Merge pull request #1763 from xexyl/carlini2020

Add 2020/carlini/try.sh, update bugs.md

2020/carlini/README.md

@@ -5,6 +5,17 @@ make
 ```
 
 
+### Bugs and (Mis)features:
+
+The current status of this entry is:
+
+```
+STATUS: INABIAF - please **DO NOT** fix
+```
+
+For more detailed information see [2020 carlini in bugs.md](/bugs.md#2020-carlini).
+
+
 ## To use:
 
 ```sh
@@ -15,16 +26,22 @@ make
 ### Try:
 
 ```sh
-# Play with a friend, P1 and P2, squares are numbered 1..9
+./try.sh
+```
+
+Or if you actually want to play:
+
+```sh
+# Play with a friend, real or imagined, P1 and P2, squares are numbered 1..9
 ./prog
 ```
 
 
 ## Judges' remarks:
 
-This program consists of a single print statement wrapped in a while loop. You
+This program consists of a single `printf(3)` statement wrapped in a `while`
-would not think that this would amount to much, but you would be very, very
+loop. You would not think that this would amount to much, but you would be very,
-wrong. A clue to what is happening and how this works is encoded in the
+very wrong. A clue to what is happening and how this works is encoded in the
 ASCII art of the program source.
 
 
@@ -51,9 +68,10 @@ Alternates between P1 and P2. Enter a digit [1-9] to move:
 
 The game ends if:
 
- * A player completes three in a row; that player wins
+ * A player completes three in a row; that player wins.
- * All squares are taken; neither player wins
+ * All squares are taken; neither player wins.
- * A player makes an illegal move; their opponent wins
+ * A player makes an illegal move; their opponent wins.
+
 
 ### LIMITATIONS
 
@@ -69,8 +87,8 @@ the program ... is hard at work processing your move! That is! Please be
 patient.
 
 After macro expansion the format string is roughly 100K. This makes some
-compilers unhappy, and others slow. (For example, passing GCC the flags -Wall
+compilers unhappy, and others slow. (For example, passing GCC the flags `-Wall
--Wextra -pedantic will result in a warning about oversized strings.)
+-Wextra -pedantic` will result in a warning about oversized strings.)
 
 Under some terminals the program may exit early. The following should always work:
 
@@ -80,7 +98,7 @@ echo "1 2 3 4 5 6 7" | ./prog
 
 ### OBFUSCATION
 
-The entirety of the program consists of a single iterated call to printf.
+The entirety of the program consists of a single iterated call to `printf(3)`.
 
 ```c
 int main() {
@@ -88,25 +106,27 @@ int main() {
 }
 ```
 
-Here, `fmt` is a single string, and `arg` is a series of arguments to printf.
+Here, `fmt` is a single string, and `arg` is a series of arguments to
+`printf(3)`.
 
-While its primary purpose is to serve as The One True Debugger, printf also happens
+While its primary purpose is to serve as The One True Debugger, `printf(3)` also happens
 to be Turing complete. (See "Control-Flow Bending: On the Effectiveness of Control-Flow
 Integrity" where we introduced this in an actual, published, academic paper. The
 things you can get away with sometimes.)
 
 We <strike>ab</strike>use this fact to implement the logic of tic-tac-toe entirely within
-this one printf call (and a call to scanf() to read user input).
+this one `printf(3)` call (and a call to `scanf(3)` to read user input).
 
 Here's (briefly) how it works.
 
+
 #### Preliminaries
 
-This program uses three printf format specifiers.
+This program uses three `printf(3)` format specifiers.
 
-- `%d` takes an integer argument and prints it
+- `%d` takes an integer argument and prints it.
 
-- `%s` takes a string argument and prints it
+- `%s` takes a string argument and prints it.
 
 - `%n` takes a pointer and writes (!!) the number of bytes printed so far.
 
@@ -114,13 +134,13 @@ Okay, everyone probably knows this. Let's get a bit more advanced.
 
 Format specifiers can take extra "arguments".
 
-- `"%hhn"`: store the number of bytes written mod 256 to the char pointer
+- `"%hhn"`: store the number of bytes written mod 256 to the `char` pointer.
 
-- `"%2$d"`: print argument 2 to printf (and not the sequentially next argument)
+- `"%2$d"`: print argument 2 to `printf(3)` (and not the sequentially next argument).
 
