lib/lockfd.c


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#include "lockfd.h"

#include <assert.h>
#include <pthread.h>

#include "xalloc.h"

static pthread_mutex_t **mutexes = NULL;

static pthread_mutex_t *get_mutex(int fd) {
    assert(fd < 3 && "todo: implement generically");

    if (!mutexes) {
        mutexes = xmalloc(3 * sizeof(char *));
        assert(mutexes);
    }

    if (!mutexes[fd]) {
        mutexes[fd] = xmalloc(sizeof(pthread_mutex_t));
        assert(mutexes[fd]);
        pthread_mutex_init(mutexes[fd], NULL); // create mutex
        assert(mutexes[fd]);
    }

    return mutexes[fd];
}

int lock_fd(int fd) { return pthread_mutex_lock(get_mutex(fd)); }

int unlock_fd(int fd) { return pthread_mutex_unlock(get_mutex(fd)); }

int lock_file(FILE *f) {
    assert(f);

    return lock_fd(fileno(f));
}

int unlock_file(FILE *f) {
    assert(f);

    return unlock_fd(fileno(f));
}