Fscanf /vfscanf problem with setting file position indicator

[maska989]

• Using fscanf with specifier %c shall move the position indicator one place further but in this case, this function tries to pass over all characters in the file.

• Tested on Host-generic-pc and Ia32-generic-qemu.

• To reproduce issue copy following code:

#include <stdio.h>
int main(void)
{
    char c[1];
    FILE *rd;

    rd = fopen("test", "w+");

    fputs("abc", rd);

    fseek(rd, 0, SEEK_SET);
    printf("\nposi before = %ld\n", ftell(rd));

    fscanf(rd, "%c", c);
    printf("\nposi after = %ld\n", ftell(rd));

    fclose(rd);
}

• Outcome on Host-generic-pc and ia32-generic-qemu:

[gerard5]

@maska989 I added a fix, please verify if it works in your test cases.

[maska989]

@gerard5 Works like a charm.

[maska989]

https://github.com/phoenix-rtos/phoenix-rtos-tests/blob/c13ef424dff7c1f0f88f02e4a67104f6d9ed5d22/libc/stdio_scanf.c#L3330-L3333