/* Support for dynamic loading of extension modules */

#include <ctype.h>	/*  for isdigit()	  */
#include <errno.h>	/*  for global errno      */
#include <string.h>	/*  for strerror()        */
#include <stdlib.h>	/*  for malloc(), free()  */
#include <sys/ldr.h>

#include "Python.h"
#include "importdl.h"


#ifdef AIX_GENUINE_CPLUSPLUS
#include "/usr/lpp/xlC/include/load.h"
#define aix_load loadAndInit
#else
#define aix_load load
#endif


extern char *Py_GetProgramName(void);

typedef struct Module {
	struct Module *next;
	void          *entry;
} Module, *ModulePtr;

const struct filedescr _PyImport_DynLoadFiletab[] = {
	{".so", "rb", C_EXTENSION},
	{"module.so", "rb", C_EXTENSION},
	{0, 0}
};

static int
aix_getoldmodules(void **modlistptr)
{
	register ModulePtr       modptr, prevmodptr;
	register struct ld_info  *ldiptr;
	register char            *ldibuf;
	register int             errflag, bufsize = 1024;
	register unsigned int    offset;
	char *progname = Py_GetProgramName();
	
	/*
	-- Get the list of loaded modules into ld_info structures.
	*/
	if ((ldibuf = malloc(bufsize)) == NULL) {
		PyErr_SetString(PyExc_ImportError, strerror(errno));
		return -1;
	}
	while ((errflag = loadquery(L_GETINFO, ldibuf, bufsize)) == -1
	       && errno == ENOMEM) {
		free(ldibuf);
		bufsize += 1024;
		if ((ldibuf = malloc(bufsize)) == NULL) {
			PyErr_SetString(PyExc_ImportError, strerror(errno));
			return -1;
		}
	}
	if (errflag == -1) {
		PyErr_SetString(PyExc_ImportError, strerror(errno));
		return -1;
	}
	/*
	-- Make the modules list from the ld_info structures.
	*/
	ldiptr = (struct ld_info *)ldibuf;
	prevmodptr = NULL;
	do {
		if (strstr(progname, ldiptr->ldinfo_filename) == NULL &&
		    strstr(ldiptr->ldinfo_filename, "python") == NULL) {
			/*
			-- Extract only the modules belonging to the main
			-- executable + those containing "python" as a
			-- substring (like the "python[version]" binary or
			-- "libpython[version].a" in case it's a shared lib).
			*/
			offset = (unsigned int)ldiptr->ldinfo_next;
			ldiptr = (struct ld_info *)((unsigned int)
						    ldiptr + offset);
			continue;
		}
		if ((modptr = (ModulePtr)malloc(sizeof(Module))) == NULL) {
			PyErr_SetString(PyExc_ImportError, strerror(errno));
			while (*modlistptr) {
				modptr = (ModulePtr)*modlistptr;
				*modlistptr = (void *)modptr->next;
				free(modptr);
			}
			return -1;
		}
		modptr->entry = ldiptr->ldinfo_dataorg;
		modptr->next  = NULL;
		if (prevmodptr == NULL)
			*modlistptr = (void *)modptr;
		else
			prevmodptr->next = modptr;
		prevmodptr = modptr;
		offset = (unsigned int)ldiptr->ldinfo_next;
		ldiptr = (struct ld_info *)((unsigned int)ldiptr + offset);
	} while (offset);
	free(ldibuf);
	return 0;
}

static int
aix_bindnewmodule(void *newmoduleptr, void *modlistptr)
{
	register ModulePtr modptr;

	/*
	-- Bind the new module with the list of loaded modules.
	*/
	for (modptr = (ModulePtr)modlistptr; modptr; modptr = modptr->next)
		if (loadbind(0, modptr->entry, newmoduleptr) != 0)
			return -1;
	return 0;
}

static void
aix_loaderror(const char *pathname)
{

	char *message[1024], errbuf[1024];
	register int i,j;

	struct errtab { 
		int errNo;
		char *errstr;
	} load_errtab[] = {
		{L_ERROR_TOOMANY,	"too many errors, rest skipped."},
		{L_ERROR_NOLIB,		"can't load library:"},
		{L_ERROR_UNDEF,		"can't find symbol in library:"},
		{L_ERROR_RLDBAD,
		 "RLD index out of range or bad relocation type:"},
		{L_ERROR_FORMAT,	"not a valid, executable xcoff file:"},
		{L_ERROR_MEMBER,
		 "file not an archive or does not contain requested member:"},
		{L_ERROR_TYPE,		"symbol table mismatch:"},
		{L_ERROR_ALIGN,		"text alignment in file is wrong."},
		{L_ERROR_SYSTEM,	"System error:"},
		{L_ERROR_ERRNO,		NULL}
	};

#define LOAD_ERRTAB_LEN	(sizeof(load_errtab)/sizeof(load_errtab[0]))
#define ERRBUF_APPEND(s) strncat(errbuf, s, sizeof(errbuf)-strlen(errbuf)-1)

	PyOS_snprintf(errbuf, sizeof(errbuf), "from module %.200s ", pathname);

	if (!loadquery(L_GETMESSAGES, &message[0], sizeof(message))) {
		ERRBUF_APPEND(strerror(errno));
		ERRBUF_APPEND("\n");
	}
	for(i = 0; message[i] && *message[i]; i++) {
		int nerr = atoi(message[i]);
		for (j=0; j<LOAD_ERRTAB_LEN ; j++) {
		    if (nerr == load_errtab[j].errNo && load_errtab[j].errstr)
			ERRBUF_APPEND(load_errtab[j].errstr);
		}
		while (isdigit(*message[i])) message[i]++ ; 
		ERRBUF_APPEND(message[i]);
		ERRBUF_APPEND("\n");
	}
	errbuf[strlen(errbuf)-1] = '\0';	/* trim off last newline */
	PyErr_SetString(PyExc_ImportError, errbuf); 
	return; 
}


dl_funcptr _PyImport_GetDynLoadFunc(const char *fqname, const char *shortname,
				    const char *pathname, FILE *fp)
{
	dl_funcptr p;

	/*
	-- Invoke load() with L_NOAUTODEFER leaving the imported symbols
	-- of the shared module unresolved. Thus we have to resolve them
	-- explicitly with loadbind. The new module is loaded, then we
	-- resolve its symbols using the list of already loaded modules
	-- (only those that belong to the python executable). Get these
	-- with loadquery(L_GETINFO).
	*/

	static void *staticmodlistptr = NULL;

	if (!staticmodlistptr)
		if (aix_getoldmodules(&staticmodlistptr) == -1)
			return NULL;
	p = (dl_funcptr) aix_load((char *)pathname, L_NOAUTODEFER, 0);
	if (p == NULL) {
		aix_loaderror(pathname);
		return NULL;
	}
	if (aix_bindnewmodule((void *)p, staticmodlistptr) == -1) {
		aix_loaderror(pathname);
		return NULL;
	}

	return p;
}