Prevalence of Confusing Code in Software Projects Atoms of - - PowerPoint PPT Presentation

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Prevalence of Confusing Code in Software Projects Atoms of - - PowerPoint PPT Presentation

Feb 17, 2023 320 likes •839 views

Prevalence of Confusing Code in Software Projects Atoms of Confusion in the Wild Dan Gopstein NYU Hongwei Henry Zhou, Phyllis Frankl, Justin Cappos AtomsOfConfusion.com 1 Atoms of Confusion in the Wild if ((err =

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SLIDE 1

Prevalence of Confusing Code in Software Projects

Atoms of Confusion in the Wild

Dan Gopstein NYU

Hongwei Henry Zhou, Phyllis Frankl, Justin Cappos AtomsOfConfusion.com

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SLIDE 2

Atoms of Confusion in the Wild

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if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail;

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SLIDE 3

Atoms of Confusion in the Wild

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if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail;

Apple’s Goto Fail bug

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SLIDE 4

Atoms of Confusion in the Wild

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if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) goto fail; goto fail;

Apple’s Goto Fail bug

Two Atoms of Confusion:

  • Assignment as Value
  • Omitted Curly Brace
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SLIDE 5

Atoms of Confusion in the Wild

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if ((err = SSLHashSHA1.update(&hashCtx, &signedParams)) != 0) { goto fail; goto fail;

Apple’s Goto Fail bug

{ }

Two Atoms of Confusion:

  • Assignment as Value
  • Omitted Curly Brace
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SLIDE 6

Outline

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Atoms of Confusion are ...

  • Confusing - Both in the lab and in the wild
  • Prevalent - Occurring frequently in practice
  • Buggy - Causing or correlated with faults
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SLIDE 7

Outline

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Atoms of Confusion are ...

  • Confusing - Both in the lab and in the wild
  • Prevalent - Occurring frequently in practice
  • Buggy - Causing or correlated with faults
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SLIDE 8

Atoms of Confusion

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Understanding Misunderstandings in Source Code

  • D. Gopstein, J. Iannacone, Y. Yan, L. DeLong,
  • Y. Zhuang, M. Yeh, J. Cappos

ESEC/FSE 2017

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SLIDE 9

printf("%d",013) Confusion

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When a person and a machine read the same piece of code, yet come to different conclusions about its output.

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Measurable printf("%d",013)

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printf("%d",11)

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SLIDE 11

Measurable

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printf("%d",013) printf("%d",11)

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SLIDE 12

Measurable

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printf("%d",013) printf("%d",11)

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SLIDE 13

Precise

The smallest piece of code that can cause confusion

Other Stuff Fluff Confusing Code Confusing Code

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SLIDE 14

Precise

The smallest piece of code that can cause confusion

Other Stuff Fluff Confusing Code Confusing Code

Atom of Confusion

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SLIDE 15

Identified Atoms

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φ

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SLIDE 16

Atoms of Confusion

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Understanding Misunderstandings in Source Code

  • D. Gopstein, J. Iannacone, Y. Yan, L. DeLong, Y. Zhuang, M. Yeh, J.

Cappos ESEC/FSE 2017

V1 && F2()

Logic as Control Flow

V1 = ++V2;

Pre-Increment

printf("%d",013)

Literal Encoding

0 && 1 || 2

Operator Precedence φ = .63 φ = .48 φ = .28 φ = .33

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SLIDE 17

Outline

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Atoms of Confusion are ...

  • Confusing - Both in the lab and in the wild
  • Prevalent - Occurring frequently in practice
  • Buggy - Causing or correlated with faults
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SLIDE 18

Classifier

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if = x 2 foo () ; if (x = 2) foo();

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SLIDE 19

Classifier

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if = x 2 foo () ; if (x = 2) foo(); Classifier

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SLIDE 20

Classifier

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if = x 2 foo () ; if (x = 2) foo(); Classifier Two Atoms of Confusion:

  • Assignment as Value
  • Omitted Curly Brace

{

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SLIDE 21

Corpus

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SLIDE 22

How Often do Atoms Occur?

