/*
 * Copyright 1995-1998 by Metro Link, Inc.
 *
 * Permission to use, copy, modify, distribute, and sell this software and its
 * documentation for any purpose is hereby granted without fee, provided that
 * the above copyright notice appear in all copies and that both that
 * copyright notice and this permission notice appear in supporting
 * documentation, and that the name of Metro Link, Inc. not be used in
 * advertising or publicity pertaining to distribution of the software without
 * specific, written prior permission.  Metro Link, Inc. makes no
 * representations about the suitability of this software for any purpose.
 *  It is provided "as is" without express or implied warranty.
 *
 * METRO LINK, INC. DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
 * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
 * EVENT SHALL METRO LINK, INC. BE LIABLE FOR ANY SPECIAL, INDIRECT OR
 * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
 * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
 * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
 * PERFORMANCE OF THIS SOFTWARE.
 */
/*
 * Copyright (c) 1997-2002 by The XFree86 Project, Inc.
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
 * THE COPYRIGHT HOLDER(S) OR AUTHOR(S) BE LIABLE FOR ANY CLAIM, DAMAGES OR
 * OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE,
 * ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * Except as contained in this notice, the name of the copyright holder(s)
 * and author(s) shall not be used in advertising or otherwise to promote
 * the sale, use or other dealings in this Software without prior written
 * authorization from the copyright holder(s) and author(s).
 */

#ifdef HAVE_XORG_CONFIG_H
#include <xorg-config.h>
#endif

#include "os.h"
/* For stat() and related stuff */
#define NO_OSLIB_PROTOTYPES
#include "xf86_OSlib.h"
#define LOADERDECLARATIONS
#include "loaderProcs.h"
#include "misc.h"
#include "xf86.h"
#include "xf86Priv.h"
#include "xf86Xinput.h"
#include "loader.h"
#include "xf86Optrec.h"

#include <sys/types.h>
#include <regex.h>
#include <dirent.h>
#include <limits.h>

typedef struct _pattern {
    const char *pattern;
    regex_t rex;
} PatternRec, *PatternPtr;

/* Prototypes for static functions */
static char *FindModule(const char *, const char *, const char **,
			PatternPtr);
static Bool CheckVersion(const char *, XF86ModuleVersionInfo *,
			 const XF86ModReqInfo *);
static void UnloadModuleOrDriver(ModuleDescPtr mod);
static char *LoaderGetCanonicalName(const char *, PatternPtr);
static void RemoveChild(ModuleDescPtr);
static ModuleDescPtr doLoadModule(const char *, const char *, const char **,
				  const char **, pointer,
				  const XF86ModReqInfo *, int *, int *);

const ModuleVersions LoaderVersionInfo = {
    XORG_VERSION_CURRENT,
    ABI_ANSIC_VERSION,
    ABI_VIDEODRV_VERSION,
    ABI_XINPUT_VERSION,
    ABI_EXTENSION_VERSION,
    ABI_FONT_VERSION
};

static void
FreeStringList(char **paths)
{
    char **p;

    if (!paths)
	return;

    for (p = paths; *p; p++)
	free(*p);

    free(paths);
}

static char **defaultPathList = NULL;

static Bool
PathIsAbsolute(const char *path)
{
    return *path == '/';
}	

/*
 * Convert a comma-separated path into a NULL-terminated array of path
 * elements, rejecting any that are not full absolute paths, and appending
 * a '/' when it isn't already present.
 */
static char **
InitPathList(const char *path)
{
    char *fullpath = NULL;
    char *elem = NULL;
    char **list = NULL, **save = NULL;
    int len;
    int addslash;
    int n = 0;

    if (!path)
	return defaultPathList;

    fullpath = strdup(path);
    if (!fullpath)
	return NULL;
    elem = strtok(fullpath, ",");
    while (elem) {
	if (PathIsAbsolute(elem))
	{
	    len = strlen(elem);
	    addslash = (elem[len - 1] != '/');
	    if (addslash)
		len++;
	    save = list;
	    list = realloc(list, (n + 2) * sizeof(char *));
	    if (!list) {
		if (save) {
		    save[n] = NULL;
		    FreeStringList(save);
		}
		free(fullpath);
		return NULL;
	    }
	    list[n] = malloc(len + 1);
	    if (!list[n]) {
		FreeStringList(list);
		free(fullpath);
		return NULL;
	    }
	    strcpy(list[n], elem);
	    if (addslash) {
		list[n][len - 1] = '/';
		list[n][len] = '\0';
	    }
	    n++;
	}
	elem = strtok(NULL, ",");
    }
    if (list)
	list[n] = NULL;
    free(fullpath);
    return list;
}

static void
FreePathList(char **pathlist)
{
    if (pathlist && pathlist != defaultPathList)
	FreeStringList(pathlist);
}

void
LoaderSetPath(const char *path)
{
    if (!path)
	return;

    defaultPathList = InitPathList(path);
}

/* Standard set of module subdirectories to search, in order of preference */
static const char *stdSubdirs[] = {
    "",
    "input/",
    "drivers/",
    "multimedia/",
    "extensions/",
    "internal/",
    NULL
};

