30eda1d2b8
Apart from the obvious little issues, this also works around a (seeming) libtool/linker: a.c defines a symbol: int kFoo; b.c uses it: extern int kFoo; int f() { return kFoo; } compile them: $ gcc -c a.c $ gcc -c b.c and create a dummy main in order to run it, main.c: int f(); int main() { return f(); } this works as expected: $ gcc main.c a.o b.o but, if we make an archive: $ ar q lib.a a.o b.o and use that: $ gcc main.c lib.a Undefined symbols for architecture x86_64 "_kFoo", referenced from: _f in lib.a(b.o) (It doesn't matter what order the .o files are put into the .a) Linux and Windows don't seem to have this problem. nm on a.o shows that the symbol is of type "C", which is a "common symbol"[1]. Basically the linker will merge multiple common symbol definitions together. If ones makes a.c read: int kFoo = 0; Then one gets a type "D" symbol - a "data section symbol" and everything works just fine. This might actually be a libtool bug instead of an ld bug: Looking at `xxd lib.a | less`, the __.SYMDEF SORTED index at the beginning of the archive doesn't contain an entry for kFoo unless initialised. Change-Id: I4cdad9ba46e9919221c3cbd79637508959359427
197 lines
4.5 KiB
C
197 lines
4.5 KiB
C
/* Copyright (c) 2014, Google Inc.
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*
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* Permission to use, copy, modify, and/or distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
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* SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION
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* OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN
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* CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE. */
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#define _BSD_SOURCE
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#if !defined(__APPLE__)
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/* _POSIX_SOURCE is needed on Linux in order to get rand_r, but on OS X causes
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* a build failure. */
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#define _POSIX_SOURCE
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#endif
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#include <openssl/lhash.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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struct dummy_lhash_node {
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char *s;
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struct dummy_lhash_node *next;
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};
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struct dummy_lhash {
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struct dummy_lhash_node *head;
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};
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static void dummy_lh_free(struct dummy_lhash *lh) {
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struct dummy_lhash_node *cur, *next;
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for (cur = lh->head; cur != NULL; cur = next) {
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next = cur->next;
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free(cur->s);
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free(cur);
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}
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}
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static size_t dummy_lh_num_items(const struct dummy_lhash *lh) {
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size_t count = 0;
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struct dummy_lhash_node *cur;
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for (cur = lh->head; cur != NULL; cur = cur->next) {
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count++;
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}
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return count;
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}
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static char *dummy_lh_retrieve(struct dummy_lhash *lh, const char *s) {
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struct dummy_lhash_node *cur;
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for (cur = lh->head; cur != NULL; cur = cur->next) {
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if (strcmp(cur->s, s) == 0) {
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return cur->s;
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}
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}
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return NULL;
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}
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static int dummy_lh_insert(struct dummy_lhash *lh, char **old_data, char *s) {
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struct dummy_lhash_node *node, *cur;
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for (cur = lh->head; cur != NULL; cur = cur->next) {
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if (strcmp(cur->s, s) == 0) {
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*old_data = cur->s;
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cur->s = s;
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return 1;
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}
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}
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node = malloc(sizeof(struct dummy_lhash_node));
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*old_data = NULL;
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node->s = s;
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node->next = lh->head;
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lh->head = node;
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return 1;
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}
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static char *dummy_lh_delete(struct dummy_lhash *lh, const void *s) {
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struct dummy_lhash_node *cur, **next_ptr;
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char *ret;
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next_ptr = &lh->head;
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for (cur = lh->head; cur != NULL; cur = cur->next) {
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if (strcmp(cur->s, s) == 0) {
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ret = cur->s;
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*next_ptr = cur->next;
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free(cur);
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return ret;
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}
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next_ptr = &cur->next;
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}
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return NULL;
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}
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static char *rand_string(unsigned *rand_state) {
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unsigned len = 1 + (rand_r(rand_state) % 3);
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char *ret = malloc(len + 1);
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unsigned i;
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for (i = 0; i < len; i++) {
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ret[i] = '0' + (rand_r(rand_state) & 7);
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}
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ret[i] = 0;
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return ret;
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}
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int main(int argc, char **argv) {
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_LHASH *lh = lh_new(NULL, NULL);
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struct dummy_lhash dummy_lh = {NULL};
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unsigned rand_state = 0;
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unsigned i;
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for (i = 0; i < 100000; i++) {
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unsigned action;
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char *s, *s1, *s2;
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if (dummy_lh_num_items(&dummy_lh) != lh_num_items(lh)) {
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fprintf(stderr, "Length mismatch\n");
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return 1;
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}
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action = rand_r(&rand_state) % 3;
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switch (action) {
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case 0:
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s = rand_string(&rand_state);
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s1 = (char *)lh_retrieve(lh, s);
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s2 = dummy_lh_retrieve(&dummy_lh, s);
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if (s1 != NULL && (s2 == NULL || strcmp(s1, s2) != 0)) {
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fprintf(stderr, "lh_retrieve failure\n");
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abort();
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}
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free(s);
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break;
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case 1:
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s = rand_string(&rand_state);
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lh_insert(lh, (void **)&s1, s);
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dummy_lh_insert(&dummy_lh, &s2, strdup(s));
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if (s1 != NULL && (s2 == NULL || strcmp(s1, s2) != 0)) {
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fprintf(stderr, "lh_insert failure\n");
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abort();
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}
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if (s1) {
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free(s1);
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}
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if (s2) {
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free(s2);
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}
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break;
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case 2:
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s = rand_string(&rand_state);
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s1 = lh_delete(lh, s);
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s2 = dummy_lh_delete(&dummy_lh, s);
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if (s1 != NULL && (s2 == NULL || strcmp(s1, s2) != 0)) {
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fprintf(stderr, "lh_insert failure\n");
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abort();
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}
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if (s1) {
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free(s1);
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}
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if (s2) {
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free(s2);
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}
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free(s);
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break;
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default:
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abort();
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}
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}
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lh_doall(lh, free);
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lh_free(lh);
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dummy_lh_free(&dummy_lh);
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printf("PASS\n");
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return 0;
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}
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