shadow/lib/commonio.c
Alejandro Colomar bddcd9b095 Remove superfluous casts
-  Every non-const pointer converts automatically to void *.
-  Every pointer converts automatically to void *.
-  void * converts to any other pointer.
-  const void * converts to any other const pointer.
-  Integer variables convert to each other.

I changed the declaration of a few variables in order to allow removing
a cast.

However, I didn't attempt to edit casts inside comparisons, since they
are very delicate.  I also kept casts in variadic functions, since they
are necessary, and in allocation functions, because I have other plans
for them.

I also changed a few casts to int that are better as ptrdiff_t.

This change has triggered some warnings about const correctness issues,
which have also been fixed in this patch (see for example src/login.c).

Signed-off-by: Alejandro Colomar <alx@kernel.org>
2023-02-09 10:03:03 -06:00

1135 lines
21 KiB
C

/*
* SPDX-FileCopyrightText: 1990 - 1994, Julianne Frances Haugh
* SPDX-FileCopyrightText: 1996 - 2001, Marek Michałkiewicz
* SPDX-FileCopyrightText: 2001 - 2006, Tomasz Kłoczko
* SPDX-FileCopyrightText: 2007 - 2011, Nicolas François
*
* SPDX-License-Identifier: BSD-3-Clause
*/
#include <config.h>
#ident "$Id$"
#include "defines.h"
#include <assert.h>
#include <sys/stat.h>
#include <stdlib.h>
#include <limits.h>
#include <utime.h>
#include <fcntl.h>
#include <errno.h>
#include <stdio.h>
#include <signal.h>
#include "nscd.h"
#include "sssd.h"
#ifdef WITH_TCB
#include <tcb.h>
#endif /* WITH_TCB */
#include "prototypes.h"
#include "commonio.h"
#include "shadowlog_internal.h"
/* local function prototypes */
static int lrename (const char *, const char *);
static /*@null@*/ /*@dependent@*/FILE *fopen_set_perms (
const char *name,
const char *mode,
const struct stat *sb);
static int create_backup (const char *, FILE *);
static void free_linked_list (struct commonio_db *);
static void add_one_entry (
struct commonio_db *db,
/*@owned@*/struct commonio_entry *p);
static bool name_is_nis (const char *name);
static int write_all (const struct commonio_db *);
static /*@dependent@*/ /*@null@*/struct commonio_entry *find_entry_by_name (
struct commonio_db *,
const char *);
static /*@dependent@*/ /*@null@*/struct commonio_entry *next_entry_by_name (
struct commonio_db *,
/*@null@*/struct commonio_entry *pos,
const char *);
static int lock_count = 0;
static bool nscd_need_reload = false;
/*
* Simple rename(P) alternative that attempts to rename to symlink
* target.
