mech_krb5/profile/prof_file.c

	prof_file.c revision 505d05c73a6e56769f263d4803b22eddd168ee24
#pragma ident   "%Z%%M% %I% %E% SMI"
/*
 * prof_file.c ---- routines that manipulate an individual profile file.
 */

#include <autoconf.h>
#include "prof_int.h"

#include <stdio.h>
#ifdef HAVE_STDLIB_H
#include <stdlib.h>
#endif
#ifdef HAVE_UNISTD_H
#include <unistd.h>
#endif
#include <string.h>
#include <stddef.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <errno.h>

#ifdef HAVE_PWD_H
#include <pwd.h>
#endif

#if defined(_WIN32)
#include <io.h>
#define HAVE_STAT
#define stat _stat
#endif

#include "k5-platform.h"

struct global_shared_profile_data {
    /* This is the head of the global list of shared trees */
    prf_data_t trees;
    /* Lock for above list.  */
    k5_mutex_t mutex;
};
#define g_shared_trees      (krb5int_profile_shared_data.trees)
#define g_shared_trees_mutex    (krb5int_profile_shared_data.mutex)

static struct global_shared_profile_data krb5int_profile_shared_data = {
    0,
    K5_MUTEX_PARTIAL_INITIALIZER
};

MAKE_INIT_FUNCTION(profile_library_initializer);
MAKE_FINI_FUNCTION(profile_library_finalizer);

int profile_library_initializer(void)
{
#if !USE_BUNDLE_ERROR_STRINGS
    add_error_table(&et_prof_error_table);
#endif
    return k5_mutex_finish_init(&g_shared_trees_mutex);
}
void profile_library_finalizer(void)
{
    if (! INITIALIZER_RAN(profile_library_initializer) || PROGRAM_EXITING())
    return;
    k5_mutex_destroy(&g_shared_trees_mutex);
#if !USE_BUNDLE_ERROR_STRINGS
    remove_error_table(&et_prof_error_table);
#endif
}

static void profile_free_file_data(prf_data_t);

#if 0

#define scan_shared_trees_locked()              \
    {                           \
        prf_data_t d;                   \
        k5_mutex_assert_locked(&g_shared_trees_mutex);  \
        for (d = g_shared_trees; d; d = d->next) {      \
        assert(d->magic == PROF_MAGIC_FILE_DATA);   \
        assert((d->flags & PROFILE_FILE_SHARED) != 0);  \
        assert(d->filespec[0] != 0);            \
        assert(d->fslen <= 1000); /* XXX */     \
        assert(d->filespec[d->fslen] == 0);     \
        assert(d->fslen = strlen(d->filespec));     \
        }                           \
    }

#define scan_shared_trees_unlocked()            \
    {                       \
        int r;                  \
        r = k5_mutex_lock(&g_shared_trees_mutex);   \
        assert (r == 0);                \
        scan_shared_trees_locked();         \
        k5_mutex_unlock(&g_shared_trees_mutex); \
    }

#else

#define scan_shared_trees_locked()  { ; }
#define scan_shared_trees_unlocked()    { ; }

#endif

static int rw_access(const_profile_filespec_t filespec)
{
#ifdef HAVE_ACCESS
    if (access(filespec, W_OK) == 0)
        return 1;
    else
        return 0;
#else
    /*
     * We're on a substandard OS that doesn't support access.  So
     * we kludge a test using stdio routines, and hope fopen
     * checks the r/w permissions.
     */
    FILE    *f;

    f = fopen(filespec, "r+");
    if (f) {
        fclose(f);
        return 1;
    }
    return 0;
#endif
}

static int r_access(const_profile_filespec_t filespec)
{
#ifdef HAVE_ACCESS
    if (access(filespec, R_OK) == 0)
        return 1;
    else
        return 0;
#else
    /*
     * We're on a substandard OS that doesn't support access.  So
     * we kludge a test using stdio routines, and hope fopen
     * checks the r/w permissions.
     */
    FILE    *f;

    f = fopen(filespec, "r");
    if (f) {
        fclose(f);
        return 1;
    }
    return 0;
#endif
}

