dso.c

apache的软件linux版本

	 * to call global constructors using the _GLOBAL__DI function,
	 * and later, global destructors using the _GLOBAL_DD
	 * funciton.  --jwe
	 */
    }
    else if (mp->gcc_ctor = (GccCDtorPtr) dlsym(mp, "_GLOBAL__DI")) {
	(*mp->gcc_ctor) ();
	mp->gcc_dtor = (GccCDtorPtr) dlsym(mp, "_GLOBAL__DD");
    }
    else
	errvalid = 0;
    return mp;
}

/*
 * Attempt to decipher an AIX loader error message and append it
 * to our static error message buffer.
 */
static void caterr(char *s)
{
    register char *p = s;

    while (*p >= '0' && *p <= '9')
	p++;
    switch (atoi(s)) {
    case L_ERROR_TOOMANY:
	strcat(errbuf, "to many errors");
	break;
    case L_ERROR_NOLIB:
	strcat(errbuf, "can't load library");
	strcat(errbuf, p);
	break;
    case L_ERROR_UNDEF:
	strcat(errbuf, "can't find symbol");
	strcat(errbuf, p);
	break;
    case L_ERROR_RLDBAD:
	strcat(errbuf, "bad RLD");
	strcat(errbuf, p);
	break;
    case L_ERROR_FORMAT:
	strcat(errbuf, "bad exec format in");
	strcat(errbuf, p);
	break;
    case L_ERROR_ERRNO:
	strcat(errbuf, strerror(atoi(++p)));
	break;
    default:
	strcat(errbuf, s);
	break;
    }
}

void *dlsym(void *handle, const char *symbol)
{
    register ModulePtr mp = (ModulePtr) handle;
    register ExportPtr ep;
    register int i;

    /*
     * Could speed up the search, but I assume that one assigns
     * the result to function pointers anyways.
     */
    for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
	if (strcmp(ep->name, symbol) == 0)
	    return ep->addr;
    errvalid++;
    strcpy(errbuf, "dlsym: undefined symbol ");
    strcat(errbuf, symbol);
    return NULL;
}

const char *dlerror(void)
{
    if (errvalid) {
	errvalid = 0;
	return errbuf;
    }
    return NULL;
}

int dlclose(void *handle)
{
    register ModulePtr mp = (ModulePtr) handle;
    int result;
    register ModulePtr mp1;

    if (--mp->refCnt > 0)
	return 0;
    if (mp->info && mp->info->fini)
	(*mp->info->fini) ();
    if (mp->cdtors) {
	CdtorPtr cp = mp->cdtors;
	while (cp->init || cp->term) {
	    if (cp->term && cp->init != (void (*)(void)) 0xffffffff)
		(*cp->term) ();
	    cp++;
	}
	/*
	 * If the function to handle global destructors for g++
	 * exists, call it.  --jwe
	 */
    }
    else if (mp->gcc_dtor) {
	(*mp->gcc_dtor) ();
    }
    result = unload(mp->entry);
    if (result == -1) {
	errvalid++;
	strcpy(errbuf, strerror(errno));
    }
    if (mp->exports) {
	register ExportPtr ep;
	register int i;
	for (ep = mp->exports, i = mp->nExports; i; i--, ep++)
	    if (ep->name)
		free(ep->name);
	free(mp->exports);
    }
    if (mp == modList)
	modList = mp->next;
    else {
	for (mp1 = modList; mp1; mp1 = mp1->next)
	    if (mp1->next == mp) {
		mp1->next = mp->next;
		break;
	    }
    }
    free(mp->name);
    free(mp);
    return result;
}

static void terminate(void)
{
    while (modList)
	dlclose(modList);
}

/*
 * Build the export table from the XCOFF .loader section.
 */
static int readExports(ModulePtr mp)
{
    LDFILE *ldp = NULL;
    SCNHDR sh, shdata;
    LDHDR *lhp;
    char *ldbuf;
    LDSYM *ls;
    int i;
    ExportPtr ep;
    struct ld_info *lp;
    char *buf;
    int size = 4 * 1024;
    void *dataorg;

