feat: real stat metadata across all filesystems, plus mkdir and rmdir

programs/lib/libc/libc.c

@@ -116,6 +116,7 @@ static inline long _zos_syscall4(long nr, long a1, long a2, long a3, long a4) {
 #define SYS_GETPID  3
 #define SYS_DUPHANDLE 98
 #define SYS_KILL    62
+#define SYS_STAT    152
 
 /* ========================================================================
    errno
@@ -136,6 +137,17 @@ struct _mtk_datetime {
     uint8_t second;
 };
 
+/* Mirrors montauk::abi::FileStat, the SYS_STAT output layout. Kept in step
+   with Api/Syscall.hpp by hand, like the syscall numbers above. */
+struct _mtk_filestat {
+    uint64_t size;
+    int64_t  mtime;
+    int64_t  ctime;
+    int64_t  atime;
+    uint32_t mode;   /* POSIX i_mode bits: type + permissions */
+    uint32_t isDir;
+};
+
 struct _DIR {
     int count;
     int index;
@@ -2311,6 +2323,19 @@ int mkdir(const char *path, unsigned int mode) {
     return (int)_zos_syscall1(SYS_FMKDIR, (long)path);
 }
 
+/* The VFS exposes no inode numbers, so derive a stable id from the path and
+   let distinct paths compare as distinct files. GCC's include-path setup
+   deduplicates directories by (st_dev, st_ino); leaving this 0 made every
+   directory "the same" and all but one include dir was silently dropped.
+   SYS_STAT supplies no inode either, so this stays in use regardless. */
+static ino_t _path_fake_ino(const char *path) {
+    unsigned long ino = 5381;
+    for (const char *p = path; *p; p++) {
+        ino = ino * 33 + (unsigned char)*p;
+    }
+    return (ino_t)(ino | 1);
+}
+
 int stat(const char *path, struct stat *buf) {
     if (path == NULL || buf == NULL) {
         errno = EINVAL;
@@ -2318,21 +2343,35 @@ int stat(const char *path, struct stat *buf) {
     }
 
     memset(buf, 0, sizeof(*buf));
+    buf->st_ino = _path_fake_ino(path);
+    buf->st_nlink = 1;
+    buf->st_blksize = 4096;
 
+    /* Preferred path: real metadata from the filesystem driver. */
+    struct _mtk_filestat st;
+    if (_zos_syscall2(SYS_STAT, (long)path, (long)&st) == 0) {
+        buf->st_mode = (mode_t)st.mode;
+        /* A driver that reports no type bits still tells us whether the
+           entry is a directory; without this S_ISREG/S_ISDIR both fail. */
+        if ((buf->st_mode & S_IFMT) == 0) {
+            buf->st_mode |= st.isDir ? S_IFDIR : S_IFREG;
+        }
+        buf->st_size = (off_t)st.size;
+        buf->st_atime = (time_t)st.atime;
+        buf->st_mtime = (time_t)st.mtime;
+        buf->st_ctime = (time_t)st.ctime;
+        buf->st_blocks = (blkcnt_t)((buf->st_size + 511) / 512);
+        return 0;
+    }
+
+    /* Fallback for a filesystem whose driver has no Stat entry point: probe
+       with open/readdir as before. Size is recoverable this way, timestamps
+       and permissions are not. */
     int h = (int)_zos_syscall1(SYS_OPEN, (long)path);
     if (h >= 0) {
         buf->st_mode = S_IFREG;
         buf->st_size = (off_t)_zos_syscall1(SYS_GETSIZE, (long)h);
         _zos_syscall1(SYS_CLOSE, (long)h);
-        /* No inodes in the VFS API: derive a stable id from the path
-           so that distinct paths compare as distinct files. */
-        unsigned long ino = 5381;
-        for (const char *p = path; *p; p++) {
-            ino = ino * 33 + (unsigned char)*p;
-        }
-        buf->st_ino = ino | 1;
-        buf->st_nlink = 1;
-        buf->st_blksize = 4096;
         buf->st_blocks = (blkcnt_t)((buf->st_size + 511) / 512);
         return 0;
     }
@@ -2340,16 +2379,6 @@ int stat(const char *path, struct stat *buf) {
     if (_path_is_directory(path)) {
         buf->st_mode = S_IFDIR;
         buf->st_size = 0;
-        /* Directories need distinct fake inodes too: GCC's include
-           path setup deduplicates directories by (st_dev, st_ino), so
-           leaving 0 here made every directory "the same" and all but
-           one include dir was silently dropped. */
-        unsigned long ino = 5381;
-        for (const char *p = path; *p; p++) {
-            ino = ino * 33 + (unsigned char)*p;
-        }
-        buf->st_ino = ino | 1;
-        buf->st_nlink = 1;
         return 0;
     }
 
@@ -2363,6 +2392,9 @@ int fstat(int fd, struct stat *buf) {
         return -1;
     }
     memset(buf, 0, sizeof(*buf));
+    /* SYS_STAT is path-based and handles do not map back to paths, so this
+       cannot report real timestamps or permissions the way stat() does.
+       Callers needing those must stat the path instead. */
     buf->st_mode = S_IFREG;
     buf->st_size = (off_t)_zos_syscall1(SYS_GETSIZE, (long)fd);
     /* Handles do not map back to paths, so fake a per-handle inode in a