X-Git-Url: https://git.distorted.org.uk/~mdw/dvdrip/blobdiff_plain/42c936a1884d40b6679ba9f7f80bf308c5fb1f7f..refs/heads/mdw/cleanup:/lib.h

diff --git a/lib.h b/lib.h
index 2b127e3..7c4a0cb 100644
--- a/lib.h
+++ b/lib.h
@@ -143,6 +143,42 @@ extern PRINTF_LIKE(2, 3) NORETURN
 	 * exit with status code 2.
 	 */
 
+/*----- Resizing buffers --------------------------------------------------*/
+
+struct buf {
+  /* A buffer for a string which can grow automatically. */
+
+  char *p;				/* pointer to the buffer */
+  size_t n, sz;				/* string length, buffer size */
+};
+#define BUF_INIT { 0, 0, 0 }
+
+static inline void buf_rewind(struct buf *b) { b->n = 0; }
+	/* Throw away the current contents of B so that new stuff gets added
+	 * to the beginning.
+	 */
+
+static inline void buf_free(struct buf *b)
+  { free(b->p); b->p = 0; b->n = b->sz = 0; }
+	/* Release the memory allocated for B.  The buffer can be reused
+	 * immediately and/or freed again safely.
+	 */
+
+extern void buf__grow(struct buf *b);
+	/* Make B's buffer larger, so that (at least) one extra byte can be
+	 * written to it.  (Internal to `buf_putc'.)
+	 */
+
+static inline void buf_putc(struct buf *b, int ch)
+  { if (b->n >= b->sz) buf__grow(b); b->p[b->n++] = ch; }
+	/* Append the character CH to the buffer B. */
+
+static inline void buf_putz(struct buf *b)
+  { if (b->n >= b->sz) buf__grow(b); b->p[b->n] = 0; }
+	/* Append a zero byte to B without increasing the string length, so
+	 * that a future `buf_putc' will overwrite it.
+	 */
+
 /*----- Resizing vectors --------------------------------------------------*/
 
 #define DEFVEC(vtype, etype)						\
@@ -204,6 +240,13 @@ extern void sit(double t);
 	 * fractional.
 	 */
 
+extern int read_line(FILE *fp, struct buf *b);
+	/* Read a line from FP, appending it to the buffer B, leaving the
+	 * string in B null-terminated (as if by `buf_putz').  Return 0 on
+	 * success, or -1 if nothing was read (not even an empty line) before
+	 * we encountered end-of-file or a read error.
+	 */
+
 extern void carefully_write(int fd, const void *buf, size_t sz);
 	/* Write SZ bytes to file descriptor FD, starting at BUF.  Report a
 	 * fatal error if this fails.  Correctly handles short writes and
@@ -258,19 +301,19 @@ extern void hide_banner(void);
 
 /*----- DVD utilities -----------------------------------------------------*/
 
-extern void open_dvd(const char *device, int mode,
-		     int *fd_out, dvd_reader_t **dvd_out);
+extern int open_dvd(const char *device, int mode,
+		    int *fd_out, dvd_reader_t **dvd_out);
 	/* Open the DEVICE.  If FD_OUT is not null, then open a file
 	 * descriptor onto the device, with the given open(2)-style MODE,
 	 * storing the descriptor in *FD_OUT; if DVD_OUT is not null, then
 	 * open a `libdvdread' handle onto the devie and store it in
 	 * *DVD_OUT.  If both are null, then why are you calling this
-	 * function?
+	 * function?  Returns 0 on success or -1 on failure.
 	 *
 	 * If DEVICE refers to an actual block device, and no medium is
 	 * currently inserted, then put up a banner prompting the user and
-	 * wait for a medium to be inserted.  Other problems are reported as
-	 * fatal errors.
+	 * wait for a medium to be inserted.  Other problems are reported to
+	 * stderr.
 	 */
 
 enum { RAW, IFO, VOB, BUP };