/*
 * Standard set of module name patterns to check, in order of preference
 * These are regular expressions (suitable for use with POSIX regex(3)).
 *
 * This list assumes that you're an ELFish platform and therefore your
 * shared libraries are named something.so.  If we're ever nuts enough
 * to port this DDX to, say, Darwin, we'll need to fix this.
 */
static PatternRec stdPatterns[] = {
    {"^lib(.*)\\.so$",},
    {"(.*)_drv\\.so$",},
    {"(.*)\\.so$",},
    {NULL,}
};

static PatternPtr
InitPatterns(const char **patternlist)
{
    char errmsg[80];
    int i, e;
    PatternPtr patterns = NULL;
    PatternPtr p = NULL;
    static int firstTime = 1;
    const char **s;

    if (firstTime) {
	/* precompile stdPatterns */
	firstTime = 0;
	for (p = stdPatterns; p->pattern; p++)
	    if ((e = regcomp(&p->rex, p->pattern, REG_EXTENDED)) != 0) {
		regerror(e, &p->rex, errmsg, sizeof(errmsg));
		FatalError("InitPatterns: regcomp error for `%s': %s\n",
			   p->pattern, errmsg);
	    }
    }

    if (patternlist) {
	for (i = 0, s = patternlist; *s; i++, s++)
	    if (*s == DEFAULT_LIST)
		i += sizeof(stdPatterns) / sizeof(stdPatterns[0]) - 1 - 1;
	patterns = malloc((i + 1) * sizeof(PatternRec));
	if (!patterns) {
	    return NULL;
	}
	for (i = 0, s = patternlist; *s; i++, s++)
	    if (*s != DEFAULT_LIST) {
		p = patterns + i;
		p->pattern = *s;
		if ((e = regcomp(&p->rex, p->pattern, REG_EXTENDED)) != 0) {
		    regerror(e, &p->rex, errmsg, sizeof(errmsg));
		    ErrorF("InitPatterns: regcomp error for `%s': %s\n",
			   p->pattern, errmsg);
		    i--;
		}
	    } else {
		for (p = stdPatterns; p->pattern; p++, i++)
		    patterns[i] = *p;
		if (p != stdPatterns)
		    i--;
	    }
	patterns[i].pattern = NULL;
    } else
	patterns = stdPatterns;
    return patterns;
}

static void
FreePatterns(PatternPtr patterns)
{
    if (patterns && patterns != stdPatterns)
	free(patterns);
}

static const char **
InitSubdirs(const char **subdirlist)
{
    int i;
    const char **tmp_subdirlist = NULL;
    char **subdirs = NULL;
    const char **s, **stmp = NULL;
    const char *osname;
    const char *slash;
    int oslen = 0, len;
    Bool indefault;

    if (subdirlist == NULL) {
	subdirlist = tmp_subdirlist = malloc(2 * sizeof(char *));
	if (subdirlist == NULL)
	    return NULL;
	subdirlist[0] = DEFAULT_LIST;
	subdirlist[1] = NULL;
    }

    LoaderGetOS(&osname, NULL, NULL, NULL);
    oslen = strlen(osname);

    {
	/* Count number of entries and check for invalid paths */
	for (i = 0, s = subdirlist; *s; i++, s++) {
	    if (*s == DEFAULT_LIST) {
		i += sizeof(stdSubdirs) / sizeof(stdSubdirs[0]) - 1 - 1;
	    } else {
		/*
		 * Path validity check.  Don't allow absolute paths, or
		 * paths containing "..".  To catch absolute paths on
		 * platforms that use driver letters, don't allow the ':'
		 * character to appear at all.
		 */
		if (**s == '/' || **s == '\\' || strchr(*s, ':') ||
		    strstr(*s, "..")) {
		    xf86Msg(X_ERROR, "InitSubdirs: Bad subdir: \"%s\"\n", *s);
		    free(tmp_subdirlist);
		    return NULL;
		}
	    }
	}
	subdirs = malloc((i * 2 + 1) * sizeof(char *));
	if (!subdirs) {
	    free(tmp_subdirlist);
	    return NULL;
	}
	i = 0;
	s = subdirlist;
	indefault = FALSE;
	while (*s) {
	    if (*s == DEFAULT_LIST) {
		/* Divert to the default list */
		indefault = TRUE;
		stmp = ++s;
		s = stdSubdirs;
	    }
	    len = strlen(*s);
	    if (**s && (*s)[len - 1] != '/') {
		slash = "/";
		len++;
	    } else
		slash = "";
	    len += oslen + 2;
	    if (!(subdirs[i] = malloc(len))) {
		while (--i >= 0)
		    free(subdirs[i]);
		free(subdirs);
		free(tmp_subdirlist);
		return NULL;
	    }
	    /* tack on the OS name */
	    sprintf(subdirs[i], "%s%s%s/", *s, slash, osname);
	    i++;
	    /* path as given */
	    subdirs[i] = strdup(*s);
	    i++;
	    s++;
	    if (indefault && !s) {
		/* revert back to the main list */
		indefault = FALSE;
		s = stmp;
	    }
	}
	subdirs[i] = NULL;
    }
    free(tmp_subdirlist);
    return (const char **)subdirs;
}

