Date: Sun, 22 Jun 2008 04:12:40 +0300 From: Giorgos Keramidas <keramida@ceid.upatras.gr> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/124863: [PATCH] make vmstat(8) a bit smarter about the number of tty rows Message-ID: <87od5u2rxz.fsf@kobe.laptop> Resent-Message-ID: <200806220120.m5M1K1YV089202@freefall.freebsd.org>
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>Number: 124863 >Category: bin >Synopsis: [PATCH] make vmstat(8) a bit smarter about the number of tty rows >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Sun Jun 22 01:20:01 UTC 2008 >Closed-Date: >Last-Modified: >Originator: Giorgos Keramidas >Release: FreeBSD 8.0-CURRENT i386 >Organization: <organization of PR author (multiple lines)> >Environment: System: FreeBSD kobe 8.0-CURRENT FreeBSD 8.0-CURRENT #1: \ Mon Jun 16 08:37:10 EEST 2008 build@kobe:/home/build/obj/home/build/src/sys/KOBE i386 >Description: The current vmstat(8) utility repeats the header line every 20 lines, and this number is hardcoded in the source of vmstat. This means that with very short xterm windows, vmstat may not display one header per terminal, and when the window size changes, it doesn't detect this and update its internal row count. The attached patch modifies vmstat() to trap SIGWINCH, and use it to update its internal 'max rows' limit of output lines. It also forces a new header to be prepended to the output on every SIGWINCH, and it changes the hardcoded '20' lines of output to 'wrows - 3' (two rows are needed for the header itself, and one for the cursor below the last output line of each screenful). >How-To-Repeat: Resize an xterm window to 80x10 lines, and watch the output of vmstat for a while, using: % vmstat 1 >Fix: The following patch is a direct `port' of the similar change I did to iostat(8) (see Subversion change r175562 for the iostat patch). --- vmstat.patch begins here --- diff -ruN old/vmstat.c new/vmstat.c --- old/vmstat.c 2008-06-22 04:06:14.000000000 +0300 +++ new/vmstat.c 2008-06-22 04:06:36.000000000 +0300 @@ -135,7 +135,10 @@ static struct vmmeter sum, osum; -static int winlines = 20; +#define VMSTAT_DEFAULT_LINES 20 /* Default number of `winlines'. */ +volatile sig_atomic_t wresized; /* Tty resized, when non-zero. */ +static int winlines = VMSTAT_DEFAULT_LINES; /* Current number of tty rows. */ + static int aflag; static int nflag; static int Pflag; @@ -164,6 +167,8 @@ static void kreado(int, void *, size_t, size_t); static char *kgetstr(const char *); static void needhdr(int); +static void needresize(int); +static void doresize(void); static void printhdr(int, u_long); static void usage(void); @@ -580,8 +585,27 @@ uptime = getuptime(); halfuptime = uptime / 2; + + /* + * If the user stops the program (control-Z) and then resumes it, + * print out the header again. + */ (void)signal(SIGCONT, needhdr); + /* + * If our standard output is a tty, then install a SIGWINCH handler + * and set wresized so that our first iteration through the main + * iostat loop will peek at the terminal's current rows to find out + * how many lines can fit in a screenful of output. + */ + if (isatty(fileno(stdout)) != 0) { + wresized = 1; + (void)signal(SIGWINCH, needresize); + } else { + wresized = 0; + winlines = VMSTAT_DEFAULT_LINES; + } + if (kd != NULL) { if (namelist[X_STATHZ].n_type != 0 && namelist[X_STATHZ].n_value != 0) @@ -607,8 +631,11 @@ bzero(last_cp_times, size_cp_times); } for (hdrcnt = 1;;) { - if (!--hdrcnt) + if (!--hdrcnt) { + if (wresized != 0) + doresize(); printhdr(ncpus, cpumask); + } if (kd != NULL) { kread(X_CPTIME, cur.cp_time, sizeof(cur.cp_time)); } else { @@ -658,6 +685,8 @@ errx(1, "%s", devstat_errbuf); break; case 1: + if (wresized != 0) + doresize(); printhdr(ncpus, cpumask); break; default: @@ -772,6 +801,47 @@ hdrcnt = 1; } +/* + * When the terminal is resized, force an update of the maximum number of rows + * printed between each header repetition. Then force a new header to be + * prepended to the next output. + */ +void +needresize(int signo) +{ + + wresized = 1; + hdrcnt = 1; +} + +/* + * Update the global `wrows' count of terminal rows. + */ +void +doresize(void) +{ + int status; + struct winsize w; + + for (;;) { + status = ioctl(fileno(stdout), TIOCGWINSZ, &w); + if (status == -1 && errno == EINTR) + continue; + else if (status == -1) + err(1, "ioctl"); + if (w.ws_row > 3) + winlines = w.ws_row; + else + winlines = VMSTAT_DEFAULT_LINES; + break; + } + + /* + * Inhibit doresize() calls until we are rescheduled by SIGWINCH. + */ + wresized = 0; +} + #ifdef notyet static void dotimes(void) --- vmstat.patch ends here --- >Release-Note: >Audit-Trail: >Unformatted:
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