libc: Add setenv/getenv

2 files changed, 86 insertions, 3 deletions

diff --git a/userland/libc/stdlib/getenv.c b/userland/libc/stdlib/getenv.c
index 0240d66..487ac76 100644
--- a/userland/libc/stdlib/getenv.c
+++ b/userland/libc/stdlib/getenv.c
@@ -1,7 +1,19 @@
 #include <stdlib.h>
+#include <string.h>
+
+// Defined in stdlib/setenv.c
+struct env {
+  char *name;
+  char *value;
+  struct env *next;
+};
+
+struct env *internal_getenv(const char *name);
 
 char *getenv(const char *name) {
-  (void)name;
-  // FIXME
-  return NULL;
+  struct env *p = internal_getenv(name);
+  if (!p) {
+    return NULL;
+  }
+  return p->value;
 }
diff --git a/userland/libc/stdlib/setenv.c b/userland/libc/stdlib/setenv.c
new file mode 100644
index 0000000..c3a5b68
--- /dev/null
+++ b/userland/libc/stdlib/setenv.c
@@ -0,0 +1,71 @@
+#include <errno.h>
+#include <stdlib.h>
+#include <string.h>
+
+struct env {
+  char *name;
+  char *value;
+  struct env *next;
+};
+
+struct env *env_head = NULL;
+
+struct env *internal_getenv(const char *name) {
+  struct env *p = env_head;
+  for (; p; p = p->next) {
+    if (0 == strcmp(p->name, name)) {
+      return p;
+    }
+  }
+  return NULL;
+}
+
+int setenv(const char *name, const char *value, int overwrite) {
+  if (NULL == name) {
+    errno = -EINVAL;
+    return -1;
+  }
+
+  int name_length = strlen(name);
+  if (0 == name_length) {
+    errno = -EINVAL;
+    return -1;
+  }
+  int value_length = strlen(value);
+
+  struct env *p = internal_getenv(name);
+  if (p) {
+    if (!overwrite) {
+      return 0;
+    }
+    char *new_ptr = realloc(p->value, value_length + 1);
+    if (!new_ptr) {
+      errno = -ENOMEM;
+      return -1;
+    }
+    p->value = new_ptr;
+    strcpy(p->value, value);
+    return 0;
+  }
+
+  struct env *new_env = malloc(sizeof(struct env));
+  if (!new_env) {
+    return -ENOMEM;
+  }
+  new_env->name = malloc(name_length + 1);
+  if (!new_env->name) {
+    free(new_env);
+    return -ENOMEM;
+  }
+  new_env->value = malloc(value_length + 1);
+  if (!new_env->value) {
+    free(new_env->name);
+    free(new_env);
+    return -ENOMEM;
+  }
+  strcpy(new_env->name, name);
+  strcpy(new_env->value, value);
+  new_env->next = env_head;
+  env_head = new_env;
+  return 0;
+}