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1 /* -*- mode: C; c-basic-offset: 3; -*- */
2 
3 /*--------------------------------------------------------------------*/
4 /*--- User-mode execve() for #! scripts.            m_ume_script.c ---*/
5 /*--------------------------------------------------------------------*/
6 
7 /*
8    This file is part of Valgrind, a dynamic binary instrumentation
9    framework.
10 
11    Copyright (C) 2000-2017 Julian Seward
12       jseward@acm.org
13 
14    This program is free software; you can redistribute it and/or
15    modify it under the terms of the GNU General Public License as
16    published by the Free Software Foundation; either version 2 of the
17    License, or (at your option) any later version.
18 
19    This program is distributed in the hope that it will be useful, but
20    WITHOUT ANY WARRANTY; without even the implied warranty of
21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
22    General Public License for more details.
23 
24    You should have received a copy of the GNU General Public License
25    along with this program; if not, write to the Free Software
26    Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
27    02111-1307, USA.
28 
29    The GNU General Public License is contained in the file COPYING.
30 */
31 
32 #include "pub_core_basics.h"
33 #include "pub_core_vki.h"
34 
35 #include "pub_core_libcbase.h"
36 #include "pub_core_libcassert.h"    // VG_(exit), vg_assert
37 #include "pub_core_libcfile.h"      // VG_(close) et al
38 #include "pub_core_libcprint.h"
39 #include "pub_core_clientstate.h"   // VG_(args_the_exename)
40 #include "pub_core_mallocfree.h"    // VG_(strdup)
41 #include "pub_core_ume.h"           // self
42 
43 #include "priv_ume.h"
44 
45 /* Return true, if the first line begins with #! and contains an
46    interpreter. */
VG_(match_script)47 Bool VG_(match_script)(const void *hdr, SizeT len)
48 {
49    const HChar* script = hdr;
50    const HChar* end    = script + len;
51    const HChar* interp = script + 2;
52 
53    if (len < 2) return False;
54    if (0 != VG_(memcmp)(hdr, "#!", 2)) return False;
55 
56    // Find interpreter name, which may be absolute or relative.
57    // First, skip over any space between the #! and the start of the
58    // interpreter name
59    while (interp < end && (*interp == ' ' || *interp == '\t')) interp++;
60 
61    // overrun?
62    if (interp >= end)   return False;  // can't find start of interp name
63 
64    // No interpreter found.
65    if (*interp == '\n') return False;
66 
67    return True;   // looks like a #! script
68 }
69 
70 
71 /* returns: 0 = success, non-0 is failure */
VG_(load_script)72 Int VG_(load_script)(Int fd, const HChar* name, ExeInfo* info)
73 {
74    HChar  hdr[4096];
75    Int    len = sizeof hdr;
76    Int    eol;
77    HChar* interp;
78    HChar* end;
79    HChar* cp;
80    HChar* arg = NULL;
81    SysRes res;
82 
83    // Read the first part of the file.
84    res = VG_(pread)(fd, hdr, len, 0);
85    if (sr_isError(res)) {
86       VG_(close)(fd);
87       return VKI_EACCES;
88    } else {
89       len = sr_Res(res);
90    }
91 
92    vg_assert('#' == hdr[0] && '!' == hdr[1]);
93 
94    end    = hdr + len;
95    interp = hdr + 2;
96    while (interp < end && (*interp == ' ' || *interp == '\t'))
97       interp++;
98 
99    /* skip over interpreter name */
100    for (cp = interp; cp < end && !VG_(isspace)(*cp); cp++)
101       ;
102 
103    eol = (*cp == '\n');
104 
105    *cp++ = '\0';
106 
107    if (!eol && cp < end) {
108       /* skip space before arg */
109       while (cp < end && VG_(isspace)(*cp) && *cp != '\n')
110          cp++;
111 
112       /* arg is from here to eol */
113       arg = cp;
114       while (cp < end && *cp != '\n')
115          cp++;
116       *cp = '\0';
117    }
118    VG_(free)(info->interp_name);
119    info->interp_name = VG_(strdup)("ume.ls.1", interp);
120    vg_assert(NULL != info->interp_name);
121    if (arg != NULL && *arg != '\0') {
122       info->interp_args = VG_(strdup)("ume.ls.2", arg);
123       vg_assert(NULL != info->interp_args);
124    }
125 
126    if (info->argv && info->argv[0] != NULL)
127      info->argv[0] = name;
128 
129    VG_(args_the_exename) = name;
130 
131    if (0)
132       VG_(printf)("#! script: interp_name=\"%s\" interp_args=\"%s\"\n",
133                   info->interp_name, info->interp_args);
134 
135    return VG_(do_exec_inner)(interp, info);
136 }
137 
138 /*--------------------------------------------------------------------*/
139 /*--- end                                                          ---*/
140 /*--------------------------------------------------------------------*/
141