xref: /illumos-kvm-cmd/envlist.c (revision 68396ea9)
1 #include <assert.h>
2 #include <errno.h>
3 #include <stdlib.h>
4 #include <string.h>
5 #include <unistd.h>
6 
7 #include "qemu-queue.h"
8 #include "envlist.h"
9 
10 struct envlist_entry {
11 	const char *ev_var;			/* actual env value */
12 	QLIST_ENTRY(envlist_entry) ev_link;
13 };
14 
15 struct envlist {
16 	QLIST_HEAD(, envlist_entry) el_entries;	/* actual entries */
17 	size_t el_count;			/* number of entries */
18 };
19 
20 static int envlist_parse(envlist_t *envlist,
21     const char *env, int (*)(envlist_t *, const char *));
22 
23 /*
24  * Allocates new envlist and returns pointer to that or
25  * NULL in case of error.
26  */
27 envlist_t *
envlist_create(void)28 envlist_create(void)
29 {
30 	envlist_t *envlist;
31 
32 	if ((envlist = malloc(sizeof (*envlist))) == NULL)
33 		return (NULL);
34 
35 	QLIST_INIT(&envlist->el_entries);
36 	envlist->el_count = 0;
37 
38 	return (envlist);
39 }
40 
41 /*
42  * Releases given envlist and its entries.
43  */
44 void
envlist_free(envlist_t * envlist)45 envlist_free(envlist_t *envlist)
46 {
47 	struct envlist_entry *entry;
48 
49 	assert(envlist != NULL);
50 
51 	while (envlist->el_entries.lh_first != NULL) {
52 		entry = envlist->el_entries.lh_first;
53 		QLIST_REMOVE(entry, ev_link);
54 
55 		free((char *)entry->ev_var);
56 		free(entry);
57 	}
58 	free(envlist);
59 }
60 
61 /*
62  * Parses comma separated list of set/modify environment
63  * variable entries and updates given enlist accordingly.
64  *
65  * For example:
66  *     envlist_parse(el, "HOME=foo,SHELL=/bin/sh");
67  *
68  * inserts/sets environment variables HOME and SHELL.
69  *
70  * Returns 0 on success, errno otherwise.
71  */
72 int
envlist_parse_set(envlist_t * envlist,const char * env)73 envlist_parse_set(envlist_t *envlist, const char *env)
74 {
75 	return (envlist_parse(envlist, env, &envlist_setenv));
76 }
77 
78 /*
79  * Parses comma separated list of unset environment variable
80  * entries and removes given variables from given envlist.
81  *
82  * Returns 0 on success, errno otherwise.
83  */
84 int
envlist_parse_unset(envlist_t * envlist,const char * env)85 envlist_parse_unset(envlist_t *envlist, const char *env)
86 {
87 	return (envlist_parse(envlist, env, &envlist_unsetenv));
88 }
89 
90 /*
91  * Parses comma separated list of set, modify or unset entries
92  * and calls given callback for each entry.
93  *
94  * Returns 0 in case of success, errno otherwise.
95  */
96 static int
envlist_parse(envlist_t * envlist,const char * env,int (* callback)(envlist_t *,const char *))97 envlist_parse(envlist_t *envlist, const char *env,
98     int (*callback)(envlist_t *, const char *))
99 {
100 	char *tmpenv, *envvar;
101 	char *envsave = NULL;
102 
103 	assert(callback != NULL);
104 
105 	if ((envlist == NULL) || (env == NULL))
106 		return (EINVAL);
107 
108 	/*
109 	 * We need to make temporary copy of the env string
110 	 * as strtok_r(3) modifies it while it tokenizes.
111 	 */
112 	if ((tmpenv = strdup(env)) == NULL)
113 		return (errno);
114 
115 	envvar = strtok_r(tmpenv, ",", &envsave);
116 	while (envvar != NULL) {
117 		if ((*callback)(envlist, envvar) != 0) {
118 			free(tmpenv);
119 			return (errno);
120 		}
121 		envvar = strtok_r(NULL, ",", &envsave);
122 	}
123 
124 	free(tmpenv);
125 	return (0);
126 }
127 
128 /*
129  * Sets environment value to envlist in similar manner
130  * than putenv(3).
