172 lines
5.6 KiB
Scheme
172 lines
5.6 KiB
Scheme
(module mach-o mzscheme
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(provide add-plt-segment)
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(define (read-ulong p)
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(integer-bytes->integer (read-bytes 4 p) #f #t))
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(define (write-ulong v out)
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(display (integer->integer-bytes v 4 #f #t) out))
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(define (check-same a b)
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(unless (= a b)
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(error 'check-same "not: ~e ~e" a b)))
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(define (round-up-page v)
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(bitwise-and #xFFFFF000 (+ v #xFFF)))
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(define move-link-edit? #t)
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(define (add-plt-segment file segdata)
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(let-values ([(p out) (open-input-output-file file 'update)])
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(dynamic-wind
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void
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(lambda ()
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(file-stream-buffer-mode out 'none)
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(check-same #xFeedFace (read-ulong p))
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(read-ulong p)
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(read-ulong p)
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(check-same #x2 (read-ulong p))
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(let* ([cnt (read-ulong p)]
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[cmdssz (read-ulong p)]
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[min-used (round-up-page cmdssz)]
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[sym-tab-pos 0]
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[dysym-pos 0]
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[hints-pos 0]
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[link-edit-pos 0]
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[link-edit-addr 0]
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[link-edit-offset 0]
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[link-edit-len 0])
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(printf "~a cmds, length 0x~x\n" cnt cmdssz)
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(read-ulong p)
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(let loop ([cnt cnt])
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(unless (zero? cnt)
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(let ([pos (file-position p)]
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[cmd (read-ulong p)]
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[sz (read-ulong p)])
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(printf "~x (~a)\n" cmd sz)
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(case cmd
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[(1)
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;; Segment
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(let ([segname (read-bytes 16 p)]
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[vmaddr (read-ulong p)]
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[vmlen (read-ulong p)]
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[offset (read-ulong p)]
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[len (read-ulong p)])
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(printf "~s\n" segname)
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(when (equal? segname #"__LINKEDIT\0\0\0\0\0\0")
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(set! link-edit-pos pos)
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(set! link-edit-addr vmaddr)
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(set! link-edit-offset offset)
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(set! link-edit-len len))
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(printf " 0x~x 0x~x -> 0x~x 0x~x\n" offset len vmaddr vmlen)
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(read-ulong p)
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(read-ulong p)
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(let ([nsects (read-ulong p)])
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(read-ulong p)
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(let loop ([nsects nsects])
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(unless (zero? nsects)
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(let ([sect (read-bytes 16 p)]
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[seg (read-bytes 16 p)]
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[vmaddr (read-ulong p)]
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[vmsz (read-ulong p)]
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[offset (read-ulong p)])
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(when ((+ offset vmsz) . > . (+ cmdssz 28))
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(when (offset . < . min-used)
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(printf " new min!\n")
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(set! min-used offset)))
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(printf " ~s,~s 0x~x 0x~x\n"
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seg sect offset vmsz)
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(read-ulong p) (read-ulong p) (read-ulong p) (read-ulong p) (read-ulong p) (read-ulong p))
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(loop (sub1 nsects))))))]
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[(2)
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;; Symbol table
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(set! sym-tab-pos pos)]
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[(#xB)
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;; Dysym
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(set! dysym-pos pos)]
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[(#x16)
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;; 2-level hints table
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(set! hints-pos pos)]
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[else
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(void)])
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(file-position p (+ pos sz))
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(loop (sub1 cnt)))))
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(printf "Start offset: 0x~x\n" min-used)
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(let ([end-cmd (+ cmdssz 28)]
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[new-cmd-sz 56]
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[outlen (round-up-page (bytes-length segdata))]
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[out-offset (if move-link-edit?
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link-edit-offset
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(+ link-edit-offset (round-up-page link-edit-len)))]
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[out-addr (+ link-edit-addr (round-up-page link-edit-len))])
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(unless ((+ end-cmd new-cmd-sz) . < . min-used)
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(error 'check-header "no room for a new section load command"))
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;; Shift commands after link-edit segment:
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(file-position p link-edit-pos)
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(let ([s (read-bytes (- end-cmd link-edit-pos) p)])
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(file-position out (+ link-edit-pos 56))
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(display s out))
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(file-position out 16)
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;; The segment:
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(write-ulong (+ cnt 1) out)
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(write-ulong (+ cmdssz new-cmd-sz) out)
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(file-position out link-edit-pos)
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(write-ulong 1 out) ; LC_SEGMENT
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(write-ulong new-cmd-sz out)
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(display #"__PLTSCHEME\0\0\0\0\0" out)
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(write-ulong out-addr out)
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(write-ulong outlen out)
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(write-ulong out-offset out)
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(write-ulong outlen out)
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(write-ulong 0 out)
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(write-ulong 0 out)
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(write-ulong 0 out)
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(write-ulong 4 out) ; 4 means SG_NORELOC
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(when move-link-edit?
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;; Update link-edit segment entry:
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(when (sym-tab-pos . > . link-edit-pos)
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(set! sym-tab-pos (+ sym-tab-pos 56)))
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(when (dysym-pos . > . link-edit-pos)
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(set! dysym-pos (+ dysym-pos 56)))
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(when (hints-pos . > . link-edit-pos)
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(set! hints-pos (+ hints-pos 56)))
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(set! link-edit-pos (+ link-edit-pos 56))
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(file-position out (+ link-edit-pos 32))
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(printf "Update to ~a\n" (+ out-offset outlen))
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(write-ulong (+ out-offset outlen) out)
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;; Read link-edit segment:
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(file-position p link-edit-offset)
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(let ([link-edit (read-bytes link-edit-len p)])
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;; Write link-edit data in new location:
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(file-position out (+ link-edit-offset outlen))
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(display link-edit out))
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;; Shift symbol-table pointer:
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(file-position p (+ sym-tab-pos 8))
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(let ([symtab-offset (read-ulong p)]
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[_ (read-ulong p)]
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[symstr-offset (read-ulong p)])
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(file-position out (+ sym-tab-pos 8))
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(write-ulong (+ symtab-offset outlen) out)
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(file-position out (+ sym-tab-pos 16))
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(write-ulong (+ symstr-offset outlen) out))
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;; Shift dysym pointers:
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(file-position p (+ dysym-pos 56))
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(let ([ind-offset (read-ulong p)])
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(file-position out (+ dysym-pos 56))
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(write-ulong (+ ind-offset outlen) out))
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;; Shift hints pointer:
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(file-position p (+ hints-pos 8))
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(let ([hints-offset (read-ulong p)])
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(file-position out (+ hints-pos 8))
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(write-ulong (+ hints-offset outlen) out)))
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;; Write segdata to former link-data offset:
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(file-position out out-offset)
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(display segdata out)
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(display (make-bytes (- outlen (bytes-length segdata)) 0) out)
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;; Result is offset where data was written:
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out-offset)))
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(lambda ()
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(close-input-port p)
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(close-output-port out))))))
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