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/* Copyright(c) 1986 Association of Universities for Research in Astronomy Inc.
*/
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <ctype.h>
#define import_kernel
#define import_knames
#define import_spp
#include <iraf.h>
#define SZ_TESTBLOCK 1024 /* for TEXT/BINARY heuristic */
#define MAX_LINELEN 256 /* when looking for newlines */
#define R 04 /* UNIX access() codes */
#define W 02
#define ctrlcode(c) ((c) >= '\007' && (c) <= '\017')
/* ZFACSS -- Try to determine if FILE is accessible in the indicated MODE.
* If file is accessible for reading and TYPE is given as TEXT_FILE,
* look at the first block of data to see if it is legal text data.
* ACCESS(file,0,0) merely checks that the file exists. Any file is a
* legal binary file.
*/
int
ZFACSS (
PKCHAR *fname,
XINT *mode,
XINT *type,
XINT *status
)
{
static char modebits[] = { 0, R, R|W, W, R|W };
register char *ip, ch;
register int n;
char buf[SZ_TESTBLOCK];
int fd, acmode, accessible, nchars, newline_seen;
struct stat fi;
/* Null filename? */
if (*(char *)fname == EOS) {
*status = NO;
return (NO);
}
/* Map IRAF access mode into UNIX access mode.
*/
if (*mode >= READ_ONLY && *mode <= APPEND)
acmode = modebits[*mode];
else if (*mode == 0 && *type != 0)
acmode = R;
else
acmode = 0;
/* Is file accessible with the given mode.
*/
accessible = (access ((char *)fname, acmode) == 0);
if (accessible && *type == DIRECTORY_FILE) {
stat ((char *)fname, &fi);
if (fi.st_mode & S_IFDIR)
*status = YES;
else
*status = NO;
return (*status);
} else if (!accessible && *type == SYMLINK_FILE) {
lstat ((char *)fname, &fi);
if (fi.st_mode & S_IFLNK)
*status = YES;
else
*status = NO;
return (*status);
}
/* If we have to check the file type (text or binary), then we must
* actually look at some file data since UNIX does not discriminate
* between text and binary files. NOTE that this heuristic is not
* completely reliable and can fail, although in practice it does
* very well.
*/
if (accessible && (acmode & R) && *type != 0) {
stat ((char *)fname, &fi);
/* Do NOT read from a special device (may block) */
if ((fi.st_mode & S_IFMT) & S_IFREG) {
/* If we are testing for a text file the portion of the file
* tested must consist of only printable ascii characters or
* whitespace, with occasional newline line delimiters.
* Control characters embedded in the text will cause the
* heuristic to fail. We require newlines to be present in
* the text to disinguish the case of a binary file containing
* only ascii data, e.g., a cardimage file.
*/
fd = open ((char *)fname, 0);
if (fd >= 0 && (nchars = read (fd, buf, SZ_TESTBLOCK)) > 0) {
ip = buf;
for (n=nchars, newline_seen=0; --n >= 0; ) {
ch = *ip++;
if (ch == '\n')
newline_seen++;
else if (!isprint(ch) && !isspace(ch) && !ctrlcode(ch))
break;
}
if (*type == TEXT_FILE) {
if (n >= 0 || (nchars > MAX_LINELEN && !newline_seen))
accessible = NO;
} else if (*type == BINARY_FILE && n < 0)
accessible = NO;
close (fd);
}
} else if (fi.st_mode & S_IFCHR && *type != TEXT_FILE)
accessible = NO;
}
(*status) = accessible;
return (*status);
}
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