lock.c

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// SPDX-FileCopyrightText: 2012-2016 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: MIT
 
#include <rz_userconf.h>
#include <stdio.h>
#include <string.h>
#include <fcntl.h>
#include <rz_util/rz_sys.h>
#include "sdb.h"
#if __WINDOWS__
#include <windows.h>
#endif
 
RZ_API const char *sdb_lock_file(const char *f) {
    static char buf[128];
    size_t len;
    if (!f || !*f) {
        return NULL;
    }
    len = strlen(f);
    if (len + 10 > sizeof buf) {
        return NULL;
    }
    memcpy(buf, f, len);
    strcpy(buf + len, ".lock");
    return buf;
}
 
RZ_API bool sdb_lock(const char *s) {
    int fd;
    char *pid, pidstr[64];
    if (!s) {
        return false;
    }
    fd = open(s, O_CREAT | O_TRUNC | O_WRONLY | O_EXCL, SDB_MODE);
    if (fd == -1) {
        return false;
    }
    pid = sdb_itoa(rz_sys_getpid(), pidstr, 10);
    if (pid) {
        if ((write(fd, pid, strlen(pid)) < 0) || (write(fd, "\n", 1) < 0)) {
            close(fd);
            return false;
        }
    }
    close(fd);
    return true;
}
 
RZ_API int sdb_lock_wait(const char *s) {
    // TODO use flock() here
    // wait forever here?
    while (!sdb_lock(s)) {
        // TODO: if waiting too much return 0
        rz_sys_sleep(1);
    }
    return 1;
}
 
RZ_API void sdb_unlock(const char *s) {
    // flock (fd, LOCK_UN);
    unlink(s);
}