From ccd46ce2a784fffb6e7280c00da1f8c4cd809f5b Mon Sep 17 00:00:00 2001
From: dtb <trinity@trinity.moe>
Date: Sun, 15 Jan 2023 18:54:58 -0500
Subject: [PATCH] p(1)

---
 p/Makefile |  2 ++
 p/p.c      | 56 ++++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 58 insertions(+)
 create mode 100644 p/Makefile
 create mode 100644 p/p.c

diff --git a/p/Makefile b/p/Makefile
new file mode 100644
index 0000000..a5c66ed
--- /dev/null
+++ b/p/Makefile
@@ -0,0 +1,2 @@
+p: p.c
+	$(CC) $(CFLAGS) -o p p.c
diff --git a/p/p.c b/p/p.c
new file mode 100644
index 0000000..5cb02a1
--- /dev/null
+++ b/p/p.c
@@ -0,0 +1,56 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+#if !defined EX_USAGE || !defined EX_SOFTWARE
+#	include <sysexits.h>
+#endif
+
+/* Done while looking at plan9ports' src/cmd/p.c.
+ * Taken from plan9 are the interface (minus p(1)'s shell escaping and the
+ * ability to page multiple files) and the practice of reading /dev/tty to get
+ * keyboard input without going through stdin. Also, a newline is now printed
+ * before querying the keyboard. */
+
+static size_t l = 22; /* plan9 default */
+
+static char *program_name = "p";
+
+static int print_lines(FILE *f, size_t l){
+	int c;
+
+	while((c = getc(f)) != EOF)
+		if((c = putc(c, stdout)) == EOF || (l -= (c == '\n')) == 0)
+			break;
+
+	return c;
+}
+
+int main(int argc, char *argv[]){
+	unsigned char cmd[99+1];
+	char *p;
+	FILE *t;
+
+	if(argc == 0)
+		argv = &program_name;
+
+	if(argc > 1){
+		fprintf(stderr, "Usage: %s\n", argv[0]);
+		return EX_USAGE;
+	}
+
+	if((t = fopen("/dev/tty", "rb")) == NULL){
+		fprintf(stderr, "%s: Could not open /dev/tty\n", argv[0]);
+		return EX_SOFTWARE;
+	}
+
+	while(print_lines(stdin, l) != EOF){
+		fgets(cmd, (sizeof cmd) / (sizeof *cmd), t);
+		for(p = cmd; *p != '\0' && strchr(" \t", *p) != NULL; ++p);
+		if(feof(t) || (*p | 32) == 'q')
+			break;
+	}
+
+exit:	fclose(t);
+	return 0;
+}