Make a little more effort to avoid touching certain generated files if

they were not changed.  This makes 'make depend' more useful.

usr.sbin/config/config.h

@@ -192,6 +192,7 @@ char	*get_word();
 char	*get_quoted_word();
 char	*path();
 char	*raise();
+void	moveifchanged();
 
 int	do_trace;
 

usr.sbin/config/main.c

@@ -44,8 +44,11 @@ static char sccsid[] = "@(#)main.c	8.1 (Berkeley) 6/6/93";
 #include <sys/types.h>
 #include <sys/stat.h>
 #include <sys/file.h>
+#include <sys/mman.h>
 #include <stdio.h>
 #include <ctype.h>
+#include <err.h>
+#include <sysexits.h>
 #include "y.tab.h"
 #include "config.h"
 
@@ -328,3 +331,65 @@ path(file)
 	}
 	return (cp);
 }
+
+/*
+ * moveifchanged --
+ *	compare two files; rename if changed.
+ */
+void
+moveifchanged(const char *from_name, const char *to_name)
+{
+	char *p, *q;
+	int changed;
+	size_t tsize;
+	struct stat from_sb, to_sb;
+	int from_fd, to_fd;
+
+	changed = 0;
+
+	if ((from_fd = open(from_name, O_RDONLY)) < 0)
+		err(EX_OSERR, "moveifchanged open(%s)", from_name);
+
+	if ((to_fd = open(to_name, O_RDONLY)) < 0)
+		changed++;
+
+	if (!changed && fstat(from_fd, &from_sb) < 0)
+		err(EX_OSERR, "moveifchanged fstat(%s)", from_name);
+
+	if (!changed && fstat(to_fd, &to_sb) < 0)
+		err(EX_OSERR, "moveifchanged fstat(%s)", to_name);
+
+	if (!changed && from_sb.st_size != to_sb.st_size)
+		changed++;
+
+	tsize = (size_t)from_sb.st_size;
+
+	if (!changed) {
+		p = mmap(NULL, tsize, PROT_READ, 0, from_fd, (off_t)0);
+		if ((long)p == -1)
+			err(EX_OSERR, "mmap %s", from_name);
+		q = mmap(NULL, tsize, PROT_READ, 0, to_fd, (off_t)0);
+		if ((long)q == -1)
+			err(EX_OSERR, "mmap %s", to_name);
+
+		changed = memcmp(p, q, tsize);
+		munmap(p, tsize);
+		munmap(q, tsize);
+	}
+	if (changed) {
+		if (rename(from_name, to_name) < 0)
+			err(EX_OSERR, "rename(%s, %s)", from_name, to_name);
+	} else {
+		if (unlink(from_name) < 0)
+			err(EX_OSERR, "unlink(%s, %s)", from_name);
+	}
+
+#ifdef DIAG
+	if (changed)
+		printf("CHANGED! rename (%s, %s)\n", from_name, to_name);
+	else
+		printf("SAME! unlink (%s)\n", from_name);
+#endif
+
+	return;
+}

usr.sbin/config/mkglue.c

@@ -346,9 +346,9 @@ vector()
 	int dev_id;
 	FILE *fp;
 
-	fp = fopen(path("vector.h"), "w");
+	fp = fopen(path("vector.h.new"), "w");
 	if (fp == NULL) {
-		perror(path("vector.h"));
+		perror(path("vector.h.new"));
 		exit(1);
 	}
 	fprintf(fp, "/*\n");
@@ -367,6 +367,7 @@ vector()
 	fprintf(fp, "\"\n\n");
 	fprintf(fp, "#define\tNR_DEVICES\t%d\n", dev_id);
 	(void) fclose(fp);
+	moveifchanged(path("vector.h.new"), path("vector.h"));
 }
 
 vector_devtab(fp, table, dev_idp)

usr.sbin/config/mkioconf.c

@@ -608,9 +608,9 @@ i386_ioconf()
 	static char *old_d_name;
 	static char old_shandler[32 + 1];
 
-	fp = fopen(path("ioconf.c"), "w");
+	fp = fopen(path("ioconf.c.new"), "w");
 	if (fp == 0) {
-		perror(path("ioconf.c"));
+		perror(path("ioconf.c.new"));
 		exit(1);
 	}
 	fprintf(fp, "/*\n");
@@ -622,9 +622,9 @@ i386_ioconf()
 	fprintf(fp, "#include \"ioconf.h\"\n");
 	fprintf(fp, "\n");
 	fprintf(fp, "#define C (caddr_t)\n");
-	fp1 = fopen(path("ioconf.h"), "w");
+	fp1 = fopen(path("ioconf.h.new"), "w");
 	if (fp1 == 0) {
-		perror(path("ioconf.h"));
+		perror(path("ioconf.h.new"));
 		exit(1);
 	}
 	fprintf(fp1, "/*\n");
@@ -701,6 +701,8 @@ i386_ioconf()
 	fprintf(fp1, "\n");
 	fprintf(fp1, "#endif /* IOCONF_H */\n");
 	(void) fclose(fp1);
+	moveifchanged(path("ioconf.c.new"), path("ioconf.c"));
+	moveifchanged(path("ioconf.h.new"), path("ioconf.h"));
 }
 
 isa_biotab(fp, table)

usr.sbin/config/mkmakefile.c

@@ -150,9 +150,9 @@ makefile()
 		perror(line);
 		exit(1);
 	}
-	ofp = fopen(path("Makefile"), "w");
+	ofp = fopen(path("Makefile.new"), "w");
 	if (ofp == 0) {
-		perror(path("Makefile"));
+		perror(path("Makefile.new"));
 		exit(1);
 	}
 	fprintf(ofp, "KERN_IDENT=%s\n", raise(ident));
@@ -234,6 +234,7 @@ makefile()
 	}
 	(void) fclose(ifp);
 	(void) fclose(ofp);
+	moveifchanged(path("Makefile.new"), path("Makefile"));
 #ifdef notyet
 	if (warn_make_clean) {
 		printf("WARNING: Unknown options used (not in ../../conf/options or ./options.%s).\n", machinename);

usr.sbin/config/mkswapconf.c

@@ -66,6 +66,7 @@ do_swap(fl)
 	register struct file_list *fl;
 {
 	FILE *fp;
+	char  newswapname[80];
 	char  swapname[80];
 	register struct file_list *swap;
 	dev_t dev;
@@ -75,9 +76,10 @@ do_swap(fl)
 		return (fl->f_next);
 	}
 	(void) sprintf(swapname, "swap%s.c", fl->f_fn);
-	fp = fopen(path(swapname), "w");
+	(void) sprintf(newswapname, "swap%s.c.new", fl->f_fn);
+	fp = fopen(path(newswapname), "w");
 	if (fp == 0) {
-		perror(path(swapname));
+		perror(path(newswapname));
 		exit(1);
 	}
 	fprintf(fp, "#include <sys/param.h>\n");
@@ -90,7 +92,7 @@ do_swap(fl)
 	 */
 	swap = fl->f_next;
 	if (swap == 0 || swap->f_type != SWAPSPEC) {
-		(void) unlink(path(swapname));
+		(void) unlink(path(newswapname));
 		fclose(fp);
 		return (swap);
 	}
@@ -107,6 +109,7 @@ do_swap(fl)
 	fprintf(fp, "\n");
 	fprintf(fp, "void\nsetconf()\n{\n}\n");
 	fclose(fp);
+	moveifchanged(path(newswapname), path(swapname));
 	return (swap);
 }