source: MondoRescue/branches/stable/mindi-busybox/libpwdgrp/pwd_grp.c@ 1770

/* vi: set sw=4 ts=4: */
/*  Copyright (C) 2003     Manuel Novoa III
 *
 *  Licensed under GPL v2, or later.  See file LICENSE in this tarball.
 */

/*  Nov 6, 2003  Initial version.
 *
 *  NOTE: This implementation is quite strict about requiring all
 *    field seperators.  It also does not allow leading whitespace
 *    except when processing the numeric fields.  glibc is more
 *    lenient.  See the various glibc difference comments below.
 *
 *  TODO:
 *    Move to dynamic allocation of (currently statically allocated)
 *      buffers; especially for the group-related functions since
 *      large group member lists will cause error returns.
 *
 */

#include "libbb.h"
#include <features.h>
#include <assert.h>

#ifndef _PATH_SHADOW
#define _PATH_SHADOW    "/etc/shadow"
#endif
#ifndef _PATH_PASSWD
#define _PATH_PASSWD    "/etc/passwd"
#endif
#ifndef _PATH_GROUP
#define _PATH_GROUP "/etc/group"
#endif

/**********************************************************************/
/* Sizes for statically allocated buffers. */

/* If you change these values, also change _SC_GETPW_R_SIZE_MAX and
 * _SC_GETGR_R_SIZE_MAX in libc/unistd/sysconf.c to match */
#define PWD_BUFFER_SIZE 256
#define GRP_BUFFER_SIZE 256

/**********************************************************************/
/* Prototypes for internal functions. */

static int bb__pgsreader(int (*parserfunc)(void *d, char *line), void *data,
        char *__restrict line_buff, size_t buflen, FILE *f);

static int bb__parsepwent(void *pw, char *line);
static int bb__parsegrent(void *gr, char *line);
#if ENABLE_USE_BB_SHADOW
static int bb__parsespent(void *sp, char *line);
#endif

/**********************************************************************/
/* We avoid having big global data. */

struct statics {
    /* Smaller things first */
    struct passwd getpwuid_resultbuf;
    struct group getgrgid_resultbuf;
    struct passwd getpwnam_resultbuf;
    struct group getgrnam_resultbuf;

    char getpwuid_buffer[PWD_BUFFER_SIZE];
    char getgrgid_buffer[GRP_BUFFER_SIZE];
    char getpwnam_buffer[PWD_BUFFER_SIZE];
    char getgrnam_buffer[GRP_BUFFER_SIZE];
#if 0
    struct passwd fgetpwent_resultbuf;
    struct group fgetgrent_resultbuf;
    struct spwd fgetspent_resultbuf;
    char fgetpwent_buffer[PWD_BUFFER_SIZE];
    char fgetgrent_buffer[GRP_BUFFER_SIZE];
    char fgetspent_buffer[PWD_BUFFER_SIZE];
#endif
#if 0 //ENABLE_USE_BB_SHADOW
    struct spwd getspuid_resultbuf;
    struct spwd getspnam_resultbuf;
    char getspuid_buffer[PWD_BUFFER_SIZE];
    char getspnam_buffer[PWD_BUFFER_SIZE];
#endif
// Not converted - too small to bother
//pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER;
//FILE *pwf /*= NULL*/;
//FILE *grf /*= NULL*/;
//FILE *spf /*= NULL*/;
#if 0
    struct passwd getpwent_pwd;
    struct group getgrent_gr;
    char getpwent_line_buff[PWD_BUFFER_SIZE];
    char getgrent_line_buff[GRP_BUFFER_SIZE];
#endif
#if 0 //ENABLE_USE_BB_SHADOW
    struct spwd getspent_spwd;
    struct spwd sgetspent_spwd;
    char getspent_line_buff[PWD_BUFFER_SIZE];
    char sgetspent_line_buff[PWD_BUFFER_SIZE];
#endif
};

static struct statics *ptr_to_statics;

static struct statics *get_S(void)
{
    if (!ptr_to_statics)
        ptr_to_statics = xzalloc(sizeof(*ptr_to_statics));
    return ptr_to_statics;
}

