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      1 
      2 /*--------------------------------------------------------------------*/
      3 /*--- Startup: search PATH for an executable    initimg-pathscan.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 #include "pub_core_debuglog.h"
     34 #include "pub_core_libcbase.h"
     35 #include "pub_core_libcassert.h"
     36 #include "pub_core_libcfile.h"
     37 #include "pub_core_libcproc.h"
     38 #include "pub_core_libcprint.h"
     39 #include "pub_core_xarray.h"
     40 #include "pub_core_clientstate.h"
     41 #include "pub_core_aspacemgr.h"
     42 #include "pub_core_mallocfree.h"
     43 #include "pub_core_machine.h"
     44 #include "pub_core_ume.h"
     45 #include "pub_core_options.h"
     46 #include "pub_core_tooliface.h"       /* VG_TRACK */
     47 #include "pub_core_initimg.h"         /* self */
     48 
     49 #include "priv_initimg_pathscan.h"
     50 
     51 
     52 /*====================================================================*/
     53 /*=== Find executable                                              ===*/
     54 /*====================================================================*/
     55 
     56 /* Scan a colon-separated list, and call a function on each element.
     57    The string must be mutable, because we insert a temporary '\0', but
     58    the string will end up unmodified.  (*func) should return True if it
     59    doesn't need to see any more.
     60 
     61    This routine will return True if (*func) returns True and False if
     62    it reaches the end of the list without that happening.
     63 */
     64 static Bool scan_colsep(HChar *colsep, Bool (*func)(const HChar *))
     65 {
     66    HChar *cp, *entry;
     67    int end;
     68 
     69    if (colsep == NULL ||
     70        *colsep == '\0')
     71       return False;
     72 
     73    entry = cp = colsep;
     74 
     75    do {
     76       end = (*cp == '\0');
     77 
     78       if (*cp == ':' || *cp == '\0') {
     79 	 HChar save = *cp;
     80 
     81 	 *cp = '\0';
     82 	 if ((*func)(entry)) {
     83             *cp = save;
     84 	    return True;
     85          }
     86 	 *cp = save;
     87 	 entry = cp+1;
     88       }
     89       cp++;
     90    } while(!end);
     91 
     92    return False;
     93 }
     94 
     95 /* Need a static copy because can't use dynamic mem allocation yet */
     96 static HChar executable_name_in [VKI_PATH_MAX];
     97 static HChar executable_name_out[VKI_PATH_MAX];
     98 
     99 static Bool match_executable(const HChar *entry)
    100 {
    101    HChar buf[VG_(strlen)(entry) + VG_(strlen)(executable_name_in) + 3];
    102 
    103    /* empty PATH element means '.' */
    104    if (*entry == '\0')
    105       entry = ".";
    106 
    107    VG_(snprintf)(buf, sizeof(buf), "%s/%s", entry, executable_name_in);
    108 
    109    // Don't match directories
    110    if (VG_(is_dir)(buf))
    111       return False;
    112 
    113    // If we match an executable, we choose that immediately.  If we find a
    114    // matching non-executable we remember it but keep looking for an
    115    // matching executable later in the path.
    116    if (VG_(access)(buf, True/*r*/, False/*w*/, True/*x*/) == 0) {
    117       VG_(strncpy)( executable_name_out, buf, VKI_PATH_MAX-1 );
    118       executable_name_out[VKI_PATH_MAX-1] = 0;
    119       return True;      // Stop looking
    120    } else if (VG_(access)(buf, True/*r*/, False/*w*/, False/*x*/) == 0
    121            && VG_STREQ(executable_name_out, ""))
    122    {
    123       VG_(strncpy)( executable_name_out, buf, VKI_PATH_MAX-1 );
    124       executable_name_out[VKI_PATH_MAX-1] = 0;
    125       return False;     // Keep looking
    126    } else {
    127       return False;     // Keep looking
    128    }
    129 }
    130 
    131 // Returns NULL if it wasn't found.
    132 const HChar* ML_(find_executable) ( const HChar* exec )
    133 {
    134    vg_assert(NULL != exec);
    135    if (VG_(strchr)(exec, '/')) {
    136       // Has a '/' - use the name as is
    137       VG_(strncpy)( executable_name_out, exec, VKI_PATH_MAX-1 );
    138    } else {
    139       // No '/' - we need to search the path
    140       HChar* path;
    141       VG_(strncpy)( executable_name_in,  exec, VKI_PATH_MAX-1 );
    142       VG_(memset) ( executable_name_out, 0,    VKI_PATH_MAX );
    143       path = VG_(getenv)("PATH");
    144       scan_colsep(path, match_executable);
    145    }
    146    return VG_STREQ(executable_name_out, "") ? NULL : executable_name_out;
    147 }
    148 
    149 /*--------------------------------------------------------------------*/
    150 /*--- end                                                          ---*/
    151 /*--------------------------------------------------------------------*/
    152