*/
int lrename (const char *old, const char *new)
{
int res;
char *r = NULL;
#ifndef __GLIBC__
char resolved_path[PATH_MAX];
#endif /* !__GLIBC__ */
struct stat sb;
if (lstat (new, &sb) == 0 && S_ISLNK (sb.st_mode)) {
#ifdef __GLIBC__ /* now a POSIX.1-2008 feature */
r = realpath (new, NULL);
#else /* !__GLIBC__ */
r = realpath (new, resolved_path);
#endif /* !__GLIBC__ */
if (NULL == r) {
perror ("realpath in lrename()");
} else {
new = r;
}
}
res = rename (old, new);
#ifdef __GLIBC__
free (r);
#endif /* __GLIBC__ */
return res;
}
static /*@null@*/ /*@dependent@*/FILE *fopen_set_perms (
const char *name,
const char *mode,
const struct stat *sb)
{
FILE *fp;
mode_t mask;
mask = umask (0777);
fp = fopen (name, mode);
(void) umask (mask);
if (NULL == fp) {
return NULL;
}
if (fchown (fileno (fp), sb->st_uid, sb->st_gid) != 0) {
goto fail;
}
if (fchmod (fileno (fp), sb->st_mode & 0664) != 0) {
goto fail;
}
return fp;
fail:
(void) fclose (fp);
/* fopen_set_perms is used for intermediate files */
(void) unlink (name);
return NULL;
}
static int create_backup (const char *backup, FILE * fp)
{
struct stat sb;
struct utimbuf ub;
FILE *bkfp;
int c;
if (fstat (fileno (fp), &sb) != 0) {
return -1;
}
bkfp = fopen_set_perms (backup, "w", &sb);
if (NULL == bkfp) {
return -1;
}
/* TODO: faster copy, not one-char-at-a-time. --marekm */
c = 0;
if (fseek (fp, 0, SEEK_SET) == 0) {
while ((c = getc (fp)) != EOF) {
if (putc (c, bkfp) == EOF) {
break;
}
}
}
if ((c != EOF) || (ferror (fp) != 0) || (fflush (bkfp) != 0)) {
(void) fclose (bkfp);
/* FIXME: unlink the backup file? */
return -1;
}
if (fsync (fileno (bkfp)) != 0) {
(void) fclose (bkfp);
/* FIXME: unlink the backup file? */
return -1;
}
if (fclose (bkfp) != 0) {
/* FIXME: unlink the backup file? */
return -1;
}
ub.actime = sb.st_atime;
ub.modtime = sb.st_mtime;
(void) utime (backup, &ub);
return 0;
}
static void free_linked_list (struct commonio_db *db)
{
struct commonio_entry *p;
while (NULL != db->head) {
p = db->head;
db->head = p->next;
free (p->line);
if (NULL != p->eptr) {
db->ops->free (p->eptr);
}
free (p);
}
db->tail = NULL;
}
int commonio_setname (struct commonio_db *db, const char *name)
{
snprintf (db->filename, sizeof (db->filename), "%s", name);
db->setname = true;
return 1;
}
bool commonio_present (const struct commonio_db *db)
{
return (access (db->filename, F_OK) == 0);
}
int do_fcntl_lock (const char *file, bool log, short type)
{
int fd;
struct flock lck = {
.l_type = type,
.l_whence = SEEK_SET,
.l_start = 0,
.l_len = 0,
};
fd = open (file, O_WRONLY, 0600);
if (-1 == fd) {
if (log) {
(void) fprintf (shadow_logfd, "%s: %s: %s\n",
shadow_progname, file, strerror (errno));
}
return 0;
}
fcntl (fd, F_OFD_SETLKW, &lck);
close(fd);
return(1);
}
int commonio_lock_nowait (struct commonio_db *db, bool log)
{
char* file = NULL;
char* lock = NULL;
size_t lock_file_len;
size_t file_len;
int err = 0;
if (db->locked) {
return 1;
}
file_len = strlen(db->filename) + 11;/* %lu max size */
lock_file_len = strlen(db->filename) + 6; /* sizeof ".lock" */
file = (char*)malloc(file_len);
if (file == NULL) {
goto cleanup_ENOMEM;
}
lock = (char*)malloc(lock_file_len);
if (lock == NULL) {
goto cleanup_ENOMEM;
}
snprintf (file, file_len, "%s.%lu",
db->filename, (unsigned long) getpid ());
if (do_fcntl_lock (db->filename, log, F_WRLCK | F_RDLCK) != 0) {
db->locked = true;
lock_count++;
err = 1;
}
cleanup_ENOMEM:
free(file);
free(lock);
return err;
}
int commonio_lock (struct commonio_db *db)
{
int i;
#ifdef HAVE_LCKPWDF
/*
* Only if the system libc has a real lckpwdf() - the one from
* lockpw.c calls us and would cause infinite recursion!
* It is also not used with the prefix option.
*/
if (!db->setname) {
/*
* Call lckpwdf() on the first lock.
