Merge pull request #5131 from keszybz/environment-generators

Environment generators

1 files changed, 186 insertions, 26 deletions

diff --git a/src/basic/env-util.c b/src/basic/env-util.c
index 96da38d45e..2ca64c3301 100644
--- a/src/basic/env-util.c
+++ b/src/basic/env-util.c
@@ -26,6 +26,7 @@
 
 #include "alloc-util.h"
 #include "env-util.h"
+#include "escape.h"
 #include "extract-word.h"
 #include "macro.h"
 #include "parse-util.h"
@@ -247,7 +248,7 @@ fail:
         return NULL;
 }
 
-_pure_ static bool env_match(const char *t, const char *pattern) {
+static bool env_match(const char *t, const char *pattern) {
         assert(t);
         assert(pattern);
 
@@ -273,6 +274,19 @@ _pure_ static bool env_match(const char *t, const char *pattern) {
         return false;
 }
 
+static bool env_entry_has_name(const char *entry, const char *name) {
+        const char *t;
+
+        assert(entry);
+        assert(name);
+
+        t = startswith(entry, name);
+        if (!t)
+                return false;
+
+        return *t == '=';
+}
+
 char **strv_env_delete(char **x, unsigned n_lists, ...) {
         size_t n, i = 0;
         char **k, **r;
@@ -386,18 +400,24 @@ char **strv_env_unset_many(char **l, ...) {
 
 int strv_env_replace(char ***l, char *p) {
         char **f;
+        const char *t, *name;
 
         assert(p);
 
         /* Replace first occurrence of the env var or add a new one in the
          * string list. Drop other occurences. Edits in-place. Does not copy p.
+         * p must be a valid key=value assignment.
          */
 
+        t = strchr(p, '=');
+        assert(t);
+
+        name = strndupa(p, t - p);
+
         for (f = *l; f && *f; f++)
-                if (env_match(*f, p)) {
-                        free(*f);
-                        *f = p;
-                        strv_env_unset(f + 1, p);
+                if (env_entry_has_name(*f, name)) {
+                        free_and_replace(*f, p);
+                        strv_env_unset(f + 1, *f);
                         return 0;
                 }
 
@@ -434,7 +454,7 @@ fail:
         return NULL;
 }
 
-char *strv_env_get_n(char **l, const char *name, size_t k) {
+char *strv_env_get_n(char **l, const char *name, size_t k, unsigned flags) {
         char **i;
 
         assert(name);
@@ -442,18 +462,25 @@ char *strv_env_get_n(char **l, const char *name, size_t k) {
         if (k <= 0)
                 return NULL;
 
-        STRV_FOREACH(i, l)
+        STRV_FOREACH_BACKWARDS(i, l)
                 if (strneq(*i, name, k) &&
                     (*i)[k] == '=')
                         return *i + k + 1;
 
+        if (flags & REPLACE_ENV_USE_ENVIRONMENT) {
+                const char *t;
+
+                t = strndupa(name, k);
+                return getenv(t);
+        };
+
         return NULL;
 }
 
 char *strv_env_get(char **l, const char *name) {
         assert(name);
 
-        return strv_env_get_n(l, name, strlen(name));
+        return strv_env_get_n(l, name, strlen(name), 0);
 }
 
 char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const char *p, void *userdata), void *userdata) {
@@ -492,19 +519,26 @@ char **strv_env_clean_with_callback(char **e, void (*invalid_callback)(const cha
         return e;
 }
 
-char *replace_env(const char *format, char **env) {
+char *replace_env_n(const char *format, size_t n, char **env, unsigned flags) {
         enum {
                 WORD,
                 CURLY,
-                VARIABLE
+                VARIABLE,
+                VARIABLE_RAW,
+                TEST,
+                DEFAULT_VALUE,
+                ALTERNATE_VALUE,
         } state = WORD;
 
-        const char *e, *word = format;
-        char *r = NULL, *k;
+        const char *e, *word = format, *test_value;
+        char *k;
+        _cleanup_free_ char *r = NULL;
+        size_t i, len;
+        int nest = 0;
 
         assert(format);
 
-        for (e = format; *e; e ++) {
+        for (e = format, i = 0; *e && i < n; e ++, i ++) {
 
                 switch (state) {
 
@@ -517,24 +551,36 @@ char *replace_env(const char *format, char **env) {
                         if (*e == '{') {
                                 k = strnappend(r, word, e-word-1);
                                 if (!k)
-                                        goto fail;
+                                        return NULL;
 
                                 free(r);
                                 r = k;
 
                                 word = e-1;
                                 state = VARIABLE;
-
+                                nest++;
                         } else if (*e == '$') {
                                 k = strnappend(r, word, e-word);
                                 if (!k)
-                                        goto fail;
+                                        return NULL;
 
                                 free(r);
                                 r = k;
 
