badvpn/misc/stdbuf_cmdline.h

/**
 * @file stdbuf_cmdline.h
 * @author Ambroz Bizjak <ambrop7@gmail.com>
 * 
 * @section LICENSE
 * 
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. Neither the name of the author nor the
 *    names of its contributors may be used to endorse or promote products
 *    derived from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 * 
 * @section DESCRIPTION
 * 
 * Builds command line for running a program via stdbuf.
 */

#ifndef BADVPN_STDBUF_CMDLINE_H
#define BADVPN_STDBUF_CMDLINE_H

#include <string.h>

#include <misc/debug.h>
#include <misc/cmdline.h>
#include <misc/balloc.h>

#define STDBUF_EXEC "/usr/bin/stdbuf"

/**
 * Builds the initial part of command line for calling a program via stdbuf
 * with standard output buffering set to line-buffered.
 * 
 * @param out {@link CmdLine} to append the result to. Note than on failure, only
 *            some part of the cmdline may have been appended.
 * @param exec path to the executable. Must not contain nulls. 
 * @param exec_len number of characters in exec
 * @return 1 on success, 0 on failure
 */
static int build_stdbuf_cmdline (CmdLine *out, const char *exec, size_t exec_len) WARN_UNUSED;

int build_stdbuf_cmdline (CmdLine *out, const char *exec, size_t exec_len)
{
    ASSERT(!memchr(exec, '\0', exec_len))
    
    if (!CmdLine_AppendMulti(out, 3, STDBUF_EXEC, "-o", "L")) {
        goto fail1;
    }
    
    if (exec[0] == '/') {
        if (!CmdLine_AppendNoNull(out, exec, exec_len)) {
            goto fail1;
        }
    } else {
        bsize_t size = bsize_add(bsize_fromsize(exec_len), bsize_fromsize(3));
        char *real_exec = BAllocSize(size);
        if (!real_exec) {
            goto fail1;
        }
        
        memcpy(real_exec, "./", 2);
        memcpy(real_exec + 2, exec, exec_len);
        real_exec[2 + exec_len] = '\0';
        
        int res = CmdLine_Append(out, real_exec);
        free(real_exec);
        if (!res) {
            goto fail1;
        }
    }
    
    return 1;
    
fail1:
    return 0;
}

#endif