prf_data_t
profile_make_prf_data(const char *filename)
{
    prf_data_t d;
    size_t len, flen, slen;
    char *fcopy;

    flen = strlen(filename);
    slen = offsetof(struct _prf_data_t, filespec);
    len = slen + flen + 1;
    if (len < sizeof(struct _prf_data_t))
    len = sizeof(struct _prf_data_t);
    d = malloc(len);
    if (d == NULL)
    return NULL;
    memset(d, 0, len);
    fcopy = (char *) d + slen;
    assert(fcopy == d->filespec);
    strcpy(fcopy, filename);
    d->refcount = 1;
    d->comment = NULL;
    d->magic = PROF_MAGIC_FILE_DATA;
    d->root = NULL;
    d->next = NULL;
    d->fslen = flen;
    return d;
}

errcode_t profile_open_file(const_profile_filespec_t filespec,
                prf_file_t *ret_prof)
{
    prf_file_t  prf;
    errcode_t   retval;
    char        *home_env = 0;
    unsigned int    len;
    prf_data_t  data;
    char        *expanded_filename;

    retval = CALL_INIT_FUNCTION(profile_library_initializer);
    if (retval)
        return retval;

    scan_shared_trees_unlocked();

    prf = (prf_file_t) malloc(sizeof(struct _prf_file_t));
    if (!prf)
        return ENOMEM;
    memset(prf, 0, sizeof(struct _prf_file_t));
    prf->magic = PROF_MAGIC_FILE;

    len = strlen(filespec)+1;
    if (filespec[0] == '~' && filespec[1] == '/') {
        home_env = getenv("HOME");
#ifdef HAVE_PWD_H
        if (home_env == NULL) {
            uid_t uid;
            struct passwd *pw;
#ifdef HAVE_GETPWUID_R
            struct passwd pwx;
            char pwbuf[BUFSIZ];
#endif

            uid = getuid();
#ifndef HAVE_GETPWUID_R
            pw = getpwuid(uid);
#elif defined(GETPWUID_R_4_ARGS)
            /* earlier POSIX drafts */
            pw = getpwuid_r(uid, &pwx, pwbuf, sizeof(pwbuf));
#else
            /* POSIX */
            if (getpwuid_r(uid, &pwx, pwbuf, sizeof(pwbuf), &pw) != 0)
            /* Probably already null, but let's make sure.  */
            pw = NULL;
#endif /* getpwuid variants */
            if (pw != NULL && pw->pw_dir[0] != 0)
            home_env = pw->pw_dir;
        }
#endif
        if (home_env)
            len += strlen(home_env);
    }
    expanded_filename = malloc(len);
    if (expanded_filename == 0)
        return errno;
    if (home_env) {
        strcpy(expanded_filename, home_env);
        strcat(expanded_filename, filespec+1);
    } else
        memcpy(expanded_filename, filespec, len);

    retval = k5_mutex_lock(&g_shared_trees_mutex);
    if (retval) {
        free(expanded_filename);
        free(prf);
        scan_shared_trees_unlocked();
        return retval;
    }
    scan_shared_trees_locked();
    for (data = g_shared_trees; data; data = data->next) {
        if (!strcmp(data->filespec, expanded_filename)
        /* Check that current uid has read access.  */
        && r_access(data->filespec))
        break;
    }
    if (data) {
        retval = profile_update_file_data(data);
        data->refcount++;
        (void) k5_mutex_unlock(&g_shared_trees_mutex);
        free(expanded_filename);
        prf->data = data;
        *ret_prof = prf;
        scan_shared_trees_unlocked();
        return retval;
    }
    (void) k5_mutex_unlock(&g_shared_trees_mutex);
    data = profile_make_prf_data(expanded_filename);
    if (data == NULL) {
        free(prf);
        free(expanded_filename);
        return ENOMEM;
    }
    free(expanded_filename);
    prf->data = data;

    retval = k5_mutex_init(&data->lock);
    if (retval) {
        free(data);
        free(prf);
        return retval;
    }

    retval = profile_update_file(prf);
    if (retval) {
        profile_close_file(prf);
        return retval;
    }

    retval = k5_mutex_lock(&g_shared_trees_mutex);
    if (retval) {
        profile_close_file(prf);
        scan_shared_trees_unlocked();
        return retval;
    }
    scan_shared_trees_locked();
    data->flags |= PROFILE_FILE_SHARED;
    data->next = g_shared_trees;
    g_shared_trees = data;
    scan_shared_trees_locked();
    (void) k5_mutex_unlock(&g_shared_trees_mutex);