* If it succeeds, call *_lock() only once
* (no retries, it should always succeed).
*/
if (0 == lock_count) {
if (lckpwdf () == -1) {
if (geteuid () != 0) {
(void) fprintf (shadow_logfd,
"%s: Permission denied.\n",
shadow_progname);
}
return 0; /* failure */
}
}
if (commonio_lock_nowait (db, true) != 0) {
return 1; /* success */
}
ulckpwdf ();
return 0; /* failure */
}
#endif /* !HAVE_LCKPWDF */
/*
* lckpwdf() not used - do it the old way.
*/
#ifndef LOCK_TRIES
#define LOCK_TRIES 15
#endif
#ifndef LOCK_SLEEP
#define LOCK_SLEEP 1
#endif
for (i = 0; i < LOCK_TRIES; i++) {
if (i > 0) {
sleep (LOCK_SLEEP); /* delay between retries */
}
if (commonio_lock_nowait (db, i==LOCK_TRIES-1) != 0) {
return 1; /* success */
}
/* no unnecessary retries on "permission denied" errors */
if (geteuid () != 0) {
(void) fprintf (shadow_logfd, "%s: Permission denied.\n",
shadow_progname);
return 0;
}
}
return 0; /* failure */
}
static void dec_lock_count (void)
{
if (lock_count > 0) {
lock_count--;
if (lock_count == 0) {
/* Tell nscd when lock count goes to zero,
if any of the files were changed. */
if (nscd_need_reload) {
nscd_flush_cache ("passwd");
nscd_flush_cache ("group");
sssd_flush_cache (SSSD_DB_PASSWD | SSSD_DB_GROUP);
nscd_need_reload = false;
}
#ifdef HAVE_LCKPWDF
ulckpwdf ();
#endif /* HAVE_LCKPWDF */
}
}
}
int commonio_unlock (struct commonio_db *db)
{
if (db->isopen) {
db->readonly = true;
if (commonio_close (db) == 0) {
if (db->locked) {
dec_lock_count ();
}
return 0;
}
}
if (db->locked) {
db->locked = false;
do_fcntl_lock (db->filename, false, F_UNLCK);
dec_lock_count ();
return 1;
}
return 0;
}
/*
* Add an entry at the end.
*
* defines p->next, p->prev
* (unfortunately, owned special are not supported)
*/
static void add_one_entry (struct commonio_db *db,
/*@owned@*/struct commonio_entry *p)
{
/*@-mustfreeonly@*/
p->next = NULL;
p->prev = db->tail;
/*@=mustfreeonly@*/
if (NULL == db->head) {
db->head = p;
}
if (NULL != db->tail) {
db->tail->next = p;
}
db->tail = p;
}
static bool name_is_nis (const char *name)
{
return (('+' == name[0]) || ('-' == name[0]));
}
/*
* New entries are inserted before the first NIS entry. Order is preserved
* when db is written out.
*/
#ifndef KEEP_NIS_AT_END
#define KEEP_NIS_AT_END 1
#endif
#if KEEP_NIS_AT_END
static void add_one_entry_nis (struct commonio_db *db,
/*@owned@*/struct commonio_entry *newp);
/*
* Insert an entry between the regular entries, and the NIS entries.
