使用gdb查找未知函數在C中的作用

Question

我有一個函數m（int i，char c），它需要並返回「-abc ... xyz」之間的一個char，並且還需要一個整數i。

基本上我沒有辦法看到函數的源代碼，但可以調用它並獲取返回值。使用gdb/C，解密函數的最佳方式是什麼？我試過尋找使用連續字符和整數輸入的模式，但沒有提供任何東西。

如果有幫助，下面是測試的返回值，與前兩位是參數，最後一位是返回值的一些結果：

0 a i 
0 b l 
0 c t 
0 d x 
0 e f 
0 f v 

1 a q 
1 b i 
1 c y 
1 d e 

2 a a 
2 b y 
2 c f 
2 d n 

拆卸提供以下功能：

0x00014354 <m+0>: save %sp, -144, %sp 
0x00014358 <m+4>: st %i0, [ %fp + 0x44 ] 
0x0001435c <m+8>: mov %i1, %g1 
0x00014360 <m+12>: stb %g1, [ %fp + 0x48 ] 
0x00014364 <m+16>: st %sp, [ %fp + -40 ] 
0x00014368 <m+20>: mov 0x1b, %g1 
0x0001436c <m+24>: stb %g1, [ %fp + -17 ] 
0x00014370 <m+28>: clr [ %fp + -24 ] 
0x00014374 <m+32>: ldub [ %fp + -17 ], %g1 
0x00014378 <m+36>: sll %g1, 0x18, %g1 
0x0001437c <m+40>: sra %g1, 0x18, %g1 
0x00014380 <m+44>: add %g1, 7, %g1 
0x00014384 <m+48>: srl %g1, 3, %g1 
0x00014388 <m+52>: sll %g1, 3, %g1 
0x0001438c <m+56>: sub %sp, %g1, %sp 
0x00014390 <m+60>: add %sp, 0x5c, %g1 
0x00014394 <m+64>: add %g1, 7, %g1 
0x00014398 <m+68>: srl %g1, 3, %g1 
0x0001439c <m+72>: sll %g1, 3, %g1 
0x000143a0 <m+76>: st %g1, [ %fp + -44 ] 
0x000143a4 <m+80>: mov 0x2d, %g1 
0x000143a8 <m+84>: ld [ %fp + -44 ], %o4 
0x000143ac <m+88>: stb %g1, [ %o4 ] 
0x000143b0 <m+92>: mov 1, %g1 
0x000143b4 <m+96>: st %g1, [ %fp + -28 ] 
0x000143b8 <m+100>: ldub [ %fp + -17 ], %g1 
0x000143bc <m+104>: sll %g1, 0x18, %g1 
0x000143c0 <m+108>: sra %g1, 0x18, %o5 
0x000143c4 <m+112>: ld [ %fp + -28 ], %g1 
0x000143c8 <m+116>: cmp %o5, %g1 
0x000143cc <m+120>: ble 0x14400 <m+172> 
0x000143d0 <m+124>: nop 
0x000143d4 <m+128>: ld [ %fp + -28 ], %g1 
0x000143d8 <m+132>: ld [ %fp + -44 ], %o4 
0x000143dc <m+136>: add %o4, %g1, %o5 
0x000143e0 <m+140>: ld [ %fp + -28 ], %g1 
0x000143e4 <m+144>: add %g1, 0x60, %g1 
0x000143e8 <m+148>: stb %g1, [ %o5 ] 
0x000143ec <m+152>: ld [ %fp + -28 ], %g1 
0x000143f0 <m+156>: inc %g1 
0x000143f4 <m+160>: st %g1, [ %fp + -28 ] 
0x000143f8 <m+164>: b 0x143b8 <m+100> 
0x000143fc <m+168>: nop 
0x00014400 <m+172>: ldub [ %fp + -17 ], %g1 
0x00014404 <m+176>: sll %g1, 0x18, %g1 
0x00014408 <m+180>: sra %g1, 0x18, %o5 
0x0001440c <m+184>: ld [ %fp + 0x44 ], %g1 
0x00014410 <m+188>: mov %g1, %o0 
0x00014414 <m+192>: mov %o5, %o1 
0x00014418 <m+196>: call 0x2727c <.rem@plt> 
0x0001441c <m+200>: nop 
0x00014420 <m+204>: mov %o0, %g1 
0x00014424 <m+208>: st %g1, [ %fp + 0x44 ] 
0x00014428 <m+212>: ldub [ %fp + 0x48 ], %g1 
0x0001442c <m+216>: sll %g1, 0x18, %g1 
0x00014430 <m+220>: sra %g1, 0x18, %g1 
0x00014434 <m+224>: cmp %g1, 0x2d 
0x00014438 <m+228>: be 0x1449c <m+328> 
0x0001443c <m+232>: nop 
0x00014440 <m+236>: ldub [ %fp + 0x48 ], %g1 
0x00014444 <m+240>: sll %g1, 0x18, %g1 
0x00014448 <m+244>: sra %g1, 0x18, %g1 
0x0001444c <m+248>: cmp %g1, 0x60 
0x00014450 <m+252>: bg 0x14464 <m+272> 
0x00014454 <m+256>: nop 
0x00014458 <m+260>: clr [ %fp + -24 ] 
0x0001445c <m+264>: b 0x1449c <m+328> 
0x00014460 <m+268>: nop 
0x00014464 <m+272>: ldub [ %fp + 0x48 ], %g1 
0x00014468 <m+276>: sll %g1, 0x18, %g1 
0x0001446c <m+280>: sra %g1, 0x18, %g1 
