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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_xarray.h"
     39 #include "pub_core_clientstate.h"
     40 #include "pub_core_mallocfree.h"    // VG_(strdup)
     41 #include "pub_core_ume.h"           // self
     42 
     43 #include "priv_ume.h"
     44 
     45 Bool VG_(match_script)(const void *hdr, Int len)
     46 {
     47    const HChar* script = hdr;
     48    const HChar* end    = script + len;
     49    const HChar* interp = script + 2;
     50 
     51    // len < 4: need '#', '!', plus at least a '/' and one more char
     52    if (len < 4) return False;
     53    if (0 != VG_(memcmp)(hdr, "#!", 2)) return False;
     54 
     55    // Find interpreter name, make sure it's an absolute path (starts with
     56    // '/') and has at least one more char.  First, skip over any space
     57    // between the #! and the start of the interpreter name
     58    while (interp < end && VG_(isspace)(*interp)) interp++;
     59 
     60    // overrun?
     61    if (interp >= end)   return False;  // can't find start of interp name
     62 
     63    // interp should now point at the /
     64    if (*interp != '/')  return False;  // absolute path only for interpreter
     65 
     66    // check for something plausible after the /
     67    interp++;
     68    if (interp >= end)   return False;
     69    if (VG_(isspace)(*interp)) return False;
     70 
     71    // Here we should get the full interpreter name and check it with
     72    // check_executable().  See the "EXEC FAILED" failure when running shell
     73    // for an example.
     74 
     75    return True;   // looks like a #! script
     76 }
     77 
     78 
     79 /* returns: 0 = success, non-0 is failure */
     80 Int VG_(load_script)(Int fd, const HChar* name, ExeInfo* info)
     81 {
     82    HChar  hdr[4096];
     83    Int    len = 4096;
     84    Int    eol;
     85    HChar* interp;
     86    HChar* end;
     87    HChar* cp;
     88    HChar* arg = NULL;
     89    SysRes res;
     90 
     91    // Read the first part of the file.
     92    res = VG_(pread)(fd, hdr, len, 0);
     93    if (sr_isError(res)) {
     94       VG_(close)(fd);
     95       return VKI_EACCES;
     96    } else {
     97       len = sr_Res(res);
     98    }
     99 
    100    vg_assert('#' == hdr[0] && '!' == hdr[1]);
    101 
    102    end    = hdr + len;
    103    interp = hdr + 2;
    104    while (interp < end && VG_(isspace)(*interp))
    105       interp++;
    106 
    107    vg_assert(*interp == '/');   /* absolute path only for interpreter */
    108 
    109    /* skip over interpreter name */
    110    for (cp = interp; cp < end && !VG_(isspace)(*cp); cp++)
    111       ;
    112 
    113    eol = (*cp == '\n');
    114 
    115    *cp++ = '\0';
    116 
    117    if (!eol && cp < end) {
    118       /* skip space before arg */
    119       while (cp < end && VG_(isspace)(*cp) && *cp != '\n')
    120          cp++;
    121 
    122       /* arg is from here to eol */
    123       arg = cp;
    124       while (cp < end && *cp != '\n')
    125          cp++;
    126       *cp = '\0';
    127    }
    128 
    129    info->interp_name = VG_(strdup)("ume.ls.1", interp);
    130    vg_assert(NULL != info->interp_name);
    131    if (arg != NULL && *arg != '\0') {
    132       info->interp_args = VG_(strdup)("ume.ls.2", arg);
    133       vg_assert(NULL != info->interp_args);
    134    }
    135 
    136    if (info->argv && info->argv[0] != NULL)
    137      info->argv[0] = name;
    138 
    139    VG_(args_the_exename) = name;
    140 
    141    if (0)
    142       VG_(printf)("#! script: interp_name=\"%s\" interp_args=\"%s\"\n",
    143                   info->interp_name, info->interp_args);
    144 
    145    return VG_(do_exec_inner)(interp, info);
    146 }
    147 
    148 /*--------------------------------------------------------------------*/
    149 /*--- end                                                          ---*/
    150 /*--------------------------------------------------------------------*/
    151