Add -A flag to adjust existing time stamps.

Print name by which program was started in usage() message.

MFC after:  2 weeks

2 files changed, 130 insertions, 23 deletions

diff --git a/usr.bin/touch/touch.1 b/usr.bin/touch/touch.1
index 8c7ab8b..6231905 100644
--- a/usr.bin/touch/touch.1
+++ b/usr.bin/touch/touch.1
@@ -43,6 +43,7 @@
 .Nd change file access and modification times
 .Sh SYNOPSIS
 .Nm
+.Op Fl A Ar [-][[hh]mm]SS
 .Op Fl acfhm
 .Op Fl r Ar file
 .Op Fl t Ar [[CC]YY]MMDDhhmm[.SS]
@@ -50,17 +51,79 @@
 .Sh DESCRIPTION
 The
 .Nm
-utility sets the modification and access times of files to the
-current time of day.
-If the file does not exist, it is created with default permissions.
+utility sets the modification and access times of files.
+If any file does not exist, it is created with default permissions.
+.Pp
+By default,
+.Nm 
+changes both modification and access times.  The
+.Fl a
+and 
+.Fl m
+flags may be used to select the access time or the modification time
+individually.
+Selecting both is equivalent to the default.
+The base times for the modification are both set to the current time.
+The 
+.Fl t
+flag explicitly specifies a single time for both values, and the
+.Fl r
+flag specifies to set the times from those of a different file.
+The 
+.Fl A
+flag adjusts the values by a specified amount.
+This adjustment is done after first establishing the base times.
 .Pp
 The following options are available:
 .Bl -tag -width Ds
+.It Fl A 
+Adjust the access and modification time stamps for the file by the
+specified value.
+This flag is intended for use in modifying files with a time stamp
+relative to an incorrect time zone.
+It always modifies both the access time and the modification time.
+.Pp
+The argument is of the form
+.Dq [-][[hh]mm]SS
+where each pair of letters represents the following:
+.Pp
+.Bl -tag -width Ds -compact -offset indent
+.It Ar -
+Make the adjustment negative: the new time stamp is set to be before
+the old one.
+.It Ar hh
+The hour of the day, from 00 to 23.
+.It Ar mm
+The minute of the hour, from 00 to 59.
+.It Ar SS
+The second of the minute, from 00 to 59.
+.El
+.Pp
+When used in conjunction with the
+.Fl a
+flag only, the modification time is adjusted by the time specified as
+argument to the
+.Fl A
+flag, while the access time is modified from the base time described
+above.
+Similarly, when used in conjunction with the
+.Fl m
+flag only, the access time is adjusted by the time specified as
+argument to the
+.Fl A
+flag, while the access time is modified from the base time described
+above.
+.Pp
+If the file does not exist, and creation is allowed,
+.Fl A
+does not change its time stamps.
 .It Fl a
 Change the access time of the file.
-The modification time of the file is not changed unless the
+The modification time of the file is not changed unless one of the
+.Fl A
+or
 .Fl m
-flag is also specified.
+flags is also specified.
 .It Fl c
 Do not create the file if it does not exist.
 The
@@ -80,15 +143,17 @@ implies
 and thus will not create any new files.
 .It Fl m
 Change the modification time of the file.
-The access time of the file is not changed unless the
+The access time of the file is not changed unless one of the
+.Fl A
+or
 .Fl a
-flag is also specified.
+flags is also specified.
 .It Fl r
 Use the access and modifications times from the specified file
 instead of the current time of day.
 .It Fl t
 Change the access and modification times to the specified time.
-The argument should be in the form
+The argument is of the form
 .Dq [[CC]YY]MMDDhhmm[.SS]
 where each pair of letters represents the following:
 .Pp
@@ -110,15 +175,15 @@ Otherwise, a
 .Dq CC
 value of 20 is used.
 .It Ar MM
-The month of the year, from 1 to 12.
+The month of the year, from 01 to 12.
 .It Ar DD
-the day of the month, from 1 to 31.
+the day of the month, from 01 to 31.
 .It Ar hh
-The hour of the day, from 0 to 23.
+The hour of the day, from 00 to 23.
 .It Ar mm
-The minute of the hour, from 0 to 59.
+The minute of the hour, from 00 to 59.
 .It Ar SS
-The second of the minute, from 0 to 61.
+The second of the minute, from 00 to 61.
 .El
 .Pp
 If the
diff --git a/usr.bin/touch/touch.c b/usr.bin/touch/touch.c
index 8853eca..ef2c6af 100644
--- a/usr.bin/touch/touch.c
+++ b/usr.bin/touch/touch.c
@@ -62,7 +62,8 @@ int	rw(char *, struct stat *, int);
 void	stime_arg1(char *, struct timeval *);
 void	stime_arg2(char *, int, struct timeval *);
 void	stime_file(char *, struct timeval *);
-void	usage(void);
+int	timeoffset(char *);
+void	usage(char *);
 
