Merge pull request #780 from xexyl/2001-anonymous-orig-cpp

2001/anonymous/README.md

@@ -22,12 +22,12 @@ author's remarks it should be executed). He managed to do this with linux
 but it will not work with macOS (see [bugs.md](/bugs.md) for why this is); this
 is not a bug but a feature inherent in what it does.
 
-Although it took a fair bit of debugging it turns out all that
+Although it took a fair bit of debugging it turns out all that had to change
-needed to be changed was:
+was:
 
-- `#include <sys/mman.h>` for `mmap()`.
+- `#include <sys/mman.h>` for `mmap()` and `munmap()`.
-- have `main()` call another function which is the recursive function; this
+- have `main()` call another function which is no longer a recursive function;
-prevented `main()` from entering an infinite loop.
+this prevented `main()` from entering an infinite recursive loop.
 
 Without either of these it would crash and prevent modification of the 32-bit
 [ELF](https://en.wikipedia.org/wiki/Executable_and_Linkable_Format) (not elf :-)
@@ -41,9 +41,13 @@ macOS and linux).
 
 There was one other thing that had to be done though. Since the program used to
 recursively call (infinite recursion, seemingly) `main()` and since that cannot
-be done what had to be done is first call `munmap()` and `close()` (else one
+be done what had to be done instead is after the new function (`pain()` since it
-would get text file busy error) and then run `execv()` again like the function
+was a pain to fix :-) ) returns to first call `munmap()` and `close()` (else
-`pain()` (was in `main()`) did but with a slight change.
+one would get text file busy error) and then the program can call `execv()` again like the
+function `pain()` (was in `main()`) did but with a slight change. See commit
+`2159caec4677e0f25ad704a74e04c8196fd6c343` for details. Notice that
+the location of the calls to `munmap()` and `close() followed by `execv()` do
+matter!
 
