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[src/trunk]: src/libexec/ld.elf_so Separate matched symbol functionality out ...



details:   https://anonhg.NetBSD.org/src/rev/69b5f16c0018
branches:  trunk
changeset: 1007751:69b5f16c0018
user:      kamil <kamil%NetBSD.org@localhost>
date:      Sat Feb 29 04:21:42 2020 +0000

description:
Separate matched symbol functionality out of _rtld_symlook_obj()

Simplifies the code and it will allow to use the matched symbol
functionality by other users.

diffstat:

 libexec/ld.elf_so/symbol.c |  221 ++++++++++++++++++++++++--------------------
 1 files changed, 118 insertions(+), 103 deletions(-)

diffs (257 lines):

diff -r d4f2b4d5c064 -r 69b5f16c0018 libexec/ld.elf_so/symbol.c
--- a/libexec/ld.elf_so/symbol.c        Sat Feb 29 04:02:06 2020 +0000
+++ b/libexec/ld.elf_so/symbol.c        Sat Feb 29 04:21:42 2020 +0000
@@ -1,4 +1,4 @@
-/*     $NetBSD: symbol.c,v 1.69 2017/08/09 18:44:32 joerg Exp $         */
+/*     $NetBSD: symbol.c,v 1.70 2020/02/29 04:21:42 kamil Exp $         */
 
 /*
  * Copyright 1996 John D. Polstra.
@@ -40,7 +40,7 @@
 
 #include <sys/cdefs.h>
 #ifndef lint
-__RCSID("$NetBSD: symbol.c,v 1.69 2017/08/09 18:44:32 joerg Exp $");
+__RCSID("$NetBSD: symbol.c,v 1.70 2020/02/29 04:21:42 kamil Exp $");
 #endif /* not lint */
 
 #include <err.h>
@@ -193,6 +193,119 @@
        return def;
 }
 
+static bool
+_rtld_symlook_obj_matched_symbol(const char *name,
+    const Obj_Entry *obj, u_int flags, const Ver_Entry *ventry,
+    unsigned long symnum, const Elf_Sym **vsymp, int *vcount)
+{
+       const Elf_Sym  *symp;
+       const char     *strp;
+       Elf_Half verndx;
+
+       symp = obj->symtab + symnum;
+       strp = obj->strtab + symp->st_name;
+       rdbg(("check \"%s\" vs \"%s\" in %s", name, strp, obj->path));
+       if (name[1] != strp[1] || strcmp(name, strp))
+               return false;
+#if defined(__mips__) || defined(__vax__)
+       if (symp->st_shndx == SHN_UNDEF)
+               continue;
+#else
+       /*
+        * XXX DANGER WILL ROBINSON!
+        * If we have a function pointer in the executable's
+        * data section, it points to the executable's PLT
+        * slot, and there is NO relocation emitted.  To make
+        * the function pointer comparable to function pointers
+        * in shared libraries, we must resolve data references
+        * in the libraries to point to PLT slots in the
+        * executable, if they exist.
+        */
+       if (symp->st_shndx == SHN_UNDEF &&
+           ((flags & SYMLOOK_IN_PLT) ||
+           symp->st_value == 0 ||
+           ELF_ST_TYPE(symp->st_info) != STT_FUNC))
+               return false;
+#endif
+
+       if (ventry == NULL) {
+               if (obj->versyms != NULL) {
+                       verndx = VER_NDX(obj->versyms[symnum].vs_vers);
+                       if (verndx > obj->vertabnum) {
+                               _rtld_error("%s: symbol %s references "
+                                   "wrong version %d", obj->path,
+                                   &obj->strtab[symnum], verndx);
+                               return false;
+                       }
+
+                       /*
+                        * If we are not called from dlsym (i.e. this
+                        * is a normal relocation from unversioned
+                        * binary), accept the symbol immediately
+                        * if it happens to have first version after
+                        * this shared object became versioned.
+                        * Otherwise, if symbol is versioned and not
+                        * hidden, remember it. If it is the only
+                        * symbol with this name exported by the shared
+                        * object, it will be returned as a match at the
+                        * end of the function. If symbol is global
+                        * (verndx < 2) accept it unconditionally.
+                        */
+                       if (!(flags & SYMLOOK_DLSYM) &&
+                           verndx == VER_NDX_GIVEN) {
+                               *vsymp = symp;
+                               return true;
+                       } else if (verndx >= VER_NDX_GIVEN) {
+                               if (!(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN)) {
+                                       if (*vsymp == NULL)
+                                               *vsymp = symp;
+                                       (*vcount)++;
+                               }
+                               return false;
+                       }
+               }
+               *vsymp = symp;
+               return true;
+       } else {
+               if (obj->versyms == NULL) {
+                       if (_rtld_object_match_name(obj, ventry->name)){
+                               _rtld_error("%s: object %s should "
+                                   "provide version %s for symbol %s",
+                                   _rtld_objself.path, obj->path,
+                                   ventry->name, &obj->strtab[symnum]);
+                               return false;
+                       }
+               } else {
+                       verndx = VER_NDX(obj->versyms[symnum].vs_vers);
+                       if (verndx > obj->vertabnum) {
+                               _rtld_error("%s: symbol %s references "
+                                   "wrong version %d", obj->path,
+                                   &obj->strtab[symnum], verndx);
+                               return false;
+                       }
+                       if (obj->vertab[verndx].hash != ventry->hash ||
+                           strcmp(obj->vertab[verndx].name, ventry->name)) {
+                               /*
+                               * Version does not match. Look if this
+                               * is a global symbol and if it is not
+                               * hidden. If global symbol (verndx < 2)
+                               * is available, use it. Do not return
+                               * symbol if we are called by dlvsym,
+                               * because dlvsym looks for a specific
+                               * version and default one is not what
+                               * dlvsym wants.
+                               */
+                               if ((flags & SYMLOOK_DLSYM) ||
+                                   (obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN) ||
+                                   (verndx >= VER_NDX_GIVEN))
+                                       return false;
+                       }
+               }
+               *vsymp = symp;
+               return true;
+       }
+}
+
 /*
  * Search the symbol table of a single shared object for a symbol of
  * the given name.  Returns a pointer to the symbol, or NULL if no
@@ -207,115 +320,17 @@
 {
        unsigned long symnum;
        const Elf_Sym *vsymp = NULL;
-       Elf_Half verndx;
        int vcount = 0;
 
