From 9c1f015c21211c5df5822f70d3d5be81bd54fee2 Mon Sep 17 00:00:00 2001
From: Michael Forney <mforney@mforney.org>
Date: Wed, 22 Jan 2020 11:50:03 -0800
Subject: [PATCH 4/4] tool: Implement compdb

This tool outputs a JSON compilation database[0], which is used for
integration with certain IDEs (for example, GNOME Builder).

Fixes #33.

[0] https://clang.llvm.org/docs/JSONCompilationDatabase.html
---
 samu.1 | 21 +++++++++++--
 tool.c | 99 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 117 insertions(+), 3 deletions(-)

diff --git a/samu.1 b/samu.1
index a4f3f70..0f10e93 100644
--- a/samu.1
+++ b/samu.1
@@ -1,4 +1,4 @@
-.Dd July 3, 2019
+.Dd January 22, 2019
 .Dt SAMU 1
 .Os
 .Sh NAME
@@ -20,6 +20,12 @@
 .Fl t Cm clean
 .Op Fl gr
 .Op Ar target...
+.Nm
+.Op Fl C Ar dir
+.Op Fl f Ar buildfile
+.Fl t Cm compdb
+.Op Fl x
+.Op Ar rule...
 .Sh DESCRIPTION
 .Nm
 loads a build manifest from
@@ -48,6 +54,12 @@ Targets built with
 rules are only removed if
 .Fl g
 is specified.
+.Pp
+If the
+.Cm compdb
+tool is used, a compilation database
+.Lk ( https://clang.llvm.org/docs/JSONCompilationDatabase.html )
+is printed instead.
 .Sh OPTIONS
 .Bl -tag -width Ds
 .It Fl C
@@ -106,9 +118,10 @@ only print a diagnostic message.
 .It Fl t
 Instead of building, invoke a subtool.
 All arguments and flags after the subtool are interpreted by the subtool.
-Currently,
+The currently supported subtools are
 .Cm clean
-is the only subtool.
+and
+.Cm compdb .
 .It Fl g
 When cleaning, also clean outputs of
 .Sy generator
@@ -117,6 +130,8 @@ actions.
 .Ar targets
 are interpreted as rules, and all outputs of actions with the specified rule
 types will be cleaned instead.
+.It Fl x
+When printing a compilation database, replace @$rspfile with $rspfile_content (with <blank> in place of <newline>).
 .El
 .Sh ENVIRONMENT
 .Bl -tag -width SAMUFLAGS
diff --git a/tool.c b/tool.c
index aae97c0..f77931e 100644
--- a/tool.c
+++ b/tool.c
@@ -1,7 +1,10 @@
+#define _POSIX_C_SOURCE 200809L
 #include <errno.h>
+#include <limits.h>
 #include <stdbool.h>
 #include <stdio.h>
 #include <string.h>
+#include <unistd.h>
 #include "arg.h"
 #include "env.h"
 #include "graph.h"
@@ -123,8 +126,104 @@ clean(int argc, char *argv[])
 	return ret;
 }
 
+static void
+printjson(const char *s, size_t n, bool join)
+{
+	size_t i;
+	char c;
+
+	for (i = 0; i < n; ++i) {
+		c = s[i];
+		switch (c) {
+		case '"':
+		case '\\':
+			putchar('\\');
+			break;
+		case '\n':
+			if (join)
+				c = ' ';
+			break;
+		case '\0':
+			return;
+		}
+		putchar(c);
+	}
+}
+
+static int
+compdb(int argc, char *argv[])
+{
+	char dir[PATH_MAX], *p;
+	struct edge *e;
+	struct string *cmd, *rspfile, *content;
+	bool expandrsp = false, first = true;
+	int i;
+	size_t off;
+
+	ARGBEGIN {
+	case 'x':
+		expandrsp = true;
+		break;
+	default:
+		fprintf(stderr, "usage: %s ... -t compdb [-x] rules...\n", argv0);
+		return 2;
+	} ARGEND
+
+	if (!getcwd(dir, sizeof(dir)))
+		fatal("getcwd:");
+
+	putchar('[');
+	for (e = alledges; e; e = e->allnext) {
+		if (e->nin == 0)
+			continue;
+		for (i = 0; i < argc; ++i) {
+			if (strcmp(e->rule->name, argv[i]) == 0) {
+				if (first)
+					first = false;
+				else
+					putchar(',');
+
+				printf("\n  {\n    \"directory\": \"");
+				printjson(dir, -1, false);
+
+				printf("\",\n    \"command\": \"");
+				cmd = edgevar(e, "command", true);
+				rspfile = expandrsp ? edgevar(e, "rspfile", true) : NULL;
+				p = rspfile ? strstr(cmd->s, rspfile->s) : NULL;
+				if (!p || p == cmd->s || p[-1] != '@') {
+					printjson(cmd->s, cmd->n, false);
+				} else {
+					off = p - cmd->s;
+					printjson(cmd->s, off - 1, false);
+					content = edgevar(e, "rspfile_content", true);
+					printjson(content->s, content->n, true);
+					off += rspfile->n;
+					printjson(cmd->s + off, cmd->n - off, false);
+				}
+
+				printf("\",\n    \"file\": \"");
+				printjson(e->in[0]->path->s, -1, false);
+
+				printf("\",\n    \"output\": \"");
+				printjson(e->out[0]->path->s, -1, false);
+
+				printf("\",\n  }");
+				break;
+			}
+		}
+	}
+	puts("\n]");
+
+	fflush(stdout);
+	if (ferror(stdout))
+		fatal("write failed");
+
+	return 0;
+}
+
 static const struct tool tools[] = {
 	{"clean", clean},
+	{"compdb", compdb},
 };
 
 const struct tool *
-- 
2.24.0