reimplement glib functions

sway/env.c

@@ -0,0 +1,110 @@
+#define _POSIX_C_SOURCE 200809L
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+extern char **environ;
+
+int _env_var_name_eq(char *env_name, char *cmp) {
+	size_t i = 0;
+	int reached_eq;
+	while (1) {
+		char current_char = env_name[i];
+		char cmp_char = cmp[i];
+
+		int is_eq = current_char == '=';
+		int is_null = current_char == '\0';
+
+		if (is_eq) reached_eq = 1;
+		if (is_null && !reached_eq) return 0;
+		if (is_eq && cmp_char == '\0') return 1;
+		if (is_eq || cmp_char == '\0') return 0;
+		if (current_char != cmp_char) return 0;
+
+		i++;
+	}
+}
+
+typedef struct {
+	char *ptr;
+	size_t idx;
+} _env_info;
+
+_env_info _env_get(char **envp, char *name) {
+	char *strp;
+	size_t i = 0;
+	while ((strp = envp[i]) != NULL) {
+		if (_env_var_name_eq(strp, name)) return (_env_info){strp, i};
+		i++;
+	}
+
+	return (_env_info){NULL, 0};
+}
+
+size_t _env_len(char **envp) {
+	char *strp;
+	size_t i = 0;
+
+	while ((strp = envp[i]) != NULL) {
+		i++;
+	}
+
+	return i;
+}
+
+char **_env_clone(char **envp, size_t reserve) {
+	char **new_envp = calloc(_env_len(envp) + 1 + reserve, sizeof(char *));
+
+	char *strp;
+	size_t i = 0;
+
+	while ((strp = envp[i]) != NULL) {
+		size_t n = strlen(strp) + 1;
+		char *new_strp = malloc(n);
+		memcpy(new_strp, strp, n);
+		new_envp[i] = new_strp;
+		i++;
+	}
+
+	return new_envp;
+}
+
+void env_free(char **envp) {
+	char *strp;
+	size_t i = 0;
+	while ((strp = envp[i]) != NULL) {
+		free(strp);
+		i++;
+	}
+
+	free(envp);
+}
+
+// copy the global environment array into a newly-allocated one
+// you are responsible for deallocating it after use
+char **env_get_envp() { return _env_clone(environ, 0); }
+
+// use env_get_envp() to acquire an envp
+// might clone and deallocate the given envp
+char **env_setenv(char **envp, char *name, char *value) {
+	size_t name_len = strlen(name);
+	size_t value_len = strlen(value);
+	char *newp = malloc(name_len + value_len + 2);
+	memcpy(newp, name, name_len);
+	memcpy(newp + name_len + 1, value, value_len);
+	newp[name_len] = '=';
+	newp[name_len + value_len + 1] = '\0';
+
+	_env_info existing = _env_get(envp, name);
+	if (existing.ptr != NULL) {
+		free(existing.ptr);
+		envp[existing.idx] = newp;
+		return envp;
+	} else {
+		char **new_envp = _env_clone(envp, 1);
+		new_envp[_env_len(envp)] = newp;
+		env_free(envp);
+		return new_envp;
+	}
+}