                                 word = e+1;
                                 state = WORD;
+
+                        } else if (flags & REPLACE_ENV_ALLOW_BRACELESS && strchr(VALID_CHARS_ENV_NAME, *e)) {
+                                k = strnappend(r, word, e-word-1);
+                                if (!k)
+                                        return NULL;
+
+                                free(r);
+                                r = k;
+
+                                word = e-1;
+                                state = VARIABLE_RAW;
+
                         } else
                                 state = WORD;
                         break;
@@ -543,31 +589,109 @@ char *replace_env(const char *format, char **env) {
                         if (*e == '}') {
                                 const char *t;
 
-                                t = strempty(strv_env_get_n(env, word+2, e-word-2));
+                                t = strv_env_get_n(env, word+2, e-word-2, flags);
 
                                 k = strappend(r, t);
                                 if (!k)
-                                        goto fail;
+                                        return NULL;
 
                                 free(r);
                                 r = k;
 
                                 word = e+1;
                                 state = WORD;
+                        } else if (*e == ':') {
+                                if (!(flags & REPLACE_ENV_ALLOW_EXTENDED))
+                                        /* Treat this as unsupported syntax, i.e. do no replacement */
+                                        state = WORD;
+                                else {
+                                        len = e-word-2;
+                                        state = TEST;
+                                }
+                        }
+                        break;
+
+                case TEST:
+                        if (*e == '-')
+                                state = DEFAULT_VALUE;
+                        else if (*e == '+')
+                                state = ALTERNATE_VALUE;
+                        else {
+                                state = WORD;
+                                break;
+                        }
+
+                        test_value = e+1;
+                        break;
+
+                case DEFAULT_VALUE: /* fall through */
+                case ALTERNATE_VALUE:
+                        assert(flags & REPLACE_ENV_ALLOW_EXTENDED);
+
+                        if (*e == '{') {
+                                nest++;
+                                break;
+                        }
+
+                        if (*e != '}')
+                                break;
+
+                        nest--;
+                        if (nest == 0) { // || !strchr(e+1, '}')) {
+                                const char *t;
+                                _cleanup_free_ char *v = NULL;
+
+                                t = strv_env_get_n(env, word+2, len, flags);
+
+                                if (t && state == ALTERNATE_VALUE)
+                                        t = v = replace_env_n(test_value, e-test_value, env, flags);
+                                else if (!t && state == DEFAULT_VALUE)
+                                        t = v = replace_env_n(test_value, e-test_value, env, flags);
+
+                                k = strappend(r, t);
+                                if (!k)
+                                        return NULL;
+
+                                free(r);
+                                r = k;
+
+                                word = e+1;
+                                state = WORD;
+                        }
+                        break;
+
+                case VARIABLE_RAW:
+                        assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
+
+                        if (!strchr(VALID_CHARS_ENV_NAME, *e)) {
+                                const char *t;
+
+                                t = strv_env_get_n(env, word+1, e-word-1, flags);
+
+                                k = strappend(r, t);
+                                if (!k)
+                                        return NULL;
+
+                                free(r);
+                                r = k;
+
+                                word = e--;
+                                i--;
+                                state = WORD;
                         }
                         break;
                 }
         }
 
-        k = strnappend(r, word, e-word);
-        if (!k)
-                goto fail;
+        if (state == VARIABLE_RAW) {
+                const char *t;
 
-        free(r);
-        return k;
+                assert(flags & REPLACE_ENV_ALLOW_BRACELESS);
 
-fail:
-        return mfree(r);
+                t = strv_env_get_n(env, word+1, e-word-1, flags);
+                return strappend(r, t);
+        } else
+                return strnappend(r, word, e-word);
 }
 
 char **replace_env_argv(char **argv, char **env) {
@@ -623,7 +747,7 @@ char **replace_env_argv(char **argv, char **env) {
                 }
 
                 /* If ${FOO} appears as part of a word, replace it by the variable as-is */
-                ret[k] = replace_env(*i, env);
+                ret[k] = replace_env(*i, env, 0);
                 if (!ret[k]) {
                         strv_free(ret);
                         return NULL;
@@ -644,3 +768,39 @@ int getenv_bool(const char *p) {
 
         return parse_boolean(e);
 }
+
+int serialize_environment(FILE *f, char **environment) {
+        char **e;
+
+        STRV_FOREACH(e, environment) {
+                _cleanup_free_ char *ce;
+
+                ce = cescape(*e);
+                if (!ce)
+                        return -ENOMEM;
+
+                fprintf(f, "env=%s\n", *e);
+        }
+
+        /* caller should call ferror() */
+
+        return 0;
+}
+
+int deserialize_environment(char ***environment, const char *line) {
+        char *uce = NULL;
+        int r;
+
+        assert(line);
+        assert(environment);
+
+        assert(startswith(line, "env="));
+        r = cunescape(line + 4, UNESCAPE_RELAX, &uce);
+        if (r < 0)
+                return r;
+
+        if (!env_assignment_is_valid(uce))
+                return -EINVAL;
+
+        return strv_env_replace(environment, uce);
+}