filesystem: implement os_modtime for unix

Change-Id: If030d526f29aa786b5a37402413d804752286cf5

firmware/target/hosted/filesystem-app.h

@@ -82,6 +82,7 @@ ssize_t app_write(int fildes, const void *buf, size_t nbyte);
 #endif /* HAVE_SDL_THREADS */
 int     app_remove(const char *path);
 int     app_rename(const char *old, const char *new);
+#define app_modtime     os_modtime
 #define app_filesize    os_filesize
 #define app_fsamefile   os_fsamefile
 int     app_relate(const char *path1, const char *path2);

firmware/target/hosted/filesystem-hosted.h

@@ -33,6 +33,7 @@ void * os_lc_open(const char *ospath);
 #define _FILESYSTEM_HOSTED__FILE_H_
 
 #ifndef OSFUNCTIONS_DECLARED
+int os_modtime(const char *path, time_t modtime);
 off_t os_filesize(int osfd);
 int os_fsamefile(int osfd1, int osfd2);
 int os_relate(const char *path1, const char *path2);

firmware/target/hosted/filesystem-unix.c

@@ -23,6 +23,7 @@
 #include <sys/stat.h>
 #include <string.h>
 #include <errno.h>
+#include <utime.h>
 #include "config.h"
 #include "system.h"
 #include "file.h"
@@ -35,6 +36,17 @@
 #define SAME_FILE_INFO(sb1p, sb2p) \
     ((sb1p)->st_dev == (sb2p)->st_dev && (sb1p)->st_ino == (sb2p)->st_ino)
 
+int os_modtime(const char *path, time_t modtime)
+{
+    struct utimbuf times =
+    {
+        .actime = modtime,
+        .modtime = modtime,
+    };
+
+    return utime(path, &times);
+}
+
 off_t os_filesize(int osfd)
 {
     struct stat sb;