Add test-chmtime: a utility to change mtime on files

This is intended to be a portable replacement for our usage
of date(1), touch(1), and Perl one-liners in tests.

Usage: test-chtime (+|=|-|=+|=-)<seconds> <file>..."

  '+' increments the mtime on the files by <seconds>
  '-' decrements the mtime on the files by <seconds>
  '=' sets the mtime on the file to exactly <seconds>
  '=+' and '=-' sets the mtime on the file to <seconds> after or
      before the current time.

Signed-off-by: Eric Wong <normalperson@yhbt.net>
Signed-off-by: Junio C Hamano <junkio@cox.net>

.gitignore

@@ -139,6 +139,7 @@ git-whatchanged
 git-write-tree
 git-core-*/?*
 gitweb/gitweb.cgi
+test-chmtime
 test-date
 test-delta
 test-dump-cache-tree

Makefile

@@ -829,7 +829,7 @@ GIT-CFLAGS: .FORCE-GIT-CFLAGS
 
 export NO_SVN_TESTS
 
-test: all
+test: all test-chmtime$X
 	$(MAKE) -C t/ all
 
 test-date$X: test-date.c date.o ctype.o
@@ -844,6 +844,9 @@ test-dump-cache-tree$X: dump-cache-tree.o $(GITLIBS)
 test-sha1$X: test-sha1.o $(GITLIBS)
 	$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $(filter %.o,$^) $(LIBS)
 
+test-chmtime$X: test-chmtime.c
+	$(CC) $(ALL_CFLAGS) -o $@ $(ALL_LDFLAGS) $<
+
 check-sha1:: test-sha1$X
 	./test-sha1.sh
 

test-chmtime.c

@@ -0,0 +1,61 @@
+#include "git-compat-util.h"
+#include <utime.h>
+
+static const char usage_str[] = "(+|=|=+|=-|-)<seconds> <file>...";
+
+int main(int argc, const char *argv[])
+{
+	int i;
+	int set_eq;
+	long int set_time;
+	char *test;
+	const char *timespec;
+
+	if (argc < 3)
+		goto usage;
+
+	timespec = argv[1];
+	set_eq = (*timespec == '=') ? 1 : 0;
+	if (set_eq) {
+		timespec++;
+		if (*timespec == '+') {
+			set_eq = 2; /* relative "in the future" */
+			timespec++;
+		}
+	}
+	set_time = strtol(timespec, &test, 10);
+	if (*test) {
+		fprintf(stderr, "Not a base-10 integer: %s\n", argv[1] + 1);
+		goto usage;
+	}
+	if ((set_eq && set_time < 0) || set_eq == 2) {
+		time_t now = time(NULL);
+		set_time += now;
+	}
+
+	for (i = 2; i < argc; i++) {
+		struct stat sb;
+		struct utimbuf utb;
+
+		if (stat(argv[i], &sb) < 0) {
+			fprintf(stderr, "Failed to stat %s: %s\n",
+			        argv[i], strerror(errno));
+			return -1;
+		}
+
+		utb.actime = sb.st_atime;
+		utb.modtime = set_eq ? set_time : sb.st_mtime + set_time;
+
+		if (utime(argv[i], &utb) < 0) {
+			fprintf(stderr, "Failed to modify time on %s: %s\n",
+			        argv[i], strerror(errno));
+			return -1;
+		}
+	}
+
+	return 0;
+
+usage:
+	fprintf(stderr, "Usage: %s %s\n", argv[0], usage_str);
+	return -1;
+}