acme: check file content before declaring file "modified since last read"

Bad remote file systems can change mtime unexpectedly,
and then there is the problem that git rebase and similar
operations like to change the files and then change them back,
modifying the mtimes but not the content.

Avoid spurious Put errors on both of those by checking file
content.

(False positive "modified since last read" make the real ones
difficult to notice.)

src/cmd/acme/acme.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 	/* for generating syms in mkfile only: */

src/cmd/acme/addr.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/buff.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 
@@ -231,7 +232,7 @@ bufloader(void *v, uint q0, Rune *r, int nr)
 }
 
 uint
-loadfile(int fd, uint q0, int *nulls, int(*f)(void*, uint, Rune*, int), void *arg)
+loadfile(int fd, uint q0, int *nulls, int(*f)(void*, uint, Rune*, int), void *arg, DigestState *h)
 {
 	char *p;
 	Rune *r;
@@ -253,6 +254,8 @@ loadfile(int fd, uint q0, int *nulls, int(*f)(void*, uint, Rune*, int), void *ar
 			warning(nil, "read error in Buffer.load");
 			break;
 		}
+		if(h != nil)
+			sha1((uchar*)p+m, n, nil, h);
 		m += n;
 		p[m] = 0;
 		l = m;
@@ -269,11 +272,11 @@ loadfile(int fd, uint q0, int *nulls, int(*f)(void*, uint, Rune*, int), void *ar
 }
 
 uint
-bufload(Buffer *b, uint q0, int fd, int *nulls)
+bufload(Buffer *b, uint q0, int fd, int *nulls, DigestState *h)
 {
 	if(q0 > b->nc)
 		error("internal error: bufload");
-	return loadfile(fd, q0, nulls, bufloader, b);
+	return loadfile(fd, q0, nulls, bufloader, b, h);
 }
 
 void

src/cmd/acme/cols.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/dat.h

@@ -105,7 +105,7 @@ struct Buffer
 };
 void		bufinsert(Buffer*, uint, Rune*, uint);
 void		bufdelete(Buffer*, uint, uint);
-uint		bufload(Buffer*, uint, int, int*);
+uint		bufload(Buffer*, uint, int, int*, DigestState*);
 void		bufread(Buffer*, uint, Rune*, uint);
 void		bufclose(Buffer*);
 void		bufreset(Buffer*);
@@ -135,8 +135,9 @@ struct File
 	Rune		*name;	/* name of associated file */
 	int		nname;	/* size of name */
 	uvlong	qidpath;	/* of file when read */
-	ulong		mtime;	/* of file when read */
+	ulong	mtime;	/* of file when read */
 	int		dev;		/* of file when read */
+	uchar	sha1[20];	/* of file when read */
 	int		unread;	/* file has not been read from disk */
 	int		editclean;	/* mark clean after edit command */
 
@@ -152,7 +153,7 @@ void		fileclose(File*);
 void		filedelete(File*, uint, uint);
 void		filedeltext(File*, Text*);
 void		fileinsert(File*, uint, Rune*, uint);
-uint		fileload(File*, uint, int, int*);
+uint		fileload(File*, uint, int, int*, DigestState*);
 void		filemark(File*);
 void		filereset(File*);
 void		filesetname(File*, Rune*, int);

src/cmd/acme/disk.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/ecmd.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "edit.h"
 #include "fns.h"
@@ -336,7 +337,7 @@ e_cmd(Text *t, Cmd *cp)
 	}
 	elogdelete(f, q0, q1);
 	nulls = 0;
-	loadfile(fd, q1, &nulls, readloader, f);
+	loadfile(fd, q1, &nulls, readloader, f, nil);
 	free(s);
 	close(fd);
 	if(nulls)

src/cmd/acme/edit.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "edit.h"
 #include "fns.h"

src/cmd/acme/elog.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 #include "edit.h"

src/cmd/acme/exec.c

@@ -9,6 +9,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include <9pclient.h>
 #include "dat.h"
 #include "fns.h"
@@ -635,6 +636,30 @@ get(Text *et, Text *t, Text *argt, int flag1, int _0, Rune *arg, int narg)
 	xfidlog(w, "get");
 }
 
+static void
+checksha1(char *name, File *f, Dir *d)
+{
+	int fd, n;
+	DigestState *h;
+	uchar out[20];
+	uchar *buf;
+	
+	fd = open(name, OREAD);
+	if(fd < 0)
+		return;
+	h = sha1(nil, 0, nil, nil);
+	buf = emalloc(8192);
+	while((n = read(fd, buf, 8192)) > 0)
+		sha1(buf, n, nil, h);
+	close(fd);
+	sha1(nil, 0, out, h);
+	if(memcmp(out, f->sha1, sizeof out) == 0) {
+		f->dev = d->dev;
+		f->qidpath = d->qid.path;
+		f->mtime = d->mtime;
+	}
+}	
+
 void
 putfile(File *f, int q0, int q1, Rune *namer, int nname)
 {
@@ -646,13 +671,15 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 	Dir *d, *d1;
 	Window *w;
 	int isapp;
+	DigestState *h;
 