0x00014470 <m+284>: cmp %g1, 0x7a 
0x00014474 <m+288>: ble 0x14488 <m+308> 
0x00014478 <m+292>: nop 
0x0001447c <m+296>: clr [ %fp + -24 ] 
0x00014480 <m+300>: b 0x1449c <m+328> 
0x00014484 <m+304>: nop 
0x00014488 <m+308>: ldub [ %fp + 0x48 ], %g1 
0x0001448c <m+312>: sll %g1, 0x18, %g1 
0x00014490 <m+316>: sra %g1, 0x18, %g1 
0x00014494 <m+320>: add %g1, -96, %g1 
0x00014498 <m+324>: st %g1, [ %fp + -24 ] 
0x0001449c <m+328>: clr [ %fp + -28 ] 
0x000144a0 <m+332>: ldub [ %fp + -17 ], %g1 
0x000144a4 <m+336>: sll %g1, 0x18, %g1 
0x000144a8 <m+340>: sra %g1, 0x18, %o5 
0x000144ac <m+344>: ld [ %fp + -28 ], %g1 
0x000144b0 <m+348>: cmp %o5, %g1 
0x000144b4 <m+352>: ble 0x14568 <m+532> 
0x000144b8 <m+356>: nop 
0x000144bc <m+360>: ld [ %fp + 0x44 ], %g1 
0x000144c0 <m+364>: sll %g1, 3, %l0 
0x000144c4 <m+368>: ld [ %fp + -28 ], %o0 
0x000144c8 <m+372>: ld [ %fp + -28 ], %o1 
0x000144cc <m+376>: call 0x272ac <.umul@plt> 
0x000144d0 <m+380>: nop 
0x000144d4 <m+384>: mov %o0, %g1 
0x000144d8 <m+388>: add %l0, %g1, %g1 
0x000144dc <m+392>: add %g1, 8, %o5 
0x000144e0 <m+396>: ldub [ %fp + -17 ], %g1 
0x000144e4 <m+400>: sll %g1, 0x18, %g1 
0x000144e8 <m+404>: sra %g1, 0x18, %g1 
0x000144ec <m+408>: mov %o5, %o0 
0x000144f0 <m+412>: mov %g1, %o1 
0x000144f4 <m+416>: call 0x2727c <.rem@plt> 
0x000144f8 <m+420>: nop 
0x000144fc <m+424>: mov %o0, %g1 
0x00014500 <m+428>: st %g1, [ %fp + -32 ] 
0x00014504 <m+432>: ld [ %fp + -32 ], %g1 
0x00014508 <m+436>: ld [ %fp + -44 ], %o5 
0x0001450c <m+440>: add %o5, %g1, %g1 
0x00014510 <m+444>: ldub [ %g1 ], %g1 
0x00014514 <m+448>: sll %g1, 0x18, %g1 
0x00014518 <m+452>: sra %g1, 0x18, %g1 
0x0001451c <m+456>: st %g1, [ %fp + -36 ] 
0x00014520 <m+460>: ld [ %fp + -32 ], %g1 
0x00014524 <m+464>: ld [ %fp + -44 ], %o4 
0x00014528 <m+468>: add %o4, %g1, %o5 
0x0001452c <m+472>: ld [ %fp + -28 ], %g1 
0x00014530 <m+476>: ld [ %fp + -44 ], %o4 
0x00014534 <m+480>: add %o4, %g1, %g1 
0x00014538 <m+484>: ldub [ %g1 ], %g1 
0x0001453c <m+488>: stb %g1, [ %o5 ] 
0x00014540 <m+492>: ld [ %fp + -28 ], %g1 
0x00014544 <m+496>: ld [ %fp + -44 ], %o4 
0x00014548 <m+500>: add %o4, %g1, %o5 
0x0001454c <m+504>: ld [ %fp + -36 ], %g1 
0x00014550 <m+508>: stb %g1, [ %o5 ] 
0x00014554 <m+512>: ld [ %fp + -28 ], %g1 
0x00014558 <m+516>: inc %g1 
0x0001455c <m+520>: st %g1, [ %fp + -28 ] 
0x00014560 <m+524>: b 0x144a0 <m+332> 
0x00014564 <m+528>: nop 
0x00014568 <m+532>: ld [ %fp + -24 ], %g1 
0x0001456c <m+536>: ld [ %fp + -44 ], %o5 
0x00014570 <m+540>: add %o5, %g1, %g1 
0x00014574 <m+544>: ldub [ %g1 ], %g1 
0x00014578 <m+548>: sll %g1, 0x18, %g1 
0x0001457c <m+552>: sra %g1, 0x18, %g1 
0x00014580 <m+556>: ld [ %fp + -40 ], %sp 
0x00014584 <m+560>: mov %g1, %i0 
0x00014588 <m+564>: ret 
0x0001458c <m+568>: restore 

Answer 1

看拆卸：

gdb ./prog 
b FUNCTION_NAME_HERE 
r 
disassemble 

編輯：

反彙編看起來像SPARC。 您可能希望通過檢查出棧鋪設時的SPARC架構的開始：

http://www.sics.se/~psm/sparcstack.html

％FP聽起來像framepointer。沒有那麼多使用％fp的加載指令。我的猜測是

0x000143d4 <m+128>: ld [ %fp + -28 ], %g1 
0x000143d8 <m+132>: ld [ %fp + -44 ], %o4 

是函數的參數。