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setjmp.c リンカ・ローダ実践開発テクニック坂井弘亮(20) coding(134)

Last updated at 2024-07-28Posted at 2024-07-14

リンカ・ローダ

各社のリンカ、ローダ、libralian、locator、boot loaderなどの機能を調べる上で、
「リンカ・ローダ実践開発テクニック」坂井弘亮
は、手がかりをつかめるかもしれない。

リンカ・ローダ実践開発テクニック―実行ファイルを作成するために必須の技術-COMPUTER-TECHNOLOGY-坂井-弘亮
https://www.amazon.co.jp//dp/4789838072/
https://bookmeter.com/books/630946

参考文献にあるLinkers & Loadersは斜め読みしただけで、自分ではこういう道具は作らないだろうと勝手に思っていた。本書では簡易リンカの作成と、道具の作り方まで有るのがすごい。「setjmp()とlongjmp()」というコラムが１頁に入りきらず４頁になっているのに、節にしていないところも興味深い。

<この項は書きかけです。順次追記します。>
This article is not completed. I will add some words in order.

content

content
https://shop.cqpub.co.jp/hanbai/books/38/38071.html

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binary.c リンカ・ローダ実践開発テクニック坂井弘亮(2) coding(90)
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combine.c リンカ・ローダ実践開発テクニック坂井弘亮(3) coding(91)
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continue.c リンカ・ローダ実践開発テクニック坂井弘亮(6) coding(95)
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down.c リンカ・ローダ実践開発テクニック坂井弘亮(7) coding(96)
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ctors.c リンカ・ローダ実践開発テクニック坂井弘亮(8) coding(97)
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edata.c リンカ・ローダ実践開発テクニック坂井弘亮(10) coding(124)
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elfread.c リンカ・ローダ実践開発テクニック坂井弘亮(11) coding(125)
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edata.c リンカ・ローダ実践開発テクニック坂井弘亮(12) coding(126)
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hello.c リンカ・ローダ実践開発テクニック坂井弘亮(13) coding(127)
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inicialize.c リンカ・ローダ実践開発テクニック坂井弘亮(14) coding(128)
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layer.c リンカ・ローダ実践開発テクニック坂井弘亮(15) coding(129)
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ordermain.c リンカ・ローダ実践開発テクニック坂井弘亮(16) coding(130)
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pointer.c リンカ・ローダ実践開発テクニック坂井弘亮(17) coding(131)
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rasm.c リンカ・ローダ実践開発テクニック坂井弘亮(18) coding(132)
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section.c リンカ・ローダ実践開発テクニック坂井弘亮(19) coding(133)
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setjmp.c リンカ・ローダ実践開発テクニック坂井弘亮(20) coding(134)
https://qiita.com/kaizen_nagoya/items/648200e728c982e79819

sample.c リンカ・ローダ実践開発テクニック坂井弘亮(21) coding(135)
https://qiita.com/kaizen_nagoya/items/360d99ed47ddc4780bf2

N3220 Information technology — Programming languages — C N3220 working draft
https://www.open-std.org/JTC1/SC22/WG14/www/docs/n3220.pdf
N3219 Information technology — Programming languages — C ISO/IEC 9899:2023 DIS Draft
https://www.open-std.org/jtc1/sc22/wg14/www/docs/n3219.pdf

プログラムには少し手を入れています。最近の型宣言に厳しい感じで。

estjmp.c

 <stdio.h>
#include <setjmp.h>

static jmp_buf buf;

int func(void)
{
  printf("func()\n");
  _longjmp(buf, 1);
  printf("return from _longjmp()\n");
}

int main(void)
{
  int ret;

  ret = _setjmp(buf);
  printf("return from _setjmp()\n");
  if (ret == 0) {
    printf("return with zero.\n");
    func();
    printf("return from func()\n");
  } else {
    /* _longjmp() からの復旧 */
    printf("ret = %d\n", ret);
  }
  printf("exit.\n");
  exit (0);
}

setjmp

C N3219 7 Library 7.13 Non-localjumps
7.13.1 Save calling environment 7.13.1.1 The setjmp macro

Synopsis

#include <setjmp.h>
int setjmp(jmp_buf env);

Description

The setjmp macro saves its calling environment in its jmp_buf argument for later use by the longjmp function.

Returns

If the return is from a direct invocation, the setjmp macro returns the value zero. If the return is from a call to the longjmp function, the setjmp macro returns a nonzero value.

Environmental limits

An invocation of the setjmp macro shall appear only in one of the following contexts:
— the entire controlling expression of a selection or iteration statement;
— one operand of a relational or equality operator with the other operand an integer constant expression, with the resulting expression being the entire controlling expression of a selection or iteration statement;
— the operand of a unary ! operator with the resulting expression being the entire controlling expression of a selection or iteration statement; or
— the entire expression of an expression statement (possibly cast to void).
If the invocation appears in any other context, the behavior is undefined.

longjmp

C N3219 7 Library 7.13 Non-localjumps
7.13.2 Restore calling environment 7.13.2.1 The longjmp function

Synopsis

#include <setjmp.h>
[[noreturn]] void longjmp(jmp_buf env, int val);

Description

The longjmp function restores the environment saved by the most recent invocation of the setjmp macro in the same invocation of the program with the corresponding jmp_buf argument. If there has been no such invocation, or if the invocation was from another thread of execution, or if the function containing the invocation of the setjmp macro has terminated execution290) in the interim, or if the invocation of the setjmp macro was within the scope of an identifier with variably modified type and execution has left that scope in the interim, the behavior is undefined.
All accessible objects have values, and all other components of the abstract machine291) have state, as of the time the longjmp function was called, except that the representation of objects of automatic storage duration that are local to the function containing the invocation of the corresponding setjmp macro that do not have volatile-qualified type and have been changed between the setjmp invocation and longjmp call is indeterminate.

Returns

After longjmp is completed, thread execution continues as if the corresponding invocation of the setjmp macro had just returned the value specified by val. The longjmp function cannot cause the setjmp macro to return the value 0; if val is 0, the setjmp macro returns the value 1.
EXAMPLE The longjmp function that returns control back to the point of the setjmp invocation can cause memory associated with a variable length array object to be squandered.

#include <setjmp.h> jmp_buf buf;
void g(int n);
void h(int n);
int n = 6; void f(void)
{
}
int x[n]; setjmp(buf); g(n);
// valid: f is not terminated
// a may remain allocated
// b may remain allocated // can cause memory loss
void g(int n) {
int a[n];
h(n); }
void h(int n) {
}
int b[n]; longjmp(buf, 2);

290)For example, by executing a return statement or because another longjmp call has caused a transfer to a setjmp invocation in a function earlier in the set of nested calls.
291)This includes, but is not limited to, the floating-point environment and the state of open files.

setjmp.c リンカ・ローダ実践開発テクニック坂井弘亮(20) coding(134)

リンカ・ローダ

content

setjmp

Synopsis

Description

Returns

Environmental limits

longjmp

Synopsis

Description

Returns

関連資料

自己記事一覧

文書履歴(document history)

最後までおよみいただきありがとう4ざいました。

Thank you very much for reading to the last sentence.

setjmp.c リンカ・ローダ実践開発テクニック 坂井弘亮(20) coding(134)

リンカ・ローダ

content

setjmp

Synopsis

Description

Returns

Environmental limits

longjmp

Synopsis

Description

Returns

関連資料

自己記事一覧

文書履歴(document history)

最後までおよみいただきありがとう4ざいました。

Thank you very much for reading to the last sentence.

setjmp.c リンカ・ローダ実践開発テクニック坂井弘亮(20) coding(134)