*
* defines newp->next, newp->prev
* (unfortunately, owned special are not supported)
*/
static void add_one_entry_nis (struct commonio_db *db,
/*@owned@*/struct commonio_entry *newp)
{
struct commonio_entry *p;
for (p = db->head; NULL != p; p = p->next) {
if (name_is_nis (p->eptr ? db->ops->getname (p->eptr)
: p->line)) {
/*@-mustfreeonly@*/
newp->next = p;
newp->prev = p->prev;
/*@=mustfreeonly@*/
if (NULL != p->prev) {
p->prev->next = newp;
} else {
db->head = newp;
}
p->prev = newp;
return;
}
}
add_one_entry (db, newp);
}
#endif /* KEEP_NIS_AT_END */
/* Initial buffer size, as well as increment if not sufficient
(for reading very long lines in group files). */
#define BUFLEN 4096
int commonio_open (struct commonio_db *db, int mode)
{
char *buf;
char *cp;
char *line;
struct commonio_entry *p;
void *eptr = NULL;
int flags = mode;
size_t buflen;
int fd;
int saved_errno;
mode &= ~O_CREAT;
if ( db->isopen
|| ( (O_RDONLY != mode)
&& (O_RDWR != mode))) {
errno = EINVAL;
return 0;
}
db->readonly = (mode == O_RDONLY);
if (!db->readonly && !db->locked) {
errno = EACCES;
return 0;
}
db->head = NULL;
db->tail = NULL;
db->cursor = NULL;
db->changed = false;
fd = open (db->filename,
(db->readonly ? O_RDONLY : O_RDWR)
| O_NOCTTY | O_NONBLOCK | O_NOFOLLOW);
saved_errno = errno;
db->fp = NULL;
if (fd >= 0) {
#ifdef WITH_TCB
if (tcb_is_suspect (fd) != 0) {
(void) close (fd);
errno = EINVAL;
return 0;
}
#endif /* WITH_TCB */
db->fp = fdopen (fd, db->readonly ? "r" : "r+");
saved_errno = errno;
if (NULL == db->fp) {
(void) close (fd);
}
}
errno = saved_errno;
/*
* If O_CREAT was specified and the file didn't exist, it will be
* created by commonio_close(). We have no entries to read yet. --marekm
*/
if (NULL == db->fp) {
if (((flags & O_CREAT) != 0) && (ENOENT == errno)) {
db->isopen = true;
return 1;
}
return 0;
}
/* Do not inherit fd in spawned processes (e.g. nscd) */
fcntl (fileno (db->fp), F_SETFD, FD_CLOEXEC);
buflen = BUFLEN;
buf = (char *) malloc (buflen);
if (NULL == buf) {
goto cleanup_ENOMEM;
}
while (db->ops->fgets (buf, buflen, db->fp) == buf) {
while ( ((cp = strrchr (buf, '\n')) == NULL)
&& (feof (db->fp) == 0)) {
size_t len;
buflen += BUFLEN;
cp = (char *) realloc (buf, buflen);
if (NULL == cp) {
goto cleanup_buf;
}
buf = cp;
len = strlen (buf);
if (db->ops->fgets (buf + len,
(int) (buflen - len),
db->fp) == NULL) {
goto cleanup_buf;
}
}
cp = strrchr (buf, '\n');
if (NULL != cp) {
*cp = '\0';
}
line = strdup (buf);
if (NULL == line) {
goto cleanup_buf;
}
if (name_is_nis (line)) {
eptr = NULL;
} else {
eptr = db->ops->parse (line);
if (NULL != eptr) {
eptr = db->ops->dup (eptr);
if (NULL == eptr) {
goto cleanup_line;
}
}
}
p = (struct commonio_entry *) malloc (sizeof *p);
if (NULL == p) {
goto cleanup_entry;
}
p->eptr = eptr;
p->line = line;
p->changed = false;
add_one_entry (db, p);
}
free (buf);
if (ferror (db->fp) != 0) {
