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805e021f CE |
1 | /* |
2 | * Copyright 2010, Sine Nomine Associates and others. | |
3 | * All Rights Reserved. | |
4 | * | |
5 | * This software has been released under the terms of the IBM Public | |
6 | * License. For details, see the LICENSE file in the top-level source | |
7 | * directory or online at http://www.openafs.org/dl/license10.html | |
8 | */ | |
9 | ||
10 | /* exec-related helper routines */ | |
11 | ||
12 | #include <afsconfig.h> | |
13 | #include <afs/param.h> | |
14 | ||
15 | #include <roken.h> | |
16 | ||
17 | /* helper for afs_exec_alt; just constructs the string for the 'alternate' | |
18 | * program */ | |
19 | static char * | |
20 | construct_alt(const char *argv0, const char *prefix, const char *suffix) | |
21 | { | |
22 | size_t prefix_len = strlen(prefix); | |
23 | size_t suffix_len = strlen(suffix); | |
24 | size_t replace_len; | |
25 | char *alt, *replace; | |
26 | ||
27 | alt = malloc(strlen(argv0) + prefix_len + suffix_len + 1); | |
28 | if (!alt) { | |
29 | return NULL; | |
30 | } | |
31 | strcpy(alt, argv0); | |
32 | ||
33 | replace = strrchr(alt, '/'); | |
34 | if (replace) { | |
35 | replace++; | |
36 | } else { | |
37 | replace = alt; | |
38 | } | |
39 | ||
40 | replace_len = strlen(replace); | |
41 | ||
42 | memmove(replace + prefix_len, replace, replace_len); | |
43 | memcpy(replace, prefix, prefix_len); | |
44 | /* basically strcat(replace, suffix), but a touch faster */ | |
45 | memcpy(replace + prefix_len + replace_len, suffix, suffix_len + 1); | |
46 | ||
47 | return alt; | |
48 | } | |
49 | ||
50 | /** | |
51 | * execute an alternate version of the running program. | |
52 | * | |
53 | * This takes the current argc/argv, and executes an "anternate" version | |
54 | * of the current program ("alternate" meaning e.g. DAFS/non-DAFS, | |
55 | * 32-bit/64-bit, etc). For example, if the current running program is | |
56 | * fssync-debug, running afs_exec_alt(argc, argc, "da", NULL) will try | |
57 | * to execute a "dafssync-debug" program, if it can be run. | |
58 | * | |
59 | * @param[in] argc argc for the current program | |
60 | * @param[in] argv argv for the current program | |
61 | * @param[in] prefix prefix for the alternate program (or NULL) | |
62 | * @param[in] suffix suffix for the alternate program (or NULL) | |
63 | * | |
64 | * @return the program that we failed to run, or NULL if we failed | |
65 | * before constructing it. This string must be freed by the caller | |
66 | * | |
67 | * @pre at least one of 'prefix' or 'suffix' is non-NULL and non-empty | |
68 | * | |
69 | * @note if successful, never returns | |
70 | */ | |
71 | char * | |
72 | afs_exec_alt(int argc, char **argv, const char *prefix, const char *suffix) | |
73 | { | |
74 | char **targv = NULL; | |
75 | char *ret = NULL; | |
76 | int errno_save; | |
77 | int i = 0; | |
78 | ||
79 | if (!prefix) { | |
80 | prefix = ""; | |
81 | } | |
82 | if (!suffix) { | |
83 | suffix = ""; | |
84 | } | |
85 | ||
86 | if (prefix[0] == '\0' && suffix[0] == '\0') { | |
87 | /* we'd be exec'ing ourselves; that's no good */ | |
88 | errno = EINVAL; | |
89 | return NULL; | |
90 | } | |
91 | ||
92 | targv = malloc(sizeof(char*) * (argc+1)); | |
93 | if (!targv) { | |
94 | goto error; | |
95 | } | |
96 | ||
97 | targv[0] = construct_alt(argv[0], prefix, suffix); | |
98 | if (!targv[0]) { | |
99 | goto error; | |
100 | } | |
101 | ||
102 | for (i = 1; i < argc; i++) { | |
103 | targv[i] = strdup(argv[i]); | |
104 | if (!targv[i]) { | |
105 | goto error; | |
106 | } | |
107 | } | |
108 | targv[i] = NULL; | |
109 | ||
110 | execvp(targv[0], targv); | |
111 | ||
112 | error: | |
113 | /* we only call free() beyond this point, which I don't think would ever | |
114 | * muck with errno, but I don't trust everyone's libc... */ | |
115 | errno_save = errno; | |
116 | if (targv) { | |
117 | i--; | |
118 | for (; i >= 1; i--) { | |
119 | free(targv[i]); | |
120 | } | |
121 | ret = targv[0]; | |
122 | free(targv); | |
123 | } | |
124 | errno = errno_save; | |
125 | return ret; | |
126 | } |