Rewrite in C

3 files changed, 126 insertions, 103 deletions

diff --git a/Makefile b/Makefile
new file mode 100644
index 0000000..5b08578
--- /dev/null
+++ b/Makefile
@@ -0,0 +1 @@
+build: build.c
diff --git a/build b/build
deleted file mode 100755
index b6d3653..0000000
--- a/build
+++ /dev/null
@@ -1,103 +0,0 @@
-#!/usr/bin/perl
-
-# build -- process and act on embedded build instructions
-
-use strict;
-use warnings;
-
-# parse arguments
-
-my ($debug, $fork) = (0, 0);
-my $usage = "usage: $0 [-dddf] file [...]\n";
-
-while (@ARGV and ($_ = $ARGV[0]) =~ /^-/) {
-	shift @ARGV;
-	last if $_ eq '--';
-	$debug++ for /(d)/g;
-	$fork++ if /f/;
-	die $usage if /[^-df]/;
-}
-
-die $usage if not @ARGV;
-
-# find build line(s) in each file
-
-my $i;
-for my $file (@ARGV) {
-	my ($cmd, $target, @deps);
-	open my $f, '<', $file or die "could not open $file: $!\n";
-	$i = 1;
-	while (<$f>) {
-		if (not $cmd and m{
-			^ .*
-			(?: (?:build|generate) \s+ (?:it \s+)? with
-			  | (?:built|generated) \s+ with
-			  | the \s+ command
-			  | run(?:ning)?
-			  | issu(?:e|ing)
-			) \s+
-			(.+?) \s* (?: > \s* (.+?))? \.? \s*
-			(?:\*/)? \s* $
-		}x) {
-			warn "$file build line: $_" if $debug > 2;
-			$cmd = $1;
-			$target = $2;
-		}
-		elsif (not @deps and m{
-			^ .*
-			(?: depends \s+ on
-			  | dependent \s+ on
-			) \s+
-			(?: the \s+ files? \s+ )?
-			(.+?) \.? \s*
-			(?:\*/)? \s* $
-		}x) {
-			warn "$file dependency line: $_" if $debug > 2;
-			push @deps, $_ for split /,?\s+/, $1;
-			if ($deps[-2] eq 'and') {
-				$deps[-2] = $deps[-1];
-				pop @deps;
-			}
-		}
-		last if ++$i > 20;
-	}
-	warn "$file dependencies: @deps\n" if $debug > 1;
-	build($file, $cmd, $target, @deps) if $cmd;
-	warn "$file: no build line found\n" if not $cmd;
-}
-
-# build target according to build line
-
-sub build {
-	my ($source, $cmd, $target, @deps) = @_;
-	my $m = (stat$target)[9];
-
-	if (! -e $target) {
-		warn "$source: building because $target does not exist\n"
-			if $debug;
-		goto update;
-	}
-
-	for ($source, @deps) {
-		if (! -e $_) {
-			warn "$source: non-existent dependency '$_'\n";
-			next;
-		}
-		if ($m < (stat$_)[9]) {
-			warn "$source: building because $_ is modified\n"
-				if $debug;
-			goto update;
-		}
-	}
-	warn "$source: $target already up-to-date\n";
-	return;
-
-update:
-	warn "$source: $cmd > $target\n";
-	if ($fork) {
-		exec('/bin/sh', '-c', "$cmd > $target") if fork() == 0;
-	} else {
-		system("$cmd > $target");
-	}
-	return;
-}
diff --git a/build.c b/build.c
new file mode 100644
index 0000000..e69164c
--- /dev/null
+++ b/build.c
@@ -0,0 +1,125 @@
+#include <ctype.h>
+#include <err.h>
+#include <stdlib.h>
+#include <stdio.h>
+#include <string.h>
+#include <sys/stat.h>
+
+#define USAGE "usage: %s file [...]\n", argv[0]
+
+int
+main(int argc, char *argv[])
+{
+	char *b, *bb, *bbb, buf[1024], *cmd[32], dep[1024], *t, *tt, tgt[64];
+	FILE *fp;
+	int i, icmd, j, max;
+	struct stat sb, ssb;
+
+	tgt[0] = dep[0] = 0;
+
+	/* process arguments */
+	if (argc-1 == 0) {
+		fprintf(stderr, USAGE);
+		return 1;
+	}
+
+	/* allocate memory */
+	for (i = 0; i < 32; i++) {
+		cmd[i] = malloc(1024*sizeof(char));
+		if (!cmd[i]) err(1, "malloc");
+	}
+
+	/* process each file */
+	for (i = 1, icmd = 0; i < argc; i++, icmd = 0) {
+		fp = fopen(argv[i], "r");
+		if (!fp) err(1, "fopen");
+
+		/* read line by line */
+		while (fgets(buf, sizeof(buf), fp)) {
+			buf[strcspn(buf, "\n")] = 0;
+
+			/* parse line */
+			b = buf;
+			for (b++; *b; b++) {
+				if (!(*(b+1) && *(b+2) && *(b+3))) continue;
+				if (!(*b == ' ' || *b == '	')) continue;
+
+				/* command line */
+				if (*(b+1) == '$' && *(b+2) == ' ') {
+					strncpy(cmd[icmd++],b+3,sizeof(buf)-1);
+
+					/* find target */
+					for (b = b+3; *b; b++) {
+						if (!(*b+1)) continue;
+						if (*b != '>') continue;
+						strncpy(tgt,b+1,sizeof(tgt)-1);
+
+					}
+					continue;
+				}
+
+				/* depend line */
+				if (*(b+1) == '%' && *(b+2) == ' ') {
+					strncpy(dep, b+3, sizeof(dep)-1);
+					continue;
+				}
+			}
+		}
+
+		if (!icmd) {
+			fprintf(stderr, "%s: no command line found\n", argv[i]);
+			continue;
+		}
+
+		if (!*tgt)
+			goto build;
+
+		/* compare source > target */
+		for (t = tgt; *t; t++)
+			if (!isspace(*t)) break;
+		for (tt = tgt; *tt; tt++)
+			if (isspace(*tt)) { *tt = 0; break; }
+		if (stat(t, &ssb))
+			err(1, t);
+		if (stat(argv[i], &sb))
+			err(1, argv[i]);
+		if (sb.st_mtime > ssb.st_mtime)
+			goto build;
+
+		/* compare dependencies > target */
+		if (*dep) {
+			for (t = dep; *t; t++)
+				if (!isspace(*t)) break;
+			for (j = 0; t[j]; j++) {
+				if (isspace(t[j]) || t[j+1] == 0) {
+					tt = strdup(t);
+					tt[j+(t[j+1]==0)] = 0;
+
+					if (stat(tt, &sb))
+						err(1, tt);
+					free(tt);
+					if (sb.st_mtime > ssb.st_mtime)
+						goto build;
+
+					for (; t[j]; j++)
+						if (!isspace(t[j])) break;
+					t += j;
+					j = 0;
+				}
+			}
+		}
+
+		fprintf(stderr, "%s: already up-to-date\n", argv[i]);
+		goto done;
+
+build:
+		/* run commands */
+		for (j = 0; j < icmd; j++) {
+			fprintf(stderr, "%s: %s\n", argv[i], cmd[j]);
+			system(cmd[j]);
+		}
+
+done:
+		fclose(fp);
+	}
+}