goto cleanup_errno;
}
if ((NULL != db->ops->open_hook) && (db->ops->open_hook () == 0)) {
goto cleanup_errno;
}
db->isopen = true;
return 1;
cleanup_entry:
if (NULL != eptr) {
db->ops->free (eptr);
}
cleanup_line:
free (line);
cleanup_buf:
free (buf);
cleanup_ENOMEM:
errno = ENOMEM;
cleanup_errno:
saved_errno = errno;
free_linked_list (db);
fclose (db->fp);
db->fp = NULL;
errno = saved_errno;
return 0;
}
/*
* Sort given db according to cmp function (usually compares uids)
*/
int
commonio_sort (struct commonio_db *db, int (*cmp) (const void *, const void *))
{
struct commonio_entry **entries, *ptr;
size_t n = 0, i;
#if KEEP_NIS_AT_END
struct commonio_entry *nis = NULL;
#endif
for (ptr = db->head;
(NULL != ptr)
#if KEEP_NIS_AT_END
&& ((NULL == ptr->line)
|| (('+' != ptr->line[0])
&& ('-' != ptr->line[0])))
#endif
;
ptr = ptr->next) {
n++;
}
#if KEEP_NIS_AT_END
if (NULL != ptr) {
nis = ptr;
}
#endif
if (n <= 1) {
return 0;
}
entries = malloc (n * sizeof (struct commonio_entry *));
if (entries == NULL) {
return -1;
}
n = 0;
for (ptr = db->head;
#if KEEP_NIS_AT_END
nis != ptr;
#else
NULL != ptr;
#endif
/*@ -nullderef @*/
ptr = ptr->next
/*@ +nullderef @*/
) {
entries[n] = ptr;
n++;
}
qsort (entries, n, sizeof (struct commonio_entry *), cmp);
/* Take care of the head and tail separately */
db->head = entries[0];
n--;
#if KEEP_NIS_AT_END
if (NULL == nis)
#endif
{
db->tail = entries[n];
}
db->head->prev = NULL;
db->head->next = entries[1];
entries[n]->prev = entries[n - 1];
#if KEEP_NIS_AT_END
entries[n]->next = nis;
#else
entries[n]->next = NULL;
#endif
/* Now other elements have prev and next entries */
for (i = 1; i < n; i++) {
entries[i]->prev = entries[i - 1];
entries[i]->next = entries[i + 1];
}
free (entries);
db->changed = true;
return 0;
}
/*
* Sort entries in db according to order in another.
*/
int commonio_sort_wrt (struct commonio_db *shadow,
const struct commonio_db *passwd)
{
struct commonio_entry *head = NULL, *pw_ptr, *spw_ptr;
const char *name;
if ((NULL == shadow) || (NULL == shadow->head)) {
return 0;
}
for (pw_ptr = passwd->head; NULL != pw_ptr; pw_ptr = pw_ptr->next) {
if (NULL == pw_ptr->eptr) {
continue;
}
name = passwd->ops->getname (pw_ptr->eptr);
for (spw_ptr = shadow->head;
NULL != spw_ptr;
spw_ptr = spw_ptr->next) {
if (NULL == spw_ptr->eptr) {
continue;
}
if (strcmp (name, shadow->ops->getname (spw_ptr->eptr))
== 0) {
break;
}
}
if (NULL == spw_ptr) {
continue;
}
commonio_del_entry (shadow, spw_ptr);
spw_ptr->next = head;
head = spw_ptr;
}
for (spw_ptr = head; NULL != spw_ptr; spw_ptr = head) {
head = head->next;
if (NULL != shadow->head) {
shadow->head->prev = spw_ptr;
}
spw_ptr->next = shadow->head;
shadow->head = spw_ptr;
}
shadow->head->prev = NULL;
shadow->changed = true;
return 0;
}
/*
* write_all - Write the database to its file.
*
* It returns 0 if all the entries could be written correctly.
