *component_end != '\0')
+	component_end++;
+
+      /* Temporarily replace the slash with a null terminator, so we can create
+         the directory up to this component.  */
+      char saved_char = *component_end;
+      *component_end = '\0';
+
+      /* If we get EEXIST and the existing path is a directory, then we're
+         happy.  If it exists, but it's a regular file and this is not the last
+         component, we'll fail at the next component.  If this is the last
+         component, the caller will fail with ENOTDIR when trying to
+         open/create a file under that path.  */
+      if (mkdir (start, 0700) != 0)
+	if (errno != EEXIST)
+	  return false;
+
+      /* Restore the overwritten char.  */
+      *component_end = saved_char;
+      component_start = component_end;
+    }
+}
diff --git a/gdb/common/filestuff.h b/gdb/common/filestuff.h
index e9328f5..ecfc18d 100644
--- a/gdb/common/filestuff.h
+++ b/gdb/common/filestuff.h
@@ -122,4 +122,14 @@ typedef std::unique_ptr<DIR, gdb_dir_deleter> gdb_dir_up;
    we're expecting a regular file.  */
 extern bool is_regular_file (const char *name, int *errno_ptr);
 
+
+/* A cheap (as in low-quality) recursive mkdir.  Try to create all the
+   parents directories up to DIR and DIR itself.  Stop if we hit an
+   error along the way.  There is no attempt to remove created
+   directories in case of failure.
+
+   Returns false on failure and sets errno.  */
+
+extern bool mkdir_recursive (const char *dir);
+
 #endif /* FILESTUFF_H */