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

/*  sltdl: a surrogate ltdl implementation                         */

/*  Copyright (C) 2019 SysDeer Technologies, LLC                   */

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

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

#include <limits.h>

#include <dlfcn.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"

#include "sltdl_module.h"

#ifdef  O_EXEC

#define SLTDL_MODULE_OPEN_OPTIONS (O_CLOEXEC|O_EXEC)

#else

#define SLTDL_MODULE_OPEN_OPTIONS (O_CLOEXEC)

#endif

static int     lt_status;

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;

static struct lt_modctx * lt_modv_head;

static struct lt_modctx * lt_modv_tail;

static struct lt_modctx * lt_modv_next;

static struct lt_modctx * lt_modv_cap;

static int lt_setstatus(int ret, int status)

{

	lt_status = status;

	return ret;

}

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 lt_setstatus(1,SLTDL_PATH_INVALID_FIRST_CHAR);

	elements = 1;

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

		if (*ch == ':') {

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

				return lt_setstatus(1,SLTDL_PATH_INVALID_FIRST_CHAR);

			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 lt_setstatus(1,SLTDL_SYSTEM_ERROR);

	}

	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 lt_setstatus(1,SLTDL_SYSTEM_ERROR);

		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 lt_setstatus(0,SLTDL_OK);

}

int lt_dlsetsearchpath(const char * path)

{

	int ret;

	lt_slock();

	ret = lt_dlsetsearchpath_locked(path);

	return lt_sunlock(ret,lt_status);

}

static int lt_dladdsearchdir_locked(const char * path)

{

	int          ret;

	const char * ch;

	char *       buf;

	off_t        alen;

	off_t        plen;

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

		return lt_setstatus(1,SLTDL_PATH_INVALID_FIRST_CHAR);

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

		if (*ch == ':')

			return lt_setstatus(1,SLTDL_PATH_INVALID_SEPARATTOR_CHAR);

	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_setstatus(0,SLTDL_OK);

	}

	/* (allocation needed) */

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

		return lt_setstatus(1,SLTDL_SYSTEM_ERROR);

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

	ret = lt_dlsetsearchpath_locked(buf);

	free(buf);

	return ret;

}

int lt_dladdsearchdir(const char * path)

{

	int ret;

	lt_slock();

	ret = lt_dladdsearchdir_locked(path);

	return lt_sunlock(ret,lt_status);

}

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 (!mark)

		return lt_dladdsearchdir(path);

	lt_slock();

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

		return lt_sunlock(1,SLTDL_PATH_INVALID_FIRST_CHAR);

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

		if (*ch == ':')

			return lt_sunlock(1,SLTDL_PATH_INVALID_SEPARATTOR_CHAR);

	alen = strlen(path);

	plen = strlen(lt_upath);

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

		return lt_sunlock(1,SLTDL_PATH_INVALID_MARK);

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

		return lt_sunlock(1,SLTDL_PATH_INVALID_MARK);

	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,SLTDL_OK);

			}

		}

	}

	/* (allocation needed) */

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

		return lt_sunlock(1,SLTDL_SYSTEM_ERROR);

	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,lt_status);

}

static int lt_dlpathopen_locked(

	const char *  module,

	const char ** extv,

	char **       mpath)

{

	int           fdat;

	int           fdmod;

	char **       ppath;

	const char ** pext;

	size_t        plen;

	size_t        mlen;

	size_t        elen;

	char          path[1024];

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

		return lt_setstatus(-1,SLTDL_PATH_INVALID_LEN);

	memcpy(path,module,mlen);

	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 lt_setstatus(-1,SLTDL_PATH_INVALID_LEN);

				}

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

				path[mlen+elen] = 0;

				fdmod = openat(fdat,path,SLTDL_MODULE_OPEN_OPTIONS,0);

				if (fdmod >= 0) {

					if (mpath) {

						plen  = strlen(*ppath);

						plen += mlen + 1 + elen + 1;

						if (!(*mpath = malloc(plen))) {

							close(fdat);

							close(fdmod);

							return lt_setstatus(-1,SLTDL_SYSTEM_ERROR);