static void
FreeSubdirs(const char **subdirs)
{
    const char **s;

    if (subdirs) {
	for (s = subdirs; *s; s++)
	    free((char *)*s);
	free(subdirs);
    }
}

static char *
FindModuleInSubdir(const char *dirpath, const char *module)
{
    struct dirent *direntry = NULL;
    DIR *dir = NULL;
    char *ret = NULL, tmpBuf[PATH_MAX];
    struct stat stat_buf;

    dir = opendir(dirpath);
    if (!dir)
        return NULL;

    while ((direntry = readdir(dir))) {
        if (direntry->d_name[0] == '.')
            continue;
        snprintf(tmpBuf, PATH_MAX, "%s%s/", dirpath, direntry->d_name);
	/* the stat with the appended / fails for normal files,
	   and works for sub dirs fine, looks a bit strange in strace
	   but does seem to work */
        if ((stat(tmpBuf, &stat_buf) == 0) && S_ISDIR(stat_buf.st_mode)) {
            if ((ret = FindModuleInSubdir(tmpBuf, module)))
                break;
            continue;
        }
 
        snprintf(tmpBuf, PATH_MAX, "lib%s.so", module);
        if (strcmp(direntry->d_name, tmpBuf) == 0) {
            if (asprintf(&ret, "%s%s", dirpath, tmpBuf) == -1)
		ret = NULL;
            break;
        }

        snprintf(tmpBuf, PATH_MAX, "%s_drv.so", module);
        if (strcmp(direntry->d_name, tmpBuf) == 0) {
            if (asprintf(&ret, "%s%s", dirpath, tmpBuf) == -1)
		ret = NULL;
            break;
        }

        snprintf(tmpBuf, PATH_MAX, "%s.so", module);
        if (strcmp(direntry->d_name, tmpBuf) == 0) {
            if (asprintf(&ret, "%s%s", dirpath, tmpBuf) == -1)
		ret = NULL;
            break;
        }
    }
    
    closedir(dir);
    return ret;
}

static char *
FindModule(const char *module, const char *dirname, const char **subdirlist,
	   PatternPtr patterns)
{
    char buf[PATH_MAX + 1];
    char *dirpath = NULL;
    char *name = NULL;
    int dirlen;
    const char **subdirs = NULL;
    const char **s;

    dirpath = (char *)dirname;
    if (strlen(dirpath) > PATH_MAX)
	return NULL;
    
    subdirs = InitSubdirs(subdirlist);
    if (!subdirs)
	return NULL;

    for (s = subdirs; *s; s++) {
	if ((dirlen = strlen(dirpath) + strlen(*s)) > PATH_MAX)
	    continue;
	strcpy(buf, dirpath);
	strcat(buf, *s);
        if ((name = FindModuleInSubdir(buf, module)))
            break;
    }

    FreeSubdirs(subdirs);
    if (dirpath != dirname)
	free(dirpath);

    return name;
}

char **
LoaderListDirs(const char **subdirlist, const char **patternlist)
{
    char buf[PATH_MAX + 1];
    char **pathlist;
    char **elem;
    const char **subdirs;
    const char **s;
    PatternPtr patterns;
    PatternPtr p;
    DIR *d;
    struct dirent *dp;
    regmatch_t match[2];
    struct stat stat_buf;
    int len, dirlen;
    char *fp;
    char **listing = NULL;
    char **save;
    char **ret = NULL;
    int n = 0;

    if (!(pathlist = InitPathList(NULL)))
	return NULL;
    if (!(subdirs = InitSubdirs(subdirlist)))
	goto bail;
    if (!(patterns = InitPatterns(patternlist)))
	goto bail;