-- `"%8d"`: pad the printed integer to 8 characters
+- `"%8d"`: pad the printed integer to 8 characters.
 
-- `"%3$.*4$d"`: print argument 3 to printf with as many zeros as in argument 4.
+- `"%3$.*4$d"`: print argument 3 to `printf(3)` with as many zeros as in argument 4.
 
 For example, the following expression
 
@@ -135,16 +155,17 @@ x = 10;
 ```
 
 because it will print out `0000000005` (5 padded to size 10) and then write the
-number of bytes written to x.
+number of bytes written to `x`.
 
-#### Printf Oriented Programming
+
+#### `printf(3)` Oriented Programming
 
 Alright, now we can get to the real fun.
 
-We perform arbitrary computation with printf treating memory as a binary
+We perform arbitrary computation with `printf(3)` treating memory as a binary
 array--one bit per pair of bytes:
 
-- The zero bit is represented by the sequence `00 00`
+- The zero bit is represented by the sequence `00 00`.
 
 - The one-bit is represented by the sequence `xx 00` where `xx` is any non-zero byte.
 
@@ -190,13 +211,14 @@ and again, because `strlen(x)` is either `1` or `0` we have
 From here we can compute any binary circuit. Doing something efficient,
 though, still takes work.
 
+
 #### Tic-Tac-Toe
 
 The game itself is represented as a board of 18 bits, 9 bits per player, along
 with a turn counter that alternates between player 1 and player 2.
 
-To detect who has won, we implement the following logic. Let A, B, and C be
+To detect who has won, we implement the following logic. Let `A`, `B`, and `C` be
-pointers to three squares in a row to test, and D be where to save if there is a
+pointers to three squares in a row to test, and `D` be where to save if there is a
 win or not.
 
 ```c
@@ -217,7 +239,7 @@ the following expression
 "%1$hhn%1$s" (repeated 256 times)
 ```
 
-where argument 1 is a pointer to a temporary variable followed by a null byte.
+where argument 1 is a pointer to a temporary variable followed by a NUL byte.
 
 This works because if the current count is 0 mod 256, then `"%1$hhn"` will write
 zero to argument 1 and then "%1$s" will never emit any text. If, on the other
@@ -229,8 +251,8 @@ Checking if there has been an invalid move is achieved similarly.
 
 In order to decide what to print out, we have to cast the "in-memory" array of
 bits to Xs and Os to print out. This is actually rather straightforward. Given
-in 1$ the pointer to player 1's square, and 2$ the pointer to player 2's, and
+in `1$` the pointer to player 1's square, and `2$` the pointer to player 2's, and
-in 3$ the pointer to the board string, we can compute
+in `3$` the pointer to the board string, we can compute
 
 ```c
 "%1$s" (repeated 47 times) "%2$s" (repeated 56 times) %1$32d%3$hhn"
@@ -242,21 +264,22 @@ which will, in effect, compute
 *r3 = (*r1) * 47 + (*r2) * 56 + 32
 ```
 
-which will output `' '` if neither are true, `'X'` if r1 is, or `'O'` if r2 is.
+which will output `' '` if neither are true, `'X'` if `r1` is true, or `'O'` if
+`r2` is true.
 
 
 #### Further Obfuscations
 
 In order to be able to finally display the board, while still only using one
-printf statement, we finish the statement with
+`printf(3)` statement, we finish the statement with
 
 ```c
 "\n\033[2J\n%26$s"
 ```
 
 which is the escape sequence to clear the screen, and then prints argument 26.
-Argument 26 is a pointer to a char* in memory, that initially is undefined,
+Argument 26 is a pointer to a `char*` in memory, that initially is undefined,
-but within the printf statement we will construct this string to look like a
+but within the `printf(3)` statement we will construct this string to look like a
 tic-tac-toe board.
 
 After the board, we need to print one of the following strings:
@@ -282,10 +305,10 @@ before, we set byte four to be
 
 The byte `'I'` and `'S'` can always be the same, and we do the same for `'E'`/`'N'`.
 
-We do this same on-the-fly creation of the `scanf()` format string, but for a
+We do this same on-the-fly creation of the `scanf(3)` format string, but for a
-different reason. We first want to run `printf()` to show the first board, and
+different reason. We first want to run `printf(3)` to show the first board, and
-then alternate between runs to `scanf()` and `printf()` reading and then
+then alternate between runs to `scanf(3)` and `printf(3)` reading and then
-displaying moves. Importantly, we *do not* want a final scanf when the game
+displaying moves. Importantly, we *do not* want a final `scanf(3)` when the game
 ends. It should just exit.
 
 One option would be to implement the logic as
@@ -298,7 +321,7 @@ while (*ok) {
 }
 ```
 