131  *
132  * Returns 0 in success, errno otherwise.
133  */
134 int
envlist_setenv(envlist_t * envlist,const char * env)135 envlist_setenv(envlist_t *envlist, const char *env)
136 {
137 	struct envlist_entry *entry = NULL;
138 	const char *eq_sign;
139 	size_t envname_len;
140 
141 	if ((envlist == NULL) || (env == NULL))
142 		return (EINVAL);
143 
144 	/* find out first equals sign in given env */
145 	if ((eq_sign = strchr(env, '=')) == NULL)
146 		return (EINVAL);
147 	envname_len = eq_sign - env + 1;
148 
149 	/*
150 	 * If there already exists variable with given name
151 	 * we remove and release it before allocating a whole
152 	 * new entry.
153 	 */
154 	for (entry = envlist->el_entries.lh_first; entry != NULL;
155 	    entry = entry->ev_link.le_next) {
156 		if (strncmp(entry->ev_var, env, envname_len) == 0)
157 			break;
158 	}
159 
160 	if (entry != NULL) {
161 		QLIST_REMOVE(entry, ev_link);
162 		free((char *)entry->ev_var);
163 		free(entry);
164 	} else {
165 		envlist->el_count++;
166 	}
167 
168 	if ((entry = malloc(sizeof (*entry))) == NULL)
169 		return (errno);
170 	if ((entry->ev_var = strdup(env)) == NULL) {
171 		free(entry);
172 		return (errno);
173 	}
174 	QLIST_INSERT_HEAD(&envlist->el_entries, entry, ev_link);
175 
176 	return (0);
177 }
178 
179 /*
180  * Removes given env value from envlist in similar manner
181  * than unsetenv(3).  Returns 0 in success, errno otherwise.
182  */
183 int
envlist_unsetenv(envlist_t * envlist,const char * env)184 envlist_unsetenv(envlist_t *envlist, const char *env)
185 {
186 	struct envlist_entry *entry;
187 	size_t envname_len;
188 
189 	if ((envlist == NULL) || (env == NULL))
190 		return (EINVAL);
191 
192 	/* env is not allowed to contain '=' */
193 	if (strchr(env, '=') != NULL)
194 		return (EINVAL);
195 
196 	/*
197 	 * Find out the requested entry and remove
198 	 * it from the list.
199 	 */
200 	envname_len = strlen(env);
201 	for (entry = envlist->el_entries.lh_first; entry != NULL;
202 	    entry = entry->ev_link.le_next) {
203 		if (strncmp(entry->ev_var, env, envname_len) == 0)
204 			break;
205 	}
206 	if (entry != NULL) {
207 		QLIST_REMOVE(entry, ev_link);
208 		free((char *)entry->ev_var);
209 		free(entry);
210 
211 		envlist->el_count--;
212 	}
213 	return (0);
214 }
215 
216 /*
217  * Returns given envlist as array of strings (in same form that
218  * global variable environ is).  Caller must free returned memory
219  * by calling free(3) for each element and for the array.  Returned
220  * array and given envlist are not related (no common references).
221  *
222  * If caller provides count pointer, number of items in array is
223  * stored there.  In case of error, NULL is returned and no memory
224  * is allocated.
225  */
226 char **
envlist_to_environ(const envlist_t * envlist,size_t * count)227 envlist_to_environ(const envlist_t *envlist, size_t *count)
228 {
229 	struct envlist_entry *entry;
230 	char **env, **penv;
231 
232 	penv = env = malloc((envlist->el_count + 1) * sizeof (char *));
233 	if (env == NULL)
234 		return (NULL);
235 
236 	for (entry = envlist->el_entries.lh_first; entry != NULL;
237 	    entry = entry->ev_link.le_next) {
238 		*(penv++) = strdup(entry->ev_var);
239 	}
240 	*penv = NULL; /* NULL terminate the list */
241 
242 	if (count != NULL)
243 		*count = envlist->el_count;
244 
245 	return (env);
246 }
247