/* Always use in this order, get_S() must be called first */
#define RESULTBUF(name) &((S = get_S())->name##_resultbuf)
#define BUFFER(name)    (S->name##_buffer)

/**********************************************************************/
/* For the various fget??ent_r funcs, return
 *
 *  0: success
 *  ENOENT: end-of-file encountered
 *  ERANGE: buflen too small
 *  other error values possible. See bb__pgsreader.
 *
 * Also, *result == resultbuf on success and NULL on failure.
 *
 * NOTE: glibc difference - For the ENOENT case, glibc also sets errno.
 *   We do not, as it really isn't an error if we reach the end-of-file.
 *   Doing so is analogous to having fgetc() set errno on EOF.
 */
/**********************************************************************/

int fgetpwent_r(FILE *__restrict stream, struct passwd *__restrict resultbuf,
                char *__restrict buffer, size_t buflen,
                struct passwd **__restrict result)
{
    int rv;

    *result = NULL;

    rv = bb__pgsreader(bb__parsepwent, resultbuf, buffer, buflen, stream);
    if (!rv) {
        *result = resultbuf;
    }

    return rv;
}

int fgetgrent_r(FILE *__restrict stream, struct group *__restrict resultbuf,
                char *__restrict buffer, size_t buflen,
                struct group **__restrict result)
{
    int rv;

    *result = NULL;

    rv = bb__pgsreader(bb__parsegrent, resultbuf, buffer, buflen, stream);
    if (!rv) {
        *result = resultbuf;
    }

    return rv;
}

#if ENABLE_USE_BB_SHADOW
int fgetspent_r(FILE *__restrict stream, struct spwd *__restrict resultbuf,
                char *__restrict buffer, size_t buflen,
                struct spwd **__restrict result)
{
    int rv;

    *result = NULL;

    rv = bb__pgsreader(bb__parsespent, resultbuf, buffer, buflen, stream);
    if (!rv) {
        *result = resultbuf;
    }

    return rv;
}
#endif

/**********************************************************************/
/* For the various fget??ent funcs, return NULL on failure and a
 * pointer to the appropriate struct (statically allocated) on success.
 * TODO: audit & stop using these in bbox, they pull in static buffers */
/**********************************************************************/

#if 0
struct passwd *fgetpwent(FILE *stream)
{
    struct statics *S;
    struct passwd *resultbuf = RESULTBUF(fgetpwent);
    char *buffer = BUFFER(fgetpwent);
    struct passwd *result;

    fgetpwent_r(stream, resultbuf, buffer, sizeof(BUFFER(fgetpwent)), &result);
    return result;
}

struct group *fgetgrent(FILE *stream)
{
    struct statics *S;
    struct group *resultbuf = RESULTBUF(fgetgrent);
    char *buffer = BUFFER(fgetgrent);
    struct group *result;

    fgetgrent_r(stream, resultbuf, buffer, sizeof(BUFFER(fgetgrent)), &result);
    return result;
}
#endif

#if ENABLE_USE_BB_SHADOW
#if 0
struct spwd *fgetspent(FILE *stream)
{
    struct statics *S;
    struct spwd *resultbuf = RESULTBUF(fgetspent);
    char *buffer = BUFFER(fgetspent);
    struct spwd *result;

    fgetspent_r(stream, resultbuf, buffer, sizeof(BUFFER(fgetspent)), &result);
    return result;
}
#endif

int sgetspent_r(const char *string, struct spwd *result_buf,
                char *buffer, size_t buflen, struct spwd **result)
{
    int rv = ERANGE;

    *result = NULL;

    if (buflen < PWD_BUFFER_SIZE) {
    DO_ERANGE:
        errno=rv;
        goto DONE;
    }

    if (string != buffer) {
        if (strlen(string) >= buflen) {
            goto DO_ERANGE;
        }
        strcpy(buffer, string);
    }

    rv = bb__parsespent(result_buf, buffer);
    if (!rv) {
        *result = result_buf;
    }

