The Architecture of Open Source Applications : GDB

1. GDB Stan Shebs 아꿈사

2. http://cafe.naver.com/architect1.cafe 이상훈

3. 목차 • GDB

4. 소개 • GDB

5. 목표 • 내부

6. 구조

7. 다이어그램 • 내부

8. 동작

9. 예시 • 데이터

10. 구조 • 심볼사이드 • 타겟사이드 • 인터페이스 • 개발프로세스 • 교훈

11. 목차 • GDB

12. 소개 • GDB

13. 목표 • 다이어그램 • 내부

14. 동작

17. GDB

18. 소개 • GNU Debugger • GNU(GNU is not Unix) = OS • GCC, Emacs, ... • Richard Stallman

19. 목차 • GDB

20. 소개 • GDB

21. 목표 • 다이어그램 • 내부

22. 동작

25. GDB

26. 목표 • responsive • permissive • handle large programs • different compilers • optimized programs • able to run everywhere

27. 목차 • GDB

28. 소개 • GDB

29. 목표 • 내부

30. 구조

32. 동작

35. 다이어그램

36. Symbol

37. Side • symbolic information • function and variable names and types • line numbers • parses expressions • ﬁnds memory address by line number

38. Target

39. Side • start and stop the program • read memory and registers • modify them • catch signals

40. Target

41. Side • ptrace (process trace) • embedded system

42. Both

43. Side • independent • read code, display variables without running the program • machine-language debugging without symbols

44. Both

45. Side

46. 목차 • GDB

47. 소개 • GDB

48. 목표 • 내부

49. 구조

50. 다이어그램 • 동작

53. Operation • print int-type variable • 1. command interpreter (tree traversal) • 2. ﬁnd variable address (symbol table) • 3. call target-side function(read 4-byte) • 4. formatting function(decimal number)

54. Operation • “step” command • program counter(PC) register

55. 목차 • GDB

56. 소개 • GDB

57. 목표 • 내부

58. 구조

60. 동작

63. Data

64. Structure • Breakpoints • Symbols Symbol tables • Stack frames • Expressions • Values

65. Data

66. Structure •Breakpoints • Symbols Symbol tables • Stack frames • Expressions • Values

67. Breakpoints • 유저에게 노출되고 조작되는 구조체 • break 명령으로 생성, location 설정 • location = function name, line number, memory address • 결국은 주소값으로 계산됨

68. Breakpoints • 원래 형태도 보관(재컴파일, 리로딩) • 한 location이 여러곳을 가리킬 수 있음 • inline function, template methods

69. Data

70. Structure • Breakpoints • Symbols Symbol tables • Stack frames • Expressions • Values

71. Symbols

73. Symbol

74. Tables • LARGE (up to gigabytes of RAM) • Major performance bottle-neck • string -- address map

75. Data

76. Structure • Breakpoints • Symbols Symbol tables •Stack frames • Expressions • Values

77. Stackframes • push program counter(PC) to stack with arguments • vary from chip architecture, OS, compiler, optimization options

78. Stackframes • [stack frame to new chip] == BIG JOB! • buggy programs, incomplete frames, can stop anywhere, highly optimized programs

79. Data

80. Structure • Breakpoints • Symbols Symbol tables • Stack frames •Expressions • Values

81. Expressions • Build Tree structure (of node objects) • node object = union - support different languages • ex) Fortran var. - C var.

82. Data

83. Structure • Breakpoints • Symbols Symbol tables • Stack frames • Expressions •Values

84. Values • Even value is structure • Various properties • r-value, l-value • bool - constructed lazily

85. 목차 • GDB

86. 소개 • GDB

87. 목표 • 내부

88. 구조

90. 동작

93. Symbol

94. Side • read executable ﬁle • extract symbolic information • build symbol table

95. Symbol

96. Side • BFD (Binary File Descriptor) universal library - handle exe obj ﬁle • 1. COFF (Common Object ﬁle format) System V Unix, MS Windows • 2. ELF(Executable and Linkable Format) Unix, Linux, embedded systems

97. Symbol

98. Side • Partial Symbol Tables Read global symbols ﬁrst Dynamically read rest symbols

99. Symbol

100. Side • Language support Yacc grammar fed by lexical analyzer

101. 목차 • GDB

102. 소개 • GDB

103. 목표 • 내부

104. 구조

106. 동작

107. 예시 • 데이터

109. Target

110. Side • Manipulation of program execution raw data • step instructions • dump raw memory - no need symbol data

111. Target

112. Side • Target Vector • target vector, which is basically a class of objects • each deﬁnes the speciﬁcs of a type of target system

113. Target

114. Side

115. Target

116. Side • Target can be changed • target vector get variable from exe ﬁle before program run • target vector get variable from memory after program run

117. Target

118. Side • Those targets are managed by Target Stack.

119. Target

120. Side • Gdbarch • Object-based design • Object per architecture

121. Target

122. Side • Execution Control • wait_for_inferior() • trap instruction, breakpoint check( condition)

123. Target

124. Side • The Remote Protocol • designed for embedded systems • protocol is simple.

125. Target

126. Side • GDBserver • Receive Packets • mini GDB

127. 목차 • GDB

128. 소개 • GDB

129. 목표 • 내부

130. 구조

132. 동작

133. 예시 • 데이터

135. Interfaces • 1. Command Line Interface - Use GNU library [readline] • interpret) “command option...” - command table, expression

136. Interfaces • 2. Machine Interface • easy to parse by GUI programs

137. Interfaces • 3. Others - few GUI interfaces - GDBtk, Insight... - but no killer program

138. 목차 • GDB

139. 소개 • GDB

140. 목표 • 내부

141. 구조

143. 동작

144. 예시 • 데이터

146. 개발

147. 프로세스 •초기

148. 성당

149. 모델(시장과

150. 성당) -

151. 닫힌

152. 개발.

153. 개발

154. 후

155. 배포. •1999년

156. 소스저장소

157. 오픈 -

158. 좀

159. 더

160. 많은

161. 관리자 -

162. 개발

163. 속도

164. 향상

165. 개발

166. 프로세스 • Test suite - Highly system speciﬁc • DejaGNU - testing framework • Send command - pattern matching the output (regular expressions)

167. 개발

168. 프로세스 • 18,000 test cases • No one has access to all platform (that might be affected by a change) • 10-20 failures OK.

169. 목차 • GDB

170. 소개 • GDB

171. 목표 • 내부

172. 구조

174. 동작

175. 예시 • 데이터

177. 교훈 • Open Development Wins • Make a Plan, but Expect It to Change • Don't Get Too Attached to the Code

178. The End

The Architecture of Open Source Applications : GDB

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Editor's Notes