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improve swap

--- a/rc/bin/cpurc

+++ b/rc/bin/cpurc

@@ -76,4 +76,4 @@

 # mode of /proc/*/ctl is inherited across rfork, and sets modes on

 # other /proc files, such as note, so let listen be killed.

-dontkill '^(ipconfig|factotum|mntgen|venti|kfs|cwfs.*|cs|dns|reboot)$'

+dontkill '^(ipconfig|factotum|mntgen|venti|kfs|cwfs.*|cs|dns|reboot|usbd|disk)$'

--- a/rc/bin/dontkill

+++ b/rc/bin/dontkill

@@ -7,4 +7,4 @@

 }

 # see /sys/src/9/port/proc.c:/^killbig

 pids=`{psu | awk '$NF ~ /'$1'/ {print $2}'}

-~ $#pids 0 || chmod -w /proc/^$pids^/ctl

+~ $#pids 0 || for(p in /proc/^$pids^/ctl){chmod +w $p; echo noswap >$p; chmod -w $p}

--- a/rc/bin/termrc

+++ b/rc/bin/termrc

@@ -103,4 +103,4 @@

 if(test -f /dev/apm)

 	aux/apm

-dontkill '^(ipconfig|factotum|mntgen|kfs|cwfs.*|cs|dns|listen|reboot)$'

+dontkill '^(ipconfig|factotum|mntgen|kfs|cwfs.*|cs|dns|listen|reboot|usbd|disk)$'

--- a/sys/man/8/swap

+++ b/sys/man/8/swap

@@ -6,11 +6,14 @@

 .I file 

 .SH DESCRIPTION

 .I Swap

-establishes a file or device for the system to swap on.

+establishes a file for the system to swap on.

 If

 .I file

-is a device, the device is used directly; if a directory,

-a unique file is created in that directory on which to swap.

+is an existing file, it is used for system swap. If it

+does not exist, a new file is created. If

+.I file

+is a directory, a unique file is created in that directory

+on which to swap.

 The environment variable

 .B swap

 is set to the full name of the resulting file.

@@ -27,4 +30,10 @@

 .SH BUGS

 Swapping to a file served by a local user-level process, such as

 .IR kfs (4),

-can lead to deadlock; use raw devices or remote files instead.

+will lead to deadlock if the process isn't made non-swappable

+(see the

+.B noswap

+ctl-message in

+.IR proc (3)).

+.SH "SEE ALSO"

+.IR proc (3)

--- a/sys/src/cmd/swap.c

+++ b/sys/src/cmd/swap.c

@@ -1,66 +1,54 @@

 #include <u.h>

 #include <libc.h>

-void error(char *);

-

 void

 main(int argc, char **argv)

 {

-	Dir *d;

 	int swapfd, cswfd;

-	char buf[128], *p;

-	int i, j;

+	char buf[1024], *p;

+	Dir *d;

-	if(argc != 2) {

-		print("Usage: swap path\n");

-		exits("swap: failed");

+	ARGBEGIN {

+	} ARGEND;

+

+	if(argc != 1){

+		fprint(2, "Usage: swap file\n");

+		exits("usage");

 	}

-	d = dirstat(argv[1]);

-	if(d == nil){

-		print("swap: can't stat %s: %r\n", argv[1]);

-		exits("swap: failed");

+	swapfd = -1;

+	if(d = dirstat(p = *argv)){

+		if(d->mode & DMDIR){

+			p = getenv("sysname");

+			if(p == 0)

+				p = "swap";

+			snprint(buf, sizeof buf, "%s/%sXXXXXXX", *argv, p);

+			p = mktemp(buf);

+		} else

+			swapfd = open(p, ORDWR);

 	}

-	if(d->type != 'M'){		/* kernel device */

-		swapfd = open(argv[1], ORDWR);

-		p = argv[1];

-	}

-	else {

-		p = getenv("sysname");

-		if(p == 0)

-			p = "swap";

-		sprint(buf, "%s/%sXXXXXXX", argv[1], p);

-		p = mktemp(buf);

-		swapfd = create(p, ORDWR|ORCLOSE, 0600);

-	}

+	if(d == nil || (d->mode & DMDIR)){

+		if((swapfd = create(p, ORDWR|ORCLOSE, 0600)) >= 0){

+			Dir nd;

-	if(swapfd < 0 || (p[0] == '/' && p[1] == '\0')) {

-		print("swap: failed to make a file: %r\n");

-		exits("swap: failed");

+			nulldir(&nd);

+			nd.mode = DMTMP|0600;

+			dirfwstat(swapfd, &nd);

+		}

 	}

+	if(swapfd < 0)

+		sysfatal("%r");

+	if(fd2path(swapfd, p = buf, sizeof buf))

+		sysfatal("fd2path: %r");

+	if(putenv("swap", p) < 0)

+		sysfatal("putenv: %r");

-	i = create("/env/swap", OWRITE, 0666);

-	if(i < 0) 

-		error("open /env/swap");

-

-	if(write(i, p, strlen(p)) != strlen(p))

-		error("sysname");

-	close(i);

 	print("swap: %s\n", p);

-	cswfd = open("/dev/swap", OWRITE);

-	if(cswfd < 0)

-		error("open: /dev/swap");

+	if((cswfd = open("/dev/swap", OWRITE)) < 0)

+		sysfatal("open: %r");

+	if(fprint(cswfd, "%d", swapfd) < 0)

+		sysfatal("write: %r");

-	j = sprint(buf, "%d", swapfd);

-	if(write(cswfd, buf, j) != j)

-		error("write: /dev/swap");

 	exits(0);

-}

-

-void

-error(char *s)

-{

-	perror(s);

-	exits(s);

 }

-- 

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