Add an option "-J" / "--pipe-buffer-size" to set the size of the output pipe buffer when the output is a pipe, and when that option is not specified, automatically increase the output pipe buffer size to match that of the input, when the first input is also a pipe (#188).

src/include/options.h

@@ -72,6 +72,7 @@ struct opts_s {
 	size_t lastwritten;            /* show N bytes last written */
 	off_t rate_limit;              /* rate limit, in bytes per second */
 	size_t buffer_size;            /* buffer size, in bytes (0=default) */
+	size_t pipe_buffer_size;       /* pipe buffer size, in bytes (0=default) */
 	off_t size;                    /* total size of data */
 	off_t error_skip_block;        /* skip block size, 0 for adaptive */
 	pid_t remote;                  /* PID of pv to update settings of */

src/include/pv-internal.h

@@ -201,7 +201,8 @@ struct pvstate_s {
 		/*@null@*/ char *default_bar_style; /* which bar style to use by default */
 		off_t error_skip_block;          /* skip block size, 0 for adaptive */
 		off_t rate_limit;                /* rate limit, in bytes per second */
-		size_t target_buffer_size;       /* buffer size (0=default) */
+		size_t target_buffer_size;       /* transfer buffer size (0=default) */
+		size_t pipe_buffer_size;         /* pipe buffer size (0=default) */
 		off_t size;                      /* total size of data */
 		unsigned int skip_errors;        /* skip read errors counter */
 		int output_fd;                   /* fd to write output to */

src/include/pv.h

@@ -260,6 +260,7 @@ extern void pv_state_sparse_output_set(pvstate_t, bool);
 extern void pv_state_rate_limit_set(pvstate_t, off_t);
 extern void pv_state_target_buffer_size_set(pvstate_t, size_t);
 extern void pv_state_no_splice_set(pvstate_t, bool);
+extern void pv_state_pipe_buffer_size_set(pvstate_t, size_t);
 extern void pv_state_discard_input_set(pvstate_t, bool);
 extern void pv_state_size_set(pvstate_t, off_t);
 extern void pv_state_interval_set(pvstate_t, double);