src/lib/module-dir.c

	module-dir.c revision 7782e9d99d3d6de1c9c54919811038e2a705ea08
/* Copyright (c) 2003-2009 Dovecot authors, see the included COPYING file */

#include "lib.h"
#include "array.h"
#include "module-dir.h"

#ifdef HAVE_MODULES

#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <dlfcn.h>

#ifndef RTLD_GLOBAL
#  define RTLD_GLOBAL 0
#endif

#ifndef RTLD_NOW
#  define RTLD_NOW 0
#endif

void *module_get_symbol(struct module *module, const char *symbol)
{
    const char *error;
    void *ret;

    /* clear out old errors */
    (void)dlerror();

    /* get our init func */
    ret = dlsym(module->handle, symbol);
    if (ret == NULL) {
        error = dlerror();
        if (error != NULL) {
            i_error("module %s: dlsym(%s) failed: %s",
                module->path, symbol, error);
            ret = NULL;
        }
    }

    return ret;
}

const char *module_file_get_name(const char *fname)
{
    const char *p;

    /* [lib][nn_]name(.so) */
    if (strncmp(fname, "lib", 3) == 0)
        fname += 3;

    for (p = fname; *p != '\0'; p++) {
        if (*p < '0' || *p > '9')
            break;
    }
    if (*p == '_')
        fname = p + 1;

    p = strstr(fname, MODULE_SUFFIX);
    if (p == NULL)
        return fname;

    return t_strdup_until(fname, p);
}

static void *get_symbol(struct module *module, const char *symbol, bool quiet)
{
    if (quiet)
        return dlsym(module->handle, symbol);

    return module_get_symbol(module, symbol);
}

static void module_free(struct module *module)
{
    if (module->deinit != NULL)
        module->deinit();
    if (dlclose(module->handle) != 0)
        i_error("dlclose(%s) failed: %m", module->path);
    i_free(module->path);
    i_free(module->name);
    i_free(module);
}

static struct module *
module_load(const char *path, const char *name, bool require_init_funcs,
        const char *version)
{
    void *handle;
    struct module *module;
    const char *const *module_version;

    handle = dlopen(path, RTLD_GLOBAL | RTLD_NOW);
    if (handle == NULL) {
        i_error("dlopen(%s) failed: %s", path, dlerror());
        return NULL;
    }

    module = i_new(struct module, 1);
    module->path = i_strdup(path);
    module->name = i_strdup(name);
    module->handle = handle;

    module_version = version == NULL ? NULL :
        get_symbol(module, t_strconcat(name, "_version", NULL), TRUE);
    if (module_version != NULL &&
        strcmp(*module_version, version) != 0) {
        i_error("Module is for different version %s: %s",
            *module_version, path);
        module_free(module);
        return NULL;
    }

    /* get our init func */
    module->init = (void (*)(void))
        get_symbol(module, t_strconcat(name, "_init", NULL),
               !require_init_funcs);
    module->deinit = module->init == NULL ? NULL : (void (*)(void))
        get_symbol(module, t_strconcat(name, "_deinit", NULL),
               !require_init_funcs);

    if ((module->init == NULL || module->deinit == NULL) &&
        require_init_funcs) {
        i_error("Module doesn't have %s function: %s",
            module->init == NULL ? "init" : "deinit", path);
        module->deinit = NULL;
        module_free(module);
        return NULL;
    }

    if (getenv("DEBUG") != NULL)
        i_info("Module loaded: %s", path);
    return module;
}

static int module_name_cmp(const void *p1, const void *p2)
{
    const char *const *n1 = p1, *const *n2 = p2;
    const char *s1 = *n1, *s2 = *n2;

    if (strncmp(s1, "lib", 3) == 0)
        s1 += 3;
    if (strncmp(s2, "lib", 3) == 0)
        s2 += 3;

    return strcmp(s1, s2);
}

static bool module_want_load(const char **names, const char *name)
{
    size_t len;

    if (names == NULL)
        return TRUE;

    len = strlen(name);
    if (len > 7 && strcmp(name + len - 7, "_plugin") == 0)
        name = t_strndup(name, len - 7);

    for (; *names != NULL; names++) {
        if (strcmp(*names, name) == 0) {
            *names = "";
            return TRUE;
        }
    }
    return FALSE;
}

static void check_duplicates(ARRAY_TYPE(const_string) *names,
                 const char *name, const char *dir)
{
    const char *const *names_p, *base_name, *tmp;
    unsigned int i, count;

    base_name = module_file_get_name(name);
    names_p = array_get(names, &count);
    for (i = 0; i < count; i++) {
        tmp = module_file_get_name(names_p[i]);

        if (strcmp(tmp, base_name) == 0)
            i_fatal("Multiple files for module %s: %s/%s, %s/%s",
                base_name, dir, name, dir, names_p[i]);
    }
}

