Changeset da54714 in mainline

Timestamp:

2025-03-11T10:50:28Z (24 hours ago)

Author:

GitHub <noreply@…>

Branches:

master

Parents:

0ae9e18

git-author:

Matěj Volf <git@…> (2025-03-11 10:50:28)

git-committer:

GitHub <noreply@…> (2025-03-11 10:50:28)

Message:

partially implement key-based pthread local storage (#245)

• check for hash section presence in rtld

• implement pthread thread-local storage keys without destructors and key recycling

Location:

uspace/lib

Files:

• c/generic/rtld/symbol.c (modified) (1 diff)
• posix/meson.build (modified) (1 diff)
• posix/src/pthread/keys.c (modified) (1 diff)
• posix/test/main.c (modified) (1 diff)
• posix/test/pthread/keys.c (added)

uspace/lib/c/generic/rtld/symbol.c

@@ -65 +65 @@
 static elf_symbol_t *def_find_in_module(const char *name, module_t *m)
 {
+        if (m->dyn.hash == NULL) {
+                /* No hash table */
+                return NULL;
+        }
+
         elf_symbol_t *sym_table;
         elf_symbol_t *s, *sym;

uspace/lib/posix/meson.build

@@ -61 +61 @@
         'test/stdlib.c',
         'test/unistd.c',
+        'test/pthread/keys.c',
 )
 

uspace/lib/posix/src/pthread/keys.c

@@ -36 +36 @@
 #include <pthread.h>
 #include <errno.h>
+#include <fibril.h>
+#include <stdatomic.h>
 #include "../internal/common.h"
+
+#include <stdio.h>
+#define DPRINTF(format, ...) ((void) 0);
+
+static atomic_ushort next_key = 1; // skip the key 'zero'
+
+/*
+ * For now, we just support maximum of 100 keys. This can be improved
+ * in the future by implementing a dynamically growing array with
+ * reallocations, but that will require more synchronization.
+ */
+#define PTHREAD_KEYS_MAX 100
+
+static fibril_local void *key_data[PTHREAD_KEYS_MAX];
 
 void *pthread_getspecific(pthread_key_t key)
 {
-        not_implemented();
-        return NULL;
+        assert(key < PTHREAD_KEYS_MAX);
+        assert(key < next_key);
+        assert(key > 0);
+
+        DPRINTF("pthread_getspecific(%d) = %p\n", key, key_data[key]);
+        return key_data[key];
 }
 
 int pthread_setspecific(pthread_key_t key, const void *data)
 {
-        not_implemented();
-        return ENOTSUP;
+        DPRINTF("pthread_setspecific(%d, %p)\n", key, data);
+        assert(key < PTHREAD_KEYS_MAX);
+        assert(key < next_key);
+        assert(key > 0);
+
+        key_data[key] = (void *) data;
+        return EOK;
 }
 
 int pthread_key_delete(pthread_key_t key)
 {
+        /* see https://github.com/HelenOS/helenos/pull/245#issuecomment-2706795848 */
         not_implemented();
-        return ENOTSUP;
+        return EOK;
 }
 
 int pthread_key_create(pthread_key_t *key, void (*destructor)(void *))
 {
-        not_implemented();
-        return ENOTSUP;
+        unsigned short k = atomic_fetch_add(&next_key, 1);
+        DPRINTF("pthread_key_create(%p, %p) = %d\n", key, destructor, k);
+        if (k >= PTHREAD_KEYS_MAX) {
+                atomic_store(&next_key, PTHREAD_KEYS_MAX + 1);
+                return ELIMIT;
+        }
+        if (destructor != NULL) {
+                /* Inlined not_implemented() macro to add custom message */
+                static int __not_implemented_counter = 0;
+                if (__not_implemented_counter == 0) {
+                        fprintf(stderr, "pthread_key_create: destructors not supported\n");
+                }
+                __not_implemented_counter++;
+        }
+
+        *key = k;
+        return EOK;
 }
 

uspace/lib/posix/test/main.c

@@ -34 +34 @@
 PCUT_IMPORT(stdlib);
 PCUT_IMPORT(unistd);
+PCUT_IMPORT(pthread_keys);
 
 PCUT_MAIN();