1 atom every ~12 lines 1 atom every ~44 lines

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SLIDE 23

Which Atoms Occur Most Frequently?

1 every ~51 lines 1 every ~1.6 million

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SLIDE 24

Are Confusing Patterns Less Common?

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φ

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SLIDE 25

Prevalent

ulpmc->cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE) | is_t4(sc) ? F_ULP_MEMIO_ORDER : F_T5_ULP_MEMIO_IMM);

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https://github.com/freebsd/freebsd/blob/3c60e22da7d4460db7adb2b916f55e22b7d60e26/sys/dev/cxgbe/tom/t4_ddp.c#L766

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SLIDE 26

Prevalent

ulpmc->cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE) | is_t4(sc) ? F_ULP_MEMIO_ORDER : F_T5_ULP_MEMIO_IMM);

Contains:

  • Operator Precedence
  • Conditional Operator
  • Implicit Predicate

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https://github.com/freebsd/freebsd/blob/3c60e22da7d4460db7adb2b916f55e22b7d60e26/sys/dev/cxgbe/tom/t4_ddp.c#L766

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SLIDE 27

Prevalent

ulpmc->cmd = htobe32(V_ULPTX_CMD(ULP_TX_MEM_WRITE) | is_t4(sc) ? F_ULP_MEMIO_ORDER : F_T5_ULP_MEMIO_IMM);

Contains:

  • Operator Precedence
  • Conditional Operator
  • Implicit Predicate

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https://github.com/freebsd/freebsd/blob/3c60e22da7d4460db7adb2b916f55e22b7d60e26/sys/dev/cxgbe/tom/t4_ddp.c#L766

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SLIDE 28

Outline

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Atoms of Confusion are ...

  • Confusing - Both in the lab and in the wild
  • Prevalent - Occurring frequently in practice
  • Buggy - Causing or correlated with faults
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SLIDE 29

Are Atoms Removed More In Bug Fix Commits?

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SLIDE 30

Are Atoms Commented More Often?

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SLIDE 31

Are Atoms Commented More Often?

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1.00

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SLIDE 32

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x))

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SLIDE 33

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => ???

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SLIDE 34

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1

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SLIDE 35

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1 ABS(-2) => ???

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SLIDE 36

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1 ABS(-2) => 2

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SLIDE 37

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1 ABS(-2) => 2 ABS(1-2) => ???

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SLIDE 38

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1 ABS(-2) => 2 ABS(1-2) => 1

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SLIDE 39

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1) => 1 ABS(-2) => 2 ABS(1-2) => 1 -3

X

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SLIDE 40

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2)

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SLIDE 41

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) (( x ) < 0 ? (- x ) : ( x ))

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SLIDE 42

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) (( x ) < 0 ? (- x ) : ( x ))

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SLIDE 43

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) ((1-2) < 0 ? (-1-2) : (1-2))

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SLIDE 44

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) ((1-2) < 0 ? (-1-2) : (1-2))

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SLIDE 45

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) ((1-2) < 0 ? (-1-2) : (1-2))

  • 3
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SLIDE 46

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x)) ABS(1-2) ((1-2) < 0 ? (-1-2) : (1-2))

  • 3
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SLIDE 47

Buggy

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https://github.com/torvalds/linux/commit/7aa92c4229fefff0cab6930cf977f4a0e3e606d8

#define ABS(x) ((x) < 0 ? (-x) : (x))

Macro Operator Precedence

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SLIDE 48

Buggy

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SLIDE 49

Summary

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Atoms of Confusion are ...

  • Confusing

○ Atoms are statistically more confusing than other code in the lab ○ Atoms are 13% more likely to be commented than other code

  • Prevalent

○ We found millions of examples in our corpus ○ 1 in ~23 lines of code has an atom

  • Buggy

○ Bug-fix commits are 25% more likely remove atoms ○ We found and fixed a handful of bugs in Linux

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SLIDE 50

Prevalence of Confusing Code in Software Projects

Atoms of Confusion in the Wild

Dan Gopstein NYU

Hongwei Henry Zhou, Phyllis Frankl, Justin Cappos AtomsOfConfusion.com

Thank You

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