Barry Flartus
2018-11-07 23:00:14 UTC
Hello,
I am encountering some issues that I believe are musl related when trying to
use pthreads from a shared object. Below is a minimal example (2 files) of
the problem.
==================== test.c ====================
// Compile with
// musl-gcc -Wall -lpthread -shared -fPIC test.c -o test.so
#include <pthread.h>
#include <stdio.h>
static void *launch(void *arg);
int start_thread(void);
void entry_point(void) __attribute__((constructor));
static pthread_t gthread;
static void *launch(void *arg)
{
for (int i = 0; i < 4; i++){
printf("[%d] Hello from the thread\n", i);
}
return NULL;
}
int start_thread(void)
{
printf("Starting the thread\n");
return pthread_create(>hread, NULL, launch, NULL);
}
void entry_point(void){
puts("Starting Execution");
int res = start_thread();
printf("start_thread returned %d\n", res);
if (res == 0){
pthread_join(gthread, NULL);
} else {
printf("pthread_create() returned an error. Aborting.\n");
}
}
==================== launch.c ====================
// Compile with:
// gcc launch.c -ldl -o launch
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
int main(){
void *handle;
puts("\nLaunching test...");
handle = dlopen("./test.so", RTLD_NOW);
if (!handle) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
dlerror();
return EXIT_SUCCESS;
}
When the above examples are compiled with gcc, everything works correctly
and
produces the following output:
Launching test...
Starting Execution
Starting the threadstart_thread returned 0
[0] Hello from the thread
[1] Hello from the thread
[2] Hello from the thread
[3] Hello from the thread
When I switch to musl pthread_create() returns the integer '38', which is an
undocumented return value. I assume this corresponds with ENOSYS from
errno.h
but I can't seem to figure out why this is happening.
Output:
Launching test...
Starting Execution
Starting the thread
start_thread returned 38
pthread_create() returned an error. Aborting.
Is this even supported by musl? If so, where have I gone wrong?
Thanks in advance!
I am encountering some issues that I believe are musl related when trying to
use pthreads from a shared object. Below is a minimal example (2 files) of
the problem.
==================== test.c ====================
// Compile with
// musl-gcc -Wall -lpthread -shared -fPIC test.c -o test.so
#include <pthread.h>
#include <stdio.h>
static void *launch(void *arg);
int start_thread(void);
void entry_point(void) __attribute__((constructor));
static pthread_t gthread;
static void *launch(void *arg)
{
for (int i = 0; i < 4; i++){
printf("[%d] Hello from the thread\n", i);
}
return NULL;
}
int start_thread(void)
{
printf("Starting the thread\n");
return pthread_create(>hread, NULL, launch, NULL);
}
void entry_point(void){
puts("Starting Execution");
int res = start_thread();
printf("start_thread returned %d\n", res);
if (res == 0){
pthread_join(gthread, NULL);
} else {
printf("pthread_create() returned an error. Aborting.\n");
}
}
==================== launch.c ====================
// Compile with:
// gcc launch.c -ldl -o launch
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
int main(){
void *handle;
puts("\nLaunching test...");
handle = dlopen("./test.so", RTLD_NOW);
if (!handle) {
fprintf(stderr, "%s\n", dlerror());
exit(EXIT_FAILURE);
}
dlerror();
return EXIT_SUCCESS;
}
When the above examples are compiled with gcc, everything works correctly
and
produces the following output:
Launching test...
Starting Execution
Starting the threadstart_thread returned 0
[0] Hello from the thread
[1] Hello from the thread
[2] Hello from the thread
[3] Hello from the thread
When I switch to musl pthread_create() returns the integer '38', which is an
undocumented return value. I assume this corresponds with ENOSYS from
errno.h
but I can't seem to figure out why this is happening.
Output:
Launching test...
Starting Execution
Starting the thread
start_thread returned 38
pthread_create() returned an error. Aborting.
Is this even supported by musl? If so, where have I gone wrong?
Thanks in advance!