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  1. //
  2. // WILL NOT WORK ON ideone.com!!! COMPILE ON YOUR OWN LINUX MACHINE USING
  3. //
  4. // gcc -std=gnu11 -Wall -Wextra -Wconversion -Werror -pedantic -pedantic-errors -o prog prog.c
  5. //
  6.  
  7. #include <alloca.h>
  8. #include <assert.h>
  9. #include <errno.h>
  10. #include <fcntl.h>
  11. #include <stdio.h>
  12. #include <stdlib.h>
  13. #include <string.h>
  14. #include <sys/types.h>
  15. #include <unistd.h>
  16.  
  17. void pputs(char const * const string) {
  18.         printf("%d(%d): ", getpid(), getppid());
  19.         puts(string);
  20. }
  21.  
  22. int main() {
  23. 		pputs(__FILE__);
  24.         pputs("reading from stdin [press Enter]");
  25.         assert(errno == 0);
  26.         read(STDIN_FILENO, alloca(0x100), 0x100);
  27.         assert(errno == 0);
  28.         pputs("forking");
  29.         if (fork()) {
  30.                 // parent
  31.                 sleep(1);
  32.                 pputs("slept one second");
  33.                 pputs("reading from stdin [should fail with EWOULDBLOCK]");
  34.                 assert(errno == 0);
  35.                 read(STDIN_FILENO, alloca(0x100), 0x100);
  36.                 assert(errno == EWOULDBLOCK);
  37.                 errno = 0;
  38.                 pputs(strerror(EWOULDBLOCK));
  39.         } else {
  40.                 // child
  41.                 pputs("setting stdin to non-blocking");
  42.                 int const flags = fcntl(STDIN_FILENO, F_GETFL, 0);
  43.                 fcntl(STDIN_FILENO, F_SETFL, flags | O_NONBLOCK);
  44.         }
  45.         pputs("exiting");
  46.         exit(EXIT_SUCCESS);
  47. }
Runtime error #stdin #stdout #stderr 0s 15240KB
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		 stdout
					

				
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1310(1309): prog.cpp
1310(1309): reading from stdin [press Enter]
1310(1309): forking
1362(1310): setting stdin to non-blocking
1362(1310): exiting
1310(1309): prog.cpp
1310(1309): reading from stdin [press Enter]
1310(1309): forking
1310(1309): slept one second
1310(1309): reading from stdin [should fail with EWOULDBLOCK]


	

		
	 
	
		
	
		 stderr
					

				
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prog: prog.cpp:36: int main(): Assertion `errno == EWOULDBLOCK' failed.


    

	
			

					
			
			
			
			
			
			
			
			

			
			
			
		

	
		
		

			

			                        







			
			

				

	
					
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language:

						
C++14 (gcc 8.3)

					

					

						
created:
								
						
7 years ago

					

					

						
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