    for (elem = pathlist; *elem; elem++) {
	for (s = subdirs; *s; s++) {
	    if ((dirlen = strlen(*elem) + strlen(*s)) > PATH_MAX)
		continue;
	    strcpy(buf, *elem);
	    strcat(buf, *s);
	    fp = buf + dirlen;
	    if (stat(buf, &stat_buf) == 0 && S_ISDIR(stat_buf.st_mode) &&
		(d = opendir(buf))) {
		if (buf[dirlen - 1] != '/') {
		    buf[dirlen++] = '/';
		    fp++;
		}
		while ((dp = readdir(d))) {
		    if (dirlen + strlen(dp->d_name) > PATH_MAX)
			continue;
		    strcpy(fp, dp->d_name);
		    if (!(stat(buf, &stat_buf) == 0 &&
			  S_ISREG(stat_buf.st_mode)))
			continue;
		    for (p = patterns; p->pattern; p++) {
			if (regexec(&p->rex, dp->d_name, 2, match, 0) == 0 &&
			    match[1].rm_so != -1) {
			    len = match[1].rm_eo - match[1].rm_so;
			    save = listing;
			    listing = realloc(listing,
					       (n + 2) * sizeof(char *));
			    if (!listing) {
				if (save) {
				    save[n] = NULL;
				    FreeStringList(save);
				}
				closedir(d);
				goto bail;
			    }
			    listing[n] = malloc(len + 1);
			    if (!listing[n]) {
				FreeStringList(listing);
				closedir(d);
				goto bail;
			    }
			    strncpy(listing[n], dp->d_name + match[1].rm_so,
				    len);
			    listing[n][len] = '\0';
			    n++;
			    break;
			}
		    }
		}
		closedir(d);
	    }
	}
    }
    if (listing)
	listing[n] = NULL;
    ret = listing;

bail:
    FreePatterns(patterns);
    FreeSubdirs(subdirs);
    FreePathList(pathlist);
    return ret;
}

void
LoaderFreeDirList(char **list)
{
    FreeStringList(list);
}

static Bool
CheckVersion(const char *module, XF86ModuleVersionInfo * data,
	     const XF86ModReqInfo * req)
{
    int vercode[4];
    char verstr[4];
    long ver = data->xf86version;
    MessageType errtype;

    xf86Msg(X_INFO, "Module %s: vendor=\"%s\"\n",
	    data->modname ? data->modname : "UNKNOWN!",
	    data->vendor ? data->vendor : "UNKNOWN!");

    /* Check for the different scheme used in XFree86 4.0.x releases:
     * ((((((((major << 7) | minor) << 7) | subminor) << 5) | beta) << 5) | alpha)
     * Since it wasn't used in 4.1.0 or later, limit to versions in the 4.0.x
     * range, which limits the overlap with the new version scheme to conflicts
     * with 6.71.8.764 through 6.72.39.934.
     */
    if ((ver > (4 << 24)) && (ver < ( (4 << 24) + (1 << 17)))) {
	/* 4.0.x and earlier */
	verstr[1] = verstr[3] = 0;
	verstr[2] = (ver & 0x1f) ? (ver & 0x1f) + 'a' - 1 : 0;
	ver >>= 5;
	verstr[0] = (ver & 0x1f) ? (ver & 0x1f) + 'A' - 1 : 0;
	ver >>= 5;
	vercode[2] = ver & 0x7f;
	ver >>= 7;
	vercode[1] = ver & 0x7f;
	ver >>= 7;
	vercode[0] = ver;
	xf86ErrorF("\tcompiled for %d.%d", vercode[0], vercode[1]);
	if (vercode[2] != 0)
	    xf86ErrorF(".%d", vercode[2]);
	xf86ErrorF("%s%s, module version = %d.%d.%d\n", verstr, verstr + 2,
		   data->majorversion, data->minorversion, data->patchlevel);
    } else {
	vercode[0] = ver / 10000000;
	vercode[1] = (ver / 100000) % 100;
	vercode[2] = (ver / 1000) % 100;
	vercode[3] = ver % 1000;
	xf86ErrorF("\tcompiled for %d.%d.%d", vercode[0], vercode[1],
		   vercode[2]);
	if (vercode[3] != 0)
	    xf86ErrorF(".%d", vercode[3]);
	xf86ErrorF(", module version = %d.%d.%d\n", data->majorversion,
		   data->minorversion, data->patchlevel);
    }

    if (data->moduleclass)
	xf86ErrorFVerb(2, "\tModule class: %s\n", data->moduleclass);

    ver = -1;
    if (data->abiclass) {
	int abimaj, abimin;
	int vermaj, vermin;

	if (!strcmp(data->abiclass, ABI_CLASS_ANSIC))
	    ver = LoaderVersionInfo.ansicVersion;
	else if (!strcmp(data->abiclass, ABI_CLASS_VIDEODRV))
	    ver = LoaderVersionInfo.videodrvVersion;
	else if (!strcmp(data->abiclass, ABI_CLASS_XINPUT))
	    ver = LoaderVersionInfo.xinputVersion;
	else if (!strcmp(data->abiclass, ABI_CLASS_EXTENSION))
	    ver = LoaderVersionInfo.extensionVersion;
	else if (!strcmp(data->abiclass, ABI_CLASS_FONT))
	    ver = LoaderVersionInfo.fontVersion;

