printf, stdout and setvbuf

[vippstar]

Is there a memory leak in this particular program:

#include <stdio.h>
#include <stdlib.h>

int main(void) {

printf("Hello, world\n");
if(setvbuf(stdout, NULL, _IONBF, 0) != 0) {
perror("setvbuf");
return EXIT_FAILURE;
}
return 0;
}

I imagine the case that printf() provides stdout a malloc'ed buffer.
I know implementations do this, but I can't find the wording in the
standard that mentions this.

[santosh]

vi******@gmail.com wrote:

Is there a memory leak in this particular program:

#include <stdio.h>
#include <stdlib.h>

int main(void) {

printf("Hello, world\n");
if(setvbuf(stdout, NULL, _IONBF, 0) != 0) {
perror("setvbuf");
return EXIT_FAILURE;
}
return 0;
}

I imagine the case that printf() provides stdout a malloc'ed buffer.
I know implementations do this, but I can't find the wording in the
standard that mentions this.

Well, your program exhibits undefined behaviour because you are calling
setvbuf after an I/O operation has already been done on stdout.

[vippstar]

On Jul 13, 4:41 pm, santosh <[e-mail]:

[e-mail] wrote:

Is there a memory leak in this particular program:

#include <stdio.h>
#include <stdlib.h>

int main(void) {

printf("Hello, world\n");
if(setvbuf(stdout, NULL, _IONBF, 0) != 0) {
perror("setvbuf");
return EXIT_FAILURE;
}
return 0;
}

I imagine the case that printf() provides stdout a malloc'ed buffer.
I know implementations do this, but I can't find the wording in the
standard that mentions this.

Well, your program exhibits undefined behaviour because you are calling
setvbuf after an I/O operation has already been done on stdout.

Oh! Then nevermind. Now it makes sense.