From dcb7758a74fb5ff4f8b6eecb6589223a408f3f9b Mon Sep 17 00:00:00 2001
From: John Ankarstrom <john@ankarstrom.se>
Date: Tue, 6 Jul 2021 21:15:06 +0200
Subject: Rewrite in C

---
 build.c | 125 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 125 insertions(+)
 create mode 100644 build.c

(limited to 'build.c')

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);
+	}
+}
-- 
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