	abimaj = GET_ABI_MAJOR(data->abiversion);
	abimin = GET_ABI_MINOR(data->abiversion);
	xf86ErrorFVerb(2, "\tABI class: %s, version %d.%d\n",
		       data->abiclass, abimaj, abimin);
	if (ver != -1) {
	    vermaj = GET_ABI_MAJOR(ver);
	    vermin = GET_ABI_MINOR(ver);
	    if (abimaj != vermaj) {
		if (LoaderOptions & LDR_OPT_ABI_MISMATCH_NONFATAL)
		    errtype = X_WARNING;
		else
		    errtype = X_ERROR;
		xf86MsgVerb(errtype, 0,
			    "module ABI major version (%d) doesn't"
			    " match the server's version (%d)\n",
			    abimaj, vermaj);
		if (!(LoaderOptions & LDR_OPT_ABI_MISMATCH_NONFATAL))
		    return FALSE;
	    } else if (abimin > vermin) {
		if (LoaderOptions & LDR_OPT_ABI_MISMATCH_NONFATAL)
		    errtype = X_WARNING;
		else
		    errtype = X_ERROR;
		xf86MsgVerb(errtype, 0,
			    "module ABI minor version (%d) is "
			    "newer than the server's version "
			    "(%d)\n", abimin, vermin);
		if (!(LoaderOptions & LDR_OPT_ABI_MISMATCH_NONFATAL))
		    return FALSE;
	    }
	}
    }

    /* Check against requirements that the caller has specified */
    if (req) {
	if (req->majorversion != MAJOR_UNSPEC) {
	    if (data->majorversion != req->majorversion) {
		xf86MsgVerb(X_WARNING, 2, "module major version (%d) "
			    "doesn't match required major version (%d)\n",
			    data->majorversion, req->majorversion);
		return FALSE;
	    } else if (req->minorversion != MINOR_UNSPEC) {
		if (data->minorversion < req->minorversion) {
		    xf86MsgVerb(X_WARNING, 2, "module minor version (%d) "
				"is less than the required minor version (%d)\n",
				data->minorversion, req->minorversion);
		    return FALSE;
		} else if (data->minorversion == req->minorversion &&
			   req->patchlevel != PATCH_UNSPEC) {
		    if (data->patchlevel < req->patchlevel) {
			xf86MsgVerb(X_WARNING, 2, "module patch level (%d) "
				    "is less than the required patch level (%d)\n",
				    data->patchlevel, req->patchlevel);
			return FALSE;
		    }
		}
	    }
	}
	if (req->moduleclass) {
	    if (!data->moduleclass ||
		strcmp(req->moduleclass, data->moduleclass)) {
		xf86MsgVerb(X_WARNING, 2, "Module class (%s) doesn't match "
			    "the required class (%s)\n",
			    data->moduleclass ? data->moduleclass : "<NONE>",
			    req->moduleclass);
		return FALSE;
	    }
	} else if (req->abiclass != ABI_CLASS_NONE) {
	    if (!data->abiclass || strcmp(req->abiclass, data->abiclass)) {
		xf86MsgVerb(X_WARNING, 2, "ABI class (%s) doesn't match the "
			    "required ABI class (%s)\n",
			    data->abiclass ? data->abiclass : "<NONE>",
			    req->abiclass);
		return FALSE;
	    }
	}
	if ((req->abiclass != ABI_CLASS_NONE) &&
	    req->abiversion != ABI_VERS_UNSPEC) {
	    int reqmaj, reqmin, maj, min;

	    reqmaj = GET_ABI_MAJOR(req->abiversion);
	    reqmin = GET_ABI_MINOR(req->abiversion);
	    maj = GET_ABI_MAJOR(data->abiversion);
	    min = GET_ABI_MINOR(data->abiversion);
	    if (maj != reqmaj) {
		xf86MsgVerb(X_WARNING, 2, "ABI major version (%d) doesn't "
			    "match the required ABI major version (%d)\n",
			    maj, reqmaj);
		return FALSE;
	    }
	    /* XXX Maybe this should be the other way around? */
	    if (min > reqmin) {
		xf86MsgVerb(X_WARNING, 2, "module ABI minor version (%d) "
			    "is newer than that available (%d)\n", min, reqmin);
		return FALSE;
	    }
	}
    }
    return TRUE;
}

static ModuleDescPtr
AddSibling(ModuleDescPtr head, ModuleDescPtr new)
{
    new->sib = head;
    return new;
}

pointer
LoadSubModule(pointer _parent, const char *module,
	      const char **subdirlist, const char **patternlist,
	      pointer options, const XF86ModReqInfo * modreq,
	      int *errmaj, int *errmin)
{
    ModuleDescPtr submod;
    ModuleDescPtr parent = (ModuleDescPtr)_parent;

    xf86MsgVerb(X_INFO, 3, "Loading sub module \"%s\"\n", module);

