From 7aaf4f2423e2bcabce508e91255de673db50b728 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?John=20Ankarstr=C3=B6m?= <john@ankarstrom.se>
Date: Mon, 7 Jun 2021 16:36:05 +0200
Subject: Add [-w write-file] option

ksh will write lines to write-file containing information about
the status of the shell:

 after prompt:          empty line
 after command entry:   "cmd" followed by command
 after cwd change:      "cwd" followed by new cwd

fg is handled specially, printing a new "cmd" line with the original
command associated with the job.
---
 jobs.c  |  7 +++++++
 ksh.Man |  7 ++++++-
 main.c  | 12 ++++++++++++
 misc.c  | 12 ++++++++++--
 path.c  |  2 ++
 sh.h    |  1 +
 6 files changed, 38 insertions(+), 3 deletions(-)

diff --git a/jobs.c b/jobs.c
index c8cc781..65c364f 100644
--- a/jobs.c
+++ b/jobs.c
@@ -840,6 +840,8 @@ j_resume(cp, bg)
 		shprintf("[%d] ", j->job);
 
 	running = 0;
+	if (writefd)
+		dprintf(writefd, "cmd");
 	for (p = j->proc_list; p != (Proc *) 0; p = p->next) {
 		if (p->state == PSTOPPED) {
 			p->state = PRUNNING;
@@ -847,9 +849,14 @@ j_resume(cp, bg)
 			running = 1;
 		}
 		shprintf("%s%s", p->command, p->next ? "| " : null);
+		if (writefd)
+			dprintf(writefd, "%s%s",
+				p->command, p->next ? "| " : null);
 	}
 	shprintf("%s", newline);
 	shf_flush(shl_stdout);
+	if (writefd)
+		dprintf(writefd, "\n");
 	if (running)
 		j->state = PRUNNING;
 
diff --git a/ksh.Man b/ksh.Man
index 69ea1f0..80ad538 100644
--- a/ksh.Man
+++ b/ksh.Man
@@ -43,7 +43,7 @@ sh \- Public domain Bourne shell
 .sh(
 \fBsh\fP
 .sh)
-[\fB\(+-abCefhiklmnprsuvxX\fP] [\fB\(+-o\fP \fIoption\fP] [ [ \fB\-c\fP \fIcommand-string\fP [\fIcommand-name\fP] | \fB\-s\fP | \fIfile\fP ] [\fIargument\fP ...] ]
+[\fB\(+-abCefhiklmnprsuvxX\fP] [\fB\(+-o\fP \fIoption\fP] [\fB-w\fP \fIwrite-file\fP]] [ [ \fB\-c\fP \fIcommand-string\fP [\fIcommand-name\fP] | \fB\-s\fP | \fIfile\fP ] [\fIargument\fP ...] ]
 .ad b
 .\"}}}
 .\"{{{  Description
@@ -72,6 +72,11 @@ the shell reads commands from standard input; all non-option arguments
 are positional parameters
 .IP \fB\-r\fP
 restricted mode \(em see below
+.IP "\fB\-w\fP \fIwrite-file\fP"
+the shell writes to \fIwrite-file\fR an empty line after each
+prompt, a line beginning with \fIcwd\fR after each directory change
+and a line beginning with \fIcmd\fR after each interactive command
+entry.
 .PP
 In addition to the above, the options described in the \fBset\fP built-in
 command can also be used on the command line.
diff --git a/main.c b/main.c
index 41d4d80..dad50d3 100644
--- a/main.c
+++ b/main.c
@@ -278,6 +278,9 @@ main(int argc, char *argv[])
 	/* Set this before parsing arguments */
 	Flag(FPRIVILEGED) = getuid() != ksheuid || getgid() != getegid();
 
+	/* set before parse_args */
+	writefd = 0;
+
 	/* this to note if monitor is set on command line (see below) */
 	Flag(FMONITOR) = 127;
 	argi = parse_args(argv, OF_CMDLINE, (int *) 0);
@@ -286,6 +289,10 @@ main(int argc, char *argv[])
 		/* NOTREACHED */
 	}
 
+	/* print initial cwd */
+	if (writefd)
+		dprintf(writefd, "cwd%s\n", current_wd);
+
 	if (Flag(FCOMMAND)) {
 		s = pushs(SSTRING, ATEMP);
 		if (!(s->start = s->str = argv[argi++]))
@@ -578,7 +585,12 @@ shell(s, toplevel)
 			set_prompt(PS1, s);
 		}
 
+		if (interactive && writefd)
+			dprintf(writefd, "\n");
 		t = compile(s);
+		if (interactive && writefd && s->start[0] != '\n')
+			dprintf(writefd, "cmd%s", s->start);
+
 		if (t != NULL && t->type == TEOF) {
 			if (wastty && Flag(FIGNOREEOF) && --attempts > 0) {
 				shellf("Use `exit' to leave ksh\n");
diff --git a/misc.c b/misc.c
index 393da1c..80ce13b 100644
--- a/misc.c
+++ b/misc.c
@@ -347,7 +347,7 @@ parse_args(argv, what, setargsp)
 	int	what;		/* OF_CMDLINE or OF_SET */
 	int	*setargsp;
 {
-	static char cmd_opts[NELEM(goptions) + 3]; /* o:\0 */
+	static char cmd_opts[NELEM(goptions) + 5]; /* o:w:\0 */
 	static char set_opts[NELEM(goptions) + 5]; /* Ao;s\0 */
 	char *opts;
 	char *array = (char *) 0;
@@ -359,7 +359,7 @@ parse_args(argv, what, setargsp)
 		char *p, *q;
 
 		/* see cmd_opts[] declaration */
-		strlcpy(cmd_opts, "o:", sizeof cmd_opts);
+		strlcpy(cmd_opts, "o:w:", sizeof cmd_opts);
 		p = cmd_opts + strlen(cmd_opts);
 		/* see set_opts[] declaration */
 		strlcpy(set_opts, "A:o;s", sizeof set_opts);
@@ -423,6 +423,14 @@ parse_args(argv, what, setargsp)
 			}
 			break;
 
+		  case 'w':
+			writefd = open(go.optarg, O_WRONLY);
+			if (writefd == -1) {
+				bi_errorf("could not open %s", go.optarg);
+				return -1;
+			}
+			break;
+
 		  case '?':
 			return -1;
 
diff --git a/path.c b/path.c
index bb18075..70d8a71 100644
--- a/path.c
+++ b/path.c
@@ -198,6 +198,8 @@ set_current_wd(pathx)
 	if (len > current_wd_size)
 		current_wd = aresize(current_wd, current_wd_size = len, APERM);
 	memcpy(current_wd, p, len);
+	if (writefd)
+		dprintf(writefd, "cwd%s\n", p);
 	if (p != pathx && p != null)
 		afree(p, ATEMP);
 }
diff --git a/sh.h b/sh.h
index 222b77c..6cd656d 100644
--- a/sh.h
+++ b/sh.h
@@ -186,6 +186,7 @@ EXTERN	uid_t	ksheuid;	/* effective uid of shell */
 EXTERN	int	exstat;		/* exit status */
 EXTERN	int	subst_exstat;	/* exit status of last $(..)/`..` */
 EXTERN	const char *safe_prompt; /* safe prompt if PS1 substitution fails */
+EXTERN	int	writefd;	/* open file descriptor to -w file */
 
 /*
  * Area-based allocation built on malloc/free
-- 
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