lib: add cli preprocessor for | actions

This patch adds a CLI preprocessor function that activates when `|` is
found in the command. This is the start of adding support for some text
processing utilities intended for inline use. The first one implemented
here is `| include`, which provides grep-like filtering of command
output.

Signed-off-by: Quentin Young <qlyoung@cumulusnetworks.com>

lib/command.c

@@ -1174,6 +1174,55 @@ DECLARE_KOOH(cmd_execute_done, (struct vty * vty, const char *cmd_exec),
 DEFINE_KOOH(cmd_execute_done, (struct vty * vty, const char *cmd_exec),
 	    (vty, cmd_exec));
 
+/*
+ * cmd_execute hook subscriber to handle `|` actions.
+ */
+static int handle_pipe_action(struct vty *vty, const char *cmd_in,
+			      char **cmd_out)
+{
+	/* look for `|` */
+	char *orig, *working, *token;
+	char *pipe = strstr(cmd_in, "| ");
+
+	if (!pipe)
+		return 0;
+
+	/* duplicate string for processing purposes, not including pipe */
+	orig = working = XSTRDUP(MTYPE_TMP, pipe + 2);
+
+	/* retrieve action */
+	token = strsep(&working, " ");
+
+	/* match result to known actions */
+	if (strmatch(token, "include")) {
+		/* the remaining text should be a regexp */
+		char *regexp = working;
+		bool succ = vty_set_include(vty, regexp);
+		if (!succ) {
+			vty_out(vty, "%% Bad regexp '%s'", regexp);
+			goto fail;
+		}
+		cmd_out = XSTRDUP(MTYPE_TMP, cmd_in);
+		*(strstr(cmd_in, "|")) = '\0';
+	} else {
+		vty_out(vty, "%% Unknown action '%s'", token);
+		goto fail;
+	}
+
+fail:
+	XFREE(MTYPE_TMP, orig);
+	return 0;
+}
+
+static int handle_pipe_action_done(struct vty *vty, const char *cmd_exec)
+{
+	if (vty->filter) {
+		vty_set_include(vty, NULL);
+		vty_out(vty, "\n");
+	}
+	return 0;
+}
+
 int cmd_execute(struct vty *vty, const char *cmd,
 		const struct cmd_element **matched, int vtysh)
 {
@@ -2720,6 +2769,10 @@ void cmd_init(int terminal)
 	uname(&names);
 	qobj_init();
 
+	/* register command preprocessors */
+	hook_register(cmd_execute, handle_pipe_action);
+	hook_register(cmd_execute_done, handle_pipe_action_done);
+
 	varhandlers = list_new();
 
 	/* Allocate initial top vector of commands. */

lib/version.h.in

@@ -47,10 +47,10 @@
 #define FRR_CONFIG_ARGS "@CONFIG_ARGS@"
 
 #define FRR_DEFAULT_MOTD \
-	"\r\n" \
-	"Hello, this is " FRR_FULL_NAME " (version " FRR_VERSION ").\r\n" \
-	FRR_COPYRIGHT "\r\n" \
-	GIT_INFO "\r\n"
+	"\n" \
+	"Hello, this is " FRR_FULL_NAME " (version " FRR_VERSION ").\n" \
+	FRR_COPYRIGHT "\n" \
+	GIT_INFO "\n"
 
 pid_t pid_output (const char *);
 

lib/vty.c

@@ -21,10 +21,13 @@
 
 #include <zebra.h>
 
+#include <lib/version.h>
+#include <sys/types.h>
+#include <regex.h>
+
 #include "linklist.h"
 #include "thread.h"
 #include "buffer.h"
-#include <lib/version.h>
 #include "command.h"
 #include "sockunion.h"
 #include "memory.h"
@@ -35,6 +38,7 @@
 #include "privs.h"
 #include "network.h"
 #include "libfrr.h"
+#include "frrstr.h"
 
 #include <arpa/telnet.h>
 #include <termios.h>
@@ -109,6 +113,31 @@ void vty_endframe(struct vty *vty, const char *endtext)
 	vty->frame_pos = 0;
 }
 
