feat: multi-user system, bug fixes, security & performance fixes, and more

programs/src/shell/vars.cpp

@@ -0,0 +1,166 @@
+/*
+    * vars.cpp
+    * Shell variable storage, expansion, and tilde/comment processing
+    * Copyright (c) 2025-2026 Daniel Hammer
+*/
+
+#include "shell.h"
+
+// ---- Storage ----
+
+static constexpr int MAX_VARS = 32;
+
+struct ShellVar {
+    char name[32];
+    char value[128];
+};
+
+static ShellVar vars[MAX_VARS];
+static int var_count = 0;
+
+// ---- Core operations ----
+
+void var_set(const char* name, const char* value) {
+    for (int i = 0; i < var_count; i++) {
+        if (streq(vars[i].name, name)) {
+            scopy(vars[i].value, value, sizeof(vars[i].value));
+            return;
+        }
+    }
+    if (var_count < MAX_VARS) {
+        scopy(vars[var_count].name, name, sizeof(vars[var_count].name));
+        scopy(vars[var_count].value, value, sizeof(vars[var_count].value));
+        var_count++;
+    }
+}
+
+void var_unset(const char* name) {
+    for (int i = 0; i < var_count; i++) {
+        if (streq(vars[i].name, name)) {
+            for (int j = i; j < var_count - 1; j++) vars[j] = vars[j + 1];
+            var_count--;
+            return;
+        }
+    }
+}
+
+// Get variable value. Built-in dynamic vars ($?, $PWD) are synthesized on
+// demand. Returns nullptr if not found. The returned pointer for dynamic
+// vars points to a static buffer overwritten on the next call.
+const char* var_get(const char* name) {
+    // User-defined vars take priority
+    for (int i = 0; i < var_count; i++) {
+        if (streq(vars[i].name, name)) return vars[i].value;
+    }
+    // Synthesize built-in vars
+    static char synth[128];
+    if (streq(name, "?")) {
+        int_to_str(last_exit, synth, sizeof(synth));
+        return synth;
+    }
+    if (streq(name, "USER")) return session_user[0] ? session_user : nullptr;
+    if (streq(name, "HOME")) return session_home[0] ? session_home : nullptr;
+    if (streq(name, "PWD")) {
+        build_dir_path(cwd, synth, sizeof(synth));
+        return synth;
+    }
+    return nullptr;
+}
+
+// ---- Helpers used by the set builtin (main.cpp) ----
+
+// The set builtin needs to iterate user-defined vars and show built-in
+// vars. We expose a small iteration API rather than the raw array.
+
+int var_user_count() { return var_count; }
+
+const char* var_user_name(int idx) {
+    return (idx >= 0 && idx < var_count) ? vars[idx].name : nullptr;
+}
+
+const char* var_user_value(int idx) {
+    return (idx >= 0 && idx < var_count) ? vars[idx].value : nullptr;
+}
+
+// ---- Character classification ----
+
+bool is_var_char(char c) {
+    return (c >= 'a' && c <= 'z') || (c >= 'A' && c <= 'Z') ||
+           (c >= '0' && c <= '9') || c == '_';
+}
+
+// ---- Variable expansion ----
+
+void expand_vars(const char* in, char* out, int outMax) {
+    int o = 0;
+    while (*in && o < outMax - 1) {
+        if (*in == '\\' && in[1] == '$') {
+            if (o < outMax - 1) out[o++] = '$';
+            in += 2;
+            continue;
+        }
+        if (*in == '$') {
+            in++;
+            char name[32];
+            int n = 0;
+            if (*in == '{') {
+                in++;
+                while (*in && *in != '}' && n < 31) name[n++] = *in++;
+                if (*in == '}') in++;
+            } else if (*in == '?') {
+                name[n++] = '?';
+                in++;
+            } else {
+                while (is_var_char(*in) && n < 31) name[n++] = *in++;
+            }
+            name[n] = '\0';
+            if (n > 0) {
+                const char* val = var_get(name);
+                if (val) {
+                    while (*val && o < outMax - 1) out[o++] = *val++;
+                }
+            } else {
+                if (o < outMax - 1) out[o++] = '$';
+            }
+        } else {
+            out[o++] = *in++;
+        }
+    }
+    out[o] = '\0';
+}
+
+// ---- Tilde expansion ----
+
+void expand_tilde(const char* in, char* out, int outMax) {
+    int o = 0;
+    bool at_start = true;
+    while (*in && o < outMax - 1) {
+        if (at_start && *in == '~' && session_home[0]) {
+            if (in[1] == '\0' || in[1] == '/' || in[1] == ' ') {
+                const char* h = session_home;
+                while (*h && o < outMax - 1) out[o++] = *h++;
+                in++;
+            } else {
+                out[o++] = *in++;
+            }
+        } else {
+            at_start = (*in == ' ');
+            out[o++] = *in++;
+        }
+    }
+    out[o] = '\0';
+}
+
+// ---- Comment stripping ----
+
+void strip_comment(char* line) {
+    bool in_sq = false, in_dq = false;
+    for (int i = 0; line[i]; i++) {
+        if (line[i] == '\'' && !in_dq) in_sq = !in_sq;
+        else if (line[i] == '"' && !in_sq) in_dq = !in_dq;
+        else if (line[i] == '#' && !in_sq && !in_dq) {
+            line[i] = '\0';
+            return;
+        }
+    }
+}