ref: 5d4e55ea225f736f41d4e351033ba269e117c149
author: kvik <vp@kvik.link>
date: Fri May 17 17:31:26 EDT 2019
init
--- /dev/null
+++ b/mkfile
@@ -1,0 +1,14 @@
+</$objtype/mkfile
+
+TARG=watch
+OFILES=$TARG.$O
+BIN=$home/bin/$objtype
+MAN=/sys/man/1
+
+</sys/src/cmd/mkone
+
+install:V: man
+
+uninstall:V:
+ rm -f $BIN/$TARG
+ rm -f $MAN/$TARG
--- /dev/null
+++ b/watch.c
@@ -1,0 +1,204 @@
+#include <u.h>
+#include <libc.h>
+#include <regexp.h>
+
+typedef struct List List;
+struct List {+ List *next;
+ union {+ Dir;
+ Reprog *re;
+ };
+};
+
+char pwd[1024];
+int period = 1000;
+int noregroup = 0;
+List *expl;
+List *filel;
+
+void
+usage(void)
+{+ fprint(2, "usage: %s [[-e expr] ...] [-t sec] [cmd]\n", argv0);
+ exits("usage");+}
+
+void*
+emalloc(ulong sz)
+{+ void *v = malloc(sz);
+ if(v == nil)
+ sysfatal("malloc: %r");+ setmalloctag(v, getcallerpc(&sz));
+ memset(v, 0, sz);
+ return v;
+}
+char*
+estrdup(char *s)
+{+ if((s = strdup(s)) == nil)
+ sysfatal("strdup: %r");+ setmalloctag(s, getcallerpc(&s));
+ return s;
+}
+
+char*
+join(char **arg)
+{+ int i;
+ char *s, *p;
+
+ s = estrdup("");+ for(i = 0; arg[i]; i++){+ p = s;
+ if((s = smprint("%s %s", s, arg[i])) == nil)+ sysfatal("smprint: %r");+ free(p);
+ }
+ return s;
+}
+
+void
+eadd(char *exp)
+{+ List *r;
+
+ r = emalloc(sizeof(*r));
+ r->re = regcomp(exp);
+ r->next = expl;
+ expl = r;
+}
+
+void
+fadd(Dir *d)
+{+ List *f;
+
+ f = emalloc(sizeof(*f));
+ f->Dir = *d;
+ f->next = filel;
+ filel = f;
+}
+
+int
+tracked(char *name)
+{+ List *r;
+
+ for(r = expl; r; r = r->next)
+ if(regexec(r->re, name, nil, 0))
+ return 1;
+ return 0;
+}
+
+int
+changed(Dir *d)
+{+ List *f;
+
+ for(f = filel; f; f = f->next)
+ if(f->type == d->type)
+ if(f->dev == d->dev)
+ if(f->qid.path == d->qid.path)
+ if(f->qid.type == d->qid.type)
+ if(f->qid.vers == d->qid.vers)
+ return 0;
+ else{+ f->Dir = *d;
+ return 1;
+ }
+ fadd(d);
+ return 1;
+}
+
+void
+watch(void)
+{+ static int first = 1;
+ long fd, n;
+ Dir *d, *p;
+
+ for(;;){+ sleep(period);
+ if((fd = open(pwd, OREAD)) < 0)
+ sysfatal("open: %r");+ if((n = dirreadall(fd, &d)) < 0)
+ sysfatal("dirreadall: %r");+ close(fd);
+ for(p = d; n--; p++){+ if(tracked(p->name)){+ if(first){+ fadd(p);
+ continue;
+ }
+ if(changed(p)){+ free(d);
+ return;
+ }
+ }
+ }
+ first = 0;
+ free(d);
+ }
+}
+
+void
+regroup(void)
+{+ int fd, n, noteid;
+ char buf[128];
+
+ snprint(buf, sizeof buf, "/proc/%d/noteid", getppid());
+ if((fd = open(buf, OREAD)) < 0)
+ sysfatal("open: %r");+ if((n = read(fd, buf, 128)) < 0)
+ sysfatal("read: %r");+ close(fd);
+ buf[n] = 0;
+ noteid = strtol(buf, nil, 10);
+ snprint(buf, sizeof buf, "/proc/%d/noteid", getpid());
+ if((fd = open(buf, OWRITE)) < 0)
+ sysfatal("open: %r");+ if(fprint(fd, "%d", noteid) < 0)
+ sysfatal("fprint: %r");+ close(fd);
+}
+
+void
+main(int argc, char *argv[])
+{+ char *cmd;
+ Waitmsg *m;
+
+ cmd = "mk";
+ ARGBEGIN{+ case 'e':
+ eadd(EARGF(usage())); break;
+ case 't':
+ period = 1000*strtol(EARGF(usage()), nil, 10); break;
+ case 'G':
+ noregroup = 1; break;
+ default: usage();
+ }ARGEND;
+ if(expl == nil)
+ eadd("\.[chsy]$");+ if(argc > 0)
+ cmd = join(argv);
+ if(getwd(pwd, sizeof pwd) == nil)
+ sysfatal("getwd: %r");+
+ if(noregroup == 0) regroup();
+ for(;;){+ watch();
+ switch(fork()){+ case -1: sysfatal("fork: %r");+ case 0:
+ execl("/bin/rc", "rc", "-c", cmd, nil);+ sysfatal("execl: %r");+ }
+ if((m = wait()) && m->msg[0])
+ fprint(2, "watch: %s\n", m->msg);
+ free(m);
+ }
+}
--- /dev/null
+++ b/watch.man
@@ -1,0 +1,63 @@
+.TH WATCH 1
+.SH NAME
+watch \- run a command on file change
+.SH SYNOPSIS
+.B watch
+[
+.B -t
+sec
+] [[
+.B -e
+pattern
+] ... ] [
+.B command
+]
+.SH DESCRIPTION
+.PP
+Run
+.IR command
+.RB ( mk
+by default) when a change to files
+in the current directory is detected.
+.PP
+The options are as follows:
+.TF "-e pattern"
+.TP
+.BI -e pattern
+Watch files matching a
+.IR pattern ;
+it may be given multiple times and
+defaults to
+.BR \e.[chsy]$
+.TP
+.BI -t sec
+Sets the polling period;
+one second by default.
+.TP
+.B -G
+Prevents regrouping to the parent
+process' note group. The default
+to regroup was chosen to make it
+easy to kill
+.I watch
+in common use by interrupting the
+parent shell.
+.SH EXAMPLES
+.EX
+watch -e '\e.man$' 'mk install; window man -P prog' &
+.EE
+.SH SEE ALSO
+.SH SOURCE
+.B git://code.kvik.link/watch
+.SH BUGS
+.I Watch
+will not react on file removal.
+.PP
+.I Qid.vers
+is watched for changes, which is
+not maintained by every file server.
+.PP
+The polling period is actually
+.I sec
+plus the time it takes to run
+.IR command .