    if (PathIsAbsolute(module)) {
	xf86Msg(X_ERROR,
		"LoadSubModule: Absolute module path not permitted: \"%s\"\n",
		module);
	if (errmaj)
	    *errmaj = LDR_BADUSAGE;
	if (errmin)
	    *errmin = 0;
	return NULL;
    }

    submod = doLoadModule(module, NULL, subdirlist, patternlist, options,
			  modreq, errmaj, errmin);
    if (submod && submod != (ModuleDescPtr) 1) {
	parent->child = AddSibling(parent->child, submod);
	submod->parent = parent;
    }
    return submod;
}

static ModuleDescPtr
NewModuleDesc(const char *name)
{
    ModuleDescPtr mdp = calloc(1, sizeof(ModuleDesc));

    if (mdp)
	mdp->name = xstrdup(name);

    return mdp;
}

ModuleDescPtr
DuplicateModule(ModuleDescPtr mod, ModuleDescPtr parent)
{
    ModuleDescPtr ret;
    int errmaj, errmin;

    if (!mod)
	return NULL;

    ret = NewModuleDesc(mod->name);
    if (ret == NULL)
	return NULL;

    if (!(ret->handle = LoaderOpen(mod->path, &errmaj, &errmin))) {
        free(ret);
        return NULL;
    }

    ret->SetupProc = mod->SetupProc;
    ret->TearDownProc = mod->TearDownProc;
    ret->TearDownData = NULL;
    ret->child = DuplicateModule(mod->child, ret);
    ret->sib = DuplicateModule(mod->sib, parent);
    ret->parent = parent;
    ret->VersionInfo = mod->VersionInfo;
    ret->path = strdup(mod->path);

    return ret;
}

static const char *compiled_in_modules[] = {
    "ddc",
    "i2c",
    "ramdac",
    NULL
};

static ModuleDescPtr
doLoadModule(const char *module, const char *path, const char **subdirlist,
	     const char **patternlist, pointer options,
	     const XF86ModReqInfo * modreq,
	     int *errmaj, int *errmin)
{
    XF86ModuleData *initdata = NULL;
    char **pathlist = NULL;
    char *found = NULL;
    char *name = NULL;
    char **path_elem = NULL;
    char *p = NULL;
    ModuleDescPtr ret = NULL;
    PatternPtr patterns = NULL;
    int noncanonical = 0;
    char *m = NULL;
    const char **cim;

    xf86MsgVerb(X_INFO, 3, "LoadModule: \"%s\"", module);

    patterns = InitPatterns(patternlist);
    name = LoaderGetCanonicalName(module, patterns);
    noncanonical = (name && strcmp(module, name) != 0);
    if (noncanonical) {
	xf86ErrorFVerb(3, " (%s)\n", name);
	xf86MsgVerb(X_WARNING, 1,
		    "LoadModule: given non-canonical module name \"%s\"\n",
		    module);
	m = name;
    } else {
	xf86ErrorFVerb(3, "\n");
	m = (char *)module;
    }

    for (cim = compiled_in_modules; *cim; cim++)
	if (!strcmp (m, *cim))
	{
	    xf86MsgVerb(X_INFO, 3, "Module \"%s\" already built-in\n", m);
	    ret = (ModuleDescPtr) 1;
	    goto LoadModule_exit;
	}

    if (!name) {
	if (errmaj)
	    *errmaj = LDR_BADUSAGE;
	if (errmin)
	    *errmin = 0;
	goto LoadModule_fail;
    }
    ret = NewModuleDesc(name);
    if (!ret) {
	if (errmaj)
	    *errmaj = LDR_NOMEM;
	if (errmin)
	    *errmin = 0;
	goto LoadModule_fail;
    }

    pathlist = InitPathList(path);
    if (!pathlist) {
	/* This could be a malloc failure too */
	if (errmaj)
	    *errmaj = LDR_BADUSAGE;
	if (errmin)
	    *errmin = 1;
	goto LoadModule_fail;
    }

    /* 
     * if the module name is not a full pathname, we need to
     * check the elements in the path
     */
    if (PathIsAbsolute(module))
	found = xstrdup(module);
    path_elem = pathlist;
    while (!found && *path_elem != NULL) {
	found = FindModule(m, *path_elem, subdirlist, patterns);
	path_elem++;
	/*
	 * When the module name isn't the canonical name, search for the
	 * former if no match was found for the latter.
	 */
	if (!*path_elem && m == name) {
	    path_elem = pathlist;
	    m = (char *)module;
	}
    }

    /* 
     * did we find the module?
     */
    if (!found) {
	xf86Msg(X_WARNING, "Warning, couldn't open module %s\n", module);
	if (errmaj)
	    *errmaj = LDR_NOENT;
	if (errmin)
	    *errmin = 0;
	goto LoadModule_fail;
    }
    ret->handle = LoaderOpen(found, errmaj, errmin);
    if (ret->handle == NULL)
	goto LoadModule_fail;
    ret->path = strdup(found);

