1 /* Routines for dealing with '\0' separated environment vectors
2 Copyright (C) 1995-2023 Free Software Foundation, Inc.
3 This file is part of the GNU C Library.
4
5 The GNU C Library is free software; you can redistribute it and/or
6 modify it under the terms of the GNU Lesser General Public
7 License as published by the Free Software Foundation; either
8 version 2.1 of the License, or (at your option) any later version.
9
10 The GNU C Library is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 Lesser General Public License for more details.
14
15 You should have received a copy of the GNU Lesser General Public
16 License along with the GNU C Library; if not, see
17 <https://www.gnu.org/licenses/>. */
18
19 #include <malloc.h>
20 #include <string.h>
21
22 #include <envz.h>
23
24 /* The character separating names from values in an envz. */
25 #define SEP '='
26
27 /* Returns a pointer to the entry in ENVZ for NAME, or 0 if there is none.
28 If NAME contains the separator character, only the portion before it is
29 used in the comparison. */
30 char *
31 envz_entry (const char *envz, size_t envz_len, const char *name)
32 {
33 while (envz_len)
34 {
35 const char *p = name;
36 const char *entry = envz; /* Start of this entry. */
37
38 /* See how far NAME and ENTRY match. */
39 while (envz_len && *p == *envz && *p && *p != SEP)
40 p++, envz++, envz_len--;
41
42 if ((*envz == '\0' || *envz == SEP) && (*p == '\0' || *p == SEP))
43 /* Bingo! */
44 return (char *) entry;
45
46 /* No match, skip to the next entry. */
47 while (envz_len && *envz)
48 envz++, envz_len--;
49 if (envz_len)
50 envz++, envz_len--; /* skip '\0' */
51 }
52
53 return 0;
54 }
55 libc_hidden_def (envz_entry)
56
57 /* Returns a pointer to the value portion of the entry in ENVZ for NAME, or 0
58 if there is none. */
59 char *
60 envz_get (const char *envz, size_t envz_len, const char *name)
61 {
62 char *entry = envz_entry (envz, envz_len, name);
63 if (entry)
64 {
65 while (*entry && *entry != SEP)
66 entry++;
67 if (*entry)
68 entry++;
69 else
70 entry = 0; /* A null entry. */
71 }
72 return entry;
73 }
74
75 /* Remove the entry for NAME from ENVZ & ENVZ_LEN, if any. */
76 void
77 envz_remove (char **envz, size_t *envz_len, const char *name)
78 {
79 char *entry = envz_entry (*envz, *envz_len, name);
80 if (entry)
81 argz_delete (envz, envz_len, entry);
82 }
83 libc_hidden_def (envz_remove)
84
85 /* Adds an entry for NAME with value VALUE to ENVZ & ENVZ_LEN. If an entry
86 with the same name already exists in ENVZ, it is removed. If VALUE is
87 NULL, then the new entry will a special null one, for which envz_get will
88 return NULL, although envz_entry will still return an entry; this is handy
89 because when merging with another envz, the null entry can override an
90 entry in the other one. Null entries can be removed with envz_strip (). */
91 error_t
92 envz_add (char **envz, size_t *envz_len, const char *name, const char *value)
93 {
94 envz_remove (envz, envz_len, name);
95
96 if (value)
97 /* Add the new value, if there is one. */
98 {
99 size_t name_len = strlen (name);
100 size_t value_len = strlen (value);
101 size_t old_envz_len = *envz_len;
102 size_t new_envz_len = old_envz_len + name_len + 1 + value_len + 1;
103 char *new_envz = realloc (*envz, new_envz_len);
104
105 if (new_envz)
106 {
107 memcpy (new_envz + old_envz_len, name, name_len);
108 new_envz[old_envz_len + name_len] = SEP;
109 memcpy (new_envz + old_envz_len + name_len + 1, value, value_len);
110 new_envz[new_envz_len - 1] = 0;
111
112 *envz = new_envz;
113 *envz_len = new_envz_len;
114
115 return 0;
116 }
117 else
118 return ENOMEM;
119 }
120 else
121 /* Add a null entry. */
122 return __argz_add (envz, envz_len, name);
123 }
124
125 /* Adds each entry in ENVZ2 to ENVZ & ENVZ_LEN, as if with envz_add(). If
126 OVERRIDE is true, then values in ENVZ2 will supersede those with the same
127 name in ENV, otherwise not. */
128 error_t
129 envz_merge (char **envz, size_t *envz_len, const char *envz2,
130 size_t envz2_len, int override)
131 {
132 error_t err = 0;
133
134 while (envz2_len && ! err)
135 {
136 char *old = envz_entry (*envz, *envz_len, envz2);
137 size_t new_len = strlen (envz2) + 1;
138
139 if (! old)
140 err = __argz_append (envz, envz_len, envz2, new_len);
141 else if (override)
142 {
143 argz_delete (envz, envz_len, old);
144 err = __argz_append (envz, envz_len, envz2, new_len);
145 }
146
147 envz2 += new_len;
148 envz2_len -= new_len;
149 }
150
151 return err;
152 }
153
154 /* Remove null entries. */
155 void
156 envz_strip (char **envz, size_t *envz_len)
157 {
158 char *entry = *envz;
159 size_t left = *envz_len;
160 while (left)
161 {
162 size_t entry_len = strlen (entry) + 1;
163 left -= entry_len;
164 if (! strchr (entry, SEP))
165 /* Null entry. */
166 memmove (entry, entry + entry_len, left);
167 else
168 entry += entry_len;
169 }
170 *envz_len = entry - *envz;
171 }