Merge pull request #262 from xexyl/1994-shapiro-eof

Fix EOF == -1 assumption in 1994/shapiro

1994/shapiro/README.md

@@ -10,17 +10,21 @@ USA
 
         make all
 
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) pointed out a potential
+[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) fixed a bug on systems
-bug on systems where `EOF != -1`. The problem is that `getc()` and the related
+where `EOF != -1`. The problem is that `getc()` and the related functions do not
-functions do not return `-1` on EOF or error but rather `EOF` but the program
+return `-1` on EOF or error but rather `EOF`. However `EOF` is not required to be
-assumes `-1` (conversely when using the `getopt()` functions one should not
+`-1` but merely an int < 0 and this program assumed that `getc()` will return
-check for EOF but -1 as the functions return -1 not EOF but the standard does
+`-1` on EOF or error, not `EOF`. On systems where `EOF != -1` it could be a
-not require `EOF` to be -1, just a negative number. However changing it to check
+problem. For the same reason one should not use `EOF` for the `getopt()`
-for `!=EOF` caused a problem due to the clever encoding of the code. See
+functions as they return `-1` when all options are parsed (for details on the
-[bugs.md](/bugs.md) for more details if you wish to try and fix this (Cody is
+definition of `EOF` see `7.21 Input/output<stdio.h>` subsection 1 of the
-here and there working on it along with other things and will change this
+standard). An interesting problem occurred where changing the `-1` to `EOF`
-message when it's fixed assuming it's feasible).
+caused both `warning: illegal character encoding in string literal` and `error:
-
+source file is not valid UTF-8`. But since `EOF` is simply an int < 0 and making
+the loop condition check that the return value is >= 0 does not cause a
+compilation error and it functions correctly it will address the systems where
+`EOF != -1` just as if it checked for `!= EOF`. Thank you Cody for your
+assistance!
 
 ## To run:
 

1994/shapiro/shapiro.c

@@ -11,7 +11,7 @@
           /*T*/,"r");for      (;(       L/*KPUOWOWMUQ
          LLOLMPULWLWL         WLW         LWLWLWLWLWLW
          LWLWLULVOXP          LLV          LLLOLMPULOL
-        MMNP*/=getc           (J)            )!= -1;L/*
+        MMNP*/=getc           (J)            )>= 0;L/*
        OLWLRMMQUL             VOX             PLLVLLLMQO
        PMPYPXPNP              MQL              LVLLLWPSP
       XPOQNQOPMQ              LLV              LTj*/>='J'

1994/shapiro/shapiro.md

@@ -13,7 +13,7 @@ This is a very simple program:
  5. FILE *J;
  6. J=fopen(__FILE__,"r");
  7. for(;
- 8.     (L=getc(J))!=EOF;
+ 8.     (L=getc(J))>=0;
  9.     L>='J'&&L<='J'+15 && 
 10.     ((M=!M)?K=L:putchar(K-'J'|(L-'J'<<4)))
 11.    );

bugs.md

@@ -572,82 +572,6 @@ or was killed. See the README.md for more details. If you don't feel comfortable
 changing it to `EOF` Cody will happily do it for you but otherwise go right
 ahead. We'll credit you in the README.md file regardless.
 