        for (symnum = obj->buckets[fast_remainder32(hash, obj->nbuckets,
             obj->nbuckets_m, obj->nbuckets_s1, obj->nbuckets_s2)];
             symnum != ELF_SYM_UNDEFINED;
             symnum = obj->chains[symnum]) {
-               const Elf_Sym  *symp;
-               const char     *strp;
-
                assert(symnum < obj->nchains);
-               symp = obj->symtab + symnum;
-               strp = obj->strtab + symp->st_name;
-               rdbg(("check \"%s\" vs \"%s\" in %s", name, strp, obj->path));
-               if (name[1] != strp[1] || strcmp(name, strp))
-                       continue;
-#if defined(__mips__) || defined(__vax__)
-               if (symp->st_shndx == SHN_UNDEF)
-                       continue;
-#else
-               /*
-                * XXX DANGER WILL ROBINSON!
-                * If we have a function pointer in the executable's
-                * data section, it points to the executable's PLT
-                * slot, and there is NO relocation emitted.  To make
-                * the function pointer comparable to function pointers
-                * in shared libraries, we must resolve data references
-                * in the libraries to point to PLT slots in the
-                * executable, if they exist.
-                */
-               if (symp->st_shndx == SHN_UNDEF &&
-                   ((flags & SYMLOOK_IN_PLT) ||
-                   symp->st_value == 0 ||
-                   ELF_ST_TYPE(symp->st_info) != STT_FUNC))
-                       continue;
-#endif
-
-               if (ventry == NULL) {
-                       if (obj->versyms != NULL) {
-                               verndx = VER_NDX(obj->versyms[symnum].vs_vers);
-                               if (verndx > obj->vertabnum) {
-                                       _rtld_error("%s: symbol %s references "
-                                           "wrong version %d", obj->path,
-                                           &obj->strtab[symnum], verndx);
-                                       continue;
-                               }
 
-                               /*
-                                * If we are not called from dlsym (i.e. this
-                                * is a normal relocation from unversioned
-                                * binary), accept the symbol immediately
-                                * if it happens to have first version after
-                                * this shared object became versioned.
-                                * Otherwise, if symbol is versioned and not
-                                * hidden, remember it. If it is the only
-                                * symbol with this name exported by the shared
-                                * object, it will be returned as a match at the
-                                * end of the function. If symbol is global
-                                * (verndx < 2) accept it unconditionally.
-                                */
-                               if (!(flags & SYMLOOK_DLSYM) &&
-                                   verndx == VER_NDX_GIVEN) {
-                                       return symp;
-                               } else if (verndx >= VER_NDX_GIVEN) {
-                                       if (!(obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN)) {
-                                               if (vsymp == NULL)
-                                                       vsymp = symp;
-                                               vcount++;
-                                       }
-                                       continue;
-                               }
-                       }
-                       return symp;
-               } else {
-                       if (obj->versyms == NULL) {
-                               if (_rtld_object_match_name(obj, ventry->name)){
-                                       _rtld_error("%s: object %s should "
-                                           "provide version %s for symbol %s",
-                                           _rtld_objself.path, obj->path,
-                                           ventry->name, &obj->strtab[symnum]);
-                                       continue;
-                               }
-                       } else {
-                               verndx = VER_NDX(obj->versyms[symnum].vs_vers);
-                               if (verndx > obj->vertabnum) {
-                                       _rtld_error("%s: symbol %s references "
-                                           "wrong version %d", obj->path,
-                                           &obj->strtab[symnum], verndx);
-                                       continue;
-                               }
-                               if (obj->vertab[verndx].hash != ventry->hash ||
-                                   strcmp(obj->vertab[verndx].name, ventry->name)) {
-                                       /*
-                                       * Version does not match. Look if this
-                                       * is a global symbol and if it is not
-                                       * hidden. If global symbol (verndx < 2)
-                                       * is available, use it. Do not return
-                                       * symbol if we are called by dlvsym,
-                                       * because dlvsym looks for a specific
-                                       * version and default one is not what
-                                       * dlvsym wants.
-                                       */
-                                       if ((flags & SYMLOOK_DLSYM) ||
-                                           (obj->versyms[symnum].vs_vers & VER_NDX_HIDDEN) ||
-                                           (verndx >= VER_NDX_GIVEN))
-                                               continue;
-                               }
-                       }
-                       return symp;
+               if (_rtld_symlook_obj_matched_symbol(name, obj, flags,
+                   ventry, symnum, &vsymp, &vcount)) {
+                       return vsymp;
                }
        }
        if (vcount == 1)



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