cpipe.c

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// SPDX-FileCopyrightText: 2009-2020 pancake <pancake@nopcode.org>
// SPDX-License-Identifier: LGPL-3.0-only
 
#include <rz_cons.h>
#include <limits.h>
 
// TODO: remove globals, and make this stackable
// cons_pipe should be using a stack pipe_push, pipe_pop
static int backup_fd = -1;
static int backup_fdn = 1;
 
#ifndef O_BINARY
#define O_BINARY 0
#endif
 
static bool __dupDescriptor(int fd, int fdn) {
#if __WINDOWS__
    backup_fd = 2002 - (fd - 2); // windows xp has 2048 as limit fd
    return _dup2(fdn, backup_fd) != -1;
#else
    backup_fd = sysconf(_SC_OPEN_MAX) - (fd - 2); // portable getdtablesize()
    if (backup_fd < 2) {
        backup_fd = 2002 - (fd - 2); // fallback
    }
    return dup2(fdn, backup_fd) != -1;
#endif
}
 
RZ_API int rz_cons_pipe_open(const char *file, int fdn, int append) {
    if (fdn < 1) {
        return -1;
    }
    const int fd_flags = O_BINARY | O_RDWR | O_CREAT | (append ? O_APPEND : O_TRUNC);
    int fd = rz_sys_open(file, fd_flags, 0644);
    if (fd == -1) {
        eprintf("rz_cons_pipe_open: Cannot open file '%s'\n", file);
        return -1;
    }
    if (backup_fd != -1) {
        close(backup_fd);
        // already set in __dupDescriptor // backup_fd = -1;
    }
    backup_fdn = fdn;
    if (!__dupDescriptor(fd, fdn)) {
        eprintf("Cannot dup stdout to %d\n", fdn);
        return -1;
    }
    close(fdn);
    dup2(fd, fdn);
    return fd;
}
 
RZ_API void rz_cons_pipe_close(int fd) {
    if (fd != -1) {
        close(fd);
        if (backup_fd != -1) {
            dup2(backup_fd, backup_fdn);
            close(backup_fd);
            backup_fd = -1;
        }
    }
}