From 0d6093a74b5a2fd184d11d94c00f7d79be3da18e Mon Sep 17 00:00:00 2001
From: Lorenzo Cogotti <lcg@inventati.org>
Date: Tue, 3 Aug 2021 23:56:05 +0200
Subject: [PATCH] [tools/peerindex] Add support for -o option

---
 tools/peerindex/peerindex.1.in    | 13 +++++++++--
 tools/peerindex/peerindex.c       | 37 ++++++++++++++++++++++++++++++-
 tools/peerindex/peerindex_local.h |  4 ++++
 3 files changed, 51 insertions(+), 3 deletions(-)

diff --git a/tools/peerindex/peerindex.1.in b/tools/peerindex/peerindex.1.in
index 8638295..c01ba83 100644
--- a/tools/peerindex/peerindex.1.in
+++ b/tools/peerindex/peerindex.1.in
@@ -42,6 +42,14 @@ section below for usage examples.
 .SH OPTIONS
 The following options are supported:
 
+.IP "\fB\-o \fI<file>\fP" 10
+Write output to
+.BR file .
+Instead of using standard output,
+.IR @UTILITY@
+shall output PEER INDEX TABLE information to the specified file. If option
+occurs multiple times, last specified file is used.
+
 .IP "\fB\-r or \-\-only\-refs\fP" 10
 By default
 .IR @UTILITY@
@@ -67,7 +75,6 @@ may cause some peers inside PEER INDEX TABLES to be discarded (See the
 .IR OPTIONS
 section for details).
 
-
 Each peer is formatted as the following `|' separated fields:
 .RS 4
 .nf
@@ -136,7 +143,9 @@ supported compression formats. If the file extension is not recognized,
 or there is no extension, then it is assumed to be uncompressed.
 
 .SH STDOUT
-The standard output is used to print a human readable text representation of
+Unless redirected explicitly via
+.IR OPTIONS ,
+the standard output is used to print a human readable text representation of
 PEER INDEX TABLE contents, nothing else shall be written to the standard output.
 .IR @UTILITY@
 may detect and treat as error whenever the standard output is a regular file,
diff --git a/tools/peerindex/peerindex.c b/tools/peerindex/peerindex.c
index 9c1ffcd..eee55c0 100644
--- a/tools/peerindex/peerindex.c
+++ b/tools/peerindex/peerindex.c
@@ -32,6 +32,7 @@
 
 typedef enum {
 	ONLY_REFS_FLAG,
+	OUTPUT_FLAG,
 
 	NUM_FLAGS
 } PeerindexOpt;
@@ -40,6 +41,9 @@ static Optflag options[] = {
 	[ONLY_REFS_FLAG] = {
 		'r', "only-refs", NULL, "Only dump peers referenced by RIBs", ARG_NONE
 	},
+	[OUTPUT_FLAG] = {
+		'o', NULL, "file", "Write output to file", ARG_REQ
+	},
 
 	[NUM_FLAGS] = { '\0' }
 };
@@ -64,6 +68,21 @@ static void Peerindex_SetupCommandLine(char *argv0)
 		"Any diagnostic message is logged to stderr.";
 }
 
+static void Peerindex_Fatal(const char *fmt, ...)
+{
+	va_list va;
+
+	Sys_Print(STDERR, com_progName);
+	Sys_Print(STDERR, ": ERROR: ");
+
+	va_start(va, fmt);
+	Sys_VPrintf(STDERR, fmt, va);
+	va_end(va);
+
+	Sys_Print(STDERR, "\n");
+	exit(EXIT_FAILURE);
+}
+
 static void Peerindex_Warning(const char *fmt, ...)
 {
 	va_list va;
@@ -180,6 +199,20 @@ static void Peerindex_ApplyProgramOptions(void)
 		S.peerIndexClearVal = 0;
 	else
 		S.peerIndexClearVal = 0xff;  // so we always print the full table
+
+	if (options[OUTPUT_FLAG].flagged) {
+		const char *filename = options[OUTPUT_FLAG].optarg;
+
+		Fildes fd = Sys_Fopen(filename, FM_WRITE, /*hints=*/0);
+		if (fd == FILDES_BAD)
+			Peerindex_Fatal("Can't open output file \"%s\"", filename);
+
+		S.outf    = STM_FILDES(fd);
+		S.outfOps = Stm_FildesOps;
+	} else {
+		S.outf    = STM_CONHN(STDOUT);
+		S.outfOps = Stm_ConOps;
+	}
 }
 
 static void Peerindex_Init(void)
@@ -267,7 +300,7 @@ static void Peerindex_FlushPeerIndexTable(void)
 
 	Uint16 idx = 0;
 
-	Bufio_Init(&sb, STM_CONHN(STDOUT), Stm_ConOps);
+	Bufio_Init(&sb, S.outf, S.outfOps);
 
 	Bgp_StartMrtPeersv2(&it, &S.peerIndex);
 	while ((peer = Bgp_NextMrtPeerv2(&it)) != NULL) {
@@ -389,5 +422,7 @@ int main(int argc, char **argv)
 	while (i < argc)
 		Peerindex_ProcessMrtDump(argv[i++]);
 
+	if (S.outfOps->Close) S.outfOps->Close(S.outf);
+
 	return (S.nerrors > 0) ? EXIT_FAILURE : EXIT_SUCCESS;
 }
diff --git a/tools/peerindex/peerindex_local.h b/tools/peerindex/peerindex_local.h
index 216c0f6..5e698e3 100644
--- a/tools/peerindex/peerindex_local.h
+++ b/tools/peerindex/peerindex_local.h
@@ -31,6 +31,10 @@ FORCE_INLINE Boolean ISPEERINDEXREF(const PeerRefsTab tab, Uint16 idx)
 }
 
 typedef struct {
+	// Output stream
+	void         *outf;
+	const StmOps *outfOps;
+
 	// MRT input file stream
 	const char   *filename;
 	void         *inf;