print output on the same line if output is a terminal

Makefile

@@ -3,6 +3,7 @@
 PREFIX=/usr/local
 MANDIR=$(PREFIX)/share/man
 ALL_CFLAGS=$(CFLAGS) -std=c99 -Wall -Wextra -Wpedantic
+TERM=dumb # TERM=ansi for smart status printing (requires TIOCGWINSZ ioctl)
 OBJ=\
 	build.o\
 	deps.o\
@@ -13,6 +14,7 @@ OBJ=\
 	parse.o\
 	samu.o\
 	scan.o\
+	term-$(TERM).o \
 	tool.o\
 	tree.o\
 	util.o
@@ -26,6 +28,7 @@ HDR=\
 	log.h\
 	parse.h\
 	scan.h\
+	term.h\
 	tool.h\
 	tree.h\
 	util.h

build.c

@@ -16,6 +16,7 @@
 #include "env.h"
 #include "graph.h"
 #include "log.h"
+#include "term.h"
 #include "util.h"
 
 struct job {
@@ -33,6 +34,7 @@ static struct edge *work;
 static size_t nstarted, nfinished, ntotal;
 static bool consoleused;
 static struct timespec starttime;
+static bool dumb, newline;
 
 void
 buildreset(void)
@@ -255,13 +257,15 @@ static int
 jobstart(struct job *j, struct edge *e)
 {
 	extern char **environ;
-	size_t i;
+	size_t i, statuslen;
 	struct node *n;
 	struct string *rspfile, *content, *description;
 	int fd[2];
 	posix_spawn_file_actions_t actions;
 	char *argv[] = {"/bin/sh", "-c", NULL, NULL}, status[256];
 
+	newline = false;
+
 	++nstarted;
 	for (i = 0; i < e->nout; ++i) {
 		n = e->out[i];
@@ -290,9 +294,12 @@ jobstart(struct job *j, struct edge *e)
 		description = buildopts.verbose ? NULL : edgevar(e, "description", true);
 		if (!description || description->n == 0)
 			description = j->cmd;
-		formatstatus(status, sizeof(status));
+		if (!dumb)
+			putchar('\r');
+		statuslen = formatstatus(status, sizeof(status));
+		statuslen = statuslen < sizeof(status) ? statuslen : sizeof(status) - 1;
 		fputs(status, stdout);
-		puts(description->s);
+		printdesc(dumb, statuslen, description);
 	}
 
 	if ((errno = posix_spawn_file_actions_init(&actions))) {
@@ -445,8 +452,12 @@ jobdone(struct job *j)
 		j->failed = true;
 	}
 	close(j->fd);
-	if (j->buf.len && (!consoleused || j->failed))
+	if (j->buf.len && (!consoleused || j->failed)) {
+		if (!dumb)
+			putchar('\n');
 		fwrite(j->buf.data, 1, j->buf.len, stdout);
+		newline = j->buf.data[j->buf.len - 1] == '\n';
+	}
 	j->buf.len = 0;
 	e = j->edge;
 	if (e->pool) {
@@ -512,6 +523,8 @@ build(void)
 	size_t i, next = 0, jobslen = 0, numjobs = 0, numfail = 0;
 	struct edge *e;
 
+	dumb = buildopts.verbose || isdumb();
+
 	clock_gettime(CLOCK_MONOTONIC, &starttime);
 	formatstatus(NULL, 0);
 
@@ -568,6 +581,8 @@ build(void)
 				++numfail;
 		}
 	}
+	if (!dumb && jobslen && !newline)
+		putchar('\n');
 	for (i = 0; i < jobslen; ++i)
 		free(jobs[i].buf.data);
 	free(jobs);

build.ninja

@@ -17,9 +17,10 @@ build log.o: cc log.c
 build parse.o: cc parse.c
 build samu.o: cc samu.c
 build scan.o: cc scan.c
+build term-dumb.o: cc term-dumb.c
 build tool.o: cc tool.c
 build tree.o: cc tree.c
 build util.o: cc util.c
-build samu: link build.o deps.o env.o graph.o htab.o log.o parse.o samu.o scan.o tool.o tree.o util.o
+build samu: link build.o deps.o env.o graph.o htab.o log.o parse.o samu.o scan.o term-dumb.c tool.o tree.o util.o
 
 default samu

term-ansi.c

@@ -0,0 +1,44 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/ioctl.h>
+#include <unistd.h>
+#include "util.h"
+
+int
+isdumb(void)
+{
+	const char *term;
+
+	term = getenv("TERM");
+	return !isatty(1) || !term || !strcmp(term, "dumb");
+}
+
+void
+printdesc(bool dumb, size_t statuslen, struct string *description)
+{
+	struct winsize ws;
+
+	if (dumb) {
+		puts(description->s);
+		return;
+	}
+
+	ioctl(1, TIOCGWINSZ, &ws);
+	if (statuslen + description->n > ws.ws_col) {
+		switch (ws.ws_col) {
+			case 3: putchar('.');  /* fallthrough */
+			case 2: putchar('.');  /* fallthrough */
+			case 1: putchar('.');  /* fallthrough */
+			case 0: break;
+			default: printf("%.*s...%s",
+					(ws.ws_col - 3) / 2 - (int)statuslen, description->s,
+					description->s + description->n - (ws.ws_col - 3) / 2);
+		}
+	} else {
+		fputs(description->s, stdout);
+	}
+	printf("\033[K");
+	fflush(stdout);
+}

term-dumb.c

@@ -0,0 +1,19 @@
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include "util.h"
+
+int
+isdumb(void)
+{
+	return 1;
+}
+
+void
+printdesc(bool dumb, size_t statuslen, struct string *description)
+{
+	/* don't warn for unused parameters */
+	(void)dumb;
+	(void)statuslen;
+	puts(description->s);
+}

term.h

@@ -0,0 +1,9 @@
+#include <stdbool.h>
+
+struct string;
+
+/* determine if terminal is dumb or not */
+int isdumb(void);
+
+/* print description */
+void printdesc(bool dumb, size_t statuslen, struct string *description);