*/
static int write_all (const struct commonio_db *db)
/*@requires notnull db->fp@*/
{
const struct commonio_entry *p;
void *eptr;
for (p = db->head; NULL != p; p = p->next) {
if (p->changed) {
eptr = p->eptr;
assert (NULL != eptr);
if (db->ops->put (eptr, db->fp) != 0) {
return -1;
}
} else if (NULL != p->line) {
if (db->ops->fputs (p->line, db->fp) == EOF) {
return -1;
}
if (putc ('\n', db->fp) == EOF) {
return -1;
}
}
}
return 0;
}
int commonio_close (struct commonio_db *db)
{
char buf[1024];
int errors = 0;
struct stat sb;
if (!db->isopen) {
errno = EINVAL;
return 0;
}
db->isopen = false;
if (!db->changed || db->readonly) {
if (NULL != db->fp) {
(void) fclose (db->fp);
db->fp = NULL;
}
goto success;
}
if ((NULL != db->ops->close_hook) && (db->ops->close_hook () == 0)) {
goto fail;
}
memzero (&sb, sizeof sb);
if (NULL != db->fp) {
if (fstat (fileno (db->fp), &sb) != 0) {
(void) fclose (db->fp);
db->fp = NULL;
goto fail;
}
/*
* Create backup file.
*/
snprintf (buf, sizeof buf, "%s-", db->filename);
#ifdef WITH_SELINUX
if (set_selinux_file_context (db->filename, S_IFREG) != 0) {
errors++;
}
#endif
if (create_backup (buf, db->fp) != 0) {
errors++;
}
if (fclose (db->fp) != 0) {
errors++;
}
#ifdef WITH_SELINUX
if (reset_selinux_file_context () != 0) {
errors++;
}
#endif
if (errors != 0) {
db->fp = NULL;
goto fail;
}
} else {
/*
* Default permissions for new [g]shadow files.
*/
sb.st_mode = db->st_mode;
sb.st_uid = db->st_uid;
sb.st_gid = db->st_gid;
}
snprintf (buf, sizeof buf, "%s+", db->filename);
#ifdef WITH_SELINUX
if (set_selinux_file_context (db->filename, S_IFREG) != 0) {
errors++;
}
#endif
db->fp = fopen_set_perms (buf, "w", &sb);
if (NULL == db->fp) {
goto fail;
}
if (write_all (db) != 0) {
errors++;
}
if (fflush (db->fp) != 0) {
errors++;
}
if (fsync (fileno (db->fp)) != 0) {
errors++;
}
if (fclose (db->fp) != 0) {
errors++;
}
db->fp = NULL;
if (errors != 0) {
unlink (buf);
goto fail;
}
if (lrename (buf, db->filename) != 0) {
goto fail;
}
#ifdef WITH_SELINUX
if (reset_selinux_file_context () != 0) {
goto fail;
}
#endif
nscd_need_reload = true;
goto success;
fail:
errors++;
success:
free_linked_list (db);
return errors == 0;
}
static /*@dependent@*/ /*@null@*/struct commonio_entry *next_entry_by_name (
struct commonio_db *db,
/*@null@*/struct commonio_entry *pos,
const char *name)
{
struct commonio_entry *p;
void *ep;
if (NULL == pos) {
return NULL;
}
for (p = pos; NULL != p; p = p->next) {
ep = p->eptr;
if ( (NULL != ep)
&& (strcmp (db->ops->getname (ep), name) == 0)) {
break;
}
}
return p;
}
static /*@dependent@*/ /*@null@*/struct commonio_entry *find_entry_by_name (
struct commonio_db *db,
const char *name)
{
return next_entry_by_name (db, db->head, name);
}
int commonio_update (struct commonio_db *db, const void *eptr)
{
struct commonio_entry *p;
void *nentry;
if (!db->isopen || db->readonly) {
errno = EINVAL;
return 0;
}
nentry = db->ops->dup (eptr);
if (NULL == nentry) {
errno = ENOMEM;
return 0;
}
p = find_entry_by_name (db, db->ops->getname (eptr));
if (NULL != p) {
if (next_entry_by_name (db, p->next, db->ops->getname (eptr)) != NULL) {
fprintf (shadow_logfd, _("Multiple entries named '%s' in %s. Please fix this with pwck or grpck.\n"), db->ops->getname (eptr), db->filename);