 DONE:
    return rv;
}
#endif

/**********************************************************************/

#define GETXXKEY_R_FUNC         getpwnam_r
#define GETXXKEY_R_PARSER       bb__parsepwent
#define GETXXKEY_R_ENTTYPE      struct passwd
#define GETXXKEY_R_TEST(ENT)    (!strcmp((ENT)->pw_name, key))
#define GETXXKEY_R_KEYTYPE      const char *__restrict
#define GETXXKEY_R_PATHNAME     _PATH_PASSWD
#include "pwd_grp_internal.c"

#define GETXXKEY_R_FUNC         getgrnam_r
#define GETXXKEY_R_PARSER       bb__parsegrent
#define GETXXKEY_R_ENTTYPE      struct group
#define GETXXKEY_R_TEST(ENT)    (!strcmp((ENT)->gr_name, key))
#define GETXXKEY_R_KEYTYPE      const char *__restrict
#define GETXXKEY_R_PATHNAME     _PATH_GROUP
#include "pwd_grp_internal.c"

#if ENABLE_USE_BB_SHADOW
#define GETXXKEY_R_FUNC         getspnam_r
#define GETXXKEY_R_PARSER       bb__parsespent
#define GETXXKEY_R_ENTTYPE      struct spwd
#define GETXXKEY_R_TEST(ENT)    (!strcmp((ENT)->sp_namp, key))
#define GETXXKEY_R_KEYTYPE      const char *__restrict
#define GETXXKEY_R_PATHNAME     _PATH_SHADOW
#include "pwd_grp_internal.c"
#endif

#define GETXXKEY_R_FUNC         getpwuid_r
#define GETXXKEY_R_PARSER       bb__parsepwent
#define GETXXKEY_R_ENTTYPE      struct passwd
#define GETXXKEY_R_TEST(ENT)    ((ENT)->pw_uid == key)
#define GETXXKEY_R_KEYTYPE      uid_t
#define GETXXKEY_R_PATHNAME     _PATH_PASSWD
#include "pwd_grp_internal.c"

#define GETXXKEY_R_FUNC         getgrgid_r
#define GETXXKEY_R_PARSER       bb__parsegrent
#define GETXXKEY_R_ENTTYPE      struct group
#define GETXXKEY_R_TEST(ENT)    ((ENT)->gr_gid == key)
#define GETXXKEY_R_KEYTYPE      gid_t
#define GETXXKEY_R_PATHNAME     _PATH_GROUP
#include "pwd_grp_internal.c"

/**********************************************************************/
/* TODO: audit & stop using these in bbox, they pull in static buffers */

/* This one has many users */
struct passwd *getpwuid(uid_t uid)
{
    struct statics *S;
    struct passwd *resultbuf = RESULTBUF(getpwuid);
    char *buffer = BUFFER(getpwuid);
    struct passwd *result;

    getpwuid_r(uid, resultbuf, buffer, sizeof(BUFFER(getpwuid)), &result);
    return result;
}

/* This one has many users */
struct group *getgrgid(gid_t gid)
{
    struct statics *S;
    struct group *resultbuf = RESULTBUF(getgrgid);
    char *buffer = BUFFER(getgrgid);
    struct group *result;

    getgrgid_r(gid, resultbuf, buffer, sizeof(BUFFER(getgrgid)), &result);
    return result;
}

#if 0 //ENABLE_USE_BB_SHADOW
/* This function is non-standard and is currently not built.  It seems
 * to have been created as a reentrant version of the non-standard
 * functions getspuid.  Why getspuid was added, I do not know. */
int getspuid_r(uid_t uid, struct spwd *__restrict resultbuf,
               char *__restrict buffer, size_t buflen,
               struct spwd **__restrict result)
{
    int rv;
    struct passwd *pp;
    struct passwd password;
    char pwd_buff[PWD_BUFFER_SIZE];

