crt0.c

/*
 * Copyright (c) 2008-2014, Pedigree Developers
 *
 * Please see the CONTRIB file in the root of the source tree for a full
 * list of contributors.
 *
 * Permission to use, copy, modify, and distribute this software for any
 * purpose with or without fee is hereby granted, provided that the above
 * copyright notice and this permission notice appear in all copies.
 *
 * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
 * WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
 * MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
 * ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 */

#include <fcntl.h>
#include <newlib.h>
#include <stdlib.h>
#include <unistd.h>

extern int main(int, char **, char **);
extern void _init_signals(void);

void _start(char **argv, char **env) _ATTRIBUTE((noreturn))
    __attribute__((section(".text.crt0")));
void _start(char **argv, char **env)
{
    _init_signals();

    if (write(2, 0, 0) == -1)
    {
        open("/dev/tty", O_RDONLY, 0);
        open("/dev/tty", O_WRONLY, 0);
        open("/dev/tty", O_WRONLY, 0);
    }

    // Count how many args we have.
    int argc;
    if (argv == 0)
    {
        char *p = 0;
        argv = &p;
        argc = 0;
        environ = &p;
    }
    else
    {
        char **i = argv;
        argc = 0;
        while (*i++)
            argc++;
        if (!env)
            env = environ;
        i = env;
        while (env && (*i))
        {
            // Save the key.
            char *key = *i;
            char *value = *i;
            // Iterate until we see the end of the string or an '='.
            while (*value && *value != '=')
                value++;
            // If we found a '=', change it to a NULL terminator (for the key)
            // and increment position.
            if (*value == '=')
                *value++ = '\0';
            // Set the env var.
            setenv(key, value, 1);
            i++;
        }
    }

    exit(main(argc, argv, env));

    // Unreachable.
    for (;;)
        ;
}