/**************************************************************************** * libs/libc/dlfcn/lib_dlopen.c * * Licensed to the Apache Software Foundation (ASF) under one or more * contributor license agreements. See the NOTICE file distributed with * this work for additional information regarding copyright ownership. The * ASF licenses this file to you under the Apache License, Version 2.0 (the * "License"); you may not use this file except in compliance with the * License. You may obtain a copy of the License at * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the * License for the specific language governing permissions and limitations * under the License. * ****************************************************************************/ /**************************************************************************** * Included Files ****************************************************************************/ #include #include #include #include #include #include #include #include #include #include #include #include "libc.h" /**************************************************************************** * Private Functions ****************************************************************************/ /**************************************************************************** * Name: dldump_loadinfo ****************************************************************************/ #ifdef CONFIG_BUILD_PROTECTED #if defined(CONFIG_DEBUG_INFO) && defined(CONFIG_DEBUG_BINFMT) static void dldump_loadinfo(FAR struct mod_loadinfo_s *loadinfo) { int i; binfo("LOAD_INFO:\n"); binfo(" textalloc: %08lx\n", (long)loadinfo->textalloc); binfo(" datastart: %08lx\n", (long)loadinfo->datastart); binfo(" textsize: %ld\n", (long)loadinfo->textsize); binfo(" datasize: %ld\n", (long)loadinfo->datasize); binfo(" filelen: %ld\n", (long)loadinfo->filelen); binfo(" filfd: %d\n", loadinfo->filfd); binfo(" symtabidx: %d\n", loadinfo->symtabidx); binfo(" strtabidx: %d\n", loadinfo->strtabidx); binfo("ELF Header:\n"); binfo(" e_ident: %02x %02x %02x %02x\n", loadinfo->ehdr.e_ident[0], loadinfo->ehdr.e_ident[1], loadinfo->ehdr.e_ident[2], loadinfo->ehdr.e_ident[3]); binfo(" e_type: %04x\n", loadinfo->ehdr.e_type); binfo(" e_machine: %04x\n", loadinfo->ehdr.e_machine); binfo(" e_version: %08x\n", loadinfo->ehdr.e_version); binfo(" e_entry: %08lx\n", (long)loadinfo->ehdr.e_entry); binfo(" e_phoff: %d\n", loadinfo->ehdr.e_phoff); binfo(" e_shoff: %d\n", loadinfo->ehdr.e_shoff); binfo(" e_flags: %08x\n" , loadinfo->ehdr.e_flags); binfo(" e_ehsize: %d\n", loadinfo->ehdr.e_ehsize); binfo(" e_phentsize: %d\n", loadinfo->ehdr.e_phentsize); binfo(" e_phnum: %d\n", loadinfo->ehdr.e_phnum); binfo(" e_shentsize: %d\n", loadinfo->ehdr.e_shentsize); binfo(" e_shnum: %d\n", loadinfo->ehdr.e_shnum); binfo(" e_shstrndx: %d\n", loadinfo->ehdr.e_shstrndx); if (loadinfo->shdr && loadinfo->ehdr.e_shnum > 0) { for (i = 0; i < loadinfo->ehdr.e_shnum; i++) { FAR Elf_Shdr *shdr = &loadinfo->shdr[i]; binfo("Sections %d:\n", i); binfo(" sh_name: %08x\n", shdr->sh_name); binfo(" sh_type: %08x\n", shdr->sh_type); binfo(" sh_flags: %08x\n", shdr->sh_flags); binfo(" sh_addr: %08x\n", shdr->sh_addr); binfo(" sh_offset: %d\n", shdr->sh_offset); binfo(" sh_size: %d\n", shdr->sh_size); binfo(" sh_link: %d\n", shdr->sh_link); binfo(" sh_info: %d\n", shdr->sh_info); binfo(" sh_addralign: %d\n", shdr->sh_addralign); binfo(" sh_entsize: %d\n", shdr->sh_entsize); } } } #else # define dldump_loadinfo(i) #endif #endif /**************************************************************************** * Name: dldump_initializer ****************************************************************************/ #ifdef CONFIG_BUILD_PROTECTED #ifdef CONFIG_MODLIB_DUMPBUFFER static void dldump_initializer(mod_initializer_t initializer, FAR struct mod_loadinfo_s *loadinfo) { modlib_dumpbuffer("Initializer code", (FAR const uint8_t *)initializer, MIN(loadinfo->textsize - loadinfo->ehdr.e_entry, 512)); } #else # define dldump_initializer(b,l) #endif #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: dlinsert * * Description: * Verify that the file is an ELF module binary and, if so, load the * shared library into user memory and initialize it for use. * * NOTE: modlib_setsymtab() had to have been called by application logic * logic prior to calling this. Otherwise, dlinsert will be unable to * resolve symbols in the OS module. * * Input Parameters: * filename - Full path to the shared library file to be loaded * * Returned Value: * A non-NULL module handle that can be used on subsequent calls to other * shared library interfaces is returned on success. If insmod() was * unable to load the module insmod() will return a NULL handle and the * errno variable will be set appropriately. * ****************************************************************************/ #ifdef CONFIG_BUILD_PROTECTED /* The PROTECTED build is equivalent to the FLAT build EXCEPT that there * must be two copies of the module logic: One residing in kernel * space and using the kernel