    *result = NULL;
    rv = getpwuid_r(uid, &password, pwd_buff, sizeof(pwd_buff), &pp);
    if (!rv) {
        rv = getspnam_r(password.pw_name, resultbuf, buffer, buflen, result);
    }

    return rv;
}

/* This function is non-standard and is currently not built.
 * Why it was added, I do not know. */
struct spwd *getspuid(uid_t uid)
{
    struct statics *S;
    struct spwd *resultbuf = RESULTBUF(getspuid);
    char *buffer = BUFFER(getspuid);
    struct spwd *result;

    getspuid_r(uid, resultbuf, buffer, sizeof(BUFFER(getspuid)), &result);
    return result;
}
#endif

/* This one has many users */
struct passwd *getpwnam(const char *name)
{
    struct statics *S;
    struct passwd *resultbuf = RESULTBUF(getpwnam);
    char *buffer = BUFFER(getpwnam);
    struct passwd *result;

    getpwnam_r(name, resultbuf, buffer, sizeof(BUFFER(getpwnam)), &result);
    return result;
}

/* This one has many users */
struct group *getgrnam(const char *name)
{
    struct statics *S;
    struct group *resultbuf = RESULTBUF(getgrnam);
    char *buffer = BUFFER(getgrnam);
    struct group *result;

    getgrnam_r(name, resultbuf, buffer, sizeof(BUFFER(getgrnam)), &result);
    return result;
}

#if 0 //ENABLE_USE_BB_SHADOW
struct spwd *getspnam(const char *name)
{
    struct statics *S;
    struct spwd *resultbuf = RESULTBUF(getspnam);
    char *buffer = BUFFER(getspnam);
    struct spwd *result;

    getspnam_r(name, resultbuf, buffer, sizeof(BUFFER(getspnam)), &result);
    return result;
}
#endif

/* This one doesn't use static buffers */
int getpw(uid_t uid, char *buf)
{
    struct passwd resultbuf;
    struct passwd *result;
    char buffer[PWD_BUFFER_SIZE];

    if (!buf) {
        errno = EINVAL;
    } else if (!getpwuid_r(uid, &resultbuf, buffer, sizeof(buffer), &result)) {
        if (sprintf(buf, "%s:%s:%lu:%lu:%s:%s:%s\n",
                    resultbuf.pw_name, resultbuf.pw_passwd,
                    (unsigned long)(resultbuf.pw_uid),
                    (unsigned long)(resultbuf.pw_gid),
                    resultbuf.pw_gecos, resultbuf.pw_dir,
                    resultbuf.pw_shell) >= 0
            ) {
            return 0;
        }
    }

    return -1;
}

/**********************************************************************/

/* FIXME: we don't have such CONFIG_xx - ?! */

#if defined CONFIG_USE_BB_THREADSAFE_SHADOW && defined PTHREAD_MUTEX_INITIALIZER
static pthread_mutex_t mylock = PTHREAD_MUTEX_INITIALIZER;
# define LOCK       pthread_mutex_lock(&mylock)
# define UNLOCK     pthread_mutex_unlock(&mylock);
#else
# define LOCK       ((void) 0)
# define UNLOCK     ((void) 0)
#endif

static FILE *pwf /*= NULL*/;
void setpwent(void)
{
    LOCK;
    if (pwf) {
        rewind(pwf);
    }
    UNLOCK;
}

void endpwent(void)
{
    LOCK;
    if (pwf) {
        fclose(pwf);
        pwf = NULL;
    }
    UNLOCK;
}


int getpwent_r(struct passwd *__restrict resultbuf,
               char *__restrict buffer, size_t buflen,
               struct passwd **__restrict result)
{
    int rv;

    LOCK;
    *result = NULL;             /* In case of error... */

    if (!pwf) {
        pwf = fopen(_PATH_PASSWD, "r");
        if (!pwf) {
            rv = errno;
            goto ERR;
        }
    }

    rv = bb__pgsreader(bb__parsepwent, resultbuf, buffer, buflen, pwf);
    if (!rv) {
        *result = resultbuf;
    }

