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e47be608d5
dlopen() of a library that is already loaded fails. libelf_insert() rejects a name that is already in the module registry with EEXIST, and dlinsert() passes that straight out, so the second caller gets NULL. POSIX says dlopen() shall return a handle to the object, and there is no way today for two modules to hold the same library at once -- which is what a shared library is for. So dlopen() now takes another reference on a library that is already there, and dlclose() only tears it down when the last handle goes. The count lives in the dlfcn layer rather than in libelf_insert() so that insmod keeps its own behaviour: a second insmod of the same name still fails with EEXIST, which is right for a kernel module. The module name is what makes any of this possible, and a PROTECTED build did not have one. Names were defined for CONFIG_BUILD_FLAT or the kernel side of a split build, on the reasoning that only the kernel needed them, which predates dlopen() being usable from user space. Without a name the user-space copy of libelf cannot recognise a second open of a library, cannot count opens, and cannot make dlclose() mean anything -- two dlopen()s there produce two independent copies of the library and lose track of the first. Names are therefore defined wherever CONFIG_LIBC_DLFCN is, which costs NAME_MAX per loaded module in that configuration. The path no longer has to be copied either. The module name is the basename of the file and libelf_insert() takes it as a const string, so dlinsert() finds it with strrchr() instead of handing a writable duplicate of the whole path to basename(). BUILD_KERNEL is deliberately untouched. dlopen() returns NULL there unconditionally: dlinsert() is a stub, because sharing a library between processes with separate address spaces needs the text in a shared region and the data per process at a matching virtual address, which is a different problem from this one. Built for mps3-an547:picostest with and without CONFIG_LIBC_DLFCN, and for stm32f4discovery:kostest, a PROTECTED configuration, with it enabled. Assisted-by: Claude Opus 5 (1M context) <noreply@anthropic.com> Signed-off-by: Marco Casaroli <marco.casaroli@gmail.com> |
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| .. | ||
| CMakeLists.txt | ||
| elf.h | ||
| elf_addrenv.c | ||
| elf_bind.c | ||
| elf_depend.c | ||
| elf_gethandle.c | ||
| elf_getsymbol.c | ||
| elf_globals.S | ||
| elf_init.c | ||
| elf_insert.c | ||
| elf_iobuffer.c | ||
| elf_load.c | ||
| elf_loadhdrs.c | ||
| elf_read.c | ||
| elf_registry.c | ||
| elf_remove.c | ||
| elf_sections.c | ||
| elf_symbols.c | ||
| elf_symtab.c | ||
| elf_uninit.c | ||
| elf_unload.c | ||
| elf_verify.c | ||
| gnu-elf.ld.in | ||
| Kconfig | ||
| Make.defs | ||
| Makefile | ||