From 2f5a68b43ae9293a83c3b412edd2f77d4303eb11 Mon Sep 17 00:00:00 2001
From: "Peter W. Draper" <p.w.draper@durham.ac.uk>
Date: Thu, 23 Apr 2020 19:15:46 +0100
Subject: [PATCH] Add utility function to check that a directory exists and if
not report that or attempt to create it, in safe ways...
---
src/tools.c | 49 +++++++++++++++++++++++++++++++++++++++++++++++++
src/tools.h | 2 ++
2 files changed, 51 insertions(+)
diff --git a/src/tools.c b/src/tools.c
index 1287d0b634..2f1969d91d 100644
--- a/src/tools.c
+++ b/src/tools.c
@@ -24,12 +24,16 @@
/* Some standard headers. */
#include <ctype.h>
+#include <errno.h>
#include <math.h>
#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/resource.h>
+#include <sys/stat.h>
#include <sys/time.h>
+#include <sys/types.h>
+#include <unistd.h>
/* This object's header. */
#include "tools.h"
@@ -1058,3 +1062,48 @@ char *trim_both(char *s) {
if (s == NULL || strlen(s) < 2) return s;
return trim_trailing(trim_leading(s));
}
+
+/**
+ * @brief safe check directory existence and creation.
+ *
+ * Doesn't try to re-create an existing directory and makes sure that it can
+ * have files created in it. If the directory doesn't exist and we want to
+ * create it then we try to do that with an appropriate mask that should
+ * honour the users umask. If the directory is something odd like a broken
+ * link then that is dereferenced so should also result in an error, since
+ * it doesn't exist and cannot be created. Finally we check that an existing
+ * file with this name is indeed a directory.
+ *
+ * @param dir the directory we need to exist.
+ * @param create create if not already exists, otherwise non-existence is an
+ * error.
+ */
+void safe_checkdir(const char *dir, int create) {
+
+ if (access(dir, W_OK | X_OK) != 0) {
+
+ /* A file with this name and the minimally correct permissions does not
+ * exist. */
+ if (create) {
+ if (mkdir(dir, 0777) != 0)
+ error("Failed to create directory %s (%s)", dir, strerror(errno));
+ } else {
+ error("directory %s does not exist or cannot be used (%s)", dir,
+ strerror(errno));
+ }
+ } else {
+
+ /* Exists and has the minimally correct permissions, is this a
+ * directory? */
+ struct stat sb;
+ if (stat(dir, &sb) != 0) {
+ /* Weird error, can stat all existing files. */
+ error("Failed to stat directory %s (%s)", dir, strerror(errno));
+ } else if ((sb.st_mode & S_IFMT) != S_IFDIR) {
+ error("%s is not a directory, cannot use or create.", dir);
+ }
+ }
+
+ /* Success. */
+ return;
+}
diff --git a/src/tools.h b/src/tools.h
index a34904bcbb..8f7a65b7aa 100644
--- a/src/tools.h
+++ b/src/tools.h
@@ -64,4 +64,6 @@ char *trim_leading(char *s);
char *trim_trailing(char *s);
char *trim_both(char *s);
+void safe_checkdir(const char *dir, int create);
+
#endif /* SWIFT_TOOL_H */
--
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