 ERR:
    UNLOCK;
    return rv;
}

static FILE *grf /*= NULL*/;
void setgrent(void)
{
    LOCK;
    if (grf) {
        rewind(grf);
    }
    UNLOCK;
}

void endgrent(void)
{
    LOCK;
    if (grf) {
        fclose(grf);
        grf = NULL;
    }
    UNLOCK;
}

int getgrent_r(struct group *__restrict resultbuf,
               char *__restrict buffer, size_t buflen,
               struct group **__restrict result)
{
    int rv;

    LOCK;
    *result = NULL;             /* In case of error... */

    if (!grf) {
        grf = fopen(_PATH_GROUP, "r");
        if (!grf) {
            rv = errno;
            goto ERR;
        }
    }

    rv = bb__pgsreader(bb__parsegrent, resultbuf, buffer, buflen, grf);
    if (!rv) {
        *result = resultbuf;
    }

 ERR:
    UNLOCK;
    return rv;
}

#if ENABLE_USE_BB_SHADOW
static FILE *spf /*= NULL*/;
void setspent(void)
{
    LOCK;
    if (spf) {
        rewind(spf);
    }
    UNLOCK;
}

void endspent(void)
{
    LOCK;
    if (spf) {
        fclose(spf);
        spf = NULL;
    }
    UNLOCK;
}

int getspent_r(struct spwd *resultbuf, char *buffer,
               size_t buflen, struct spwd **result)
{
    int rv;

    LOCK;
    *result = NULL;             /* In case of error... */

    if (!spf) {
        spf = fopen(_PATH_SHADOW, "r");
        if (!spf) {
            rv = errno;
            goto ERR;
        }
    }

    rv = bb__pgsreader(bb__parsespent, resultbuf, buffer, buflen, spf);
    if (!rv) {
        *result = resultbuf;
    }

 ERR:
    UNLOCK;
    return rv;
}
#endif

#if 0
struct passwd *getpwent(void)
{
    static char line_buff[PWD_BUFFER_SIZE];
    static struct passwd pwd;
    struct passwd *result;

    getpwent_r(&pwd, line_buff, sizeof(line_buff), &result);
    return result;
}

struct group *getgrent(void)
{
    static char line_buff[GRP_BUFFER_SIZE];
    static struct group gr;
    struct group *result;

    getgrent_r(&gr, line_buff, sizeof(line_buff), &result);
    return result;
}
#endif

#if 0 //ENABLE_USE_BB_SHADOW
struct spwd *getspent(void)
{
    static char line_buff[PWD_BUFFER_SIZE];
    static struct spwd spwd;
    struct spwd *result;

    getspent_r(&spwd, line_buff, sizeof(line_buff), &result);
    return result;
}

struct spwd *sgetspent(const char *string)
{
    static char line_buff[PWD_BUFFER_SIZE];
    static struct spwd spwd;
    struct spwd *result;

    sgetspent_r(string, &spwd, line_buff, sizeof(line_buff), &result);
    return result;
}
#endif

int initgroups(const char *user, gid_t gid)
{
    FILE *grfile;
    gid_t *group_list;
    int num_groups, rv;
    char **m;
    struct group group;
    char buff[PWD_BUFFER_SIZE];

    rv = -1;

