diff options
Diffstat (limited to '00/README.md')
| -rw-r--r-- | 00/README.md | 21 |
1 files changed, 11 insertions, 10 deletions
diff --git a/00/README.md b/00/README.md index 199c1c8..3be7e5c 100644 --- a/00/README.md +++ b/00/README.md @@ -26,7 +26,7 @@ it even smaller if you wanted to. Let's take a look at what's inside (`od -t x1 00 00 48 89 c7 31 c0 48 89 c6 48 b8 02 00 00 00 00 00 00 00 0f 05 48 b8 72 02 40 00 00 00 00 00 48 89 c7 48 b8 41 00 00 00 00 00 00 00 48 89 c6 -48 b8 a4 01 00 00 00 00 00 00 48 89 c2 48 b8 02 +48 b8 ed 01 00 00 00 00 00 00 48 89 c2 48 b8 02 00 00 00 00 00 00 00 0f 05 48 b8 03 00 00 00 00 00 00 00 48 89 c7 48 89 c2 48 b8 6a 02 40 00 00 00 00 00 48 89 c6 31 c0 0f 05 48 89 c3 48 b8 03 @@ -181,19 +181,20 @@ Now we open our output file: - `48 89 c7` `mov rdi, rax` - `48 b8 41 00 00 00 00 00 00 00` `mov rax, 0x41` - `48 89 c6` `mov rsi, rax` -- `48 b8 a4 01 00 00 00 00 00 00` `mov rax, 0o644` +- `48 b8 ed 01 00 00 00 00 00 00` `mov rax, 0o755` - `48 89 c2` `mov rdx, rax` - `48 b8 02 00 00 00 00 00 00 00` `mov rax, 2` - `0f 05` `syscall` -In C, this is `open("out00", O_WRONLY|O_CREAT, 0644)`. -This is quite similar to our first call, with two important differences: first, -we specify `0x41` as the second argument. This tells Linux that we are writing -to the file (`O_WRONLY = 0x01`), and that we want to create it if it doesn't -exist (`O_CREAT = 0x40`). Secondly, we are setting the third argument this time. -It specifies the permissions our file is created with (`0o644` means user -read/write, group/other read). This is not very important to the actual -execution of the program, so don't worry if you don't know what it means. +In C, this is `open("out00", O_WRONLY|O_CREAT, 0755)`. This is quite similar +to our first call, with two important differences: first, we specify `0x41` as +the second argument. This tells Linux that we are writing to the file +(`O_WRONLY = 0x01`), and that we want to create it if it doesn't exist +(`O_CREAT = 0x40`). Secondly, we are setting the third argument this time. It +specifies the permissions our file is created with (`0o755` means user +read/write/execute, group/other read/execute). This is not very important to +the actual execution of the program, so don't worry if you don't know what it +means. Now we can start reading from the file. We're going to loop back to this part of the code every time we want to read a new hexadecimal number from the input |