Command line utility for inserting a dylib load command into a Mach-O binary.
Does the following (to each arch if the binary is fat):
- (Removes
LC_CODE_SIGNATUREload command if present) - Adds a
LC_LOAD_DYLIBload command to the end of the load commands - Increments the mach header's
ncmdsand adjusts itssizeofcmds
Usage: insert_dylib dylib_path binary_path [new_binary_path]
Option flags: --inplace --weak --overwrite --strip-codesig --no-strip-codesig
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.
$ 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
$ 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
$ 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
- Improved checking for free space to insert the new load command
- Allow removal of
LC_CODE_SIGNATUREif it isn't the last load command - Remove
__RESTRICT,__restrictif not enough space (suggesion by dirkg)
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