From 3019c48804fb43f97d5c8e8ee15b5ae13ab1c4a9 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Fri, 9 Jul 2021 15:32:09 +0200
Subject: Use set -e, -x in shell process, handle exit status correctly

This makes the default behavior like make(1), but it is configurable.
Furthermore, it is still a single shell process, which is arguably
a benefit.
---
 build.1 | 16 ++++------------
 build.c | 34 +++++++++++++++++++++-------------
 2 files changed, 25 insertions(+), 25 deletions(-)

diff --git a/build.1 b/build.1
index cf66324..10ae999 100644
--- a/build.1
+++ b/build.1
@@ -77,17 +77,9 @@ This means that you can keep state across multiple commands.
 Note that all commands are executed
 regardless of the exit status of previous commands.
 .Pp
+If a command fails,
 .Nm
-exits with a positive status if a command failed.
-Note that it checks the status
-of the entire command sent to the shell,
-not the individual command lines.
-To emulate the behavior of
-.Xr make 1 ,
-which fails if any individual command line fails,
-you can use
-.Ql set -e
-in your command line.
+exits with a positive status and aborts the build process.
 .
 .Sh EXAMPLES
 .Pp
@@ -120,8 +112,8 @@ Assuming that the file
 starts with the following text,
 .Bd -literal -offset indent
 \&.\\" This document is built with the following shell commands:
-\&.\\"    $ refer -p refs doc.t | troff -ms | dpost > doc.ps &&
-\&.\\"    $ ps2pdf doc.ps > doc.pdf &&
+\&.\\"    $ refer -p refs doc.t | troff -ms | dpost > doc.ps
+\&.\\"    $ ps2pdf doc.ps > doc.pdf
 \&.\\"    $ rm doc.ps
 \&.
 \&.\\" Apart from this file, it depends on the following files:
diff --git a/build.c b/build.c
index fc21925..600ac92 100644
--- a/build.c
+++ b/build.c
@@ -4,6 +4,7 @@
 #include <stdio.h>
 #include <string.h>
 #include <sys/stat.h>
+#include <sys/wait.h>
 #include <unistd.h>
 
 #define USAGE "usage: %s file [...]\n", name
@@ -32,7 +33,7 @@ main(int argc, char *argv[])
 {
 	char *b, buf[MAXBUF], *cmd[MAXCMDS], *d, *dep, *name, *tgt;
 	FILE *fp;
-	int c, dflag, fflag, i, icmd, j, s, status;
+	int c, dflag, fflag, i, icmd, j, s;
 	struct stat sb, ssb;
 
 	/* allocate memory */
@@ -43,10 +44,9 @@ main(int argc, char *argv[])
 	dep = malloc(MAXDEP*sizeof(char));
 	if (!dep) err(1, "malloc");
 	tgt = malloc(MAXTGT*sizeof(char));
-	if (!dep) err(1, "malloc");
+	if (!tgt) err(1, "malloc");
 
 	tgt[0] = dep[0] = 0;
-	status = 0;
 
 	/* process arguments */
 	name = argv[0];
@@ -85,13 +85,13 @@ main(int argc, char *argv[])
 				/* command line */
 				if (strncmp(b, "	$ ", 3) == 0
 				 || strncmp(b, " $ ", 3) == 0) {
-					strncpy(cmd[icmd++],b+3,MAXBUF-1);
+					strncpy(cmd[icmd++], b+3, MAXBUF-1);
 
 					/* find target */
 					for (b = b+3; *b; b++) {
 						if (!(*b+1)) continue;
 						if (*b != '>') continue;
-						strncpy(tgt,b+1,MAXTGT-1);
+						strncpy(tgt, b+1, MAXTGT-1);
 
 					}
 
@@ -113,7 +113,7 @@ main(int argc, char *argv[])
 
 		if (!icmd) {
 			fprintf(stderr, "%s: no command line found\n", argv[i]);
-			continue;
+			goto next;
 		}
 
 		if (fflag || !*tgt)
@@ -153,25 +153,33 @@ main(int argc, char *argv[])
 
 uptodate:
 		fprintf(stderr, "%s: already up-to-date\n", argv[i]);
-		goto done;
+		goto next;
 
 build:
 		/* run commands */
 		buf[0] = 0;
+		strcat(buf, "set -ex\n");
 		for (j = 0; j < icmd; j++) {
-			fprintf(stderr, "%s: $ %s\n", argv[i], cmd[j]);
 			strncat(buf, cmd[j], MAXBUF-1);
 			strncat(buf, "\n", MAXBUF-1);
 		}
 		s = system(buf);
-		if (s != -1)
-			status += s;
+		if (s == 0)
+			goto next;
+
+		if (WIFEXITED(s)) {
+			fprintf(stderr, "%s: exited with %d\n",
+				argv[i], WEXITSTATUS(s));
+			exit(WEXITSTATUS(s));
+		} else if (WIFSIGNALED(s)) {
+			fprintf(stderr, "%s: terminated by signal %d\n",
+				argv[i], WTERMSIG(s));
+			exit(1);
+		}
 
-done:
+next:
 		fclose(fp);
 	}
-
-	return status > 0;
 }
 
 void
-- 
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