feat: fix file rename implementation

programs/include/libc/montauk.h

@@ -89,6 +89,7 @@ extern "C" {
 #define MTK_SYS_WINSETCURSOR    68
 #define MTK_SYS_FDELETE         77
 #define MTK_SYS_FMKDIR          78
+#define MTK_SYS_FRENAME         94
 #define MTK_SYS_DRIVELIST       79
 #define MTK_SYS_AUDIOOPEN       80
 #define MTK_SYS_AUDIOCLOSE      81
@@ -377,6 +378,10 @@ static inline int mtk_mkdir(const char *path) {
     return (int)_mtk_syscall1(MTK_SYS_FMKDIR, (long)path);
 }
 
+static inline int mtk_rename(const char *oldpath, const char *newpath) {
+    return (int)_mtk_syscall2(MTK_SYS_FRENAME, (long)oldpath, (long)newpath);
+}
+
 static inline int mtk_readdir(const char *path, const char **names, int max) {
     return (int)_mtk_syscall3(MTK_SYS_READDIR, (long)path, (long)names, (long)max);
 }

programs/lib/libc/libc.c

@@ -95,6 +95,7 @@ static inline long _zos_syscall4(long nr, long a1, long a2, long a3, long a4) {
 #define SYS_FCREATE 42
 #define SYS_FDELETE 77
 #define SYS_FMKDIR  78
+#define SYS_FRENAME 94
 
 /* ========================================================================
    errno
@@ -1217,40 +1218,8 @@ int remove(const char *path) {
 }
 
 int rename(const char *oldpath, const char *newpath) {
-    /* No atomic rename syscall -- copy + delete */
     if (oldpath == NULL || newpath == NULL) return -1;
-
-    int src = (int)_zos_syscall1(SYS_OPEN, (long)oldpath);
-    if (src < 0) return -1;
-
-    unsigned long sz = (unsigned long)_zos_syscall1(SYS_GETSIZE, (long)src);
-
-    /* Create destination */
-    _zos_syscall1(SYS_FDELETE, (long)newpath);
-    int dst = (int)_zos_syscall1(SYS_FCREATE, (long)newpath);
-    if (dst < 0) {
-        _zos_syscall1(SYS_CLOSE, (long)src);
-        return -1;
-    }
-
-    /* Copy in chunks */
-    char copybuf[4096];
-    unsigned long off = 0;
-    while (off < sz) {
-        unsigned long chunk = sz - off;
-        if (chunk > sizeof(copybuf)) chunk = sizeof(copybuf);
-        int r = (int)_zos_syscall4(SYS_READ, (long)src,
-                                    (long)copybuf, (long)off, (long)chunk);
-        if (r <= 0) break;
-        _zos_syscall4(SYS_FWRITE, (long)dst,
-                       (long)copybuf, (long)off, (long)r);
-        off += (unsigned long)r;
-    }
-
-    _zos_syscall1(SYS_CLOSE, (long)src);
-    _zos_syscall1(SYS_CLOSE, (long)dst);
-    _zos_syscall1(SYS_FDELETE, (long)oldpath);
-    return 0;
+    return (int)_zos_syscall2(SYS_FRENAME, (long)oldpath, (long)newpath);
 }
 
 void perror(const char *s) {