-
-## STATUS: doesn't work with some platforms - please help us fix
-
-[Cody Boone Ferguson](/winners.html#Cody_Boone_Ferguson) pointed out a potential
-bug in [1994/shapiro](1994/shapiro/shapiro.c) on systems where `EOF != -1` as
-the code assumes that `EOF` will always be `-1`. As the standard says (see `7.21
-Input/output<stdio.h>` subsection 1) it only has to be a negative int, not
-necessarily `-1`. The problem is that the source file's last character is a
-newline (10 in decimal) and so on systems where `EOF != -1` the `getc()`
-functions would not terminate the loop (but see below). This would cause a
-breakage in the entry.
-
-However due to clever encoding of the code it is not a simple matter of applying
-the following patch:
-
-```diff
-diff --git i/1994/shapiro/shapiro.c w/1994/shapiro/shapiro.c
-index d2da120c7bc4e251b7624859e48f47f188d398e9..e054a1ceb067b82bf37c07e5ce75e82be7a03b85 100644
---- i/1994/shapiro/shapiro.c
-+++ w/1994/shapiro/shapiro.c
-@@ -9,11 +9,11 @@
-             /*PPPPVPOQMQRPR*/=0;FILE/*TPSLUMWQT*/ *
-            J/*MPRPKPLQ*/;     J=      fopen(__FILE__
-           /*T*/,"r");for      (;(       L/*KPUOWOWMUQ
-          LLOLMPULWLWL         WLW         LWLWLWLWLWLW
-          LWLWLULVOXP          LLV          LLLOLMPULOL
--        MMNP*/=getc           (J)            )!= -1;L/*
-+        MMNP*/=getc           (J)            )!=EOF;L/*
-        OLWLRMMQUL             VOX             PLLVLLLMQO
-        PMPYPXPNP              MQL              LVLLLWPSP
-       XPOQNQOPMQ              LLV              LTj*/>='J'
-      &&L/*LRPYP               OQL               QMQLLVLLL
-      OLMQVOXPL                LVL                LLVOe*/<=
-
-```
-
-as doing so will cause `warning: illegal character encoding in string
-literal` and the error `error: source file is not valid UTF-8`. Looking at the
-file you'll see on line 4 of `shapiro_t2.c`:
-
-
-```
-char *a[]={"%c+------------+\n","%c+%3dPRÒ<82>3·Âå&Â"2W6öæF6'Â"Ò<96>æVGW6'¢ <82>öV'7'Â"R2Çå&Â"Â^E33sÃ^E33³UB¶cS³<83>T2Ç^E33<83>#Ò·£<90>æF^G"¶ÕÕ³^GÃ^BÃ^RsÃ^RCÃ^R^SÃ^BÓ·£Ð^V<96>æ<86>bÇ2<96><92>æF^Gb·3<86>^V&^G¢¢^B2¶£°7<86>^V&^GB¶E^CÓÅ¢RÆbÖc³£@<97>ÖVöE^Gr¶£`<94>ÄT^D¢<82>Æ¢<92>¶£p<87><96>ÆV^F<82>ÒÒb^Fbb^B^R^B<97>^FW<86>B<96>^Bbb^B^Rbö&·<86><92><92>²£<80>ÖcFö^FWæ<86>bÓbÆÃ^SÃ"^R&<92>²<93>ÖcFö^FWæ<86><82>bÓbÆÃ^S<93>²^RÃ""'<92>²£`ö&<87>²³<93>²<97>f<86>b<96>²gvVF7<87>BÆB^CÃ<92><96>²C¶5G'ÇVæ<86>B<96>Ò^RÓÕsÂ^Es²£<90>f<86>¢BÖÓs^Bs²b<96>²7^G'<97>æFg<86>¢2Æ"R2Çå&ÂB¶^R<93>²ó<86>2GGöVGÇbÃbÓbÆB¶^RÃ^B<93>Ò§<90>f<86>¢Bæs^Bs²b<96>ò<86><82>ÆRÃBÆ^BÃ^B<93>ÒWÆ6W¶G<97>ÖV<86>br<96>²SÖ^S67F<97>ÖV<86>Âö6^VÆF<97>ÖV<86>br<96><92>²£`ö&<87>b×^S³cÇc³c·²<92>ò<86><82>Æb^WÒ^Scbb^WÒcÓ^RÃb·r^BsÂ^RF÷<96><86>R¶"¶e×<95>Âb<97>2ÇVV^F<87>^R<93>²Ó×ק 
-```
-
-when it should be something entirely different. For what it should be try
-running `make clobber all ; cat shapiro_t2.c` or else look at the second program
-in the spoilers file [shapiro.md](1994/shapiro/shapiro.md]).
-
-Cody is working will be working on this here and there but if you have a fix or
-any suggestions you're welcome to provide it or them.
-
-Cody points you to the README.md file for what should happen when the entry is
-successfully compiled (including no compilation errors when running `make
-clobber all`).
-
-Another problem is that in the [shapiro.md](shapiro.md) file the first program
-does not work.
-
-### Tips on this entry:
-
-Cody provides some tips on this entry:
-
-First: the comments are the important part of this entry. Remove them and the
-program breaks.
-
-Second and perhaps part of the problem with changing the code to `EOF` instead
-of `-1` is the `for` loop particularly to do with the bitwise operations,
-perhaps also made worse by the seemingly gibberish comments.
-
-Another important point is that the Makefile compiles the program as
-`shapiro_t1` so that the source code that corresponds with it is actually
-[shapiro.c](1994/shapiro/shapiro.c). But notice how running `shapiro_t1` results
-in different functionality than `shapiro` itself? The source code that
-`shapiro_t1` generates, `shapiro_t2.c`, is what is compiled into `shapiro`.
-
 # 1995