Add some os utilities

_os.pxd

+from posix.types cimport (blkcnt_t,
+                          blksize_t,
+                          dev_t,
+                          gid_t,
+                          ino_t,
+                          mode_t,
+                          nlink_t,
+                          off_t,
+                          time_t,
+                          uid_t)
+
+
+# Differences with posix.stat:
+#
+# - the declaration for the non-standard field st_birthtime was removed
+#   because cypclass wrapping triggers the generation of a conversion
+#   function for the stat structure which references this field.
+#
+# - the absent declaration in posix.time of struct timespec was added.
+#
+# - the declarations for the time_t fields st_atime, st_mtime, st_ctime
+#   were replaced by the fields st_atim, st_mtim, st_ctim
+#   of type struct timespec.
+
+cdef extern from "<sys/time.h>" nogil:
+    cdef struct struct_timespec "timespec":
+        time_t tv_sec
+        long int tv_nsec
+
+
+cdef extern from "<sys/stat.h>" nogil:
+    cdef cppclass struct_stat "stat":
+        dev_t   st_dev
+        ino_t   st_ino
+        mode_t  st_mode
+        nlink_t st_nlink
+        uid_t   st_uid
+        gid_t   st_gid
+        dev_t   st_rdev
+        off_t   st_size
+        blksize_t st_blksize
+        blkcnt_t st_blocks
+        struct_timespec  st_atim
+        struct_timespec  st_mtim
+        struct_timespec  st_ctim
+
+
+# POSIX dictates including both <sys/stat.h> and <unistd.h> for these
+cdef extern from "<unistd.h>" nogil:
+    int fchmod(int, mode_t)
+    int chmod(const char *, mode_t)
+
+    int fstat(int, struct_stat *)
+    int lstat(const char *, struct_stat *)
+    int stat(const char *, struct_stat *)
+
+    # Macros for st_mode
+    mode_t S_ISREG(mode_t)
+    mode_t S_ISDIR(mode_t)
+    mode_t S_ISCHR(mode_t)
+    mode_t S_ISBLK(mode_t)
+    mode_t S_ISFIFO(mode_t)
+    mode_t S_ISLNK(mode_t)
+    mode_t S_ISSOCK(mode_t)
+
+    mode_t S_IFMT
+    mode_t S_IFREG
+    mode_t S_IFDIR
+    mode_t S_IFCHR
+    mode_t S_IFBLK
+    mode_t S_IFIFO
+    mode_t S_IFLNK
+    mode_t S_IFSOCK
+
+    # Permissions
+    mode_t S_ISUID
+    mode_t S_ISGID
+    mode_t S_ISVTX
+
+    mode_t S_IRWXU
+    mode_t S_IRUSR
+    mode_t S_IWUSR
+    mode_t S_IXUSR
+
+    mode_t S_IRWXG
+    mode_t S_IRGRP
+    mode_t S_IWGRP
+    mode_t S_IXGRP
+
+    mode_t S_IRWXO
+    mode_t S_IROTH
+    mode_t S_IWOTH
+    mode_t S_IXOTH
+
+
+cdef extern from "<sys/types.h>" nogil:
+    ctypedef struct DIR
+
+
+cdef extern from "<dirent.h>" nogil:
+    cdef struct struct_dirent "dirent":
+        ino_t           d_ino
+        char            d_name[256]
+
+    DIR *opendir(const char *name)
+    struct_dirent *readdir(DIR *dirp)
+    int readdir_r(DIR *dirp, struct_dirent *entry, struct_dirent **result)
+    int closedir(DIR *dirp)
+

os.pxd

+from stdlib.string cimport Str
+from stdlib.list cimport List
+
+from libc.errno cimport errno
+
+from libc.stdio cimport FILE, fopen, fclose, fread, fwrite, ferror
+from libc.stdio cimport stdin, stdout, stderr
+
+from posix cimport unistd
+
+from ._os cimport DIR, struct_dirent, opendir, readdir, closedir
+from ._os cimport struct_stat, lstat, S_ISREG, S_ISLNK, S_ISDIR
+
+
+cdef enum:
+    _BUFSIZE = 64 * 1024
+
+
+cdef inline FILE * open(Str path, char * mode) nogil:
+    return fopen(path.bytes(), mode)
+
+
+cdef inline Str read(FILE * file, int nbytes) nogil:
+    s = Str()
+    s._str.append(_BUFSIZE, 0)
+    cdef int size
+    size = fread(s._str.data(), 1, nbytes, file)
+    if size != nbytes:
+        if ferror(file):
+            return NULL
+    s._str.resize(size)
+    return s
+
+
+cdef inline int close(FILE * file) nogil:
+    return fclose(file)
+
+
+cdef inline int write(Str data, FILE * file) nogil:
+    return fwrite(data.bytes(), 1, data._str.size(), file)
+
+
+cdef inline List[Str] listdir(Str path) nogil:
+    d = opendir(path.bytes())
+    if d is NULL:
+        return NULL
+    entries = List[Str]()
+    while True:
+        errno = 0
+        entry = readdir(d)
+        if entry is NULL:
+            break
+        entries.append(Str(entry.d_name))
+    read_error = errno
+    closedir(d)
+    if read_error:
+        return NULL
+    return entries
+
+
+cdef inline Str readlink(Str path, int max_size) nogil:
+    s = Str()
+    s._str.resize(max_size)
+    size = unistd.readlink(path.bytes(), <char*> s._str.data(), max_size)
+    if size == -1:
+        return NULL
+    s._str.resize(size)
+    return s
+
+
+cdef cypclass Stat(struct_stat):
+    Stat __new__(alloc, Str path):
+        instance = alloc()
+        s = <struct_stat *> instance
+        if s is not NULL:
+            if not lstat(path.bytes(), s):
+                return instance
+
+    bint is_regular(self):
+        return S_ISREG(self.st_mode)
+
+    bint is_symlink(self):
+        return S_ISLNK(self.st_mode)
+
+    bint is_dir(self):
+        return S_ISDIR(self.st_mode)
+
+
+cdef inline Stat stat(Str path) nogil:
+    return Stat(path)
+