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cc65/libsrc/cbm/seekdir.c

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/*
* Ullrich von Bassewitz, 2012-06-03. Based on code by Groepaz.
*/
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include "dir.h"
void __fastcall__ seekdir (register DIR* dir, long offs)
{
unsigned o;
unsigned char count;
unsigned char buf[128];
/* Make sure we have a reasonable value for offs */
if (offs > 0x1000) {
errno = EINVAL;
return;
}
/* Close the directory file descriptor */
close (dir->fd);
/* Reopen it using the old name */
dir->fd = open (dir->name, O_RDONLY);
if (dir->fd < 0) {
/* Oops! */
return;
}
/* Skip until we've reached the target offset in the directory */
o = dir->off = offs;
while (o) {
/* Determine size of next chunk to read */
if (o > sizeof (buf)) {
count = sizeof (buf);
o -= sizeof (buf);
} else {
count = offs;
o = 0;
}
/* Skip */
if (!_dirread (dir, buf, count)) {
return;
}
}
}