 NOTE: there might be educational value to see the progress of this fix; if you
 wish to see, try:
@@ -54,10 +58,36 @@ git diff 93aa8d79f208dcccc3c5a2370a727b5cf64e9c53..c48629017117379a52b1a512ef8f2
 git diff c48629017117379a52b1a512ef8f2593ca9569c8..efdee208a2bc650256637b9357ddfd0de82d2f41 anonymous.c
 git diff efdee208a2bc650256637b9357ddfd0de82d2f41..e9a3f77ea3b209e63ac3f9c06bb84ad86e5ea706 anonymous.c
 git diff d2a42f42e8f477f29e9d5ed09ce2bb349eaf7397..2159caec4677e0f25ad704a74e04c8196fd6c343 anonymous.c
+git diff 2159caec4677e0f25ad704a74e04c8196fd6c343..4bc03de321612869aebf855850c6500df95cb6ef anonymous.c
+```
+
+Finally to see from start to finish:
+
+```sh
+git diff d2a42f42e8f477f29e9d5ed09ce2bb349eaf7397..4bc03de321612869aebf855850c6500df95cb6ef anonymous.c
 ```
 
 Thank you Cody for your assistance!
 
+## Try:
+
+```sh
+./try.me.sh
+```
+
+What happens if the x86 program has already been modified by this program? The
+judges' remarks below might give you a hint!
+
+What happens if you try it on another file like [anonymous.c](anonymous.c)? Can
+you recompile it okay? What if you run it on `anonymous` itself? Can you run the
+program successfully after it without recompiling?
+
+
+## Judges' remarks:
+
+Is emulation the sincerest form of flattery?  This small program does
+quite a lot of bit twiddling.
+
 ### INABIAF - it's not a bug it's a feature! :-)
 
 If you do not specify a 32-bit ELF binary as the arg of this program it will
@@ -81,24 +111,6 @@ notice that although the binaries do differ it's not many differences and the
 output of the supplementary program both before and after is the same. See the
 author's warning about this in their remarks.
 
-## Try:
-
-```sh
-./try.me.sh
-```
-
-What happens if the x86 program has already been modified by this program? The
-judges' remarks below might give you a hint!
-
-What happens if you try it on another file like [anonymous.c](anonymous.c)? Can
-you recompile it okay? What if you run it on `anonymous` itself? Can you run the
-program successfully after it without recompiling?
-
-
-## Judges' remarks:
-
-Is emulation the sincerest form of flattery?  This small program does
-quite a lot of bit twiddling.
 
 ## Author's remarks:
 

2001/anonymous/anonymous.c

@@ -41,8 +41,8 @@ c L(E(k [(l)V(17)]),0); } V(v){ c E(B[v]); }
 int
 pain(char *ck, char **k)
 {
-c (z?(stat(M,&t)?P+=a+'{'?0:3:execv(M,k),a=G,i=P,y=G&255,sprintf(Q,y/'@'-3?"*L(V(%d+%d)+%d,0)":"R[%d]",(y&7),'\r',y/0100-1?0:G),(a+127&&a+'}'&&a+1?(a+61&&a+24&&a+025?(P=a+'H'&&a%061<=0?P:i,D(a>0?"                           R[%d]=E(~-E(R[%d])),\0               U R[%d],\0               R[%d] O,\0                                          U %d,\0R[%d]=0,"+(a&'8')*3:a  <-  'c'?" %d, %c%s = R[%d], \0    %d, *R=%c%s==R[%d], \0          R[%d]=(int)%c%s,"-a%'w'%'j'*5:"%d,%d,%s=%d,",a>0?a-'h'?a-49?a&7:g:I:g,a>0?a&7:"& "[a%3%2+1],a+72?Q:A(*R),a>0|a<-99?g:I,0) ,(char* ) P):(P=i,i=a+61?a+21?E(I):G:0, D(a%' '+29+"P O,\0 U %d,P=%d,",P,P+i,0,0,0) , p(d,"A'",b)),z):(n=g-4?g%5-1?a+127?G:I:0:(Scan(), *( x86?processor :d)=0, (int)(ss+V(i))),g%5<2?d+=sprintf( d,g%5?"    %s=E(~-E(%s)), \0    U %s,"+4*g:"%s=E(E(%s)%c%d),",Q,Q,"+    -  "[g],n,0 ),(char* ) P:(a=G-'u'?'!':'=', D(g-4?"P=%d%c=%s?%d:%d,":"*R=E(((int(*)(l,l,l))%s)(K(1),K(2),K(3))),P O,",n,a,Q,P,P+G), p(d,"A'",b) ,z)))):(Run((z=(char*)&ck,stat(k[1],&t),B=(l)mmap(0,N=i=t.st_size,PROT_READ|PROT_WRITE,1,f=open(k[1],2),0))),(((B+13)[4]=E(B+i/4),run(),P=V(-~i),(B+13)[4]=E(V(17)-4),*(int*)V(021))),sprintf(M,A(.%s%d),k[1],P),d+=sprintf( d,"%s %s '-DX=A(%s)' -o %s '-Dmagic=","cpp -std=gnu99 -Wall -Wextra -pedantic -Winfinite-recursion -Wno-bitwise-conditional-parentheses -Wno-error -Wno-implicit-function-declaration -Wno-implicit-int -Wno-int-to-pointer-cast -Wno-macro-redefined -Wno-pedantic -Wno-pointer-to-int-cast -Wno-return-type -Wno-string-plus-int -Wno-bitwise-op-parentheses -Wno-format -Wno-format-extra-args -Wno-int-conversion -Wno-unused-parameter -Wno-unsequenced -E \"-DA(X)=#X\"",__FILE__,"cpp -std=gnu99 -Wall -Wextra -pedantic -Winfinite-recursion -Wno-bitwise-conditional-parentheses -Wno-error -Wno-implicit-function-declaration -Wno-implicit-int -Wno-int-to-pointer-cast -Wno-macro-redefined -Wno-pedantic -Wno-pointer-to-int-cast -Wno-return-type -Wno-string-plus-int -Wno-bitwise-op-parentheses -Wno-format -Wno-format-extra-args -Wno-int-conversion -Wno-unused-parameter -Wno-unsequenced -E \"-DA(X)=#X\"",M,fflush(0) ),(char* ) P)); }
+c (z?(stat(M,&t)?P+=a+'{'?0:3:execv(M,k),a=G,i=P,y=G&255,sprintf(Q,y/'@'-3?"*L(V(%d+%d)+%d,0)":"R[%d]",(y&7),'\r',y/0100-1?0:G),(a+127&&a+'}'&&a+1?(a+61&&a+24&&a+025?(P=a+'H'&&a%061<=0?P:i,D(a>0?"                           R[%d]=E(~-E(R[%d])),\0               U R[%d],\0               R[%d] O,\0                                          U %d,\0R[%d]=0,"+(a&'8')*3:a  <-  'c'?" %d, %c%s = R[%d], \0    %d, *R=%c%s==R[%d], \0          R[%d]=(int)%c%s,"-a%'w'%'j'*5:"%d,%d,%s=%d,",a>0?a-'h'?a-49?a&7:g:I:g,a>0?a&7:"& "[a%3%2+1],a+72?Q:A(*R),a>0|a<-99?g:I,0) ,(char* ) P):(P=i,i=a+61?a+21?E(I):G:0, D(a%' '+29+"P O,\0 U %d,P=%d,",P,P+i,0,0,0) , p(d,"A'",b)),z):(n=g-4?g%5-1?a+127?G:I:0:(Scan(), *( x86?processor :d)=0, (int)(ss+V(i))),g%5<2?d+=sprintf( d,g%5?"    %s=E(~-E(%s)), \0    U %s,"+4*g:"%s=E(E(%s)%c%d),",Q,Q,"+    -  "[g],n,0 ),(char* ) P:(a=G-'u'?'!':'=', D(g-4?"P=%d%c=%s?%d:%d,":"*R=E(((int(*)(l,l,l))%s)(K(1),K(2),K(3))),P O,",n,a,Q,P,P+G), p(d,"A'",b) ,z)))):(Run((z=(char*)&ck,stat(k[1],&t),B=(l)mmap(0,N=i=t.st_size,PROT_READ|PROT_WRITE,1,f=open(k[1],2),0))), magic((R[4]=E(B+i/4),run(),P=V(-~i), R[4]=E(V(17)-4),*(int*)V(021))), sprintf(M,A(.%s%d),k[1],P), D("%s %s '-DX=A(%s)' -o %s '-Dmagic=",X,__FILE__,X,M,fflush(0)) ,(char* ) P));
-int
+}
-main (int cka, char **k) { char *ck = (char *)cka;
+int main (int cka, char **k) { char *ck = (char *)cka;
   (E((ck?pain((char*)cka,k):p(M,A(rm -f .%s),M),*R)));munmap(B,N);close(f);execv(k[1],k);
 }