    /* drop any explicit suffix from the module name */
    p = strchr(name, '.');
    if (p)
        *p = '\0';

    /*
     * now check if the special data object <modulename>ModuleData is
     * present.
     */
    if (asprintf(&p, "%sModuleData", name) == -1) {
	p = NULL;
	if (errmaj)
	    *errmaj = LDR_NOMEM;
	if (errmin)
	    *errmin = 0;
	goto LoadModule_fail;
    }
    initdata = LoaderSymbol(p);
    if (initdata) {
	ModuleSetupProc setup;
	ModuleTearDownProc teardown;
	XF86ModuleVersionInfo *vers;

	vers = initdata->vers;
	setup = initdata->setup;
	teardown = initdata->teardown;

        if (vers) {
            if (!CheckVersion(module, vers, modreq)) {
                if (errmaj)
                    *errmaj = LDR_MISMATCH;
                if (errmin)
                    *errmin = 0;
                goto LoadModule_fail;
            }
        } else {
            xf86Msg(X_ERROR,
                    "LoadModule: Module %s does not supply"
                    " version information\n", module);
            if (errmaj)
                *errmaj = LDR_INVALID;
            if (errmin)
                *errmin = 0;
            goto LoadModule_fail;
        }
	if (setup)
	    ret->SetupProc = setup;
	if (teardown)
	    ret->TearDownProc = teardown;
	ret->VersionInfo = vers;
    } else {
	/* No initdata is OK for external modules */
	if (options == EXTERN_MODULE)
	    goto LoadModule_exit;

	/* no initdata, fail the load */
	xf86Msg(X_ERROR, "LoadModule: Module %s does not have a %s "
		"data object.\n", module, p);
	if (errmaj)
	    *errmaj = LDR_INVALID;
	if (errmin)
	    *errmin = 0;
	goto LoadModule_fail;
    }
    if (ret->SetupProc) {
	ret->TearDownData = ret->SetupProc(ret, options, errmaj, errmin);
	if (!ret->TearDownData) {
	    goto LoadModule_fail;
	}
    } else if (options) {
	xf86Msg(X_WARNING, "Module Options present, but no SetupProc "
		"available for %s\n", module);
    }
    goto LoadModule_exit;

  LoadModule_fail:
    UnloadModule(ret);
    ret = NULL;

  LoadModule_exit:
    FreePathList(pathlist);
    FreePatterns(patterns);
    free(found);
    free(name);
    free(p);

    return ret;
}

/*
 * LoadModule: load a module
 *
 * module       The module name.  Normally this is not a filename but the
 *              module's "canonical name.  A full pathname is, however,
 *              also accepted.
 * path         A comma separated list of module directories.
 * subdirlist   A NULL terminated list of subdirectories to search.  When
 *              NULL, the default "stdSubdirs" list is used.  The default
 *              list is also substituted for entries with value DEFAULT_LIST.
 * patternlist  A NULL terminated list of regular expressions used to find
 *              module filenames.  Each regex should contain exactly one
 *              subexpression that corresponds to the canonical module name.
 *              When NULL, the default "stdPatterns" list is used.  The
 *              default list is also substituted for entries with value
 *              DEFAULT_LIST.
 * options      A NULL terminated list of Options that are passed to the
 *              module's SetupProc function.
 * modreq       An optional XF86ModReqInfo* containing
 *              version/ABI/vendor-ABI requirements to check for when
 *              loading the module.  The following fields of the
 *              XF86ModReqInfo struct are checked:
 *                majorversion - must match the module's majorversion exactly
 *                minorversion - the module's minorversion must be >= this
 *                patchlevel   - the module's minorversion.patchlevel must be
 *                               >= this.  Patchlevel is ignored when
 *                               minorversion is not set.
 *                abiclass     - (string) must match the module's abiclass
 *                abiversion   - must be consistent with the module's
 *                               abiversion (major equal, minor no older)
 *                moduleclass  - string must match the module's moduleclass
 *                               string
 *              "don't care" values are ~0 for numbers, and NULL for strings
 * errmaj       Major error return.
 * errmin       Minor error return.
 *
 */
ModuleDescPtr
LoadModule(const char *module, const char *path, const char **subdirlist,
	   const char **patternlist, pointer options,
	   const XF86ModReqInfo * modreq, int *errmaj, int *errmin)
{
  return doLoadModule(module, path, subdirlist, patternlist, options,
		      modreq, errmaj, errmin);
}

void
UnloadModule(pointer mod)
{
    UnloadModuleOrDriver((ModuleDescPtr)mod);
}

static void
UnloadModuleOrDriver(ModuleDescPtr mod)
{
    if (mod == (ModuleDescPtr) 1)
	return;

