1 files changed, 182 insertions, 0 deletions
diff --git a/src/util/envp.c b/src/util/envp.c
new file mode 100644
index 0000000..808d9b8
--- /dev/null
+++ b/src/util/envp.c
@@ -0,0 +1,182 @@
+#include "envp.h"
+
+#include "string.h"
+
+#include <stdlib.h>
+
+extern char **environ;
+
+static inline bool _envp_string_match_key(
+		const char *restrict string, const char *restrict key) {
+	for (size_t i = 0; ; ++i) {
+		if ('\0' == key[i]) {
+			return ('=' == string[i]);
+		} else if ('\0' == string[i]) {
+			return false;
+		} else if (string[i] != key[i]) {
+			return false;
+		}
+	}
+}
+
+
+static int _envp_append(envp_t *envp, char *string) {
+	/* find the end */
+	envp_t p = *envp;
+	size_t i = 0;
+	while (NULL != p[i]) i++;
+
+	/* make space for one more element */
+	p = realloc(p, ((i+2) * sizeof(char *)));
+	if (NULL == p) {
+		return -1;
+	}
+	*envp = p;
+
+	/* append element */
+	p[i+1] = 0;
+	p[i] = string;
+
+	return 0;
+}
+
+static int _envp_replace(char **old, char *new) {
+	char *oldv = *old;
+	*old = new;
+	free(oldv);
+
+	return 0;
+}
+
+
+envp_t *envp_alloc(void) {
+	envp_t envp = calloc(1, sizeof(*envp));
+	envp_t *envpp = malloc(sizeof(envpp));
+	*envpp = envp;
+	return envpp;
+}
+
+envp_t *envp_dup(void) {
+	envp_t *envp = envp_alloc();
+
+	for (size_t i = 0; NULL != environ[i]; ++i) {
+		(void)_envp_append(envp, strdup(environ[i]));
+	}
+
+	return envp;
+}
+
+static char **_envp_find_elem(envp_t envp, const char *restrict name) {
+	for (size_t i = 0; NULL != envp[i]; ++i) {
+		if (_envp_string_match_key(envp[i], name)) {
+			return &envp[i];
+		}
+	}
+
+	return NULL;
+}
+
+static char *_envp_get_elem(envp_t envp, const char *restrict name) {
+	char **elem = _envp_find_elem(envp, name);
+	return (elem ? *elem : NULL);
+}
+
+char *envp_get(envp_t *envp, const char *name) {
+	if (NULL == envp) return NULL;
+
+	char *elem = _envp_get_elem(*envp, name);
+
+	if (NULL != elem) {
+		elem = strchr(elem, '=');
+		if (NULL != elem) elem++;  /* skip over = */
+	}
+
+	return elem;
+}
+
+
+int envp_put(envp_t *envp, char *string) {
+	char envname[strchr(string, '=')-string+1];
+	strncpy(envname, string, sizeof(envname));
+
+	char **elem = _envp_find_elem(*envp, envname);
+
+	if (NULL != elem) {
+		return _envp_replace(elem, string);
+	} else {
+		return _envp_append(envp, string);
+	}
+}
+
+int envp_set(
+		envp_t *envp, const char *restrict envname, const char *restrict envval,
+		bool overwrite) {
+	char **elem = _envp_find_elem(*envp, envname);
+
+	char *string = NULL;
+	if (NULL == elem || overwrite) {
+		size_t slen = (strlen(envname) + strlen (envval) + 2);
+		string = malloc(slen * sizeof(char));
+		snprintf(string, slen, "%s=%s", envname, envval);
+	}
+
+	if (NULL != elem) {
+		if (overwrite) {
+			return _envp_replace(elem, string);
+		} else {
+			/* no change */
+			return 0;
+		}
+	} else {
+		return _envp_append(envp, string);
+	}
+}
+
+int envp_unset(envp_t *envp, const char *restrict name) {
+	size_t i;
+
+	/* find element */
+	for (i = 0; NULL != (*envp)[i]; ++i) {
+		if (_envp_string_match_key((*envp)[i], name)) {
+			break;
+		}
+	}
+
+	char *elem = (*envp)[i];
+	if (NULL == elem) {
+		/* not found -> ok */
+		return 0;
+	}
+
+	/* shift rest of elements */
+	for (; NULL != (*envp)[i]; ++i) {
+		(*envp)[i] = (*envp)[i+1];
+	}
+
+	/* delete match */
+	free(elem);
+
+	return 0;
+}
+
+void envp_merge(envp_t *dest, envp_t *const src) {
+	if (NULL == src) return;
+
+	for (size_t i = 0; NULL != (*src)[i]; ++i) {
+		envp_put(dest, strdup((*src)[i]));
+	}
+}
+
+void envp_print(envp_t *envp, FILE *restrict stream) {
+	for (size_t i = 0; NULL != (*envp)[i]; ++i) {
+		fprintf(stream, "%s\n", (*envp)[i]);
+	}
+}
+
+void envp_free(envp_t *envp) {
+	for (size_t i = 0; NULL != (*envp)[i]; ++i) {
+		free((*envp)[i]);
+	}
+	free(*envp);
+	free(envp);
+}