busybox/libbb/xgetcwd.c

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/*
* xgetcwd.c -- return current directory with unlimited length
* Copyright (C) 1992, 1996 Free Software Foundation, Inc.
* Written by David MacKenzie <djm@gnu.ai.mit.edu>.
*
* Special function for busybox written by Vladimir Oleynik <vodz@usa.net>
*/
#include <stdlib.h>
#include <errno.h>
#include <unistd.h>
#include <limits.h>
#include <sys/param.h>
#include "libbb.h"
/* Amount to increase buffer size by in each try. */
#define PATH_INCR 32
/* Return the current directory, newly allocated, arbitrarily long.
Return NULL and set errno on error.
If argument is not NULL (previous usage allocate memory), call free()
*/
char *
xgetcwd (char *cwd)
{
char *ret;
unsigned path_max;
errno = 0;
path_max = (unsigned) PATH_MAX;
path_max += 2; /* The getcwd docs say to do this. */
if(cwd==0)
cwd = xmalloc (path_max);
errno = 0;
while ((ret = getcwd (cwd, path_max)) == NULL && errno == ERANGE) {
path_max += PATH_INCR;
cwd = xrealloc (cwd, path_max);
errno = 0;
}
if (ret == NULL) {
int save_errno = errno;
free (cwd);
errno = save_errno;
perror_msg("getcwd()");
return NULL;
}
return cwd;
}