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authorpommicket <pommicket@gmail.com>2021-09-01 14:58:37 -0400
committerpommicket <pommicket@gmail.com>2021-09-01 14:58:37 -0400
commitbd739d7205b51381dd17a3fc7fedcc4b40a598c3 (patch)
tree53e146c302f3472782e0341e2379d2eac3ac3411 /00
parent6efb86d66d27710255907e2c5f0ad8da1f57da08 (diff)
finished 01, now just need to write readme
Diffstat (limited to '00')
-rw-r--r--00/README.md15
-rwxr-xr-x00/hexcompilebin632 -> 632 bytes
2 files changed, 8 insertions, 7 deletions
diff --git a/00/README.md b/00/README.md
index 3be7e5c..25dc1ae 100644
--- a/00/README.md
+++ b/00/README.md
@@ -25,7 +25,7 @@ it even smaller if you wanted to. Let's take a look at what's inside (`od -t x1
00 10 00 00 00 00 00 00 48 b8 6d 02 40 00 00 00
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 89 c7 48 b8 41 02 00 00 00 00 00 00 48 89 c6
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
@@ -179,18 +179,19 @@ Now we open our output file:
- `48 b8 72 02 40 00 00 00 00 00` `mov rax, 0x400272`
- `48 89 c7` `mov rdi, rax`
-- `48 b8 41 00 00 00 00 00 00 00` `mov rax, 0x41`
+- `48 b8 41 02 00 00 00 00 00 00` `mov rax, 0x41`
- `48 89 c6` `mov rsi, rax`
- `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, 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
+In C, this is `open("out00", O_WRONLY|O_CREAT|O_TRUNC, 0755)`. This is quite
+similar to our first call, with two important differences: first, we specify
+`0x241` as the second argument. This tells Linux that we are writing to the
+file (`O_WRONLY = 0x01`), that we want to create it if it doesn't exist
+(`O_CREAT = 0x40`), and that we want to delete any previous contents it had
+(`O_TRUNC = 0x200`). 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
diff --git a/00/hexcompile b/00/hexcompile
index 6aeed48..f4c575e 100755
--- a/00/hexcompile
+++ b/00/hexcompile
Binary files differ