 int
 main(int argc, char *argv[])
@@ -71,17 +72,22 @@ main(int argc, char *argv[])
 	struct timeval tv[2];
 	int (*stat_f)(const char *, struct stat *);
 	int (*utimes_f)(const char *, const struct timeval *);
-	int aflag, cflag, fflag, mflag, ch, fd, len, rval, timeset;
+	int Aflag, aflag, cflag, fflag, mflag, ch, fd, len, rval, timeset;
 	char *p;
+	char *myname;
 
-	aflag = cflag = fflag = mflag = timeset = 0;
+	myname = argv[0];
+	Aflag = aflag = cflag = fflag = mflag = timeset = 0;
 	stat_f = stat;
 	utimes_f = utimes;
 	if (gettimeofday(&tv[0], NULL))
 		err(1, "gettimeofday");
 
-	while ((ch = getopt(argc, argv, "acfhmr:t:")) != -1)
+	while ((ch = getopt(argc, argv, "A:acfhmr:t:")) != -1)
 		switch(ch) {
+		case 'A':
+			Aflag = timeoffset(optarg);
+			break;
 		case 'a':
 			aflag = 1;
 			break;
@@ -109,13 +115,13 @@ main(int argc, char *argv[])
 			break;
 		case '?':
 		default:
-			usage();
+			usage(myname);
 		}
 	argc -= optind;
 	argv += optind;
 
-	/* Default is both -a and -m. */
-	if (aflag == 0 && mflag == 0)
+	/* -a and -m are default unless one of them or -A is set. */
+	if (aflag == 0 && mflag == 0 && Aflag == 0)
 		aflag = mflag = 1;
 
 	/*
@@ -136,7 +142,7 @@ main(int argc, char *argv[])
 		tv[1] = tv[0];
 
 	if (*argv == NULL)
-		usage();
+		usage(myname);
 
 	for (rval = 0; *argv; ++argv) {
 		/* See if the file exists. */
@@ -158,10 +164,15 @@ main(int argc, char *argv[])
 				continue;
 		}
 
+		/* If -a or -m are not set, base time on current file time. */
 		if (!aflag)
 			TIMESPEC_TO_TIMEVAL(&tv[0], &sb.st_atimespec);
 		if (!mflag)
 			TIMESPEC_TO_TIMEVAL(&tv[1], &sb.st_mtimespec);
+		if (Aflag) {
+			tv[0].tv_sec += Aflag;
+			tv[1].tv_sec += Aflag;
+		}
 
 		/* Try utimes(2). */
 		if (!utimes_f(*argv, tv))
@@ -286,6 +297,36 @@ stime_arg2(char *arg, int year, struct timeval *tvp)
 	tvp[0].tv_usec = tvp[1].tv_usec = 0;
 }
 
+/* Calculate a time offset in seconds, given an arg of the format [-]HHMMSS. */
+int
+timeoffset(char *arg)
+{
+	int offset;
+	int isneg;
+
+	offset = 0;
+	isneg = *arg == '-';
+	if (isneg)
+		arg++;
+	switch (strlen(arg)) {
+	default:				/* invalid */
+		errx(1, "Invalid offset spec, must be [-][[HH]MM]SS");
+
+	case 6:					/* HHMMSS */
+		offset = ATOI2(arg);
+		/* FALLTHROUGH */
+	case 4:					/* MMSS */
+		offset = offset * 60 + ATOI2(arg);
+		/* FALLTHROUGH */
+	case 2:					/* SS */
+		offset = offset * 60 + ATOI2(arg);
+	}
+	if (isneg)
+		return (-offset);
+	else
+		return (offset);
+}
+
 void
 stime_file(char *fname, struct timeval *tvp)
 {
@@ -347,8 +388,9 @@ err:			rval = 1;
 }
 
 void
-usage(void)
+usage(char *myname)
 {
-	(void)fprintf(stderr, "usage: touch [-acfhm] [-r file] [-t [[CC]YY]MMDDhhmm[.SS]] file ...\n");
+	fprintf(stderr, "usage:\n" "%s [-A [-][[hh]mm]SS] [-acfhm] [-r file] "
+		"[-t [[CC]YY]MMDDhhmm[.SS]] file ...\n", myname);
 	exit(1);
 }