db->ops->free (nentry);
return 0;
}
db->ops->free (p->eptr);
p->eptr = nentry;
p->changed = true;
db->cursor = p;
db->changed = true;
return 1;
}
/* not found, new entry */
p = (struct commonio_entry *) malloc (sizeof *p);
if (NULL == p) {
db->ops->free (nentry);
errno = ENOMEM;
return 0;
}
p->eptr = nentry;
p->line = NULL;
p->changed = true;
#if KEEP_NIS_AT_END
add_one_entry_nis (db, p);
#else /* !KEEP_NIS_AT_END */
add_one_entry (db, p);
#endif /* !KEEP_NIS_AT_END */
db->changed = true;
return 1;
}
#ifdef ENABLE_SUBIDS
int commonio_append (struct commonio_db *db, const void *eptr)
{
struct commonio_entry *p;
void *nentry;
if (!db->isopen || db->readonly) {
errno = EINVAL;
return 0;
}
nentry = db->ops->dup (eptr);
if (NULL == nentry) {
errno = ENOMEM;
return 0;
}
/* new entry */
p = (struct commonio_entry *) malloc (sizeof *p);
if (NULL == p) {
db->ops->free (nentry);
errno = ENOMEM;
return 0;
}
p->eptr = nentry;
p->line = NULL;
p->changed = true;
add_one_entry (db, p);
db->changed = true;
return 1;
}
#endif /* ENABLE_SUBIDS */
void commonio_del_entry (struct commonio_db *db, const struct commonio_entry *p)
{
if (p == db->cursor) {
db->cursor = p->next;
}
if (NULL != p->prev) {
p->prev->next = p->next;
} else {
db->head = p->next;
}
if (NULL != p->next) {
p->next->prev = p->prev;
} else {
db->tail = p->prev;
}
db->changed = true;
}
/*
* commonio_remove - Remove the entry of the given name from the database.
*/
int commonio_remove (struct commonio_db *db, const char *name)
{
struct commonio_entry *p;
if (!db->isopen || db->readonly) {
errno = EINVAL;
return 0;
}
p = find_entry_by_name (db, name);
if (NULL == p) {
errno = ENOENT;
return 0;
}
if (next_entry_by_name (db, p->next, name) != NULL) {
fprintf (shadow_logfd, _("Multiple entries named '%s' in %s. Please fix this with pwck or grpck.\n"), name, db->filename);
return 0;
}
commonio_del_entry (db, p);
free (p->line);
if (NULL != p->eptr) {
db->ops->free (p->eptr);
}
return 1;
}
/*
* commonio_locate - Find the first entry with the specified name in
* the database.
*
* If found, it returns the entry and set the cursor of the database to
* that entry.
*
* Otherwise, it returns NULL.
*/
/*@observer@*/ /*@null@*/const void *commonio_locate (struct commonio_db *db, const char *name)
{
struct commonio_entry *p;
if (!db->isopen) {
errno = EINVAL;
return NULL;
}
p = find_entry_by_name (db, name);
if (NULL == p) {
errno = ENOENT;
return NULL;
}
db->cursor = p;
return p->eptr;
}
/*
* commonio_rewind - Restore the database cursor to the first entry.
*
* It returns 0 on error, 1 on success.
*/
int commonio_rewind (struct commonio_db *db)
{
if (!db->isopen) {
errno = EINVAL;
return 0;
}
db->cursor = NULL;
return 1;
}
/*
* commonio_next - Return the next entry of the specified database
*
* It returns the next entry, or NULL if no other entries could be found.
*/
/*@observer@*/ /*@null@*/const void *commonio_next (struct commonio_db *db)
{
void *eptr;
if (!db->isopen) {
errno = EINVAL;
return 0;
}
if (NULL == db->cursor) {
db->cursor = db->head;
} else {
db->cursor = db->cursor->next;
}
while (NULL != db->cursor) {
eptr = db->cursor->eptr;
if (NULL != eptr) {
return eptr;
}
db->cursor = db->cursor->next;
}
return NULL;
}