    /* We alloc space for 8 gids at a time. */
    group_list = (gid_t *) malloc(8*sizeof(gid_t *));
    if (group_list
     && ((grfile = fopen(_PATH_GROUP, "r")) != NULL)
    ) {
        *group_list = gid;
        num_groups = 1;

        while (!bb__pgsreader(bb__parsegrent, &group, buff, sizeof(buff), grfile)) {
            assert(group.gr_mem); /* Must have at least a NULL terminator. */
            if (group.gr_gid != gid) {
                for (m = group.gr_mem; *m; m++) {
                    if (!strcmp(*m, user)) {
                        if (!(num_groups & 7)) {
                            gid_t *tmp = (gid_t *)
                                realloc(group_list,
                                        (num_groups+8) * sizeof(gid_t *));
                            if (!tmp) {
                                rv = -1;
                                goto DO_CLOSE;
                            }
                            group_list = tmp;
                        }
                        group_list[num_groups++] = group.gr_gid;
                        break;
                    }
                }
            }
        }

        rv = setgroups(num_groups, group_list);
    DO_CLOSE:
        fclose(grfile);
    }

    /* group_list will be NULL if initial malloc failed, which may trigger
     * warnings from various malloc debuggers. */
    free(group_list);
    return rv;
}

int putpwent(const struct passwd *__restrict p, FILE *__restrict f)
{
    int rv = -1;

    if (!p || !f) {
        errno=EINVAL;
    } else {
        /* No extra thread locking is needed above what fprintf does. */
        if (fprintf(f, "%s:%s:%lu:%lu:%s:%s:%s\n",
                    p->pw_name, p->pw_passwd,
                    (unsigned long)(p->pw_uid),
                    (unsigned long)(p->pw_gid),
                    p->pw_gecos, p->pw_dir, p->pw_shell) >= 0
            ) {
            rv = 0;
        }
    }

    return rv;
}

int putgrent(const struct group *__restrict p, FILE *__restrict f)
{
    static const char format[] ALIGN1 = ",%s";

    char **m;
    const char *fmt;
    int rv = -1;

    if (!p || !f) {             /* Sigh... glibc checks. */
        errno=EINVAL;
    } else {
        if (fprintf(f, "%s:%s:%lu:",
                    p->gr_name, p->gr_passwd,
                    (unsigned long)(p->gr_gid)) >= 0
            ) {

            fmt = format + 1;

            assert(p->gr_mem);
            m = p->gr_mem;

            do {
                if (!*m) {
                    if (fputc('\n', f) >= 0) {
                        rv = 0;
                    }
                    break;
                }
                if (fprintf(f, fmt, *m) < 0) {
                    break;
                }
                ++m;
                fmt = format;
            } while (1);

        }

    }

    return rv;
}

#if ENABLE_USE_BB_SHADOW
static const unsigned char _sp_off[] ALIGN1 = {
    offsetof(struct spwd, sp_lstchg),       /* 2 - not a char ptr */
    offsetof(struct spwd, sp_min),          /* 3 - not a char ptr */
    offsetof(struct spwd, sp_max),          /* 4 - not a char ptr */
    offsetof(struct spwd, sp_warn),         /* 5 - not a char ptr */
    offsetof(struct spwd, sp_inact),        /* 6 - not a char ptr */
    offsetof(struct spwd, sp_expire)        /* 7 - not a char ptr */
};

int putspent(const struct spwd *p, FILE *stream)
{
    static const char ld_format[] ALIGN1 = "%ld:";

    const char *f;
    long x;
    int i;
    int rv = -1;

    /* Unlike putpwent and putgrent, glibc does not check the args. */
    if (fprintf(stream, "%s:%s:", p->sp_namp,
                (p->sp_pwdp ? p->sp_pwdp : "")) < 0
    ) {
        goto DO_UNLOCK;
    }

    for (i = 0; i < sizeof(_sp_off); i++) {
        f = ld_format;
        x = *(const long *)(((const char *) p) + _sp_off[i]);
        if (x == -1) {
            f += 3;
        }
        if (fprintf(stream, f, x) < 0) {
            goto DO_UNLOCK;
        }
    }

    if ((p->sp_flag != ~0UL) && (fprintf(stream, "%lu", p->sp_flag) < 0)) {
        goto DO_UNLOCK;
    }

    if (fputc('\n', stream) > 0) {
        rv = 0;
    }

DO_UNLOCK:
    return rv;
}
#endif

/**********************************************************************/
/* Internal uClibc functions.                                         */
/**********************************************************************/

