X-Git-Url: http://www.chiark.greenend.org.uk/ucgi/~mdw/git/disorder/blobdiff_plain/11680e1989c6c867f207be7197602776e05cae6a..16b0fea8ae1a581d568dbee2efa2932aa4e6fcce:/lib/hreader.h

diff --git a/lib/hreader.h b/lib/hreader.h
index 1eadc55..90431c1 100644
--- a/lib/hreader.h
+++ b/lib/hreader.h
@@ -28,19 +28,26 @@
  * Allows files to be read without holding them open.
  */
 struct hreader {
-  const char *path;		/* file to read */
-  off_t offset;			/* how far we've read so far */
+  char *path;                   /* file to read */
+  off_t size;                   /* file size */
+  off_t read_offset;            /* for next hreader_read() */
+  off_t buf_offset;             /* offset of start of buffer */
   char *buffer;			/* input buffer */
   size_t bufsize;		/* buffer size */
   size_t bytes;			/* size of last read */
-  size_t consumed;		/* bytes consumed by caller from last read */
 };
 
 /** @brief Initialize a hands-off reader
  * @param path File to read
  * @param h Reader to initialize
+ * @return 0 on success, -1 on error
  */
-void hreader_init(const char *path, struct hreader *h);
+int hreader_init(const char *path, struct hreader *h);
+
+/** @brief Close a hands-off reader
+ * @param h Reader to close
+ */
+void hreader_close(struct hreader *h);
 
 /** @brief Read some bytes
  * @param h Reader to read from
@@ -50,20 +57,42 @@ void hreader_init(const char *path, struct hreader *h);
  */
 int hreader_read(struct hreader *h, void *buffer, size_t n);
 
-/** @brief Read more bytes
- * @param h Reader to update
- * @return Bytes available to read
- *
- * If not all bytes were consumed so far then just returns the number
- * of bytes left to consume.
+/** @brief Read some bytes at a given offset
+ * @param h Reader to read from
+ * @param offset Offset to read at
+ * @param buffer Where to store bytes
+ * @param n Maximum bytes to read
+ * @return Bytes read, or 0 at EOF, or -1 on error
+ */
+int hreader_pread(struct hreader *h, void *buffer, size_t n, off_t offset);
+
+/** @brief Seek within a file
+ * @param h Reader to seek
+ * @param offset Offset
+ * @param whence SEEK_*
+ * @return Result offset
  */
-int hreader_fill(struct hreader *h);
+off_t hreader_seek(struct hreader *h, off_t offset, int whence);
 
-/** @brief Consume some bytes
- * @param h Reader to update
- * @param n Bytes to consume
+/** @brief Return file size
+ * @param h Reader to find size of
+ * @return Size in bytes
+ */
+static inline off_t hreader_size(const struct hreader *h) {
+  return h->size;
+}
+
+/** @brief Test for end of file
+ * @param h Reader to test
+ * @return 1 at eof, 0 otherwise
+ *
+ * This tells you whether the next read will return 0 bytes, rather than
+ * whether the last read reached end of file.  So it is slightly different to
+ * feof().
  */
-void hreader_consume(struct hreader *h, size_t n);
+static inline int hreader_eof(const struct hreader *h) {
+  return h->read_offset == h->size;
+}
 
 #endif /* HREADER_H */