    /*
     * The module might be loaded due to the LIBPATH
     * environment variable. Search for the loaded
     * module using L_GETINFO.
     */
    if ((buf = malloc(size)) == NULL) {
	errvalid++;
	strcpy(errbuf, "readExports: ");
	strcat(errbuf, strerror(errno));
	return -1;
    }
    while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
	free(buf);
	size += 4 * 1024;
	if ((buf = malloc(size)) == NULL) {
	    errvalid++;
	    strcpy(errbuf, "readExports: ");
	    strcat(errbuf, strerror(errno));
	    return -1;
	}
    }
    if (i == -1) {
	errvalid++;
	strcpy(errbuf, "readExports: ");
	strcat(errbuf, strerror(errno));
	free(buf);
	return -1;
    }
    /*
     * Traverse the list of loaded modules. The entry point
     * returned by load() does actually point to the TOC
     * entry contained in the data segment.
     */
    lp = (struct ld_info *) buf;
    while (lp) {
	if ((unsigned long) mp->entry >= (unsigned long) lp->ldinfo_dataorg &&
	    (unsigned long) mp->entry < (unsigned long) lp->ldinfo_dataorg +
	    lp->ldinfo_datasize) {
	    dataorg = lp->ldinfo_dataorg;
	    ldp = ldopen(lp->ldinfo_filename, ldp);
	    break;
	}
	if (lp->ldinfo_next == 0)
	    lp = NULL;
	else
	    lp = (struct ld_info *) ((char *) lp + lp->ldinfo_next);
    }
    free(buf);
    if (!ldp) {
	errvalid++;
	strcpy(errbuf, "readExports: ");
	strcat(errbuf, strerror(errno));
	return -1;
    }
    if (TYPE(ldp) != U802TOCMAGIC) {
	errvalid++;
	strcpy(errbuf, "readExports: bad magic");
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    /*
     * Get the padding for the data section. This is needed for
     * AIX 4.1 compilers. This is used when building the final
     * function pointer to the exported symbol.
     */
    if (ldnshread(ldp, _DATA, &shdata) != SUCCESS) {
	errvalid++;
	strcpy(errbuf, "readExports: cannot read data section header");
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) {
	errvalid++;
	strcpy(errbuf, "readExports: cannot read loader section header");
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    /*
     * We read the complete loader section in one chunk, this makes
     * finding long symbol names residing in the string table easier.
     */
    if ((ldbuf = (char *) malloc(sh.s_size)) == NULL) {
	errvalid++;
	strcpy(errbuf, "readExports: ");
	strcat(errbuf, strerror(errno));
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) {
	errvalid++;
	strcpy(errbuf, "readExports: cannot seek to loader section");
	free(ldbuf);
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    if (FREAD(ldbuf, sh.s_size, 1, ldp) != 1) {
	errvalid++;
	strcpy(errbuf, "readExports: cannot read loader section");
	free(ldbuf);
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    lhp = (LDHDR *) ldbuf;
    ls = (LDSYM *) (ldbuf + LDHDRSZ);
    /*
     * Count the number of exports to include in our export table.
     */
    for (i = lhp->l_nsyms; i; i--, ls++) {
	if (!LDR_EXPORT(*ls))
	    continue;
	mp->nExports++;
    }
    if ((mp->exports = (ExportPtr) calloc(mp->nExports, sizeof(*mp->exports))) == NULL) {
	errvalid++;
	strcpy(errbuf, "readExports: ");
	strcat(errbuf, strerror(errno));
	free(ldbuf);
	while (ldclose(ldp) == FAILURE);
	return -1;
    }
    /*
     * Fill in the export table. All entries are relative to
     * the beginning of the data origin.
     */
    ep = mp->exports;
    ls = (LDSYM *) (ldbuf + LDHDRSZ);
    for (i = lhp->l_nsyms; i; i--, ls++) {
	char *symname;
	char tmpsym[SYMNMLEN + 1];
	if (!LDR_EXPORT(*ls))
	    continue;
	if (ls->l_zeroes == 0)
	    symname = ls->l_offset + lhp->l_stoff + ldbuf;
	else {
	    /*
	     * The l_name member is not zero terminated, we
	     * must copy the first SYMNMLEN chars and make
	     * sure we have a zero byte at the end.
	     */
	    strncpy(tmpsym, ls->l_name, SYMNMLEN);
	    tmpsym[SYMNMLEN] = '\0';
	    symname = tmpsym;
	}
	ep->name = strdup(symname);
	ep->addr = (void *) ((unsigned long) dataorg +
			     ls->l_value - shdata.s_vaddr);
	ep++;
    }
    free(ldbuf);
    while (ldclose(ldp) == FAILURE);
    return 0;
}

/*
 * Find the main modules data origin. This is used as export pointer
 * for loadbind() to be able to resolve references to the main part.
 */
static void *findMain(void)
{
    struct ld_info *lp;
    char *buf;
    int size = 4 * 1024;
    int i;
    void *ret;

    if ((buf = malloc(size)) == NULL) {
	errvalid++;
	strcpy(errbuf, "findMain: ");
	strcat(errbuf, strerror(errno));
	return NULL;
    }
    while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) {
	free(buf);
	size += 4 * 1024;
	if ((buf = malloc(size)) == NULL) {
	    errvalid++;
	    strcpy(errbuf, "findMain: ");
	    strcat(errbuf, strerror(errno));
	    return NULL;
	}
    }
    if (i == -1) {
	errvalid++;
	strcpy(errbuf, "findMain: ");
	strcat(errbuf, strerror(errno));
	free(buf);
	return NULL;
    }
    /*
     * The first entry is the main module. The data segment
     * starts with the TOC entries for all exports, so the
     * data segment origin works as argument for loadbind.
     */
    lp = (struct ld_info *) buf;
    ret = lp->ldinfo_dataorg;
    free(buf);
    return ret;
}

#endif