Add --verbose|-v to test-chmtime

This allows us replace perl when getting the mtime of a file because
of time zone conversions, though at the moment only one platform which
does this has been identified: Cygwin when used with ActiveState Perl
(as usual).

The output format is:

    <mtime1> TAB <filename1> <LF>
    <mtime2> TAB <filename2> <LF>
    ...

which, if only mtime is needed can be parsed with cut(1):

    test-chmtime -v +0 filename1 | cut -f 1

Also, the change adds a description of programs features, with examples.

Signed-off-by: Alex Riesen <ariesen@harmanbecker.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

1 files changed, 70 insertions, 21 deletions

diff --git a/test-chmtime.c b/test-chmtime.c
index 90da448ebe..d5358cbaac 100644
--- a/test-chmtime.c
+++ b/test-chmtime.c
@@ -1,39 +1,83 @@
+/*
+ * This program can either change modification time of the given
+ * file(s) or just print it. The program does not change atime nor
+ * ctime (their values are explicitely preserved).
+ *
+ * The mtime can be changed to an absolute value:
+ *
+ *	test-chmtime =<seconds> file...
+ *
+ * Relative to the current time as returned by time(3):
+ *
+ *	test-chmtime =+<seconds> (or =-<seconds>) file...
+ *
+ * Or relative to the current mtime of the file:
+ *
+ *	test-chmtime <seconds> file...
+ *	test-chmtime +<seconds> (or -<seconds>) file...
+ *
+ * Examples:
+ *
+ * To just print the mtime use --verbose and set the file mtime offset to 0:
+ *
+ *	test-chmtime -v +0 file
+ *
+ * To set the mtime to current time:
+ *
+ *	test-chmtime =+0 file
+ *
+ */
 #include "git-compat-util.h"
 #include <utime.h>
 
-static const char usage_str[] = "(+|=|=+|=-|-)<seconds> <file>...";
+static const char usage_str[] = "-v|--verbose (+|=|=+|=-|-)<seconds> <file>...";
 
-int main(int argc, const char *argv[])
+static int timespec_arg(const char *arg, long int *set_time, int *set_eq)
 {
-	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) {
+	const char *timespec = arg;
+	*set_eq = (*timespec == '=') ? 1 : 0;
+	if (*set_eq) {
 		timespec++;
 		if (*timespec == '+') {
-			set_eq = 2; /* relative "in the future" */
+			*set_eq = 2; /* relative "in the future" */
 			timespec++;
 		}
 	}
-	set_time = strtol(timespec, &test, 10);
+	*set_time = strtol(timespec, &test, 10);
 	if (*test) {
-		fprintf(stderr, "Not a base-10 integer: %s\n", argv[1] + 1);
-		goto usage;
+		fprintf(stderr, "Not a base-10 integer: %s\n", arg + 1);
+		return 0;
 	}
-	if ((set_eq && set_time < 0) || set_eq == 2) {
+	if ((*set_eq && *set_time < 0) || *set_eq == 2) {
 		time_t now = time(NULL);
-		set_time += now;
+		*set_time += now;
 	}
+	return 1;
+}
+
+int main(int argc, const char *argv[])
+{
+	static int verbose;
 
-	for (i = 2; i < argc; i++) {
+	int i = 1;
+	/* no mtime change by default */
+	int set_eq = 0;
+	long int set_time = 0;
+
+	if (argc < 3)
+		goto usage;
+
+	if (strcmp(argv[i], "--verbose") == 0 || strcmp(argv[i], "-v") == 0) {
+		verbose = 1;
+		++i;
+	}
+	if (timespec_arg(argv[i], &set_time, &set_eq))
+		++i;
+	else
+		goto usage;
+
+	for (; i < argc; i++) {
 		struct stat sb;
 		struct utimbuf utb;
 
@@ -46,7 +90,12 @@ int main(int argc, const char *argv[])
 		utb.actime = sb.st_atime;
 		utb.modtime = set_eq ? set_time : sb.st_mtime + set_time;
 
-		if (utime(argv[i], &utb) < 0) {
+		if (verbose) {
+			uintmax_t mtime = utb.modtime < 0 ? 0: utb.modtime;
+			printf("%"PRIuMAX"\t%s\n", mtime, argv[i]);
+		}
+
+		if (utb.modtime != sb.st_mtime && utime(argv[i], &utb) < 0) {
 			fprintf(stderr, "Failed to modify time on %s: %s\n",
 			        argv[i], strerror(errno));
 			return -1;