jlaitine opened a new pull request, #19884:
URL: https://github.com/apache/nuttx/pull/19884
## Summary
When stdio buffering is disabled, fgetc/getchar on stdin always returned EOF
because fs_cookie and fs_oflags were left uninitialized and lib_fread_unlocked
bails out on (fs_oflags & O_RDOK) == 0.
Fix this by moving the initialization of the fs_cookie and fs_oflags outside
the CONFIG check; these fields need to be initialized regardless of
CONFIG_STDIO_DISABLE_BUFFERING.
In addition, initializing stream[i].fs_iofunc pointers to NULL is redundant
since the task group is allocated with kmm_zalloc/group_zalloc. Zero allocation
was already assumed on fs_flags, so remove the unnecessary code.
## Impact
Impacts all users of CONFIG_STDIO_DISABLE_BUFFERING=y. The C buffered I/O
API is broken. The flag just disables the internal buffering, not the break the
API (fgetc/fputc/printf/fread/fwrite).
## Testing
Tested on Pixhawk 5x board, the getchar() is broken and never returns
anything from stdin. Also putchar prints the characters to stdin due to
fs_cookie being uninitialized (left at 0).
With this fix, the getchar&putchar work again.
Test app (replaced hello.c , added CONFIG_STDIO_DISABLE_BUFFERING=y):
`
int main(int argc, FAR char *argv[])
{
int c;
printf("hello: press any key+enter\n");
fflush(stdout);
c = getchar();
printf("hello: got: %d (0x%02x)\n", c, c & 0xff);
if (c == EOF)
{
printf("hello: getchar returned EOF without blocking\n");
return 1;
}
printf("hello: echo via putchar: ");
putchar(c);
putchar('\n');
return 0;
}
`
--
This is an automated message from the Apache Git Service.
To respond to the message, please log on to GitHub and use the
URL above to go to the specific comment.
To unsubscribe, e-mail: [email protected]
For queries about this service, please contact Infrastructure at:
[email protected]
