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) 2000-2017 Julian Seward
11      jseward@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_libcbase.h"
33#include "pub_core_libcassert.h"
34#include "pub_core_libcfile.h"
35#include "pub_core_libcproc.h"
36#include "pub_core_libcprint.h"
37#include "pub_core_mallocfree.h"
38#include "pub_core_initimg.h"         /* self */
39
40#include "priv_initimg_pathscan.h"
41
42
43/*====================================================================*/
44/*=== Find executable                                              ===*/
45/*====================================================================*/
46
47/* Scan a colon-separated list, and call a function on each element.
48   The string must be mutable, because we insert a temporary '\0', but
49   the string will end up unmodified.  (*func) should return True if it
50   doesn't need to see any more.
51
52   This routine will return True if (*func) returns True and False if
53   it reaches the end of the list without that happening.
54*/
55static Bool scan_colsep(HChar *colsep, Bool (*func)(const HChar *))
56{
57   HChar *cp, *entry;
58   int end;
59
60   if (colsep == NULL ||
61       *colsep == '\0')
62      return False;
63
64   entry = cp = colsep;
65
66   do {
67      end = (*cp == '\0');
68
69      if (*cp == ':' || *cp == '\0') {
70	 HChar save = *cp;
71
72	 *cp = '\0';
73	 if ((*func)(entry)) {
74            *cp = save;
75	    return True;
76         }
77	 *cp = save;
78	 entry = cp+1;
79      }
80      cp++;
81   } while(!end);
82
83   return False;
84}
85
86
87static const HChar *executable_name_in;
88static HChar *executable_name_out;
89
90static Bool match_executable(const HChar *entry)
91{
92   /* empty ENTRY element means '.' */
93   if (*entry == '\0')
94      entry = ".";
95
96   HChar buf[VG_(strlen)(entry) + 1 + VG_(strlen)(executable_name_in) + 1];
97
98   VG_(sprintf)(buf, "%s/%s", entry, executable_name_in);
99
100   // Don't match directories
101   if (VG_(is_dir)(buf))
102      return False;
103
104   // If we match an executable, we choose that immediately.  If we find a
105   // matching non-executable we remember it but keep looking for an
106   // matching executable later in the path.
107   if (VG_(access)(buf, True/*r*/, False/*w*/, True/*x*/) == 0) {
108      VG_(free)(executable_name_out);
109      executable_name_out = VG_(strdup)("match_executable", buf);
110      return True;      // Stop looking
111   } else if (VG_(access)(buf, True/*r*/, False/*w*/, False/*x*/) == 0
112              && executable_name_out == NULL)
113   {
114      executable_name_out = VG_(strdup)("match_executable", buf);
115      return False;     // Keep looking
116   } else {
117      return False;     // Keep looking
118   }
119}
120
121// Returns NULL if it wasn't found.
122const HChar* ML_(find_executable) ( const HChar* exec )
123{
124   vg_assert(NULL != exec);
125
126   if (VG_(strchr)(exec, '/')) {
127      // Has a '/' - use the name as is even if exec is a directory.
128      // The reason is that we get a better error message this way:
129      //   valgrind  ./foo
130      //   valgrind: ./foo: is a directory
131      return exec;
132   }
133
134   // No '/' - we need to search the path
135   HChar* path = VG_(getenv)("PATH");
136
137   VG_(free)(executable_name_out);
138
139   executable_name_in  = exec;
140   executable_name_out = NULL;
141   scan_colsep(path, match_executable);
142
143   return executable_name_out;
144}
145
146/*--------------------------------------------------------------------*/
147/*--- end                                                          ---*/
148/*--------------------------------------------------------------------*/
149