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/*
 *  TCC - Tiny C Compiler - Support for -run switch
 *
 *  Copyright (c) 2001-2004 Fabrice Bellard
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 */

#include "tcc.h"

/* only native compiler supports -run */
#ifdef TCC_IS_NATIVE

#ifdef CONFIG_TCC_BACKTRACE
ST_DATA int rt_num_callers = 6;
ST_DATA const char **rt_bound_error_msg;
ST_DATA void *rt_prog_main;
#endif

#ifdef _WIN32
#define ucontext_t CONTEXT
#endif

static void set_pages_executable(void *ptr, unsigned long length);
static void set_exception_handler(void);
static int rt_get_caller_pc(addr_t *paddr, ucontext_t *uc, int level);
static void rt_error(ucontext_t *uc, const char *fmt, ...);
static int tcc_relocate_ex(TCCState *s1, void *ptr);

#ifdef _WIN64
static void win64_add_function_table(TCCState *s1);
#endif

/* ------------------------------------------------------------- */
/* Do all relocations (needed before using tcc_get_symbol())
   Returns -1 on error. */

LIBTCCAPI int tcc_relocate(TCCState *s1, void *ptr)
{
    int ret;

    if (TCC_RELOCATE_AUTO != ptr)
        return tcc_relocate_ex(s1, ptr);

    ret = tcc_relocate_ex(s1, NULL);
    if (ret < 0)
        return ret;

#ifdef HAVE_SELINUX
    {   /* Use mmap instead of malloc for Selinux.  Ref:
           http://www.gnu.org/s/libc/manual/html_node/File-Size.html */

        char tmpfname[] = "/tmp/.tccrunXXXXXX";
        int fd = mkstemp (tmpfname);

        s1->mem_size = ret;
        unlink (tmpfname);
        ftruncate (fd, s1->mem_size);

        s1->write_mem = mmap (NULL, ret, PROT_READ|PROT_WRITE,
            MAP_SHARED, fd, 0);
        if (s1->write_mem == MAP_FAILED)
            tcc_error("/tmp not writeable");

        s1->runtime_mem = mmap (NULL, ret, PROT_READ|PROT_EXEC,
            MAP_SHARED, fd, 0);
        if (s1->runtime_mem == MAP_FAILED)
            tcc_error("/tmp not executable");

        ret = tcc_relocate_ex(s1, s1->write_mem);
    }
#else
    s1->runtime_mem = tcc_malloc(ret);
    ret = tcc_relocate_ex(s1, s1->runtime_mem);
#endif
    return ret;
}

/* launch the compiled program with the given arguments */
LIBTCCAPI int tcc_run(TCCState *s1, int argc, char **argv)
{
    int (*prog_main)(int, char **);
    int ret;

    if (tcc_relocate(s1, TCC_RELOCATE_AUTO) < 0)
        return -1;

    prog_main = tcc_get_symbol_err(s1, s1->runtime_main);

#ifdef CONFIG_TCC_BACKTRACE
    if (s1->do_debug) {
        set_exception_handler();
        rt_prog_main = prog_main;
    }
#endif

#ifdef CONFIG_TCC_BCHECK
    if (s1->do_bounds_check) {
        void (*bound_init)(void);
        void (*bound_exit)(void);
        /* set error function */
        rt_bound_error_msg = tcc_get_symbol_err(s1, "__bound_error_msg");
        /* XXX: use .init section so that it also work in binary ? */
        bound_init = tcc_get_symbol_err(s1, "__bound_init");
        bound_exit = tcc_get_symbol_err(s1, "__bound_exit");
        bound_init();
        ret = (*prog_main)(argc, argv);
        bound_exit();
    } else
#endif
        ret = (*prog_main)(argc, argv);
    return ret;
}

/* relocate code. Return -1 on error, required size if ptr is NULL,
   otherwise copy code into buffer passed by the caller */
static int tcc_relocate_ex(TCCState *s1, void *ptr)
{
    Section *s;
    unsigned long offset, length;
    addr_t mem;
    int i;

    if (NULL == ptr) {
        s1->nb_errors = 0;
#ifdef TCC_TARGET_PE
        pe_output_file(s1, NULL);
#else
        tcc_add_runtime(s1);
        relocate_common_syms();
        tcc_add_linker_symbols(s1);
        build_got_entries(s1);
#endif
        if (s1->nb_errors)
            return -1;
    }

    offset = 0, mem = (addr_t)ptr;
    for(i = 1; i < s1->nb_sections; i++) {
        s = s1->sections[i];
        if (0 == (s->sh_flags & SHF_ALLOC))
            continue;
        length = s->data_offset;
        s->sh_addr = mem ? (mem + offset + 15) & ~15 : 0;
        offset = (offset + length + 15) & ~15;
    }
    offset += 16;

    /* relocate symbols */
    relocate_syms(s1, 1);
    if (s1->nb_errors)
        return -1;

#ifdef TCC_HAS_RUNTIME_PLTGOT
    s1->runtime_plt_and_got_offset = 0;
    s1->runtime_plt_and_got = (char *)(mem + offset);
    /* double the size of the buffer for got and plt entries
       XXX: calculate exact size for them? */
    offset *= 2;
#endif

    if (0 == mem)
        return offset;

    /* relocate each section */
    for(i = 1; i < s1->nb_sections; i++) {
        s = s1->sections[i];
        if (s->reloc)
            relocate_section(s1, s);
    }

    for(i = 1; i < s1->nb_sections; i++) {
        s = s1->sections[i];
        if (0 == (s->sh_flags & SHF_ALLOC))
            continue;
        length = s->data_offset;
        // printf("%-12s %08x %04x\n", s->name, s->sh_addr, length);
        ptr = (void*)s->sh_addr;
        if (NULL == s->data || s->sh_type == SHT_NOBITS)
            memset(ptr, 0, length);
        else
            memcpy(ptr, s->data, length);
        /* mark executable sections as executable in memory */
        if (s->sh_flags & SHF_EXECINSTR)
            set_pages_executable(ptr, length);
    }

#ifdef TCC_HAS_RUNTIME_PLTGOT
    set_pages_executable(s1->runtime_plt_and_got,
                         s1->runtime_plt_and_got_offset);
#endif

#ifdef _WIN64
    win64_add_function_table(s1);
#endif
    return 0;
}

/* ------------------------------------------------------------- */
/* allow to run code in memory */

static void set_pages_executable(void *ptr, unsigned long length)
{
#ifdef _WIN32
    unsigned long old_protect;
    VirtualProtect(ptr, length, PAGE_EXECUTE_READWRITE, &old_protect);
#else
#ifndef PAGESIZE
# define PAGESIZE 4096
#endif
    addr_t start, end;
    start = (addr_t)ptr & ~(PAGESIZE - 1);
    end = (addr_t)ptr + length;
    end = (end + PAGESIZE - 1) & ~(PAGESIZE - 1);
    mprotect((void *)start, end - start, PROT_READ | PROT_WRITE | PROT_EXEC);
    __clear_cache(ptr, ptr + length);
#endif
}

/* ------------------------------------------------------------- */
#ifdef CONFIG_TCC_BACKTRACE

ST_FUNC void tcc_set_num_callers(int n)
{
    rt_num_callers = n;
}

/* print the position in the source file of PC value 'pc' by reading
   the stabs debug information */