static const unsigned char pw_off[] ALIGN1 = {
    offsetof(struct passwd, pw_name),       /* 0 */
    offsetof(struct passwd, pw_passwd),     /* 1 */
    offsetof(struct passwd, pw_uid),        /* 2 - not a char ptr */
    offsetof(struct passwd, pw_gid),        /* 3 - not a char ptr */
    offsetof(struct passwd, pw_gecos),      /* 4 */
    offsetof(struct passwd, pw_dir),        /* 5 */
    offsetof(struct passwd, pw_shell)       /* 6 */
};

static int bb__parsepwent(void *data, char *line)
{
    char *endptr;
    char *p;
    int i;

    i = 0;
    do {
        p = ((char *) ((struct passwd *) data)) + pw_off[i];

        if ((i & 6) ^ 2) {  /* i!=2 and i!=3 */
            *((char **) p) = line;
            if (i==6) {
                return 0;
            }
            /* NOTE: glibc difference - glibc allows omission of
             * ':' seperators after the gid field if all remaining
             * entries are empty.  We require all separators. */
            line = strchr(line, ':');
            if (!line) {
                break;
            }
        } else {
            unsigned long t = strtoul(line, &endptr, 10);
            /* Make sure we had at least one digit, and that the
             * failing char is the next field seperator ':'.  See
             * glibc difference note above. */
            /* TODO: Also check for leading whitespace? */
            if ((endptr == line) || (*endptr != ':')) {
                break;
            }
            line = endptr;
            if (i & 1) {        /* i == 3 -- gid */
                *((gid_t *) p) = t;
            } else {            /* i == 2 -- uid */
                *((uid_t *) p) = t;
            }
        }

        *line++ = 0;
        ++i;
    } while (1);

    return -1;
}

/**********************************************************************/

static const unsigned char gr_off[] ALIGN1 = {
    offsetof(struct group, gr_name),        /* 0 */
    offsetof(struct group, gr_passwd),      /* 1 */
    offsetof(struct group, gr_gid)          /* 2 - not a char ptr */
};

static int bb__parsegrent(void *data, char *line)
{
    char *endptr;
    char *p;
    int i;
    char **members;
    char *end_of_buf;

    end_of_buf = ((struct group *) data)->gr_name; /* Evil hack! */
    i = 0;
    do {
        p = ((char *) ((struct group *) data)) + gr_off[i];

        if (i < 2) {
            *((char **) p) = line;
            line = strchr(line, ':');
            if (!line) {
                break;
            }
            *line++ = 0;
            ++i;
        } else {
            *((gid_t *) p) = strtoul(line, &endptr, 10);

            /* NOTE: glibc difference - glibc allows omission of the
             * trailing colon when there is no member list.  We treat
             * this as an error. */

            /* Make sure we had at least one digit, and that the
             * failing char is the next field seperator ':'.  See
             * glibc difference note above. */
            if ((endptr == line) || (*endptr != ':')) {
                break;
            }

            i = 1;              /* Count terminating NULL ptr. */
            p = endptr;

            if (p[1]) { /* We have a member list to process. */
                /* Overwrite the last ':' with a ',' before counting.
                 * This allows us to test for initial ',' and adds
                 * one ',' so that the ',' count equals the member
                 * count. */
                *p = ',';
                do {
                    /* NOTE: glibc difference - glibc allows and trims leading
                     * (but not trailing) space.  We treat this as an error. */
                    /* NOTE: glibc difference - glibc allows consecutive and
                     * trailing commas, and ignores "empty string" users.  We
                     * treat this as an error. */
                    if (*p == ',') {
                        ++i;
                        *p = 0; /* nul-terminate each member string. */
                        if (!*++p || (*p == ',') || isspace(*p)) {
                            goto ERR;
                        }
                    }
                } while (*++p);
            }

