iostreams: Add some documentation for the ast_iostream_* functions

Change-Id: Id71b87637f0a484eb5a1cd26c3d1c7c15c7dcf26

include/asterisk/iostream.h

@@ -44,7 +44,7 @@ struct ast_iostream;
 /*!
  * \brief Disable the iostream timeout timer.
  *
- * \param stream iostream control data.
+ * \param stream A pointer to an iostream
  *
  * \return Nothing
  */
@@ -53,7 +53,7 @@ void ast_iostream_set_timeout_disable(struct ast_iostream *stream);
 /*!
  * \brief Set the iostream inactivity timeout timer.
  *
- * \param stream iostream control data.
+ * \param stream A pointer to an iostream
  * \param timeout Number of milliseconds to wait for data transfer with the peer.
  *
  * \details This is basically how much time we are willing to spend
@@ -66,12 +66,30 @@ void ast_iostream_set_timeout_disable(struct ast_iostream *stream);
  */
 void ast_iostream_set_timeout_inactivity(struct ast_iostream *stream, int timeout);
 
+/*!
+ * \brief Set the iostream inactivity & idle timeout timers.
+ *
+ * \param stream A pointer to an iostream
+ * \param timeout Number of milliseconds to wait for initial data transfer with
+ *                the peer.
+ * \param timeout_reset Number of milliseconds to wait for subsequent data
+ *                      transfer with the peer.
+ *
+ * \details As an example, if you want to timeout a peer if they do not send an
+ *          initial message within 5 seconds or if they do not send a message at
+ *          least every 30 seconds, you would set \a timeout to \c 5000 and
+ *          \a timeout_reset to \c 30000.
+ *
+ * \note Setting either of these timeouts to -1 will disable them.
+ *
+ * \return Nothing
+ */
 void ast_iostream_set_timeout_idle_inactivity(struct ast_iostream *stream, int timeout, int timeout_reset);
 
 /*!
  * \brief Set the iostream I/O sequence timeout timer.
  *
- * \param stream iostream control data.
+ * \param stream A pointer to an iostream
  * \param start Time the I/O sequence timer starts.
  * \param timeout Number of milliseconds from the start time before timeout.
  *
@@ -89,7 +107,7 @@ void ast_iostream_set_timeout_sequence(struct ast_iostream *stream, struct timev
 /*!
  * \brief Set the iostream if it can exclusively depend upon the set timeouts.
  *
- * \param stream iostream control data.
+ * \param stream A pointer to an iostream
  * \param exclusive_input TRUE if stream can exclusively wait for fd input.
  * Otherwise, the stream will not wait for fd input.  It will wait while
  * trying to send data.
@@ -100,20 +118,146 @@ void ast_iostream_set_timeout_sequence(struct ast_iostream *stream, struct timev
  */
 void ast_iostream_set_exclusive_input(struct ast_iostream *stream, int exclusive_input);
 
+/*!
+ * \brief Get an iostream's file descriptor.
+ *
+ * \param stream A pointer to an iostream
+ *
+ * \return The file descriptor for the given iostream, or -1 if the iostream has no open
+ *         file descriptor.
+ */
 int ast_iostream_get_fd(struct ast_iostream *stream);
+
+/*!
+ * \brief Make an iostream non-blocking.
+ *
+ * \param stream A pointer to an iostream
+ *
+ * \return Nothing
+ */
 void ast_iostream_nonblock(struct ast_iostream *stream);
 
-SSL* ast_iostream_get_ssl(struct ast_iostream *stream);
+/*!
+ * \brief Get a pointer to an iostream's OpenSSL \c SSL structure
+ *
+ * \param stream A pointer to an iostream
+ *
+ * \return A pointer to the OpenSSL \c SSL structure for the given iostream, or
+ *         \c NULL if TLS has not been initiated.
+ *
+ * \note If OpenSSL support is not included in the build, this will always return
+ *       \c NULL.
+ */
+SSL *ast_iostream_get_ssl(struct ast_iostream *stream);
 
