int dhcp_settag(dhcp_t *dp, int tag, void *data, size_t len)
{
/* Add a tag to a DHCP packet. No padding. Only do the options field.
* (This is Minix, we don't need megabytes of silly bits of data.)
* The length may be zero to delete a tag.
*/
u8_t *p;
int n;
if (tag <= 0 || tag >= 255) return 0;
for (p= dp->options; p < arraylimit(dp->options) && *p != 255; p += n) {
n= 1 + 1 + p[1];
if (*p == tag) {
/* The tag is already there, remove it so it gets replaced. */
memmove(p, p + n, arraylimit(dp->options) - (p + n));
memset(arraylimit(dp->options) - n, 255, n);
n= 0;
}
}
/* Add tag. */
if (len == 0) {
/* We're merely deleting a tag. */
} else if (p + 1 + 1 + len <= arraylimit(dp->options)) {
*p++ = tag;
*p++ = len;
memcpy(p, data, len);
} else {
/* Oops, it didn't fit? Is this really Minix??? */
return 0;
}
return 1;
}
struct group *getgrent(void)
/* Read one entry from the group file. */
{
char *p;
char **mem;
/* Open the file if not yet open. */
if (grfd < 0 && setgrent() < 0) return nil;
/* Until a good line is read. */
for (;;) {
if (!getline()) return nil; /* EOF or corrupt. */
if ((entry.gr_name= scan_punct(':')) == nil) continue;
if ((entry.gr_passwd= scan_punct(':')) == nil) continue;
if ((p= scan_punct(':')) == nil) continue;
entry.gr_gid= strtol(p, nil, 0);
entry.gr_mem= mem= members;
if (*lineptr != '\n') {
do {
if ((*mem= scan_punct(',')) == nil) goto again;
if (mem < arraylimit(members) - 1) mem++;
} while (*lineptr != 0);
}
*mem= nil;
return &entry;
again:;
}
}
void forget(void *mem)
/* Some objects must be deleted in time, but not just yet. */
{
static void *death_row[2][50];
static void **dp[2]= { death_row[0], death_row[1] };
deallocate(*dp[keep]);
*dp[keep]++= mem;
if (dp[keep] == arraylimit(death_row[keep])) dp[keep]= death_row[keep];
}
static int getline(void)
/* Get one line from the password file, return 0 if bad or EOF. */
{
lineptr= pwline;
do {
if (buflen == 0) {
if ((buflen= read(pwfd, buf, sizeof(buf))) <= 0)
return 0;
bufptr= buf;
}
if (lineptr == arraylimit(pwline)) return 0;
buflen--;
} while ((*lineptr++ = *bufptr++) != '\n');
lineptr= pwline;
return 1;
}
static int getline(void)
/* Get one line from the ttytab file, return 0 if bad or EOF. */
{
lineptr= ttline;
argvptr= ttargv;
do {
if (buflen == 0) {
if ((buflen= read(ttfd, buf, sizeof(buf))) <= 0)
return 0;
bufptr= buf;
}
if (lineptr == arraylimit(ttline)) return 0;
buflen--;
} while ((*lineptr++ = *bufptr++) != '\n');
lineptr= ttline;
return 1;
}
static char *link_islink(const struct stat *stp, const char *file)
{
/* Tell if a file, which stat(2) information in '*stp', has been seen
* earlier by this function under a different name. If not return a
* null pointer with errno set to ENOENT, otherwise return the name of
* the link. Return a null pointer with an error code in errno for any
* error, using E2BIG for a too long file name.
*
* Use link_islink(nil, nil) to reset all bookkeeping.
*
* Call for a file twice to delete it from the store.
*/
typedef struct link { /* In-memory link store. */
struct link *next; /* Hash chain on inode number. */
ino_t ino; /* File's inode number. */
off_t off; /* Offset to more info in temp file. */
} link_t;
typedef struct dlink { /* On-disk link store. */
dev_t dev; /* Device number. */
char file[PATH_MAX]; /* Name of earlier seen link. */
} dlink_t;
static link_t *links[256]; /* Hash list of known links. */
static int tfd= -1; /* Temp file for file name storage. */
static dlink_t dlink;
link_t *lp, **plp;
size_t len;
off_t off;
if (file == nil) {
/* Reset everything. */
for (plp= links; plp < arraylimit(links); plp++) {
while ((lp= *plp) != nil) {
*plp= lp->next;
free(lp);
}
}
if (tfd != -1) close(tfd);
tfd= -1;
return nil;
}
/* The file must be a non-directory with more than one link. */
if (S_ISDIR(stp->st_mode) || stp->st_nlink <= 1) {
errno= ENOENT;
return nil;
}
plp= &links[stp->st_ino % arraysize(links)];
while ((lp= *plp) != nil) {
if (lp->ino == stp->st_ino) {
/* May have seen this link before. Get it and check. */
if (lseek(tfd, lp->off, SEEK_SET) == -1) return nil;
if (read(tfd, &dlink, sizeof(dlink)) < 0) return nil;
/* Only need to check the device number. */
if (dlink.dev == stp->st_dev) {
if (strcmp(file, dlink.file) == 0) {
/* Called twice. Forget about this link. */
*plp= lp->next;
free(lp);
errno= ENOENT;
return nil;
}
/* Return the name of the earlier link. */
return dlink.file;
}
}
plp= &lp->next;
}
/* First time I see this link. Add it to the store. */
if (tfd == -1) {
for (;;) {
char *tmp;
tmp= tmpnam(nil);
tfd= open(tmp, O_RDWR|O_CREAT|O_EXCL, 0600);
if (tfd < 0) {
if (errno != EEXIST) return nil;
} else {
(void) unlink(tmp);
break;
}
}
}
if ((len= strlen(file)) >= PATH_MAX) {
errno= E2BIG;
return nil;
}
dlink.dev= stp->st_dev;
strcpy(dlink.file, file);
len += offsetof(dlink_t, file) + 1;
if ((off= lseek(tfd, 0, SEEK_END)) == -1) return nil;
if (write(tfd, &dlink, len) != len) return nil;
if ((lp= malloc(sizeof(*lp))) == nil) return nil;
lp->next= nil;
lp->ino= stp->st_ino;
lp->off= off;
*plp= lp;
errno= ENOENT;
return nil;
}
