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      1 /* -*- mode: C; c-basic-offset: 3; -*- */
      2 
      3 /*--------------------------------------------------------------------*/
      4 /*--- User-mode execve() for #! scripts.            m_ume_script.c ---*/
      5 /*--------------------------------------------------------------------*/
      6 
      7 /*
      8    This file is part of Valgrind, a dynamic binary instrumentation
      9    framework.
     10 
     11    Copyright (C) 2000-2017 Julian Seward
     12       jseward (at) acm.org
     13 
     14    This program is free software; you can redistribute it and/or
     15    modify it under the terms of the GNU General Public License as
     16    published by the Free Software Foundation; either version 2 of the
     17    License, or (at your option) any later version.
     18 
     19    This program is distributed in the hope that it will be useful, but
     20    WITHOUT ANY WARRANTY; without even the implied warranty of
     21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     22    General Public License for more details.
     23 
     24    You should have received a copy of the GNU General Public License
     25    along with this program; if not, write to the Free Software
     26    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     27    02111-1307, USA.
     28 
     29    The GNU General Public License is contained in the file COPYING.
     30 */
     31 
     32 #include "pub_core_basics.h"
     33 #include "pub_core_vki.h"
     34 
     35 #include "pub_core_libcbase.h"
     36 #include "pub_core_libcassert.h"    // VG_(exit), vg_assert
     37 #include "pub_core_libcfile.h"      // VG_(close) et al
     38 #include "pub_core_libcprint.h"
     39 #include "pub_core_clientstate.h"   // VG_(args_the_exename)
     40 #include "pub_core_mallocfree.h"    // VG_(strdup)
     41 #include "pub_core_ume.h"           // self
     42 
     43 #include "priv_ume.h"
     44 
     45 /* Return true, if the first line begins with #! and contains an
     46    interpreter. */
     47 Bool VG_(match_script)(const void *hdr, SizeT len)
     48 {
     49    const HChar* script = hdr;
     50    const HChar* end    = script + len;
     51    const HChar* interp = script + 2;
     52 
     53    if (len < 2) return False;
     54    if (0 != VG_(memcmp)(hdr, "#!", 2)) return False;
     55 
     56    // Find interpreter name, which may be absolute or relative.
     57    // First, skip over any space between the #! and the start of the
     58    // interpreter name
     59    while (interp < end && (*interp == ' ' || *interp == '\t')) interp++;
     60 
     61    // overrun?
     62    if (interp >= end)   return False;  // can't find start of interp name
     63 
     64    // No interpreter found.
     65    if (*interp == '\n') return False;
     66 
     67    return True;   // looks like a #! script
     68 }
     69 
     70 
     71 /* returns: 0 = success, non-0 is failure */
     72 Int VG_(load_script)(Int fd, const HChar* name, ExeInfo* info)
     73 {
     74    HChar  hdr[4096];
     75    Int    len = sizeof hdr;
     76    Int    eol;
     77    HChar* interp;
     78    HChar* end;
     79    HChar* cp;
     80    HChar* arg = NULL;
     81    SysRes res;
     82 
     83    // Read the first part of the file.
     84    res = VG_(pread)(fd, hdr, len, 0);
     85    if (sr_isError(res)) {
     86       VG_(close)(fd);
     87       return VKI_EACCES;
     88    } else {
     89       len = sr_Res(res);
     90    }
     91 
     92    vg_assert('#' == hdr[0] && '!' == hdr[1]);
     93 
     94    end    = hdr + len;
     95    interp = hdr + 2;
     96    while (interp < end && (*interp == ' ' || *interp == '\t'))
     97       interp++;
     98 
     99    /* skip over interpreter name */
    100    for (cp = interp; cp < end && !VG_(isspace)(*cp); cp++)
    101       ;
    102 
    103    eol = (*cp == '\n');
    104 
    105    *cp++ = '\0';
    106 
    107    if (!eol && cp < end) {
    108       /* skip space before arg */
    109       while (cp < end && VG_(isspace)(*cp) && *cp != '\n')
    110          cp++;
    111 
    112       /* arg is from here to eol */
    113       arg = cp;
    114       while (cp < end && *cp != '\n')
    115          cp++;
    116       *cp = '\0';
    117    }
    118    VG_(free)(info->interp_name);
    119    info->interp_name = VG_(strdup)("ume.ls.1", interp);
    120    vg_assert(NULL != info->interp_name);
    121    if (arg != NULL && *arg != '\0') {
    122       info->interp_args = VG_(strdup)("ume.ls.2", arg);
    123       vg_assert(NULL != info->interp_args);
    124    }
    125 
    126    if (info->argv && info->argv[0] != NULL)
    127      info->argv[0] = name;
    128 
    129    VG_(args_the_exename) = name;
    130 
    131    if (0)
    132       VG_(printf)("#! script: interp_name=\"%s\" interp_args=\"%s\"\n",
    133                   info->interp_name, info->interp_args);
    134 
    135    return VG_(do_exec_inner)(interp, info);
    136 }
    137 
    138 /*--------------------------------------------------------------------*/
    139 /*--- end                                                          ---*/
    140 /*--------------------------------------------------------------------*/
    141