    *ret_prof = prf;
    return 0;
}

errcode_t profile_update_file_data(prf_data_t data)
{
    errcode_t retval;
#ifdef HAVE_STAT
    struct stat st;
#ifdef STAT_ONCE_PER_SECOND
    time_t now;
#endif
#endif
    FILE *f;

    retval = k5_mutex_lock(&data->lock);
    if (retval)
        return retval;

#ifdef HAVE_STAT
#ifdef STAT_ONCE_PER_SECOND
    now = time(0);
    if (now == data->last_stat) {
        k5_mutex_unlock(&data->lock);
        return 0;
    }
#endif
    if (stat(data->filespec, &st)) {
        retval = errno;
        k5_mutex_unlock(&data->lock);
        return retval;
    }
#ifdef STAT_ONCE_PER_SECOND
    data->last_stat = now;
#endif
    if (st.st_mtime == data->timestamp) {
        k5_mutex_unlock(&data->lock);
        return 0;
    }
    if (data->root) {
        profile_free_node(data->root);
        data->root = 0;
    }
    if (data->comment) {
        free(data->comment);
        data->comment = 0;
    }
#else
    /*
     * If we don't have the stat() call, assume that our in-core
     * memory image is correct.  That is, we won't reread the
     * profile file if it changes.
     */
    if (data->root) {
        k5_mutex_unlock(&data->lock);
        return 0;
    }
#endif
    errno = 0;
    f = fopen(data->filespec, "r");
    if (f == NULL) {
        retval = errno;
        k5_mutex_unlock(&data->lock);
        if (retval == 0)
            retval = ENOENT;
        return retval;
    }
    data->upd_serial++;
    data->flags &= PROFILE_FILE_SHARED;
    if (rw_access(data->filespec))
        data->flags |= PROFILE_FILE_RW;
    retval = profile_parse_file(f, &data->root);
    fclose(f);
    if (retval) {
        k5_mutex_unlock(&data->lock);
        return retval;
    }
#ifdef HAVE_STAT
    data->timestamp = st.st_mtime;
#endif
    k5_mutex_unlock(&data->lock);
    return 0;
}

static int
make_hard_link(const char *oldpath, const char *newpath)
{
#ifdef _WIN32
    return -1;
#else
    return link(oldpath, newpath);
#endif
}

static errcode_t write_data_to_file(prf_data_t data, const char *outfile,
                    int can_create)
{
    FILE        *f;
    profile_filespec_t new_file;
    profile_filespec_t old_file;
    errcode_t   retval = 0;

    retval = ENOMEM;

    new_file = old_file = 0;
    new_file = (char *) malloc(strlen(outfile) + 5);
    if (!new_file)
        goto errout;
    old_file = (char *) malloc(strlen(outfile) + 5);
    if (!old_file)
        goto errout;

    sprintf(new_file, "%s.$$$", outfile);
    sprintf(old_file, "%s.bak", outfile);

    errno = 0;

    f = fopen(new_file, "w");
    if (!f) {
        retval = errno;
        if (retval == 0)
            retval = PROF_FAIL_OPEN;
        goto errout;
    }

    profile_write_tree_file(data->root, f);
    if (fclose(f) != 0) {
        retval = errno;
        goto errout;
    }

