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-rw-r--r--src/ini.cpp31
1 files changed, 30 insertions, 1 deletions
diff --git a/src/ini.cpp b/src/ini.cpp
index 87897b9a4..fda62950f 100644
--- a/src/ini.cpp
+++ b/src/ini.cpp
@@ -10,6 +10,12 @@
#include "string_func.h"
#include "fileio_func.h"
+#if (defined(_POSIX_C_SOURCE) && _POSIX_C_SOURCE >= 199309L) || (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE >= 500)
+# define WITH_FDATASYNC
+# include <unistd.h>
+#endif
+
+
IniItem::IniItem(IniGroup *parent, const char *name, size_t len) : next(NULL), value(NULL), comment(NULL)
{
if (len == 0) len = strlen(name);
@@ -253,7 +259,16 @@ void IniFile::LoadFromDisk(const char *filename)
bool IniFile::SaveToDisk(const char *filename)
{
- FILE *f = fopen(filename, "w");
+ /*
+ * First write the configuration to a (temporary) file and then rename
+ * that file. This to prevent that when OpenTTD crashes during the save
+ * you end up with a truncated configuration file.
+ */
+ char file_new[MAX_PATH];
+
+ strecpy(file_new, filename, lastof(file_new));
+ strecat(file_new, ".new", lastof(file_new));
+ FILE *f = fopen(file_new, "w");
if (f == NULL) return false;
for (const IniGroup *group = this->group; group != NULL; group = group->next) {
@@ -275,6 +290,20 @@ bool IniFile::SaveToDisk(const char *filename)
}
if (this->comment) fputs(this->comment, f);
+/*
+ * POSIX (and friends) do not guarantee that when a file is closed it is
+ * flushed to the disk. So we manually flush it do disk if we have the
+ * APIs to do so. We only need to flush the data as the metadata itself
+ * (modification date etc.) is not important to us; only the real data is.
+ */
+#ifdef WITH_FDATASYNC
+ int ret = fdatasync(fileno(f));
+ fclose(f);
+ if (ret != 0) return false;
+#else
fclose(f);
+#endif
+
+ rename(file_new, filename);
return true;
}