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.)

1 files changed, 4 insertions, 3 deletions

diff --git a/src/cmd/acme/dat.h b/src/cmd/acme/dat.h
index df1a6422..8c4b14ee 100644
--- a/src/cmd/acme/dat.h
+++ b/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);