create sync state parent directories recursively

this may matter with SyncState being for example ~/.local/state/isync/.

src/common.h

@@ -186,6 +186,8 @@ void ATTR_NORETURN oom( void );
 
 int map_name( const char *arg, char **result, uint reserve, const char *in, const char *out );
 
+int mkdir_p( char *path, int len );
+
 #define DEFINE_ARRAY_TYPE(T) \
 	typedef struct { \
 		T *data; \

src/drv_maildir.c

@@ -563,21 +563,6 @@ maildir_clear_tmp( char *buf, int bufsz, int bl )
 	return DRV_OK;
 }
 
-static int
-make_box_dir( char *buf, int bl )
-{
-	char *p;
-
-	if (!mkdir( buf, 0700 ) || errno == EEXIST)
-		return 0;
-	p = memrchr( buf, '/', (size_t)bl - 1 );
-	*p = 0;
-	if (make_box_dir( buf, (int)(p - buf) ))
-		return -1;
-	*p = '/';
-	return mkdir( buf, 0700 );
-}
-
 static int
 maildir_validate( const char *box, int create, maildir_store_t *ctx )
 {
@@ -593,7 +578,7 @@ maildir_validate( const char *box, int create, maildir_store_t *ctx )
 		}
 		if (!create)
 			return DRV_BOX_BAD;
-		if (make_box_dir( buf, bl )) {
+		if (mkdir_p( buf, bl - 1 )) {
 			sys_error( "Maildir error: cannot create mailbox '%s'", buf );
 			ctx->conf->failed = FAIL_FINAL;
 			maildir_invoke_bad_callback( ctx );

src/sync_state.c

@@ -58,7 +58,7 @@ prepare_state( sync_vars_t *svars )
 		// Note that this may be shorter than the configuration value,
 		// as that may contain a filename prefix.
 		*s = 0;
-		if (mkdir( svars->dname, 0700 ) && errno != EEXIST) {
+		if (mkdir_p( svars->dname, s - svars->dname )) {
 			sys_error( "Error: cannot create SyncState directory '%s'", svars->dname );
 			return 0;
 		}

src/util.c

@@ -8,6 +8,7 @@
 #include "common.h"
 
 #include <fcntl.h>
+#include <sys/stat.h>
 #include <errno.h>
 #include <ctype.h>
 #include <pwd.h>
@@ -539,6 +540,21 @@ map_name( const char *arg, char **result, uint reserve, const char *in, const ch
 	return 0;
 }
 
+int
+mkdir_p( char *path, int len )
+{
+	if (!mkdir( path, 0700 ) || errno == EEXIST)
+		return 0;
+	char *p = memrchr( path, '/', (size_t)len );
+	*p = 0;
+	if (mkdir_p( path, (int)(p - path) )) {
+		*p = '/';
+		return -1;
+	}
+	*p = '/';
+	return mkdir( path, 0700 );
+}
+
 static int
 compare_uints( const void *l, const void *r )
 {