[tex-live] Make the extensions for formats different for each engine.

[Olaf Weber]

Olaf Weber writes:

> Putting a fingerprint in the format file itself is not mutually
> exclusive with this.

Example of how the "fingerprint" would work in case of a mismatch:

infovore:/home/olaf/web2c/src/texk/texk/web2c$ ./tex \&pdftex
This is TeXk, Version 3.141592 (Web2C 7.5.2)
 %&-line parsing enabled.
(Fatal format file error; pdftex.fmt was written by pdftex)


Sample implementation of the above (a few changes to other files are
also needed):

$ cvs diff -u tex.ch
Index: tex.ch
===================================================================
RCS file: /usr/local/cvsroot/texk/texk/web2c/tex.ch,v
retrieving revision 1.65
diff -u -r1.65 tex.ch
--- a/tex.ch    28 Mar 2004 11:43:19 -0000      1.65
+++ b/tex.ch    15 Apr 2004 19:40:35 -0000
@@ -224,6 +224,7 @@
 @!max_trie_op=ssup_trie_opcode; {largest possible trie opcode for any language}
 @!pool_name=TEX_POOL_NAME; {this is configurable, for the sake of ML-\TeX}
   {string of length |file_name_size|; tells where the string pool appears}
+@!engine_name=TEX_ENGINE_NAME; {the name of this engine}
 @#
 @!inf_mem_bot = 0;
 @!sup_mem_bot = 1;
@@ -3731,9 +3732,11 @@
 @z

 % Eliminate now-unused variable `w' in `store_fmt_file'.
+% Add format_engine.
 @x [50.1302] l.23690
 @!w: four_quarters; {four ASCII codes}
 @y
+@!format_engine: ^text_char;
 @z

 % MLTeX: dump |mltex_p| to fmt file
@@ -3760,9 +3763,11 @@

 % Eliminate now-unused variable `w' in `load_fmt_file'.
 % Add dummies for undumping encTeX into the void.
+% Add format_engine.
 @x [50.1303] l.23722
 @!w: four_quarters; {four ASCII codes}
 @y
+@!format_engine: ^text_char;
 @!dummy_xord: ASCII_code;
 @!dummy_xchr: text_char;
 @!dummy_xprn: ASCII_code;
@@ -3833,6 +3838,15 @@
 @x [50,1307] l.23779 - texarray
 dump_int(@$);@/
 @y
+dump_int(@"57325458);  {Web2C \TeX's magic constant: "W2TX"}
+{Align engine to 4 bytes with one or more trailing NUL}
+x:=strlen(engine_name);
+format_engine:=xmalloc_array(text_char,x+4);
+strcpy(format_engine, engine_name);
+for k:=x to x+3 do format_engine[k]:=0;
+x:=x+4-(x mod 4);
+dump_int(x);dump_things(format_engine[0], x);
+libc_free(format_engine);@/
 dump_int(@$);@/
 dump_int(max_halfword);@/
 dump_int(hash_high);
@@ -3854,6 +3868,28 @@
 libc_free(yhash); libc_free(zeqtb); libc_free(yzmem);
 @+Tini
 undump_int(x);
+format_debug('format magic number')(x);
+if x<>@"57325458 then goto bad_fmt; {not a format file}
+undump_int(x);
+format_debug('engine name size')(x);
+if (x<0) or (x>256) then goto bad_fmt; {corrupted format file}
+format_engine:=xmalloc_array(text_char, x);
+undump_things(format_engine[0], x);
+format_engine[x-1]:=0; {force string termination, just in case}
+if strcmp(engine_name, format_engine) then
+  begin wake_up_terminal;
+  fputs('(Fatal format file error; ', stderr);
+ at .Fatal format file error@>
+  fputs(stringcast(name_of_file+1), stderr);
+  fputs(' was written by ', stderr);
+  fputs(format_engine, stderr);
+  write_ln(stderr, ')');
+  libc_free(format_engine);
+  load_fmt_file:=false;
+  goto exit;
+end;
+libc_free(format_engine);
+undump_int(x);
 format_debug('string pool checksum')(x);
 if x<>@$ then goto bad_fmt; {check that strings are the same}
 undump_int(x);


-- 
Olaf Weber

               (This space left blank for technical reasons.)