            /* Now align (p+1), rounding up. */
            /* Assumes sizeof(char **) is a power of 2. */
            members = (char **)( (((intptr_t) p) + sizeof(char **))
                                 & ~((intptr_t)(sizeof(char **) - 1)) );

            if (((char *)(members + i)) > end_of_buf) { /* No space. */
                break;
            }

            ((struct group *) data)->gr_mem = members;

            if (--i) {
                p = endptr; /* Pointing to char prior to first member. */
                do {
                    *members++ = ++p;
                    if (!--i) break;
                    while (*++p) {}
                } while (1);
            }
            *members = NULL;

            return 0;
        }
    } while (1);

 ERR:
    return -1;
}

/**********************************************************************/

#if ENABLE_USE_BB_SHADOW
static const unsigned char sp_off[] ALIGN1 = {
    offsetof(struct spwd, sp_namp),         /* 0 */
    offsetof(struct spwd, sp_pwdp),         /* 1 */
    offsetof(struct spwd, sp_lstchg),       /* 2 - not a char ptr */
    offsetof(struct spwd, sp_min),          /* 3 - not a char ptr */
    offsetof(struct spwd, sp_max),          /* 4 - not a char ptr */
    offsetof(struct spwd, sp_warn),         /* 5 - not a char ptr */
    offsetof(struct spwd, sp_inact),        /* 6 - not a char ptr */
    offsetof(struct spwd, sp_expire),       /* 7 - not a char ptr */
    offsetof(struct spwd, sp_flag)          /* 8 - not a char ptr */
};

static int bb__parsespent(void *data, char * line)
{
    char *endptr;
    char *p;
    int i;

    i = 0;
    do {
        p = ((char *) ((struct spwd *) data)) + sp_off[i];
        if (i < 2) {
            *((char **) p) = line;
            line = strchr(line, ':');
            if (!line) {
                break;
            }
        } else {
            *((long *) p) = (long) strtoul(line, &endptr, 10);

            if (endptr == line) {
                *((long *) p) = ((i != 8) ? -1L : ((long)(~0UL)));
            }

            line = endptr;

            if (i == 8) {
                if (!*endptr) {
                    return 0;
                }
                break;
            }

            if (*endptr != ':') {
                break;
            }

        }

        *line++ = 0;
        ++i;
    } while (1);

    return EINVAL;
}
#endif

/**********************************************************************/

/* Reads until if EOF, or until if finds a line which fits in the buffer
 * and for which the parser function succeeds.
 *
 * Returns 0 on success and ENOENT for end-of-file (glibc concession).
 */

static int bb__pgsreader(int (*parserfunc)(void *d, char *line), void *data,
                char *__restrict line_buff, size_t buflen, FILE *f)
{
    int line_len;
    int skip;
    int rv = ERANGE;

    if (buflen < PWD_BUFFER_SIZE) {
        errno = rv;
    } else {
        skip = 0;
        do {
            if (!fgets(line_buff, buflen, f)) {
                if (feof(f)) {
                    rv = ENOENT;
                }
                break;
            }

            line_len = strlen(line_buff) - 1; /* strlen() must be > 0. */
            if (line_buff[line_len] == '\n') {
                line_buff[line_len] = 0;
            } else if (line_len + 2 == buflen) { /* line too long */
                ++skip;
                continue;
            }

            if (skip) {
                --skip;
                continue;
            }

            /* NOTE: glibc difference - glibc strips leading whitespace from
             * records.  We do not allow leading whitespace. */

            /* Skip empty lines, comment lines, and lines with leading
             * whitespace. */
            if (*line_buff && (*line_buff != '#') && !isspace(*line_buff)) {
                if (parserfunc == bb__parsegrent) { /* Do evil group hack. */
                    /* The group entry parsing function needs to know where
                     * the end of the buffer is so that it can construct the
                     * group member ptr table. */
                    ((struct group *) data)->gr_name = line_buff + buflen;
                }

                if (!parserfunc(data, line_buff)) {
                    rv = 0;
                    break;
                }
            }
        } while (1);

    }

    return rv;
}