remove duplicated read_buffer functions

When you take a pointer to a function in C that function is going
to appear in full in the final binary. This means that there were
3 sections of the final binary with the exact same code.

You could argue that in very high performance programs having that
function closer to the current instruction when it is needed will
give a performance boost but there are so many other places to
gain more significant speed ups in vis before that would be
remotely relevant.

In fact, removing these allows the buffer_append call to inlined
so that buffer_insert can be hopped to directly instead of
including a useless hop in the middle.

buffer.c

@@ -182,3 +182,8 @@ char *buffer_move(Buffer *buf) {
 	buffer_init(buf);
 	return data;
 }
+
+ssize_t read_into_buffer(void *context, char *data, size_t len) {
+	buffer_append(context, data, len);
+	return len;
+}

buffer.h

@@ -80,4 +80,7 @@ const char *buffer_content(Buffer*);
  */
 char *buffer_move(Buffer*);
 
+/** ``read(3p)`` like interface for reading into a Buffer (``context``) */
+ssize_t read_into_buffer(void *context, char *data, size_t len);
+
 #endif

sam.c

@@ -1743,11 +1743,6 @@ static bool cmd_write(Vis *vis, Win *win, Command *cmd, const char *argv[], Sele
 	return true;
 }
 
-static ssize_t read_buffer(void *context, char *data, size_t len) {
-	buffer_append(context, data, len);
-	return len;
-}
-
 static bool cmd_filter(Vis *vis, Win *win, Command *cmd, const char *argv[], Selection *sel, Filerange *range) {
 	if (!win)
 		return false;
@@ -1756,7 +1751,8 @@ static bool cmd_filter(Vis *vis, Win *win, Command *cmd, const char *argv[], Sel
 	buffer_init(&bufout);
 	buffer_init(&buferr);
 
-	int status = vis_pipe(vis, win->file, range, &argv[1], &bufout, read_buffer, &buferr, read_buffer, false);
+	int status = vis_pipe(vis, win->file, range, &argv[1], &bufout, read_into_buffer, &buferr,
+	                      read_into_buffer, false);
 
 	if (vis->interrupted) {
 		vis_info_show(vis, "Command cancelled");
@@ -1796,7 +1792,8 @@ static bool cmd_pipeout(Vis *vis, Win *win, Command *cmd, const char *argv[], Se
 	Buffer buferr;
 	buffer_init(&buferr);
 
-	int status = vis_pipe(vis, win->file, range, (const char*[]){ argv[1], NULL }, NULL, NULL, &buferr, read_buffer, false);
+	int status = vis_pipe(vis, win->file, range, (const char*[]){ argv[1], NULL }, NULL, NULL,
+	                      &buferr, read_into_buffer, false);
 
 	if (vis->interrupted)
 		vis_info_show(vis, "Command cancelled");

vis-cmds.c

@@ -413,7 +413,7 @@ static const char *file_open_dialog(Vis *vis, const char *pattern) {
 	Filerange empty = text_range_new(0,0);
 	int status = vis_pipe(vis, vis->win->file, &empty,
 		(const char*[]){ buffer_content0(&bufcmd), NULL },
-		&bufout, read_buffer, &buferr, read_buffer, false);
+		&bufout, read_into_buffer, &buferr, read_into_buffer, false);
 
 	if (status == 0)
 		strncpy(name, buffer_content0(&bufout), sizeof(name)-1);

vis-registers.c

@@ -21,11 +21,6 @@ static Buffer *register_buffer(Register *reg, size_t slot) {
 	return array_get(&reg->values, slot);
 }
 
-static ssize_t read_buffer(void *context, char *data, size_t len) {
-	buffer_append(context, data, len);
-	return len;
-}
-
 bool register_init(Register *reg) {
 	Buffer buf;
 	buffer_init(&buf);
@@ -83,7 +78,7 @@ const char *register_slot_get(Vis *vis, Register *reg, size_t slot, size_t *len)
 			cmd[3] = "clipboard";
 		int status = vis_pipe(vis, vis->win->file,
 			&(Filerange){ .start = 0, .end = 0 },
-			cmd, buf, read_buffer, &buferr, read_buffer, false);
+			cmd, buf, read_into_buffer, &buferr, read_into_buffer, false);
 
 		if (status != 0)
 			vis_info_show(vis, "Command failed %s", buffer_content0(&buferr));
@@ -167,7 +162,7 @@ bool register_slot_put_range(Vis *vis, Register *reg, size_t slot, Text *txt, Fi
 			cmd[3] = "clipboard";
 
 		int status = vis_pipe(vis, vis->win->file, range,
-			cmd, NULL, NULL, &buferr, read_buffer, false);
+			cmd, NULL, NULL, &buferr, read_into_buffer, false);
 
 		if (status != 0)
 			vis_info_show(vis, "Command failed %s", buffer_content0(&buferr));

vis.c

@@ -1854,18 +1854,13 @@ int vis_pipe_buf(Vis *vis, const char* buf, const char *argv[],
 	return _vis_pipe(vis, NULL, NULL, buf, argv, stdout_context, read_stdout, stderr_context, read_stderr, fullscreen);
 }
 
-static ssize_t read_buffer(void *context, char *data, size_t len) {
-	buffer_append(context, data, len);
-	return len;
-}
-
 static int _vis_pipe_collect(Vis *vis, File *file, Filerange *range, const char* buf, const char *argv[], char **out, char **err, bool fullscreen) {
 	Buffer bufout, buferr;
 	buffer_init(&bufout);
 	buffer_init(&buferr);
 	int status = _vis_pipe(vis, file, range, buf, argv,
-	                      &bufout, out ? read_buffer : NULL,
-	                      &buferr, err ? read_buffer : NULL,
+	                      &bufout, out ? read_into_buffer : NULL,
+	                      &buferr, err ? read_into_buffer : NULL,
 	                      fullscreen);
 	buffer_terminate(&bufout);
 	buffer_terminate(&buferr);