static struct module *
module_dir_load_real(const char *dir, const char *module_names,
             bool require_init_funcs, const char *version)
{
    DIR *dirp;
    struct dirent *d;
    const char *name, *p, **names_p;
    const char **module_names_arr;
    struct module *modules, *module, **module_pos;
    unsigned int i, count;
    ARRAY_TYPE(const_string) names;
    pool_t pool;

    if (getenv("DEBUG") != NULL)
        i_info("Loading modules from directory: %s", dir);

    dirp = opendir(dir);
    if (dirp == NULL) {
        if (module_names != NULL) {
            /* we were given a list of modules to load.
               we can't fail. */
            i_fatal("opendir(%s) failed: %m", dir);
        }
        if (errno != ENOENT)
            i_error("opendir(%s) failed: %m", dir);
        return NULL;
    }

    pool = pool_alloconly_create("module loader", 1024);
    p_array_init(&names, pool, 32);

    modules = NULL;
    while ((d = readdir(dirp)) != NULL) {
        name = d->d_name;

        if (name[0] == '.')
            continue;

        p = strstr(name, MODULE_SUFFIX);
        if (p == NULL || strlen(p) != 3)
            continue;

        T_BEGIN {
            check_duplicates(&names, name, dir);
        } T_END;

        name = p_strdup(pool, d->d_name);
        array_append(&names, &name, 1);
    }

    names_p = array_get_modifiable(&names, &count);
    qsort(names_p, count, sizeof(const char *), module_name_cmp);

    if (module_names == NULL)
        module_names_arr = NULL;
    else {
        module_names_arr = t_strsplit_spaces(module_names, ", ");
        /* allow giving the module names also in non-base form.
           convert them in here. */
        for (i = 0; module_names_arr[i] != NULL; i++) {
            module_names_arr[i] =
                module_file_get_name(module_names_arr[i]);
        }
    }

    module_pos = &modules;
    for (i = 0; i < count; i++) T_BEGIN {
        const char *path, *stripped_name;

        name = names_p[i];
        stripped_name = module_file_get_name(name);
        if (!module_want_load(module_names_arr, stripped_name))
            module = NULL;
        else {
            path = t_strconcat(dir, "/", name, NULL);
            module = module_load(path, stripped_name,
                         require_init_funcs, version);
            if (module == NULL && module_names_arr != NULL)
                i_fatal("Couldn't load required plugins");
        }

        if (module != NULL) {
            *module_pos = module;
            module_pos = &module->next;
        }
    } T_END;

    if (module_names_arr != NULL) {
        /* make sure all modules were found */
        for (; *module_names_arr != NULL; module_names_arr++) {
            if (**module_names_arr != '\0') {
                i_fatal("Plugin %s not found from directory %s",
                    *module_names_arr, dir);
            }
        }
    }
    pool_unref(&pool);

    if (closedir(dirp) < 0)
        i_error("closedir(%s) failed: %m", dir);

    return modules;
}

struct module *module_dir_load(const char *dir, const char *module_names,
                   bool require_init_funcs, const char *version)
{
    struct module *modules;

    T_BEGIN {
        modules = module_dir_load_real(dir, module_names,
                           require_init_funcs, version);
    } T_END;
    return modules;
}

void module_dir_init(struct module *modules)
{
    struct module *module;

    for (module = modules; module != NULL; module = module->next) {
        if (module->init != NULL) {
            T_BEGIN {
                module->init();
            } T_END;
        }
    }
}

void module_dir_deinit(struct module *modules)
{
    struct module *module, **rev;
    unsigned int i, count = 0;

    for (module = modules; module != NULL; module = module->next)
        count++;

    if (count == 0)
        return;

    /* @UNSAFE: deinitialize in reverse order */
    T_BEGIN {
        rev = t_new(struct module *, count);
        for (i = 0, module = modules; i < count; i++) {
            rev[count-i-1] = module;
            module = module->next;
        }

        for (i = 0; i < count; i++) {
            module = rev[i];

            if (module->deinit != NULL) {
                module->deinit();
                module->deinit = NULL;
            }
        }
    } T_END;
}

void module_dir_unload(struct module **modules)
{
    struct module *module, *next;

    /* Call all modules' deinit() first, so that they may still call each
       others' functions. */
    module_dir_deinit(*modules);

    for (module = *modules; module != NULL; module = next) {
        next = module->next;
        module_free(module);
    }

    *modules = NULL;
}

#else

struct module *module_dir_load(const char *dir ATTR_UNUSED,
                   const char *module_names ATTR_UNUSED,
                   bool require_init_funcs ATTR_UNUSED,
                   const char *version ATTR_UNUSED)
{
    i_error("Dynamically loadable module support not built in");
    return NULL;
}

void module_dir_deinit(struct module *modules ATTR_UNUSED)
{
}

void module_dir_unload(struct module **modules ATTR_UNUSED)
{
}

#endif