prof_file.c

/* -*- mode: c; c-basic-offset: 4; indent-tabs-mode: nil -*- */
/*
 * prof_file.c ---- routines that manipulate an individual profile file.
 */

#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
#ifndef S_ISDIR
#define S_ISDIR(x) (((x) & S_IFMT) == S_IFDIR)
#endif
#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)
{
#ifdef SHOW_INITFINI_FUNCS
    printf("profile_library_initializer\n");
#endif
    add_error_table(&et_prof_error_table);

    return k5_mutex_finish_init(&g_shared_trees_mutex);
}
void profile_library_finalizer(void)
{
    if (! INITIALIZER_RAN(profile_library_initializer) || PROGRAM_EXITING()) {
#ifdef SHOW_INITFINI_FUNCS
        printf("profile_library_finalizer: skipping\n");
#endif
        return;
    }
#ifdef SHOW_INITFINI_FUNCS
    printf("profile_library_finalizer\n");
#endif
    k5_mutex_destroy(&g_shared_trees_mutex);

    remove_error_table(&et_prof_error_table);
}

static void profile_free_file_data(prf_data_t);

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
}

int profile_file_is_writable(prf_file_t profile)
{
    if (profile && profile->data) {
        return rw_access(profile->data->filespec);
    } else {
        return 0;
    }
}

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);
    strlcpy(fcopy, filename, flen + 1);
    d->refcount = 1;
    d->magic = PROF_MAGIC_FILE_DATA;
    d->root = NULL;
    d->next = NULL;
    d->fslen = flen;
    if (k5_mutex_init(&d->lock) != 0) {
        free(d);
        return NULL;
    }
    return d;
}

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

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

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

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

            uid = getuid();
            if (!k5_getpwuid_r(uid, &pwx, pwbuf, sizeof(pwbuf), &pw)
                && pw != NULL && pw->pw_dir[0] != 0)
                home_env = pw->pw_dir;
        }
#endif
    }
    if (home_env) {
        if (asprintf(&expanded_filename, "%s%s", home_env,
                     filespec + 1) < 0)
            expanded_filename = 0;
    } else
        expanded_filename = strdup(filespec);
    if (expanded_filename == 0) {
        free(prf);
        return ENOMEM;
    }

    k5_mutex_lock(&g_shared_trees_mutex);
    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) {
        data->refcount++;
        data->last_stat = 0;    /* Make sure to stat when updating. */
        k5_mutex_unlock(&g_shared_trees_mutex);
        retval = profile_update_file_data(data, NULL);
        free(expanded_filename);
        if (retval) {
            profile_dereference_data(data);
            free(prf);
            return retval;
        }
        prf->data = data;
        *ret_prof = prf;
        return 0;
    }
    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 = profile_update_file(prf, ret_modspec);
    if (retval) {
        profile_close_file(prf);
        return retval;
    }

    k5_mutex_lock(&g_shared_trees_mutex);
    data->flags |= PROFILE_FILE_SHARED;
    data->next = g_shared_trees;
    g_shared_trees = data;
    k5_mutex_unlock(&g_shared_trees_mutex);

    *ret_prof = prf;
    return 0;
}

prf_file_t profile_open_memory(void)
{
    struct profile_node *root = NULL;
    prf_file_t file = NULL;
    prf_data_t data;

    file = calloc(1, sizeof(*file));
    if (file == NULL)
        goto errout;
    file->magic = PROF_MAGIC_FILE;

    if (profile_create_node("(root)", NULL, &root) != 0)
        goto errout;

    data = profile_make_prf_data("");
    if (data == NULL)
        goto errout;

    data->root = root;
    data->flags = PROFILE_FILE_NO_RELOAD | PROFILE_FILE_DIRTY;
    file->data = data;
    file->next = NULL;
    return file;

errout:
    free(file);
    if (root != NULL)
        profile_free_node(root);
    return NULL;
}

errcode_t profile_update_file_data_locked(prf_data_t data, char **ret_modspec)
{
    errcode_t retval;
#ifdef HAVE_STAT
    struct stat st;
    unsigned long frac;
    time_t now;
#endif
    FILE *f;
    int isdir = 0;

    /* Don't reload if the backing file isn't a regular file. */
    if ((data->flags & PROFILE_FILE_NO_RELOAD) && data->root != NULL)
        return 0;
    /* Don't reload a modified data object, as the modifications may be
     * important for this object's use. */
    if (data->flags & PROFILE_FILE_DIRTY)
        return 0;