-ssize_t ast_iostream_read(struct ast_iostream *stream, void *buf, size_t count);
-ssize_t ast_iostream_gets(struct ast_iostream *stream, char *buf, size_t count);
+/*!
+ * \brief Read data from an iostream.
+ *
+ * \param stream A pointer to an iostream
+ * \param buffer Pointer to a buffer to store the read bytes.
+ * \param count The number of bytes to read.
+ *
+ * \return Upon successful completion, returns a non-negative integer indicating
+ *         the number of bytes actually read. Otherwise, returns -1 and may set
+ *         errno to indicate the error.
+ */
+ssize_t ast_iostream_read(struct ast_iostream *stream, void *buffer, size_t count);
+
+/*!
+ * \brief Read a LF-terminated string from an iostream.
+ *
+ * \param stream A pointer to an iostream
+ * \param buffer Pointer to a buffer to store the read bytes.
+ * \param size The total size of \a buffer in bytes.
+ *
+ * \return The number of bytes stored in \a buffer, excluding the null byte used
+ *         to terminate the string. If the size of \a buffer (indicated by the
+ *         caller with the \a size argument) is not sufficient to store the
+ *         entire line it will be truncated to fit the available space. The
+ *         contents of \a buffer will always be terminated with a null byte. In
+ *         the case of an error, \c -1 will be returned and \c errno may be set
+ *         indicating the error.
+ */
+ssize_t ast_iostream_gets(struct ast_iostream *stream, char *buffer, size_t size);
+
+/*!
+ * \brief Discard the specified number of bytes from an iostream.
+ *
+ * \param stream A pointer to an iostream
+ * \param count The number of bytes to discard.
+ *
+ * \return Upon successful completion, returns the number of bytes discarded.
+ *         Otherwise, \c -1 is returned and \c errno may be set indicating the
+ *         error.
+ */
 ssize_t ast_iostream_discard(struct ast_iostream *stream, size_t count);
-ssize_t ast_iostream_write(struct ast_iostream *stream, const void *buf, size_t count);
-ssize_t __attribute__((format(printf, 2, 3))) ast_iostream_printf(
-	struct ast_iostream *stream, const char *fmt, ...);
 
-struct ast_iostream* ast_iostream_from_fd(int *fd);
+/*!
+ * \brief Write data to an iostream.
+ *
+ * \param stream A pointer to an iostream
+ * \param buffer Pointer to a buffer from which to read bytes.
+ * \param count The number of bytes from \a buffer to write.
+ *
+ * \return Upon successful completion, returns the number of bytes actually
+ *         written to the iostream. This number shall never be greater than
+ *         \a count. Otherwise, returns \c -1 and may set \c errno to indicate
+ *         the error.
+ */
+ssize_t ast_iostream_write(struct ast_iostream *stream, const void *buffer, size_t count);
+
+/*!
+ * \brief Write a formatted string to an iostream.
+ *
+ * \param stream A pointer to an iostream
+ * \param format A format string, as documented by printf(3)
+ * \param ... Arguments for the provided \a format string
+ *
+ * \return The number of bytes written, or \c -1 if an error occurs. Note that if
+ *         \c -1 is returned, the number of bytes written to the iostream is
+ *         unspecified.
+ */
+ssize_t __attribute__((format(printf, 2, 3))) ast_iostream_printf(
+	struct ast_iostream *stream, const char *format, ...);
+
+/*!
+ * \brief Create an iostream from a file descriptor.
+ *
+ * \param fd A pointer to an open file descriptor
+ *
+ * \return A newly allocated iostream or \c NULL if allocation fails.
+ */
+struct ast_iostream *ast_iostream_from_fd(int *fd);
+
+/*!
+ * \brief Begin TLS on an iostream.
+ *
+ * \param stream A pointer to an iostream pointer
+ * \param ctx A pointer to an \c SSL_CTX which will be passed to \c SSL_new()
+ * \param client Non-zero to indicate that we are the client, zero to indicate
+ *               that we are the server.
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ *
+ * \note The iostream that is passed in \a stream may be replaced with a
+ *       different one before this function returns.
+ * \note On failure, \c errno may be set providing additional information on why
+ *       the failure occurred.
+ */
 int ast_iostream_start_tls(struct ast_iostream **stream, SSL_CTX *ctx, int client);
+
+/*!
+ * \brief Close an iostream.
+ *
+ * \param stream A pointer to an iostream
+ *
+ * \retval 0 success
+ * \retval -1 failure
+ *
+ * \note On failure, \c errno may be set providing additional information on why
+ *       the failure occurred.
+ */
 int ast_iostream_close(struct ast_iostream *stream);
 
 #endif /* _ASTERISK_IOSTREAM_H */