Update README

README.md

@@ -1,87 +1,18 @@
-insert_dylib
-============
+macho_edit
+==========
 
-Command line utility for inserting a dylib load command into a Mach-O binary.
+Command line utility for modifying [Mach-O](https://en.wikipedia.org/wiki/Mach-O) binaries in various ways.
 
-Does the following (to each arch if the binary is fat):
-
-- Adds a `LC_LOAD_DYLIB` load command to the end of the load commands
-- Increments the mach header's `ncmds` and adjusts its `sizeofcmds`
-- ([Removes code signature if present](#removing-code-signature))
-
-Usage
------
-
-```
-Usage: insert_dylib dylib_path binary_path [new_binary_path]
-Option flags: --inplace --weak --overwrite --strip-codesig --no-strip-codesig --all-yes
-```
-
-`insert_dylib` inserts a load command to load the `dylib_path` in `binary_path`.
-
-Unless `--inplace` option is specified, `insert_dylib` will produce a new binary at `new_binary_path`.  
-If neither `--inplace` nor `new_binary_path` is specified, the output binary will be located at the same location as the input binary with `_patched` prepended to the name.
-
-If the `--weak` option is specified, `insert_dylib` will insert a `LC_LOAD_WEAK_DYLIB` load command instead of `LC_LOAD_DYLIB`.
-
-### Example
-
-```
-$ cat > test.c
-int main(void) {
-	printf("Testing\n");
-	return 0;}
-^D
-$ clang test.c -o test &> /dev/null
-$ insert_dylib /usr/lib/libfoo.dylib test
-The provided dylib path doesn't exist. Continue anyway? [y/n] y
-Added LC_LOAD_DYLIB to test_patched
-$ ./test
-Testing
-$ ./test_patched
-dyld: Library not loaded: /usr/lib/libfoo.dylib
-  Referenced from: /Users/Tyilo/./test_patched
-  Reason: image not found
-Trace/BPT trap: 5
-```
-
-#### `otool` `diff` between original and patched binary
-```
-$ diff -u <(otool -hl test) <(otool -hl test_patched)
---- /dev/fd/63	2014-07-30 04:08:40.000000000 +0200
-+++ /dev/fd/62	2014-07-30 04:08:40.000000000 +0200
-@@ -1,7 +1,7 @@
--test:
-+test_patched:
- Mach header
-       magic cputype cpusubtype  caps    filetype ncmds sizeofcmds      flags
-- 0xfeedfacf 16777223          3  0x80          2    16       1296 0x00200085
-+ 0xfeedfacf 16777223          3  0x80          2    17       1344 0x00200085
- Load command 0
-       cmd LC_SEGMENT_64
-   cmdsize 72
-@@ -231,3 +231,10 @@
-   cmdsize 16
-   dataoff 8296
-  datasize 64
-+Load command 16
-+          cmd LC_LOAD_DYLIB
-+      cmdsize 48
-+         name /usr/lib/libfoo.dylib (offset 24)
-+   time stamp 0 Thu Jan  1 01:00:00 1970
-+      current version 0.0.0
-+compatibility version 0.0.0
-```
+Supported functionality
+----
 
-#### `--weak` option
+- Extracting and removing archs from a fat binary.
+- Inserting an arch from another binary into a fat binary.
+- Making a fat binary thin or a thin binary fat.
+- Moving around and removing load commands.
+- Inserting new load commands. Currently only `LC_LOAD_DYLIB`, `LC_LOAD_WEAK_DYLIB` and `LC_RPATH` is supported.
+- Removing code signature (`LC_CODE_SIGNATURE`).
 
-```
-$ insert_dylib --weak /usr/lib/libfoo.dylib test test_patched2
-The provided dylib path doesn't exist. Continue anyway? [y/n] y
-Added LC_LOAD_WEAK_DYLIB to test_patched2
-$ ./test_patched2
-Testing
-```
 
 Removing code signature
 ----
@@ -94,15 +25,13 @@ However if you just do this `codesign_allocate` (used by `codesign` and `ldid`)
 .../codesign_allocate: file not in an order that can be processed (link edit information does not fill the __LINKEDIT segment):
 ```
 
-To fix this `insert_dylib` assumes that the code signature that `LC_CODE_SIGNATURE` is in the end of the `__LINKEDIT` segment and the that the segment is in the end of the architectures slice.
+To fix this `macho_edit` assumes that the code signature that `LC_CODE_SIGNATURE` is in the end of the `__LINKEDIT` segment and the that the segment is in the end of the architectures slice.
 
 It then truncate that slice to remove the code signature part of the `__LINKEDIT` segment. It also updates the `LC_SEGMENT` (or `LC_SEGMENT64`) load command for the `__LINKEDIT` segment from the new file size. If the binary is fat we also update the size and we might also move the slice and so the offset should also be updated.
 
-After removing the code signature from the `__LINKEDIT` segment, the last thing in that segment is typically the string table. As the code signature seems to be aligned by `0x10`, and so after removing the code signature, nothing points to the padding at the end of the segment, which `codesign_allocate` doesn't like either. To fix this we just increase the size of the string table in the `LC_SYMTAB` command so it also includes the padding.
+After removing the code signature from the `__LINKEDIT` segment, the last thing in that segment is typically the string table. As the code signature seems to be aligned by `0x10`, and so after removing the code signature, nothing points to the padding at the end of the segment, which `codesign_allocate` doesn't like either. To fix this we just trim the file so the string table in the `LC_SYMTAB` command is at the end of the slice.
 
 Todo
 ----
 
-- Improved checking for free space to insert the new load command
-- Allow removal of `LC_CODE_SIGNATURE` if it isn't the last load command
-- Remove `__RESTRICT,__restrict` if not enough space (suggesion by dirkg)
+- Option to modify mach header flags