-but this would DOUBLE the number of calls to printf we require. So instead we
+but this would DOUBLE the number of calls to `printf(3)` we require. So instead we
 implement it like this
 
 ```c
@@ -308,13 +331,13 @@ while (*ok) {
 }
 ```
 
-(In reality we actually pass `scanf()` as an argument to avoid the extra
+(In reality we actually pass `scanf(3)` as an argument to avoid the extra
 statement, but it has the same effect.)
 
-Notice there is now no initial `printf()`. In order make sure the program doesn't
+Notice there is now no initial `printf(3)`. In order make sure the program doesn't
-block before the first `printf()`, but we initialize the `scanf()` format to the null
+block before the first `printf(3)`, we initialize the `scanf(3)` format to the NUL
-string so that it returns right away without blocking. The first time the `printf()`
+string so that it returns right away without blocking. The first time the
-call runs, it writes out `"%hhd"` to create the `scanf()` format string.
+`printf(3)` call runs, it writes out `"%hhd"` to create the `scanf(3)` format string.
 
 
 ## Copyright and CC BY-SA 4.0 License:

2020/carlini/try.sh

@@ -0,0 +1,23 @@
+#!/usr/bin/env bash
+#
+# try.sh - demonstrate IOCCC winner 2020/carlini
+#
+
+# make sure CC is set so that when we do make CC="$CC" it isn't empty. Doing it
+# this way allows us to have the user specify a different compiler in an easy
+# way.
+if [[ -z "$CC" ]]; then
+    CC="cc"
+fi
+
+make CC="$CC" all >/dev/null || exit 1
+
+# clear screen after compilation so that only the entry is shown
+clear
+
+read -r -n 1 -p "Press any key to run: echo 1 2 3 4 5 6 7 | ./prog: "
+echo 1>&2
+echo 1 2 3 4 5 6 7 | ./prog
+echo 1>&2
+
+echo "... now go and play for real, with a friend, real or imagined." 1>&2

bugs.md

@@ -3575,6 +3575,25 @@ It will also show funny output with more than one arg. This should not be fixed
 either. But can you figure out why this happens?
 
 
+## 2020 carlini
+
+### STATUS: INABIAF - please **DO NOT** fix
+### Source code: [2020/carlini/prog.c](2020/carlini/prog.c)
+### Information: [2020/carlini/README.md](2020/carlini/README.md)
+
+The author stated that bad things happen if the entered move is outside of the
+range [1..9]. We observed a crash but we also observed a tie and other things
+besides (say with the input `-1`, `-`, `-10` and others).
+
+If a player makes a move over their opponent's place they will automatically
+lose.
+
+If a player tries to play a move they already played they will forfeit their
+move.
+
+If you have audible bells enabled the program will beep at every turn.
+
+
 ## 2020 ferguson1
 
 ### STATUS: INABIAF - please **DO NOT** fix

thanks-for-help.md

@@ -4291,6 +4291,14 @@ showing nothing at all.
 Cody also added the [try.sh](/2020/burton/try.sh) script.
 
 
+## <a name="2020_carlini"></a>[2020/carlini](/2020/carlini/prog.c) ([README.md](/2020/carlini/README.md))
+
+[Cody](#cody) added the [try.sh](/2020/carlini/try.sh) script which although at
+first glance might not appear to have a point, it actually does, namely showing
+how you can automate play and then reminding you to actually play for real, with
+a friend, whether that's real or imagined.
+
+
 ## <a name="2020_endoh2"></a>[2020/endoh2](/2020/endoh2/prog.c) ([README.md](/2020/endoh2/README.md))
 
 [Cody](#cody) copied the files from the spoiler.zip file that was password protected with