 	w = f->curtext->w;
 	name = runetobyte(namer, nname);
 	d = dirstat(name);
 	if(d!=nil && runeeq(namer, nname, f->name, f->nname)){
-		/* f->mtime+1 because when talking over NFS it's often off by a second */
-		if(f->dev!=d->dev || f->qidpath!=d->qid.path || labs((long)(f->mtime-d->mtime)) > 1){
+		if(f->dev!=d->dev || f->qidpath!=d->qid.path || f->mtime != d->mtime)
+			checksha1(name, f, d);
+		if(f->dev!=d->dev || f->qidpath!=d->qid.path || f->mtime != d->mtime) {
 			if(f->unread)
 				warning(nil, "%s not written; file already exists\n", name);
 			else
@@ -679,6 +706,7 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 	s = fbufalloc();
 	free(d);
 	d = dirfstat(fd);
+	h = sha1(nil, 0, nil, nil);
 	isapp = (d!=nil && d->length>0 && (d->qid.type&QTAPPEND));
 	if(isapp){
 		warning(nil, "%s not written; file is append only\n", name);
@@ -691,6 +719,7 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 			n = BUFSIZE/UTFmax;
 		bufread(&f->b, q, r, n);
 		m = snprint(s, BUFSIZE+1, "%.*S", n, r);
+		sha1((uchar*)s, m, nil, h);
 		if(Bwrite(b, s, m) != m){
 			warning(nil, "can't write file %s: %r\n", name);
 			goto Rescue2;
@@ -730,6 +759,8 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 			f->qidpath = d->qid.path;
 			f->dev = d->dev;
 			f->mtime = d->mtime;
+			sha1(nil, 0, f->sha1, h);
+			h = nil;
 			f->mod = FALSE;
 			w->dirty = FALSE;
 			f->unread = FALSE;
@@ -741,6 +772,7 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 	}
 	fbuffree(s);
 	fbuffree(r);
+	free(h);
 	free(d);
 	free(namer);
 	free(name);
@@ -753,6 +785,7 @@ putfile(File *f, int q0, int q1, Rune *namer, int nname)
 		Bterm(b);
 		free(b);
 	}
+	free(h);
 	fbuffree(s);
 	fbuffree(r);
 	close(fd);

src/cmd/acme/file.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 
@@ -163,11 +164,11 @@ fileunsetname(File *f, Buffer *delta)
 }
 
 uint
-fileload(File *f, uint p0, int fd, int *nulls)
+fileload(File *f, uint p0, int fd, int *nulls, DigestState *h)
 {
 	if(f->seq > 0)
 		error("undo in file.load unimplemented");
-	return bufload(&f->b, p0, fd, nulls);
+	return bufload(&f->b, p0, fd, nulls, h);
 }
 
 /* return sequence number of pending redo */

src/cmd/acme/fns.h

@@ -25,7 +25,7 @@ void	savemouse(Window*);
 int	restoremouse(Window*);
 void	clearmouse(void);
 void	allwindows(void(*)(Window*, void*), void*);
-uint loadfile(int, uint, int*, int(*)(void*, uint, Rune*, int), void*);
+uint loadfile(int, uint, int*, int(*)(void*, uint, Rune*, int), void*, DigestState*);
 void	movetodel(Window*);
 
 Window*	errorwin(Mntdir*, int);

src/cmd/acme/fsys.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/logf.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/look.c

@@ -10,6 +10,7 @@
 #include <regexp.h>
 #include <9pclient.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/regx.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/rows.c

@@ -9,6 +9,7 @@
 #include <fcall.h>
 #include <bio.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/scrl.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/text.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include <complete.h>
 #include "dat.h"
 #include "fns.h"
@@ -198,6 +199,7 @@ textload(Text *t, uint q0, char *file, int setqid)
 	Dir *d, *dbuf;
 	char *tmp;
 	Text *u;
+	DigestState *h;
 
 	if(t->ncache!=0 || t->file->b.nc || t->w==nil || t!=&t->w->body)
 		error("text.load");
@@ -220,6 +222,7 @@ textload(Text *t, uint q0, char *file, int setqid)
 		goto Rescue;
 	}
 	nulls = FALSE;
+	h = nil;
 	if(d->qid.type & QTDIR){
 		/* this is checked in get() but it's possible the file changed underfoot */
 		if(t->file->ntext > 1){
@@ -264,9 +267,17 @@ textload(Text *t, uint q0, char *file, int setqid)
 	}else{
 		t->w->isdir = FALSE;
 		t->w->filemenu = TRUE;
-		q1 = q0 + fileload(t->file, q0, fd, &nulls);
+		if(q0 == 0)
+			h = sha1(nil, 0, nil, nil);
+		q1 = q0 + fileload(t->file, q0, fd, &nulls, h);
 	}
 	if(setqid){
+		if(h != nil) {
+			sha1(nil, 0, t->file->sha1, h);
+			h = nil;
+		} else {
+			memset(t->file->sha1, 0, sizeof t->file->sha1);
+		}
 		t->file->dev = d->dev;
 		t->file->mtime = d->mtime;
 		t->file->qidpath = d->qid.path;

src/cmd/acme/time.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/util.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/wind.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"
 

src/cmd/acme/xfid.c

@@ -8,6 +8,7 @@
 #include <frame.h>
 #include <fcall.h>
 #include <plumb.h>
+#include <libsec.h>
 #include "dat.h"
 #include "fns.h"