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      1 
      2 /*--------------------------------------------------------------------*/
      3 /*--- User-mode execve() for #! scripts.            m_ume_script.c ---*/
      4 /*--------------------------------------------------------------------*/
      5 
      6 /*
      7    This file is part of Valgrind, a dynamic binary instrumentation
      8    framework.
      9 
     10    Copyright (C) 2000-2013 Julian Seward
     11       jseward (at) acm.org
     12 
     13    This program is free software; you can redistribute it and/or
     14    modify it under the terms of the GNU General Public License as
     15    published by the Free Software Foundation; either version 2 of the
     16    License, or (at your option) any later version.
     17 
     18    This program is distributed in the hope that it will be useful, but
     19    WITHOUT ANY WARRANTY; without even the implied warranty of
     20    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
     21    General Public License for more details.
     22 
     23    You should have received a copy of the GNU General Public License
     24    along with this program; if not, write to the Free Software
     25    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
     26    02111-1307, USA.
     27 
     28    The GNU General Public License is contained in the file COPYING.
     29 */
     30 
     31 #include "pub_core_basics.h"
     32 #include "pub_core_vki.h"
     33 
     34 #include "pub_core_libcbase.h"
     35 #include "pub_core_libcassert.h"    // VG_(exit), vg_assert
     36 #include "pub_core_libcfile.h"      // VG_(close) et al
     37 #include "pub_core_libcprint.h"
     38 #include "pub_core_clientstate.h"   // VG_(args_the_exename)
     39 #include "pub_core_mallocfree.h"    // VG_(strdup)
     40 #include "pub_core_ume.h"           // self
     41 
     42 #include "priv_ume.h"
     43 
     44 Bool VG_(match_script)(const void *hdr, SizeT len)
     45 {
     46    const HChar* script = hdr;
     47    const HChar* end    = script + len;
     48    const HChar* interp = script + 2;
     49 
     50    // len < 4: need '#', '!', plus at least a '/' and one more char
     51    if (len < 4) return False;
     52    if (0 != VG_(memcmp)(hdr, "#!", 2)) return False;
     53 
     54    // Find interpreter name, make sure it's an absolute path (starts with
     55    // '/') and has at least one more char.  First, skip over any space
     56    // between the #! and the start of the interpreter name
     57    while (interp < end && (*interp == ' ' || *interp == '\t')) interp++;
     58 
     59    // overrun?
     60    if (interp >= end)   return False;  // can't find start of interp name
     61 
     62    // interp should now point at the /
     63    if (*interp != '/')  return False;  // absolute path only for interpreter
     64 
     65    // check for something plausible after the /
     66    interp++;
     67    if (interp >= end)   return False;
     68    if (VG_(isspace)(*interp)) return False;
     69 
     70    // Here we should get the full interpreter name and check it with
     71    // check_executable().  See the "EXEC FAILED" failure when running shell
     72    // for an example.
     73 
     74    return True;   // looks like a #! script
     75 }
     76 
     77 
     78 /* returns: 0 = success, non-0 is failure */
     79 Int VG_(load_script)(Int fd, const HChar* name, ExeInfo* info)
     80 {
     81    HChar  hdr[4096];
     82    Int    len = sizeof hdr;
     83    Int    eol;
     84    HChar* interp;
     85    HChar* end;
     86    HChar* cp;
     87    HChar* arg = NULL;
     88    SysRes res;
     89 
     90    // Read the first part of the file.
     91    res = VG_(pread)(fd, hdr, len, 0);
     92    if (sr_isError(res)) {
     93       VG_(close)(fd);
     94       return VKI_EACCES;
     95    } else {
     96       len = sr_Res(res);
     97    }
     98 
     99    vg_assert('#' == hdr[0] && '!' == hdr[1]);
    100 
    101    end    = hdr + len;
    102    interp = hdr + 2;
    103    while (interp < end && (*interp == ' ' || *interp == '\t'))
    104       interp++;
    105 
    106    vg_assert(*interp == '/');   /* absolute path only for interpreter */
    107 
    108    /* skip over interpreter name */
    109    for (cp = interp; cp < end && !VG_(isspace)(*cp); cp++)
    110       ;
    111 
    112    eol = (*cp == '\n');
    113 
    114    *cp++ = '\0';
    115 
    116    if (!eol && cp < end) {
    117       /* skip space before arg */
    118       while (cp < end && VG_(isspace)(*cp) && *cp != '\n')
    119          cp++;
    120 
    121       /* arg is from here to eol */
    122       arg = cp;
    123       while (cp < end && *cp != '\n')
    124          cp++;
    125       *cp = '\0';
    126    }
    127 
    128    info->interp_name = VG_(strdup)("ume.ls.1", interp);
    129    vg_assert(NULL != info->interp_name);
    130    if (arg != NULL && *arg != '\0') {
    131       info->interp_args = VG_(strdup)("ume.ls.2", arg);
    132       vg_assert(NULL != info->interp_args);
    133    }
    134 
    135    if (info->argv && info->argv[0] != NULL)
    136      info->argv[0] = name;
    137 
    138    VG_(args_the_exename) = name;
    139 
    140    if (0)
    141       VG_(printf)("#! script: interp_name=\"%s\" interp_args=\"%s\"\n",
    142                   info->interp_name, info->interp_args);
    143 
    144    return VG_(do_exec_inner)(interp, info);
    145 }
    146 
    147 /*--------------------------------------------------------------------*/
    148 /*--- end                                                          ---*/
    149 /*--------------------------------------------------------------------*/
    150