proc/bad_longjmp.c

This is proc/bad_longjmp.c, an example to accompany the book, The Linux Programming Interface.

This file is not printed in the book; it is the solution to Exercise 6-2 (page 138).

The source code file is copyright 2022, Michael Kerrisk, and is licensed under the GNU General Public License, version 3.

In the listing below, the names of Linux system calls and C library functions are hyperlinked to manual pages from the Linux man-pages project, and the names of functions implemented in the book are hyperlinked to the implementations of those functions.

 

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  Cover of The Linux Programming Interface

Function list (Bold in this list means a function is not static)

/* bad_longjmp.c

   Demonstrate the incorrect use of longjmp() to jump into a function
   that has already returned. As a consequnce the program is killed by
   a SIGSEGV signal (Segmentation fault).
*/
#include <setjmp.h>
#include "tlpi_hdr.h"

static jmp_buf env;     /* Global buffer for saving environment */
static void
doJump(void)
{
    printf("Entered doJump\n");
    longjmp(env, 2);
    printf("Exiting doJump\n");
}
static void
setJump2(void)
{
    printf("Entered setJump2\n");
    setjmp(env);
    printf("Exiting setJump2\n");
}
static void
setJump(void)
{
    printf("Entered setJump\n");
    setJump2();
    printf("Exiting setJump\n");
}
int
main(int argc, char *argv[])
{
    setJump();
    doJump();
    printf("Back at main\n");

    exit(EXIT_SUCCESS);
}

 

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