Details of this program are described later in the

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Unformatted text preview: to handle this kind of error recovery. Figure 8.34 shows a simple program that illustrates this basic technique. The program uses signals and nonlocal jumps to do a soft restart whenever the user types ctrl-c at the keyboard. The sigsetjmp and siglongjmp functions are versions of setjmp and longjmp that can be used by signal handlers. The initial call to the sigsetjmp function saves the stack and signal context when the program first starts. The main routine then enters an infinite processing loop. When the user types ctrl-c, the shell sends a SIGINT signal to the process, which catches it. Instead of returning from the signal handler, which would pass back control back to the interrupted processing loop, the handler performs a nonlocal jump back to the 8.6. NONLOCAL JUMPS 439 code/ecf/setjmp.c 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 #include "csapp.h" jmp_buf buf; int error1 = 0; int error2 = 1; void foo(void), bar(void); int main() { int rc; rc = setjmp(buf); if (rc == 0) foo(); else if (rc == 1) printf("Detected an error1 condition in foo\n"); else if (rc == 2) printf("Detected an error2 condition in foo\n"); else printf("Unknown error condition in foo\n"); exit(0); } /* deeply nested function foo */ void foo(void) { if (error1) longjmp(buf, 1)...
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This note was uploaded on 09/02/2010 for the course ELECTRICAL 360 taught by Professor Schultz during the Spring '10 term at BYU.

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