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

/*  sltdl: a surrogate ltdl implementation                         */

/*  Copyright (C) 2019 Z. Gilboa                                   */

/*  Released under the Standard MIT License; see COPYING.SLTDL.    */

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

#include <limits.h>

#include <fcntl.h>

#include <stdio.h>

#include <stdlib.h>

#include <string.h>

#include <unistd.h>

#include <pthread.h>

#include <sltdl/sltdl.h>

#include "sltdl_core.h"

static off_t   lt_plen;

static off_t   lt_plocs;

static char *  lt_upath;

static char *  lt_vpath;

static char ** lt_vmark;

static char ** lt_pathv;

const char * lt_dlgetsearchpath(void)

{

	return lt_upath;

}

static int lt_dlsetsearchpath_locked(const char * path)

{

	const char *    ch;

	char *          uch;

	char *          vch;

	char **         pathv;

	off_t           elements;

	if (path[0] != '/')

		return 1;

	elements = 1;

	for (ch=&path[1]; *ch; ch++) {

		if (*ch == ':') {

			if (ch[1] != '/')

				return 1;

			elements++;

		}

	}

	if (++elements > lt_plocs) {

		if (lt_pathv) {

			free(lt_pathv);

			lt_pathv = 0;

		}

		lt_plocs  = elements;

		lt_plocs += 0x3f;

		lt_plocs |= 0x3f;

		lt_plocs ^= 0x3f;

		if (!(lt_pathv = calloc(lt_plocs,sizeof(char *))))

			return 1;

	}

	if ((ch - path) > lt_plen) {

		if (lt_upath) {

			free(lt_upath);

			lt_upath = 0;

		}

		lt_plen = ((ch - path + 1) <= 0x800)

			? 0x800 : ch - path + 1;

		lt_plen += 0x7ff;

		lt_plen |= 0x7ff;

		lt_plen ^= 0x7ff;

		if (!(lt_upath = calloc(2*lt_plen,1)))

			return 1;

		lt_vpath = &lt_upath[lt_plen];

	}

	pathv    = lt_pathv;

	*pathv++ = lt_vpath;

	for (ch=path, uch=lt_upath, vch=lt_vpath; *ch; ch++) {

		if (*ch == ':') {

			*uch++ = ch[0];

			*uch++ = ch[1];

			*vch++ = 0;

			*pathv = vch;

			*vch++ = ch[1];

			ch++;

			pathv++;

		} else {

			*uch++ = *ch;

			*vch++ = *ch;

		}

	}

	lt_vmark = pathv;

	return 0;

}

int lt_dlsetsearchpath(const char * path)

{

	lt_slock();

	return lt_sunlock(lt_dlsetsearchpath_locked(path));

}

int lt_dladdsearchdir(const char * path)

{

	int          ret;

	const char * ch;

	char *       buf;

	off_t        alen;

	off_t        plen;

	if (path[0] != '/')

		return 1;

	for (ch=path; *ch; ch++)

		if (*ch == ':')

			return 1;

	lt_slock();

	alen = strlen(path);

	plen = strlen(lt_upath);

	/* no allocation needed? */

	if (!lt_pathv[lt_plocs - 2] && ((plen + 1 + alen + 1) <= lt_plen)) {

		lt_upath[plen] = ':';

		lt_vpath[plen] = 0;

		plen++;

		strcpy(&lt_upath[plen],path);

		strcpy(&lt_vpath[plen],path);

		*lt_vmark++ = &lt_vpath[plen];

		return lt_sunlock(0);

	}

	/* (allocation needed) */

	if (!(buf = malloc(plen + 1 + alen + 1)))

		return lt_sunlock(1);

	sprintf(buf,"%s:%s",lt_upath,path);

	ret = lt_dlsetsearchpath_locked(buf);

	free(buf);

	return lt_sunlock(ret);

}

int lt_dlinsertsearchdir(const char * mark, const char * path)

{

	int          ret;

	const char * ch;

	char *       buf;

	char *       dst;

	off_t        alen;

	off_t        plen;

	off_t        slen;

	off_t        offset;

	char **      pathv;

	if (path[0] != '/')

		return 1;

	if (!mark)

		return lt_dladdsearchdir(path);

	for (ch=path; *ch; ch++)

		if (*ch == ':')

			return 1;

	lt_slock();

	alen = strlen(path);

	plen = strlen(lt_upath);

	if ((mark < lt_upath) || (mark >= &lt_upath[plen]))

		return lt_sunlock(1);

	if ((mark > lt_upath) && (mark[-1] != ':'))

		return lt_sunlock(1);

	mark = &lt_vpath[mark - lt_upath];

	/* no allocation needed? */

	if (!lt_pathv[lt_plocs - 2] && ((plen + 1 + alen + 1) <= lt_plen)) {

		for (pathv=lt_vmark; pathv>=lt_pathv; pathv--) {

			slen    = strlen(pathv[-1]);

			offset  = pathv[-1] - lt_vpath;

			offset += alen + 1;

			memcpy(&lt_upath[offset],pathv[-1],slen);

			memcpy(&lt_vpath[offset],&lt_upath[offset],slen);

			if (pathv < lt_vmark)

				lt_upath[offset + slen] = ':';

			pathv[0] = pathv[-1] + alen + 1;

			if (pathv[-1] == mark) {

				offset = mark - lt_vpath;

				strcpy(&lt_vpath[offset],path);

				memcpy(&lt_upath[offset],path,alen);

				lt_upath[offset+alen] = ':';

				lt_vmark++;

				return lt_sunlock(0);

			}

		}

	}

	/* (allocation needed) */

	if (!(buf = malloc(plen + 1 + alen + 1)))

		return lt_sunlock(1);

	for (dst=buf, pathv=lt_pathv; *pathv; pathv++) {

		if (*pathv == mark)

			dst += sprintf(dst,"%s:",path);

		if (pathv[1])

			dst += sprintf(dst,"%s:",*pathv);

		else

			dst += sprintf(dst,"%s",*pathv);

	}

	ret = lt_dlsetsearchpath_locked(buf);

	free(buf);

	return lt_sunlock(ret);

}

int lt_dlpathopen(const char * module, const char ** extv)

{

	int           fdat;

	int           fdmod;

	char **       ppath;

	const char ** pext;

	size_t        mlen;

	size_t        elen;

	char          path[1024];

	if ((mlen = strlen(module)) >= sizeof(path))

		return -1;

	memcpy(path,module,mlen);

	lt_slock();

	for (ppath=lt_pathv; *ppath; ppath++) {

		fdat = open(*ppath,O_RDONLY|O_DIRECTORY|O_CLOEXEC,0);

		if (fdat >= 0) {

			for (pext=extv; *pext; pext++) {

				if (mlen + (elen = strlen(*pext)) >= (sizeof(path))) {

					close(fdat);

					return (-1);

				}

				memcpy(&path[mlen],*pext,elen);

				path[mlen+elen] = 0;

				fdmod = openat(fdat,path,O_EXEC|O_CLOEXEC,0);

				if (fdmod >= 0) {

					close(fdat);

					return lt_sunlock(fdmod);

				}

			}

			close(fdat);

		}

	}

	return lt_sunlock(-1);

}