+bool vty_set_include(struct vty *vty, const char *regexp)
+{
+	int errcode;
+	bool ret = true;
+	char errbuf[256];
+
+	if (!regexp) {
+		memset(&vty->include, 0x00, sizeof(vty->include));
+		vty->filter = false;
+		return true;
+	}
+
+	errcode = regcomp(&vty->include, regexp,
+			  REG_EXTENDED | REG_NEWLINE | REG_NOSUB);
+	if (errcode) {
+		ret = false;
+		regerror(ret, &vty->include, errbuf, sizeof(errbuf));
+		vty_out(vty, "%% Regex compilation error: %s", errbuf);
+	} else {
+		vty->filter = true;
+	}
+
+	return ret;
+}
+
 /* VTY standard output function. */
 int vty_out(struct vty *vty, const char *format, ...)
 {
@@ -117,6 +146,7 @@ int vty_out(struct vty *vty, const char *format, ...)
 	int size = 1024;
 	char buf[1024];
 	char *p = NULL;
+	char *filtered;
 
 	if (vty->frame_pos) {
 		vty->frame_pos = 0;
@@ -158,11 +188,28 @@ int vty_out(struct vty *vty, const char *format, ...)
 		if (!p)
 			p = buf;
 
+		/* filter buffer */
+		if (vty->filter) {
+			vector lines = frrstr_split_vec(buf, "\n");
+			frrstr_filter_vec(lines, &vty->include);
+			if (buf[strlen(buf) - 1] == '\n' && vector_active(lines) > 0)
+				vector_set(lines, XSTRDUP(MTYPE_TMP, ""));
+			filtered = frrstr_join_vec(lines, "\n");
+			frrstr_strvec_free(lines);
+		} else {
+			filtered = p;
+		}
+
 		/* Pointer p must point out buffer. */
 		if (vty->type != VTY_TERM)
-			buffer_put(vty->obuf, (uint8_t *)p, len);
+			buffer_put(vty->obuf, (uint8_t *)filtered,
+				   strlen(filtered));
 		else
-			buffer_put_crlf(vty->obuf, (uint8_t *)p, len);
+			buffer_put_crlf(vty->obuf, (uint8_t *)filtered,
+					strlen(filtered));
+
+		if (vty->filter)
+			XFREE(MTYPE_TMP, filtered);
 
 		/* If p is not different with buf, it is allocated buffer.  */
 		if (p != buf)
@@ -391,7 +438,6 @@ static void vty_auth(struct vty *vty, char *buf)
 static int vty_command(struct vty *vty, char *buf)
 {
 	int ret;
-	vector vline;
 	const char *protocolname;
 	char *cp = NULL;
 
@@ -427,11 +473,6 @@ static int vty_command(struct vty *vty, char *buf)
 		/* now log the command */
 		zlog_err("%s%s", prompt_str, buf);
 	}
-	/* Split readline string up into the vector */
-	vline = cmd_make_strvec(buf);
-
-	if (vline == NULL)
-		return CMD_SUCCESS;
 
 #ifdef CONSUMED_TIME_CHECK
 	{
@@ -442,7 +483,7 @@ static int vty_command(struct vty *vty, char *buf)
 		GETRUSAGE(&before);
 #endif /* CONSUMED_TIME_CHECK */
 
-		ret = cmd_execute_command(vline, vty, NULL, 0);
+		ret = cmd_execute(vty, buf, NULL, 0);
 
 		/* Get the name of the protocol if any */
 		protocolname = frr_protoname;
@@ -475,7 +516,6 @@ static int vty_command(struct vty *vty, char *buf)
 			vty_out(vty, "%% Command incomplete.\n");
 			break;
 		}
-	cmd_free_strvec(vline);
 
 	return ret;
 }

lib/vty.h

@@ -21,6 +21,9 @@
 #ifndef _ZEBRA_VTY_H
 #define _ZEBRA_VTY_H
 
+#include <sys/types.h>
+#include <regex.h>
+
 #include "thread.h"
 #include "log.h"
 #include "sockunion.h"
@@ -47,6 +50,10 @@ struct vty {
 	/* Failure count */
 	int fail;
 
+	/* Output filer regex */
+	bool filter;
+	regex_t include;
+
 	/* Output buffer. */
 	struct buffer *obuf;
 
@@ -223,6 +230,7 @@ extern struct vty *vty_stdio(void (*atclose)(int isexit));
 extern int vty_out(struct vty *, const char *, ...) PRINTF_ATTRIBUTE(2, 3);
 extern void vty_frame(struct vty *, const char *, ...) PRINTF_ATTRIBUTE(2, 3);
 extern void vty_endframe(struct vty *, const char *);
+bool vty_set_include(struct vty *vty, const char *regexp);
 
 extern void vty_read_config(const char *, char *);
 extern void vty_time_print(struct vty *, int);