symbol table and one residing in user space * using the user space symbol table. * * dlinsert() is essentially a clone of insmod(). */ static inline FAR void *dlinsert(FAR const char *filename) { struct mod_loadinfo_s loadinfo; FAR struct module_s *modp; mod_initializer_t initializer; int ret; binfo("Loading file: %s\n", filename); /* Get exclusive access to the module registry */ modlib_registry_lock(); /* Initialize the ELF library to load the program binary. */ ret = modlib_initialize(filename, &loadinfo); dldump_loadinfo(&loadinfo); if (ret != 0) { serr("ERROR: Failed to initialize to load module: %d\n", ret); goto errout_with_lock; } /* Allocate a module registry entry to hold the module data */ modp = (FAR struct module_s *)lib_zalloc(sizeof(struct module_s)); if (ret != 0) { binfo("Failed to initialize for load of ELF program: %d\n", ret); goto errout_with_loadinfo; } /* Load the program binary */ ret = modlib_load(&loadinfo); dldump_loadinfo(&loadinfo); if (ret != 0) { binfo("Failed to load ELF program binary: %d\n", ret); goto errout_with_registry_entry; } /* Bind the program to the kernel symbol table */ ret = modlib_bind(modp, &loadinfo); if (ret != 0) { binfo("Failed to bind symbols program binary: %d\n", ret); goto errout_with_load; } /* Save the load information */ modp->textalloc = (FAR void *)loadinfo.textalloc; modp->dataalloc = (FAR void *)loadinfo.datastart; #if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MODULE) modp->textsize = loadinfo.textsize; modp->datasize = loadinfo.datasize; #endif /* Get the module initializer entry point */ initializer = (mod_initializer_t)(loadinfo.textalloc + loadinfo.ehdr.e_entry); #if defined(CONFIG_FS_PROCFS) && !defined(CONFIG_FS_PROCFS_EXCLUDE_MODULE) modp->initializer = initializer; #endif dldump_initializer(initializer, &loadinfo); /* Call the module initializer */ ret = initializer(&modp->modinfo); if (ret < 0) { binfo("Failed to initialize the module: %d\n", ret); goto errout_with_load; } /* Add the new module entry to the registry */ modlib_registry_add(modp); modlib_uninitialize(&loadinfo); modlib_registry_unlock(); return (FAR void *)modp; errout_with_load: modlib_unload(&loadinfo); modlib_undepend(modp); errout_with_registry_entry: lib_free(modp); errout_with_loadinfo: modlib_uninitialize(&loadinfo); errout_with_lock: modlib_registry_unlock(); set_errno(-ret); return NULL; } #elif defined(CONFIG_BUILD_FLAT) /* In the FLAT build, a shared library is essentially the same as a kernel * module. * * REVISIT: Missing functionality: * - No automatic binding of symbols * - No dependencies * - mode is ignored. */ static inline FAR void *dlinsert(FAR const char *filename) { FAR void *handle; FAR char *name; DEBUGASSERT(filename != NULL); name = strdup(filename); if (name == NULL) { return NULL; } /* Then install the file using the basename of the file as the module * name. */ handle = insmod(filename, basename(name)); lib_free(name); return handle; } #else /* if defined(CONFIG_BUILD_KERNEL) */ /* The KERNEL build is considerably more complex: In order to be shared, * the .text portion of the module must be (1) build for PIC/PID operation * and (2) must like in a shared memory region accessible from all * processes. The .data/.bss portion of the module must be allocated in * the user space of each process, but must lie at the same virtual address * so that it can be referenced from the one copy of the text in the shared * memory region. */ static inline FAR void *dlinsert(FAR const char *filename) { /* #warning Missing logic */ return NULL; } #endif /**************************************************************************** * Public Functions ****************************************************************************/ /**************************************************************************** * Name: dlopen * * Description: * dlopen() makes an executable object file specified by file available to * the calling program. The class of files eligible for this operation and * the manner of their construction are specified by the implementation, * though typically such files are executable objects such as shared * libraries, relocatable files or programs. Note that some implementations * permit the construction of dependencies between such objects that are * embedded within files. In such cases, a dlopen() operation will load * such dependencies in addition to the object referenced by file. * Implementations may also impose specific constraints on the construction * of programs that can employ dlopen() and its related services. * * If a file is specified in multiple dlopen() invocations, mode is * interpreted at each invocation. Note, however, that once RTLD_NOW has * been specified all relocations will have been completed rendering * further RTLD_NOW operations redundant and any further RTLD_LAZY * operations irrelevant. Similarly note that once RTLD_GLOBAL has been * specified the object will maintain the RTLD_GLOBAL status regardless * of any previous or future specification of RTLD_LOCAL, so long as the * object remains in the address space (see dlclose()). * * Symbols introduced into a program through calls to dlopen() may be * used in relocation activities. Symbols so introduced may duplicate * symbols already defined by the program or previous dlopen() * operations. To resolve the ambiguities such a situation might * present, the resolution of a symbol reference to symbol definition is * based on a symbol resolution order. Two such resolution orders are * defined: load or dependency ordering. Load order establishes an * ordering among symbol definitions, such that the definition first * loaded (including definitions from the image file and any dependent * objects loaded with it) has priority over objects added later (via * dlopen()). Load ordering is used in relocation processing. Dependency * ordering uses a breadth-first order starting with a given object, * then all of its dependencies, then any dependents of those, iterating * until all dependencies are satisfied. With the exception of the global * symbol object obtained via a dlopen() operation on a file of 0, * dependency ordering is used by the dlsym() function. Load ordering is * used in dlsym() operations upon the global symbol object. * * When an object is first made accessible via dlopen() it and its * dependent objects are added in dependency order. Once all the objects * are added, relocations are performed using load order. Note that if an * object or its dependencies had been previously loaded, the load and * dependency orders may yield different resolutions. * * The symbols introduced by dlopen() operations, and available through * dlsym() are at a minimum those which are exported as symbols of global * scope by the object. Typically such symbols will be those that were * specified in (for example) C source code as having extern linkage. The * precise manner in which an implementation constructs the set of * exported symbols for a dlopen() object is specified by that * implementation. * * Input Parameters: * file - Used to construct a pathname to the object file. If file * contains a slash character, the file argument is used as the * pathname for the file. Otherwise, file is used in an * implementation-dependent manner to yield a pathname. * * If the value of file is 0, dlopen() provides a handle on a * global symbol object. This object provides access to the symbols * from an ordered set of objects consisting of the original * program image file, together with any objects loaded at program * startup as specified by that process image file (for example, * shared libraries), and the set of objects loaded using a * dlopen() operation together with the RTLD_GLOBAL flag. As the * latter set of objects can change during execution, the set * identified by handle can also change dynamically. * * Only a single copy of an object file is brought into the address * space, even if dlopen() is invoked multiple times in reference * to the file, and even if different pathnames are used to * reference the file. * mode - Describes how dlopen() will operate upon file with respect to * the processing of relocations and the scope of visibility of the * symbols provided within file. When an object is brought into the * address space of a process, it may contain references to symbols * whose addresses are not known until the object is loaded. These * references must be relocated before the symbols can be accessed. * The mode parameter governs when these relocations take place. * See definitions above for values of the mode parameter:. * * Returned Value: * A successful dlopen() returns a handle which the caller may use on * subsequent calls to dlsym() and dlclose(). The value of this handle * should not be interpreted in any way by the caller. * * If file cannot be found, cannot be opened for reading, is not of an * appropriate object format for processing by dlopen(), or if an error * occurs during the process of loading file or relocating its symbolic * references, dlopen() will return NULL. More detailed diagnostic * information will be available through dlerror(). * * Reference: OpenGroup.org * ****************************************************************************/ FAR void *dlopen(FAR const char *file, int mode) { FAR void *handle = NULL; #ifdef CONFIG_LIBC_ENVPATH if (file[0] != '/') { FAR const char *relpath; FAR char *fullpath; ENVPATH_HANDLE env; /* Set aside the relative path */ relpath = file; /* Initialize to traverse the LD_LIBRARY_PATH variable */ env = envpath_init("LD_LIBRARY_PATH"); if (env) { /* Get the next absolute file path */ while ((fullpath = envpath_next(env, relpath)) != NULL) { /* Try to load the file at this path */ handle = dlinsert(fullpath); /* Free the allocated fullpath */ lib_free(fullpath); /* Break out of the loop with handle != NULL on success */ if (handle != NULL) { break; } } /* Release the traversal handle */ envpath_release(env); } } else #endif { /* We already have the one and only absolute path to the file to * be loaded. */ handle = dlinsert(file); } return handle; }