scsi: pvscsi: check command descriptor ring buffer size (CVE-2016-4952)
[qemu.git] / util / envlist.c
1 #include "qemu/osdep.h"
2 #include "qemu-common.h"
3 #include "qemu/queue.h"
4 #include "qemu/envlist.h"
5
6 struct envlist_entry {
7 const char *ev_var; /* actual env value */
8 QLIST_ENTRY(envlist_entry) ev_link;
9 };
10
11 struct envlist {
12 QLIST_HEAD(, envlist_entry) el_entries; /* actual entries */
13 size_t el_count; /* number of entries */
14 };
15
16 static int envlist_parse(envlist_t *envlist,
17 const char *env, int (*)(envlist_t *, const char *));
18
19 /*
20 * Allocates new envlist and returns pointer to that or
21 * NULL in case of error.
22 */
23 envlist_t *
24 envlist_create(void)
25 {
26 envlist_t *envlist;
27
28 if ((envlist = malloc(sizeof (*envlist))) == NULL)
29 return (NULL);
30
31 QLIST_INIT(&envlist->el_entries);
32 envlist->el_count = 0;
33
34 return (envlist);
35 }
36
37 /*
38 * Releases given envlist and its entries.
39 */
40 void
41 envlist_free(envlist_t *envlist)
42 {
43 struct envlist_entry *entry;
44
45 assert(envlist != NULL);
46
47 while (envlist->el_entries.lh_first != NULL) {
48 entry = envlist->el_entries.lh_first;
49 QLIST_REMOVE(entry, ev_link);
50
51 free((char *)entry->ev_var);
52 free(entry);
53 }
54 free(envlist);
55 }
56
57 /*
58 * Parses comma separated list of set/modify environment
59 * variable entries and updates given enlist accordingly.
60 *
61 * For example:
62 * envlist_parse(el, "HOME=foo,SHELL=/bin/sh");
63 *
64 * inserts/sets environment variables HOME and SHELL.
65 *
66 * Returns 0 on success, errno otherwise.
67 */
68 int
69 envlist_parse_set(envlist_t *envlist, const char *env)
70 {
71 return (envlist_parse(envlist, env, &envlist_setenv));
72 }
73
74 /*
75 * Parses comma separated list of unset environment variable
76 * entries and removes given variables from given envlist.
77 *
78 * Returns 0 on success, errno otherwise.
79 */
80 int
81 envlist_parse_unset(envlist_t *envlist, const char *env)
82 {
83 return (envlist_parse(envlist, env, &envlist_unsetenv));
84 }
85
86 /*
87 * Parses comma separated list of set, modify or unset entries
88 * and calls given callback for each entry.
89 *
90 * Returns 0 in case of success, errno otherwise.
91 */
92 static int
93 envlist_parse(envlist_t *envlist, const char *env,
94 int (*callback)(envlist_t *, const char *))
95 {
96 char *tmpenv, *envvar;
97 char *envsave = NULL;
98 int ret = 0;
99 assert(callback != NULL);
100
101 if ((envlist == NULL) || (env == NULL))
102 return (EINVAL);
103
104 if ((tmpenv = strdup(env)) == NULL)
105 return (errno);
106 envsave = tmpenv;
107
108 do {
109 envvar = strchr(tmpenv, ',');
110 if (envvar != NULL) {
111 *envvar = '\0';
112 }
113 if ((*callback)(envlist, tmpenv) != 0) {
114 ret = errno;
115 break;
116 }
117 tmpenv = envvar + 1;
118 } while (envvar != NULL);
119
120 free(envsave);
121 return ret;
122 }
123
124 /*
125 * Sets environment value to envlist in similar manner
126 * than putenv(3).
127 *
128 * Returns 0 in success, errno otherwise.
129 */
130 int
131 envlist_setenv(envlist_t *envlist, const char *env)
132 {
133 struct envlist_entry *entry = NULL;
134 const char *eq_sign;
135 size_t envname_len;
136
137 if ((envlist == NULL) || (env == NULL))
138 return (EINVAL);
139
140 /* find out first equals sign in given env */
141 if ((eq_sign = strchr(env, '=')) == NULL)
142 return (EINVAL);
143 envname_len = eq_sign - env + 1;
144
145 /*
146 * If there already exists variable with given name
147 * we remove and release it before allocating a whole
148 * new entry.
149 */
150 for (entry = envlist->el_entries.lh_first; entry != NULL;
151 entry = entry->ev_link.le_next) {
152 if (strncmp(entry->ev_var, env, envname_len) == 0)
153 break;
154 }
155
156 if (entry != NULL) {
157 QLIST_REMOVE(entry, ev_link);
158 free((char *)entry->ev_var);
159 free(entry);
160 } else {
161 envlist->el_count++;
162 }
163
164 if ((entry = malloc(sizeof (*entry))) == NULL)
165 return (errno);
166 if ((entry->ev_var = strdup(env)) == NULL) {
167 free(entry);
168 return (errno);
169 }
170 QLIST_INSERT_HEAD(&envlist->el_entries, entry, ev_link);
171
172 return (0);
173 }
174
175 /*
176 * Removes given env value from envlist in similar manner
177 * than unsetenv(3). Returns 0 in success, errno otherwise.
178 */
179 int
180 envlist_unsetenv(envlist_t *envlist, const char *env)
181 {
182 struct envlist_entry *entry;
183 size_t envname_len;
184
185 if ((envlist == NULL) || (env == NULL))
186 return (EINVAL);
187
188 /* env is not allowed to contain '=' */
189 if (strchr(env, '=') != NULL)
190 return (EINVAL);
191
192 /*
193 * Find out the requested entry and remove
194 * it from the list.
195 */
196 envname_len = strlen(env);
197 for (entry = envlist->el_entries.lh_first; entry != NULL;
198 entry = entry->ev_link.le_next) {
199 if (strncmp(entry->ev_var, env, envname_len) == 0)
200 break;
201 }
202 if (entry != NULL) {
203 QLIST_REMOVE(entry, ev_link);
204 free((char *)entry->ev_var);
205 free(entry);
206
207 envlist->el_count--;
208 }
209 return (0);
210 }
211
212 /*
213 * Returns given envlist as array of strings (in same form that
214 * global variable environ is). Caller must free returned memory
215 * by calling free(3) for each element and for the array. Returned
216 * array and given envlist are not related (no common references).
217 *
218 * If caller provides count pointer, number of items in array is
219 * stored there. In case of error, NULL is returned and no memory
220 * is allocated.
221 */
222 char **
223 envlist_to_environ(const envlist_t *envlist, size_t *count)
224 {
225 struct envlist_entry *entry;
226 char **env, **penv;
227
228 penv = env = malloc((envlist->el_count + 1) * sizeof (char *));
229 if (env == NULL)
230 return (NULL);
231
232 for (entry = envlist->el_entries.lh_first; entry != NULL;
233 entry = entry->ev_link.le_next) {
234 *(penv++) = strdup(entry->ev_var);
235 }
236 *penv = NULL; /* NULL terminate the list */
237
238 if (count != NULL)
239 *count = envlist->el_count;
240
241 return (env);
242 }