#ifdef HAVE_STAT
    now = time(0);
    if (now == data->last_stat && data->root != NULL) {
        return 0;
    }
    if (stat(data->filespec, &st)) {
        return errno;
    }
    data->last_stat = now;
#if defined HAVE_STRUCT_STAT_ST_MTIMENSEC
    frac = st.st_mtimensec;
#elif defined HAVE_STRUCT_STAT_ST_MTIMESPEC_TV_NSEC
    frac = st.st_mtimespec.tv_nsec;
#elif defined HAVE_STRUCT_STAT_ST_MTIM_TV_NSEC
    frac = st.st_mtim.tv_nsec;
#else
    frac = 0;
#endif
    if (st.st_mtime == data->timestamp
        && frac == data->frac_ts
        && data->root != NULL) {
        return 0;
    }
    if (data->root) {
        profile_free_node(data->root);
        data->root = 0;
    }

    /* Only try to reload regular files, not devices such as pipes. */
    if ((st.st_mode & S_IFMT) != S_IFREG)
        data->flags |= PROFILE_FILE_NO_RELOAD;
#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) {
        return 0;
    }
#endif

#ifdef HAVE_STAT
    isdir = S_ISDIR(st.st_mode);
#endif
    if (!isdir) {
        errno = 0;
        f = fopen(data->filespec, "r");
        if (f == NULL)
            return (errno != 0) ? errno : ENOENT;
        set_cloexec_file(f);
    }

    data->upd_serial++;

    if (isdir) {
        retval = profile_process_directory(data->filespec, &data->root);
    } else {
        retval = profile_parse_file(f, &data->root, ret_modspec);
        (void)fclose(f);
    }
    if (retval) {
        return retval;
    }
    assert(data->root != NULL);
#ifdef HAVE_STAT
    data->timestamp = st.st_mtime;
    data->frac_ts = frac;
#endif
    return 0;
}

errcode_t profile_update_file_data(prf_data_t data, char **ret_modspec)
{
    errcode_t retval;

    k5_mutex_lock(&data->lock);
    retval = profile_update_file_data_locked(data, ret_modspec);
    k5_mutex_unlock(&data->lock);
    return retval;
}

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;
    if (asprintf(&new_file, "%s.$$$", outfile) < 0) {
        new_file = NULL;
        goto errout;
    }
    if (asprintf(&old_file, "%s.bak", outfile) < 0) {
        old_file = NULL;
        goto errout;
    }

    errno = 0;

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

    set_cloexec_file(f);
    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;
        }
    }

    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;

    k5_mutex_lock(&data->lock);
    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;

    /* Do nothing if this data object has no backing file. */
    if (*data->filespec == '\0')
        return 0;

    k5_mutex_lock(&data->lock);

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

    retval = write_data_to_file(data, data->filespec, 0);
    data->flags &= ~PROFILE_FILE_DIRTY;
    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;

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



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

void profile_lock_global(void)
{
    k5_mutex_lock(&g_shared_trees_mutex);
}
void profile_unlock_global(void)
{
    k5_mutex_unlock(&g_shared_trees_mutex);
}

prf_file_t profile_copy_file(prf_file_t oldfile)
{
    prf_file_t file;

    file = calloc(1, sizeof(*file));
    if (file == NULL)
        return NULL;
    file->magic = PROF_MAGIC_FILE;

    /* Shared data objects can just have their reference counts incremented. */
    if (oldfile->data->flags & PROFILE_FILE_SHARED) {
        profile_lock_global();
        oldfile->data->refcount++;
        profile_unlock_global();
        file->data = oldfile->data;
        return file;
    }

    /* Otherwise we need to copy the data object. */
    file->data = profile_make_prf_data(oldfile->data->filespec);
    if (file->data == NULL) {
        free(file);
        return NULL;
    }
    k5_mutex_lock(&oldfile->data->lock);
    file->data->flags = oldfile->data->flags;
    file->data->last_stat = oldfile->data->last_stat;
    file->data->frac_ts = oldfile->data->frac_ts;
    file->data->root = profile_copy_node(oldfile->data->root);
    k5_mutex_unlock(&oldfile->data->lock);
    if (file->data->root == NULL) {
        profile_free_file(file);
        return NULL;
    }

    return file;
}

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)
{
    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);
    data->magic = 0;
    k5_mutex_destroy(&data->lock);
    free(data);
}

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;
}