    if (mod == NULL || mod->name == NULL)
	return;

    xf86MsgVerb(X_INFO, 3, "UnloadModule: \"%s\"\n", mod->name);

    if ((mod->TearDownProc) && (mod->TearDownData))
	mod->TearDownProc(mod->TearDownData);
    LoaderUnload(mod->name, mod->handle);

    if (mod->child)
	UnloadModuleOrDriver(mod->child);
    if (mod->sib)
	UnloadModuleOrDriver(mod->sib);
    free(mod->path);
    free(mod->name);
    free(mod);
}

void
UnloadSubModule(pointer _mod)
{
    ModuleDescPtr mod = (ModuleDescPtr)_mod;

    if (mod == NULL || mod->name == NULL)
	return;

    xf86MsgVerb(X_INFO, 3, "UnloadSubModule: \"%s\"\n", mod->name);

    if ((mod->TearDownProc) && (mod->TearDownData))
	mod->TearDownProc(mod->TearDownData);
    LoaderUnload(mod->name, mod->handle);

    RemoveChild(mod);

    if (mod->child)
	UnloadModuleOrDriver(mod->child);

    free(mod->path);
    free(mod->name);
    free(mod);
}

static void
RemoveChild(ModuleDescPtr child)
{
    ModuleDescPtr mdp;
    ModuleDescPtr prevsib;
    ModuleDescPtr parent;

    if (!child->parent)
	return;

    parent = child->parent;
    if (parent->child == child) {
	parent->child = child->sib;
	return;
    }

    prevsib = parent->child;
    mdp = prevsib->sib;
    while (mdp && mdp != child) {
	prevsib = mdp;
	mdp = mdp->sib;
    }
    if (mdp == child)
	prevsib->sib = child->sib;
    return;
}

void
LoaderErrorMsg(const char *name, const char *modname, int errmaj, int errmin)
{
    const char *msg;
    MessageType type = X_ERROR;

    switch (errmaj) {
    case LDR_NOERROR:
	msg = "no error";
	break;
    case LDR_NOMEM:
	msg = "out of memory";
	break;
    case LDR_NOENT:
	msg = "module does not exist";
	break;
    case LDR_NOSUBENT:
	msg = "a required submodule could not be loaded";
	break;
    case LDR_NOSPACE:
	msg = "too many modules";
	break;
    case LDR_NOMODOPEN:
	msg = "open failed";
	break;
    case LDR_UNKTYPE:
	msg = "unknown module type";
	break;
    case LDR_NOLOAD:
	msg = "loader failed";
	break;
    case LDR_ONCEONLY:
	msg = "already loaded";
        type = X_INFO;
	break;
    case LDR_NOPORTOPEN:
	msg = "port open failed";
	break;
    case LDR_NOHARDWARE:
	msg = "no hardware found";
	break;
    case LDR_MISMATCH:
	msg = "module requirement mismatch";
	break;
    case LDR_BADUSAGE:
	msg = "invalid argument(s) to LoadModule()";
	break;
    case LDR_INVALID:
	msg = "invalid module";
	break;
    case LDR_BADOS:
	msg = "module doesn't support this OS";
	break;
    case LDR_MODSPECIFIC:
	msg = "module-specific error";
	break;
    default:
	msg = "unknown error";
    }
    if (name)
	xf86Msg(type, "%s: Failed to load module \"%s\" (%s, %d)\n",
		name, modname, msg, errmin);
    else
	xf86Msg(type, "Failed to load module \"%s\" (%s, %d)\n",
		modname, msg, errmin);
}

/* Given a module path or file name, return the module's canonical name */
static char *
LoaderGetCanonicalName(const char *modname, PatternPtr patterns)
{
    char *str;
    const char *s;
    int len;
    PatternPtr p;
    regmatch_t match[2];

    /* Strip off any leading path */
    s = strrchr(modname, '/');
    if (s == NULL)
	s = modname;
    else
	s++;

    /* Find the first regex that is matched */
    for (p = patterns; p->pattern; p++)
	if (regexec(&p->rex, s, 2, match, 0) == 0 && match[1].rm_so != -1) {
	    len = match[1].rm_eo - match[1].rm_so;
	    str = malloc(len + 1);
	    if (!str)
		return NULL;
	    strncpy(str, s + match[1].rm_so, len);
	    str[len] = '\0';
	    return str;
	}

    /* If there is no match, return the whole name minus the leading path */
    return strdup(s);
}

/*
 * Return the module version information.
 */
unsigned long
LoaderGetModuleVersion(ModuleDescPtr mod)
{
    if (!mod || mod == (ModuleDescPtr) 1 || !mod->VersionInfo)
	return 0;

    return MODULE_VERSION_NUMERIC(mod->VersionInfo->majorversion,
				  mod->VersionInfo->minorversion,
				  mod->VersionInfo->patchlevel);
}
