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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) 2000-2007 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_threadstate.h"     /* ThreadArchState */
     48 #include "pub_core_initimg.h"         /* self */
     49 
     50 #include "priv_initimg_pathscan.h"
     51 
     52 
     53 /*====================================================================*/
     54 /*=== Find executable                                              ===*/
     55 /*====================================================================*/
     56 
     57 /* Scan a colon-separated list, and call a function on each element.
     58    The string must be mutable, because we insert a temporary '\0', but
     59    the string will end up unmodified.  (*func) should return True if it
     60    doesn't need to see any more.
     61 
     62    This routine will return True if (*func) returns True and False if
     63    it reaches the end of the list without that happening.
     64 */
     65 static Bool scan_colsep(char *colsep, Bool (*func)(const char *))
     66 {
     67    char *cp, *entry;
     68    int end;
     69 
     70    if (colsep == NULL ||
     71        *colsep == '\0')
     72       return False;
     73 
     74    entry = cp = colsep;
     75 
     76    do {
     77       end = (*cp == '\0');
     78 
     79       if (*cp == ':' || *cp == '\0') {
     80 	 char save = *cp;
     81 
     82 	 *cp = '\0';
     83 	 if ((*func)(entry)) {
     84             *cp = save;
     85 	    return True;
     86          }
     87 	 *cp = save;
     88 	 entry = cp+1;
     89       }
     90       cp++;
     91    } while(!end);
     92 
     93    return False;
     94 }
     95 
     96 /* Need a static copy because can't use dynamic mem allocation yet */
     97 static HChar executable_name_in [VKI_PATH_MAX];
     98 static HChar executable_name_out[VKI_PATH_MAX];
     99 
    100 static Bool match_executable(const char *entry)
    101 {
    102    HChar buf[VG_(strlen)(entry) + VG_(strlen)(executable_name_in) + 3];
    103 
    104    /* empty PATH element means '.' */
    105    if (*entry == '\0')
    106       entry = ".";
    107 
    108    VG_(snprintf)(buf, sizeof(buf), "%s/%s", entry, executable_name_in);
    109 
    110    // Don't match directories
    111    if (VG_(is_dir)(buf))
    112       return False;
    113 
    114    // If we match an executable, we choose that immediately.  If we find a
    115    // matching non-executable we remember it but keep looking for an
    116    // matching executable later in the path.
    117    if (VG_(access)(buf, True/*r*/, False/*w*/, True/*x*/) == 0) {
    118       VG_(strncpy)( executable_name_out, buf, VKI_PATH_MAX-1 );
    119       executable_name_out[VKI_PATH_MAX-1] = 0;
    120       return True;      // Stop looking
    121    } else if (VG_(access)(buf, True/*r*/, False/*w*/, False/*x*/) == 0
    122            && VG_STREQ(executable_name_out, ""))
    123    {
    124       VG_(strncpy)( executable_name_out, buf, VKI_PATH_MAX-1 );
    125       executable_name_out[VKI_PATH_MAX-1] = 0;
    126       return False;     // Keep looking
    127    } else {
    128       return False;     // Keep looking
    129    }
    130 }
    131 
    132 // Returns NULL if it wasn't found.
    133 HChar* ML_(find_executable) ( const HChar* exec )
    134 {
    135    vg_assert(NULL != exec);
    136    if (VG_(strchr)(exec, '/')) {
    137       // Has a '/' - use the name as is
    138       VG_(strncpy)( executable_name_out, exec, VKI_PATH_MAX-1 );
    139    } else {
    140       // No '/' - we need to search the path
    141       HChar* path;
    142       VG_(strncpy)( executable_name_in,  exec, VKI_PATH_MAX-1 );
    143       VG_(memset) ( executable_name_out, 0,    VKI_PATH_MAX );
    144       path = VG_(getenv)("PATH");
    145       scan_colsep(path, match_executable);
    146    }
    147    return VG_STREQ(executable_name_out, "") ? NULL : executable_name_out;
    148 }
    149 
    150 /*--------------------------------------------------------------------*/
    151 /*--- end                                                          ---*/
    152 /*--------------------------------------------------------------------*/
    153