    unlink(old_file);
    if (make_hard_link(outfile, old_file) == 0) {
        /* Okay, got the hard link.  Yay.  Now we've got our
           backup version, so just put the new version in
           place.  */
        if (rename(new_file, outfile)) {
        /* Weird, the rename didn't work.  But the old version
           should still be in place, so no special cleanup is
           needed.  */
        retval = errno;
        goto errout;
        }
    } else if (errno == ENOENT && can_create) {
        if (rename(new_file, outfile)) {
        retval = errno;
        goto errout;
        }
    } else {
        /* Couldn't make the hard link, so there's going to be a
           small window where data->filespec does not refer to
           either version.  */
#ifndef _WIN32
        sync();
#endif
        if (rename(outfile, old_file)) {
        retval = errno;
        goto errout;
        }
        if (rename(new_file, outfile)) {
        retval = errno;
        rename(old_file, outfile); /* back out... */
        goto errout;
        }
    }

    data->flags = 0;
    if (rw_access(outfile))
        data->flags |= PROFILE_FILE_RW;
    retval = 0;

errout:
    if (new_file)
        free(new_file);
    if (old_file)
        free(old_file);
    return retval;
}

errcode_t profile_flush_file_data_to_buffer (prf_data_t data, char **bufp)
{
    errcode_t   retval;
    retval = k5_mutex_lock(&data->lock);
    if (retval)
        return retval;
    retval = profile_write_tree_to_buffer(data->root, bufp);
    k5_mutex_unlock(&data->lock);
    return retval;
}

errcode_t profile_flush_file_data(prf_data_t data)
{
    errcode_t   retval = 0;

    if (!data || data->magic != PROF_MAGIC_FILE_DATA)
        return PROF_MAGIC_FILE_DATA;

    retval = k5_mutex_lock(&data->lock);
    if (retval)
        return retval;

    if ((data->flags & PROFILE_FILE_DIRTY) == 0) {
        k5_mutex_unlock(&data->lock);
        return 0;
    }

    retval = write_data_to_file(data, data->filespec, 0);
    k5_mutex_unlock(&data->lock);
    return retval;
}

errcode_t profile_flush_file_data_to_file(prf_data_t data, const char *outfile)
{
    errcode_t retval = 0;

    if (!data || data->magic != PROF_MAGIC_FILE_DATA)
    return PROF_MAGIC_FILE_DATA;

    retval = k5_mutex_lock(&data->lock);
    if (retval)
    return retval;
    retval = write_data_to_file(data, outfile, 1);
    k5_mutex_unlock(&data->lock);
    return retval;
}


void profile_dereference_data(prf_data_t data)
{
    int err;
    scan_shared_trees_unlocked();
    err = k5_mutex_lock(&g_shared_trees_mutex);
    if (err)
    return;
    profile_dereference_data_locked(data);
    (void) k5_mutex_unlock(&g_shared_trees_mutex);
    scan_shared_trees_unlocked();
}
void profile_dereference_data_locked(prf_data_t data)
{
    data->refcount--;
    if (data->refcount == 0)
    profile_free_file_data(data);
}

int profile_lock_global()
{
    return k5_mutex_lock(&g_shared_trees_mutex);
}
int profile_unlock_global()
{
    return k5_mutex_unlock(&g_shared_trees_mutex);
}

void profile_free_file(prf_file_t prf)
{
    profile_dereference_data(prf->data);
    free(prf);
}

/* Call with mutex locked!  */
static void profile_free_file_data(prf_data_t data)
{
    scan_shared_trees_locked();
    if (data->flags & PROFILE_FILE_SHARED) {
    /* Remove from linked list.  */
    if (g_shared_trees == data)
        g_shared_trees = data->next;
    else {
        prf_data_t prev, next;
        prev = g_shared_trees;
        next = prev->next;
        while (next) {
        if (next == data) {
            prev->next = next->next;
            break;
        }
        prev = next;
        next = next->next;
        }
    }
    }
    if (data->root)
    profile_free_node(data->root);
    if (data->comment)
    free(data->comment);
    data->magic = 0;
    k5_mutex_destroy(&data->lock);
    free(data);
    scan_shared_trees_locked();
}

errcode_t profile_close_file(prf_file_t prf)
{
    errcode_t   retval;

    retval = profile_flush_file(prf);
    if (retval)
        return retval;
    profile_free_file(prf);
    return 0;
}