Re: [9fans] Small program "PlanKey" (paraphrase of DOSKey)

[Pietro Gagliardi <pietro10@mac.com>]

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This code is interesting. I do see one problem: commands that take up
more than one line won't be stored in the history properly, so each
line will get its own entry. But this is a nice use of pipes!

On Jan 23, 2009, at 5:03 AM, pavel.klinkovsky@gmail.com wrote:

> Hi all,
>
> In Plan9 I missed the simple way to repeat previous (or previous of
> previous etc.) command in the terminal.
> I prepared a very small (an stupid) program to allow that.
>
> Compile the following source code and run it in that way:
> 8.out | rc -i
>
> You can insert the commands, and if you want to walk through the
> "history", just press CTRL+K (backward) or CTRL+L (foreward).
>
> That is all, folks. ;-)
>
> Pavel
>
>
> #include <u.h>
> #include <libc.h>
>
> enum
> {
> 	KCtrlD = 0x04,
> 	KCtrlK = 0x0B,
> 	KCtrlL = 0x0C,
> 	KDelete = 0x7F,
>
> 	MaxLen = 128,
> 	MaxDepth = 10
> };
>
> struct Line
> {
> 	int len;
> 	char buf[MaxLen];
> };
> typedef struct Line Line;
>
> void
> main(void)
> {
> 	// Console control file descriptor
> 	int cfd;
> 	// End flag
> 	int end = 0;
> 	// Actual read character
> 	char c;
> 	// Array of BackSpaces
> 	char bs[MaxLen];
> 	// Array of Lines
> 	Line line[MaxDepth];
> 	// Index of actual line
> 	int act = 0;
> 	// Index of stored line
> 	int stored = 0;
>
> 	memset(bs, '\b', sizeof(bs));
> 	memset(line, 0, sizeof(line));
>
> 	cfd = open("/dev/consctl", OWRITE);
> 	if (cfd < 0)
> 		sysfatal("%r");
> 	write(cfd, "rawon", 5);
>
> 	while (!end) {
> 		if (read(0, &c, sizeof(c)) < 0)
> 			sysfatal("%r");
>
> 		switch (c) {
> 		case KCtrlD:
> 		case KDelete:
> 			end++;
> 			break;
>
> 		case '\b':
> 			if (line[act].len > 0) {
> 				line[act].len--;
> 				write(2, &c, sizeof(c));
> 			}
> 			break;
>
> 		case '\n':
> 			if (line[act].len > 0)
> 				write(1, line[act].buf, line[act].len);
> 			write(1, &c, sizeof(c));
> 			write(2, &c, sizeof(c));
> 			act = stored = (act + 1) % MaxDepth;
> 			line[act].len = 0;
> 			break;
>
> 		case KCtrlK:
> 			write(2, bs, line[act].len);
> 			stored = (stored + MaxDepth - 1) % MaxDepth;
> 			line[act] = line[stored];
> 			write(2, line[act].buf, line[act].len);
> 			break;
>
> 		case KCtrlL:
> 			write(2, bs, line[act].len);
> 			stored = (stored + 1) % MaxDepth;
> 			line[act] = line[stored];
> 			write(2, line[act].buf, line[act].len);
> 			break;
>
> 		case -0x11:
> 			read(0, &c, sizeof(c));
> 			read(0, &c, sizeof(c));
> 			break;
>
> 		default:
> 			if (line[act].len < MaxLen) {
> 				line[act].buf[line[act].len++] = c;
> 				write(2, &c, sizeof(c));
> 			}
> 			break;
> 		}
> 	}
>
> 	close(cfd);
>
> 	exits(nil);
> }
>


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