Wrap file metadata calls

Co-authored-by: Andrew Kesterson <andrew@aklabs.net>

include/akstdlib.h

@@ -76,6 +76,8 @@
 #include <stddef.h>
 #include <stdint.h>
 #include <stdio.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
 /* off_t, for the aksl_fseeko/aksl_ftello pair. POSIX, like aksl_realpath. */
 #include <sys/types.h>
 
@@ -808,6 +810,57 @@ akerr_ErrorContext AKERR_NOIGNORE *aksl_strhash_djb2_str(const char *str, uint32
 
 /** @} */
 
+/**
+ * @brief stat(2).
+ * @param[in] pathname Path to inspect. Required.
+ * @param[out] dest File metadata. Required.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_stat(const char *pathname, struct stat *dest);
+
+/**
+ * @brief lstat(2), inspecting a symbolic link itself.
+ * @param[in] pathname Path to inspect. Required.
+ * @param[out] dest File metadata. Required.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_lstat(const char *pathname, struct stat *dest);
+
+/**
+ * @brief fstat(2).
+ * @param[in] fd Open file descriptor.
+ * @param[out] dest File metadata. Required.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_fstat(int fd, struct stat *dest);
+
+/**
+ * @brief fstatat(2).
+ * @param[in] dirfd Directory descriptor, or AT_FDCWD.
+ * @param[in] pathname Path to inspect. Required.
+ * @param[out] dest File metadata. Required.
+ * @param[in] flags libc fstatat flags, passed unchanged.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_fstatat(int dirfd, const char *pathname, struct stat *dest, int flags);
+
+/**
+ * @brief statvfs(3).
+ * @param[in] path Path on the filesystem. Required.
+ * @param[out] dest Filesystem metadata. Required.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_statvfs(const char *path, struct statvfs *dest);
+
+/**
+ * @brief fstatvfs(3).
+ * @param[in] fd Open file descriptor.
+ * @param[out] dest Filesystem metadata. Required.
+ * @return NULL on success, an error context otherwise.
+ */
+akerr_ErrorContext AKERR_NOIGNORE *aksl_fstatvfs(int fd, struct statvfs *dest);
+
+
 /* ====================================================================== */
 /** @name Streams: open, read, write, close
  *