tclLoadAix.c Go to the documentation of this file. /* * tclLoadAix.c -- * * This file implements the dlopen and dlsym APIs under the AIX operating * system, to enable the Tcl "load" command to work. This code was * provided by Jens-Uwe Mager. * * This file is subject to the following copyright notice, which is * different from the notice used elsewhere in Tcl. The file has been * modified to incorporate the file dlfcn.h in-line. * * Copyright (c) 1992,1993,1995,1996, Jens-Uwe Mager, Helios Software GmbH * Not derived from licensed software. * * Permission is granted to freely use, copy, modify, and redistribute * this software, provided that the author is not construed to be liable * for any results of using the software, alterations are clearly marked * as such, and this notice is not modified. * * RCS: @(#) $Id: tclLoadAix.c,v 1.6 2007/04/16 13:36:36 dkf Exp $ * * Note: this file has been altered from the original in a few ways in order * to work properly with Tcl. */ /* * @(#)dlfcn.c 1.7 revision of 95/08/14 19:08:38 * This is an unpublished work copyright (c) 1992 HELIOS Software GmbH * 30159 Hannover, Germany */ #include <stdio.h> #include <errno.h> #include <string.h> #include <stdlib.h> #include <sys/types.h> #include <sys/ldr.h> #include <a.out.h> #include <ldfcn.h> #include "../compat/dlfcn.h" /* * We simulate dlopen() et al. through a call to load. Because AIX has no call * to find an exported symbol we read the loader section of the loaded module * and build a list of exported symbols and their virtual address. */ typedef struct { char *name; /* The symbols's name. */ void *addr; /* Its relocated virtual address. */ } Export, *ExportPtr; /* * xlC uses the following structure to list its constructors and destructors. * This is gleaned from the output of munch. */ typedef struct { void (*init)(void); /* call static constructors */ void (*term)(void); /* call static destructors */ } Cdtor, *CdtorPtr; /* * The void * handle returned from dlopen is actually a ModulePtr. */ typedef struct Module { struct Module *next; char *name; /* module name for refcounting */ int refCnt; /* the number of references */ void *entry; /* entry point from load */ struct dl_info *info; /* optional init/terminate functions */ CdtorPtr cdtors; /* optional C++ constructors */ int nExports; /* the number of exports found */ ExportPtr exports; /* the array of exports */ } Module, *ModulePtr; /* * We keep a list of all loaded modules to be able to call the fini handlers * and destructors at atexit() time. */ static ModulePtr modList; /* * The last error from one of the dl* routines is kept in static variables * here. Each error is returned only once to the caller. */ static char errbuf[BUFSIZ]; static int errvalid; static void caterr(char *); static int readExports(ModulePtr); static void terminate(void); static void *findMain(void);  void * dlopen( const char *path, int mode) { register ModulePtr mp; static void *mainModule; /* * Upon the first call register a terminate handler that will close all * libraries. Also get a reference to the main module for use with * loadbind. */ if (!mainModule) { mainModule = findMain(); if (mainModule == NULL) { return NULL; } atexit(terminate); } /* * Scan the list of modules if we have the module already loaded. */ for (mp = modList; mp; mp = mp->next) { if (strcmp(mp->name, path) == 0) { mp->refCnt++; return (void *) mp; } } mp = (ModulePtr) calloc(1, sizeof(*mp)); if (mp == NULL) { errvalid++; strcpy(errbuf, "calloc: "); strcat(errbuf, strerror(errno)); return NULL; } mp->name = malloc((unsigned) (strlen(path) + 1)); strcpy(mp->name, path); /* * load should be declared load(const char *...). Thus we cast the path to * a normal char *. Ugly. */ mp->entry = (void *) load((char *)path, L_NOAUTODEFER, NULL); if (mp->entry == NULL) { free(mp->name); free(mp); errvalid++; strcpy(errbuf, "dlopen: "); strcat(errbuf, path); strcat(errbuf, ": "); /* * If AIX says the file is not executable, the error can be further * described by querying the loader about the last error. */ if (errno == ENOEXEC) { char *tmp[BUFSIZ/sizeof(char *)], **p; if (loadquery(L_GETMESSAGES, tmp, sizeof(tmp)) == -1) { strcpy(errbuf, strerror(errno)); } else { for (p=tmp ; *p ; p++) { caterr(*p); } } } else { strcat(errbuf, strerror(errno)); } return NULL; } mp->refCnt = 1; mp->next = modList; modList = mp; if (loadbind(0, mainModule, mp->entry) == -1) { loadbindFailure: dlclose(mp); errvalid++; strcpy(errbuf, "loadbind: "); strcat(errbuf, strerror(errno)); return NULL; } /* * If the user wants global binding, loadbind against all other loaded * modules. */ if (mode & RTLD_GLOBAL) { register ModulePtr mp1; for (mp1 = mp->next; mp1; mp1 = mp1->next) { if (loadbind(0, mp1->entry, mp->entry) == -1) { goto loadbindFailure; } } } if (readExports(mp) == -1) { dlclose(mp); return NULL; } /* * If there is a dl_info structure, call the init function. */ if (mp->info = (struct dl_info *)dlsym(mp, "dl_info")) { if (mp->info->init) { (*mp->info->init)(); } } else { errvalid = 0; } /* * If the shared object was compiled using xlC we will need to call static * constructors (and later on dlclose destructors). */ if (mp->cdtors = (CdtorPtr) dlsym(mp, "__cdtors")) { while (mp->cdtors->init) { (*mp->cdtors->init)(); mp->cdtors++; } } else { errvalid = 0; } return (void *) 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)) { /* INTL: "C", UTF safe. */ 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))); /* INTL: "C", UTF safe. */ 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; }  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) { while (mp->cdtors->term) { (*mp->cdtors->term)(); mp->cdtors++; } } 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; const char *errMsg; #define Error(msg) do{errMsg=(msg);goto error;}while(0) #define SysErr() Error(strerror(errno)) ldp = ldopen(mp->name, ldp); if (ldp == NULL) { struct ld_info *lp; char *buf; int size = 0; if (errno != ENOENT) { SysErr(); } /* * The module might be loaded due to the LIBPATH environment variable. * Search for the loaded module using L_GETINFO. */ while (1) { size += 4 * 1024; buf = malloc(size); if (buf == NULL) { SysErr(); } i = loadquery(L_GETINFO, buf, size); if (i != -1) { break; } free(buf); if (errno != ENOMEM) { SysErr(); } } /* * Traverse the list of loaded modules. The entry point returned by * load() does actually point to the data segment origin. */ lp = (struct ld_info *) buf; while (lp) { if (lp->ldinfo_dataorg == mp->entry) { 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) { SysErr(); } } if (TYPE(ldp) != U802TOCMAGIC) { Error("bad magic"); } /* * 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) { Error("cannot read data section header"); } if (ldnshread(ldp, _LOADER, &sh) != SUCCESS) { Error("cannot read loader section header"); } /* * We read the complete loader section in one chunk, this makes finding * long symbol names residing in the string table easier. */ ldbuf = (char *) malloc(sh.s_size); if (ldbuf == NULL) { SysErr(); } if (FSEEK(ldp, sh.s_scnptr, BEGINNING) != OKFSEEK) { free(ldbuf); Error("cannot seek to loader section"); } if (FREAD(ldbuf, sh.s_size, 1, ldp) != 1) { free(ldbuf); Error("cannot read loader section"); } 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++; } mp->exports = (ExportPtr) calloc(mp->nExports, sizeof(*mp->exports)); if (mp->exports == NULL) { free(ldbuf); SysErr(); } /* * Fill in the export table. All entries are relative to the entry point * we got from load. */ ep = mp->exports; ls = (LDSYM *)(ldbuf + LDHDRSZ); for (i=lhp->l_nsyms ; i!=0 ; 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 = malloc((unsigned) (strlen(symname) + 1)); strcpy(ep->name, symname); ep->addr = (void *)((unsigned long) mp->entry + ls->l_value - shdata.s_vaddr); ep++; } free(ldbuf); while (ldclose(ldp) == FAILURE) { /* Empty body */ } return 0; /* * This is a factoring out of the error-handling code to make the rest of * the function much simpler to read. */ error: errvalid++; strcpy(errbuf, "readExports: "); strcat(errbuf, errMsg); if (ldp != NULL) { while (ldclose(ldp) == FAILURE) { /* Empty body */ } } return -1; }  /* * Find the main modules entry point. 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; buf = malloc(size); if (buf == NULL) { goto error; } while ((i = loadquery(L_GETINFO, buf, size)) == -1 && errno == ENOMEM) { free(buf); size += 4*1024; buf = malloc(size); if (buf == NULL) { goto error; } } if (i == -1) { free(buf); goto error; } /* * The first entry is the main module. The entry point returned by load() * does actually point to the data segment origin. */ lp = (struct ld_info *) buf; ret = lp->ldinfo_dataorg; free(buf); return ret; error: errvalid++; strcpy(errbuf, "findMain: "); strcat(errbuf, strerror(errno)); return NULL; }  /* * Local Variables: * mode: c * c-basic-offset: 4 * fill-column: 78 * End: */

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