execute: support minimal environment variable replacement when executing processes

[elogind.git] / src / util.c

diff --git a/src/util.c b/src/util.c
index 8360eb68fd435244a976981c9a4e15a5618053df..cdfc9e0158828f70d6adbcd4550e3973739faaf1 100644 (file)
--- a/src/util.c
+++ b/src/util.c
@@ -360,7 +360,8 @@ char *split(const char *c, size_t *l, const char *separator, char **state) {
 /* Split a string into words, but consider strings enclosed in '' and
  * "" as words even if they include spaces. */
 char *split_quoted(const char *c, size_t *l, char **state) {
-        char *current;
+        char *current, *e;
+        bool escaped = false;
 
         current = *state ? *state : (char*) c;
 
@@ -371,26 +372,45 @@ char *split_quoted(const char *c, size_t *l, char **state) {
 
         if (*current == '\'') {
                 current ++;
-                *l = strcspn(current, "'");
-                *state = current+*l;
 
-                if (**state == '\'')
-                        (*state)++;
+                for (e = current; *e; e++) {
+                        if (escaped)
+                                escaped = false;
+                        else if (*e == '\\')
+                                escaped = true;
+                        else if (*e == '\'')
+                                break;
+                }
+
+                *l = e-current;
+                *state = *e == 0 ? e : e+1;
         } else if (*current == '\"') {
                 current ++;
-                *l = strcspn(current, "\"");
-                *state = current+*l;
 
-                if (**state == '\"')
-                        (*state)++;
+                for (e = current; *e; e++) {
+                        if (escaped)
+                                escaped = false;
+                        else if (*e == '\\')
+                                escaped = true;
+                        else if (*e == '\"')
+                                break;
+                }
+
+                *l = e-current;
+                *state = *e == 0 ? e : e+1;
         } else {
-                *l = strcspn(current, WHITESPACE);
-                *state = current+*l;
+                for (e = current; *e; e++) {
+                        if (escaped)
+                                escaped = false;
+                        else if (*e == '\\')
+                                escaped = true;
+                        else if (strchr(WHITESPACE, *e))
+                                break;
+                }
+                *l = e-current;
+                *state = e;
         }
 
-        /* FIXME: Cannot deal with strings that have spaces AND ticks
-         * in them */
-
         return (char*) current;
 }
 
@@ -593,15 +613,23 @@ int get_process_cmdline(pid_t pid, size_t max_length, char **line) {
         return 0;
 }
 
-char *strappend(const char *s, const char *suffix) {
-        size_t a, b;
+char *strnappend(const char *s, const char *suffix, size_t b) {
+        size_t a;
         char *r;
 
+        if (!s && !suffix)
+                return strdup("");
+
+        if (!s)
+                return strndup(suffix, b);
+
+        if (!suffix)
+                return strdup(s);
+
         assert(s);
         assert(suffix);
 
         a = strlen(s);
-        b = strlen(suffix);
 
         if (!(r = new(char, a+b+1)))
                 return NULL;
@@ -613,6 +641,10 @@ char *strappend(const char *s, const char *suffix) {
         return r;
 }
 
+char *strappend(const char *s, const char *suffix) {
+        return strnappend(s, suffix, suffix ? strlen(suffix) : 0);
+}
+
 int readlink_malloc(const char *p, char **r) {
         size_t l = 100;
 
@@ -1109,7 +1141,7 @@ char *cescape(const char *s) {
         return r;
 }
 
-char *cunescape(const char *s) {
+char *cunescape_length(const char *s, size_t length) {
         char *r, *t;
         const char *f;
 
@@ -1117,10 +1149,10 @@ char *cunescape(const char *s) {
 
         /* Undoes C style string escaping */
 
-        if (!(r = new(char, strlen(s)+1)))
+        if (!(r = new(char, length+1)))
                 return r;
 
-        for (f = s, t = r; *f; f++) {
+        for (f = s, t = r; f < s + length; f++) {
 
                 if (*f != '\\') {
                         *(t++) = *f;
@@ -1162,6 +1194,11 @@ char *cunescape(const char *s) {
                         *(t++) = '\'';
                         break;
 
+                case 's':
+                        /* This is an extension of the XDG syntax files */
+                        *(t++) = ' ';
+                        break;
+
                 case 'x': {
                         /* hexadecimal encoding */
                         int a, b;
@@ -1212,7 +1249,7 @@ char *cunescape(const char *s) {
                 default:
                         /* Invalid escape code, let's take it literal then */
                         *(t++) = '\\';
-                        *(t++) = 'f';
+                        *(t++) = *f;
                         break;
                 }
         }
@@ -1222,6 +1259,9 @@ finish:
         return r;
 }
 
+char *cunescape(const char *s) {
+        return cunescape_length(s, strlen(s));
+}
 
 char *xescape(const char *s, const char *bad) {
         char *r, *t;
@@ -2664,6 +2704,100 @@ void status_welcome(void) {
 #endif
 }
 
+char *replace_env(const char *format, char **env) {
+        enum {
+                WORD,
+                DOLLAR,
+                VARIABLE
+        } state = WORD;
+
+        const char *e, *word = format;
+        char *r = NULL, *k;
+
+        assert(format);
+
+        for (e = format; *e; e ++) {
+
+                switch (state) {
+
+                case WORD:
+                        if (*e == '$')
+                                state = DOLLAR;
+                        break;
+
+                case DOLLAR:
+                        if (*e == '(') {
+                                if (!(k = strnappend(r, word, e-word-1)))
+                                        goto fail;
+
+                                free(r);
+                                r = k;
+
+                                word = e-1;
+                                state = VARIABLE;
+
+                        } else if (*e == '$') {
+                                if (!(k = strnappend(r, word, e-word)))
+                                        goto fail;
+
+                                free(r);
+                                r = k;
+
+                                word = e+1;
+                                state = WORD;
+                        } else
+                                state = WORD;
+                        break;
+
+                case VARIABLE:
+                        if (*e == ')') {
+                                char *t;
+
+                                if ((t = strv_env_get_with_length(env, word+2, e-word-2))) {
+                                        if (!(k = strappend(r, t)))
+                                                goto fail;
+
+                                        free(r);
+                                        r = k;
+
+                                        word = e+1;
+                                }
+
+                                state = WORD;
+                        }
+                        break;
+                }
+        }
+
+        if (!(k = strnappend(r, word, e-word)))
+                goto fail;
+
+        free(r);
+        return k;
+
+fail:
+        free(r);
+        return NULL;
+}
+
+char **replace_env_argv(char **argv, char **env) {
+        char **r, **i;
+        unsigned k;
+
+        if (!(r = new(char*, strv_length(argv)+1)))
+                return NULL;
+
+        STRV_FOREACH(i, argv) {
+                if (!(r[k++] = replace_env(*i, env))) {
+                        strv_free(r);
+                        return NULL;
+                }
+        }
+
+        r[k] = NULL;
+        return r;
+}
+
 static const char *const ioprio_class_table[] = {
         [IOPRIO_CLASS_NONE] = "none",
         [IOPRIO_CLASS_RT] = "realtime",