						}

						sprintf(*mpath,"%s/%s",*ppath,path);

					}

					close(fdat);

					return lt_setstatus(fdmod,SLTDL_OK);

				}

			}

			close(fdat);

		}

	}

	return lt_setstatus(-1,SLTDL_PATH_NO_ENTRY);

}

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

{

	int ret;

	lt_slock();

	ret = lt_dlpathopen_locked(module,extv,0);

	return lt_sunlock(ret,lt_status);

}

static struct lt_modctx * lt_dlopen_locked(

	const char *  module,

	const char ** extv,

	int           mode)

{

	int                 fdmod;

	char *              mpath;

	void *              maddr;

	struct lt_modctx *  modctx;

	struct lt_modctx *  modctx_buf;

	/* path open */

	if ((fdmod = lt_dlpathopen_locked(module,extv,&mpath)) < 0)

		return 0;

	close(fdmod);

	/* entry alloc */

	if (lt_modv_next == lt_modv_cap) {

		if (!(modctx_buf = calloc(64,sizeof(*modctx)))) {

			free(mpath);

			lt_setstatus(0,SLTDL_SYSTEM_ERROR);

			return 0;

		}

		lt_modv_next = modctx_buf;

		lt_modv_cap  = &lt_modv_next[64];

	}

	/* dlopen */

	if (!(maddr = dlopen(mpath,mode))) {

		free(mpath);

		lt_setstatus(0,SLTDL_DLFCN_ERROR);

		return 0;

	}

	/* already dlopen'ed? */

	for (modctx=lt_modv_head; modctx; modctx=modctx->mnext) {

		if (!strcmp(modctx->mpath,mpath)) {

			free(mpath);

			modctx->mrefs++;

			return modctx;

		}

	}

	/* module entry */

	modctx        = lt_modv_next;

	modctx->maddr = maddr;

	modctx->mpath = mpath;

	modctx->mrefs = 1;

	lt_modv_next++;

	/* add to list */

	if (lt_modv_tail) {

		lt_modv_tail->mnext = modctx;

		lt_modv_tail        = modctx;

	} else {

		lt_modv_head        = modctx;

		lt_modv_tail        = modctx;

	}

	/* all done */

	return modctx;

}

struct lt_modctx * lt_dlopen(const char * module)

{

	struct lt_modctx * modctx;

	const char *       extv[2] = {"",0};

	lt_slock();

	modctx = lt_dlopen_locked(module,extv,RTLD_NOW);

	lt_sunlock(0,lt_status);

	return modctx;

}

struct lt_modctx * lt_dlopenext(const char * module)

{

	struct lt_modctx * modctx;

	const char *       extv[3] = {"",OS_LIB_SUFFIX,0};

	lt_slock();

	modctx = lt_dlopen_locked(module,extv,RTLD_NOW);

	lt_sunlock(0,lt_status);

	return modctx;

}

struct lt_modctx * lt_dlopenadvise(const char * module, struct lt_modctl * modctl)

{

	(void)modctl;

	return lt_dlopenext(module);

}

void * lt_dlsym(struct lt_modctx * modctx, const char * symname)

{

	return dlsym(modctx->maddr,symname);

}

int lt_dlclose(struct lt_modctx * modctx)

{

	struct lt_modctx * pmod;

	lt_slock();

	for (pmod=lt_modv_head; pmod ; pmod=pmod->mnext) {

		if (pmod == modctx) {

			if (pmod->mrefs) {

				pmod->mrefs--;

				return lt_sunlock(0,SLTDL_OK);

			}

			return lt_sunlock(-1,SLTDL_MODULE_REF_COUNT);

		}

	}

	return lt_sunlock(-1,SLTDL_MODULE_PTR_INVALID);

}