Apache: The Definitive Guide, Second Edition

15.3. The Module Structure

Now we will look in detail at each entry in the module structure. We examine the entries in the order in which they are used, which is not the order in which they appear in the structure, and also show how they are used in the standard Apache modules.

15.3.1. Create Per-Server Config Structure

void *module_create_svr_config(pool *pPool, server_rec *pServer)

This structure creates the per-server configuration structure for the module. It is called once for the main server and once per virtual host. It allocates and initializes the memory for the per-server configuration and returns a pointer to it. pServer points to the server_rec for the current server.

15.3.1.1. Example

From mod_env.c:

typedef struct {
    table *vars;
    char *unsetenv;
    int vars_present;
} env_server_config_rec;

void *create_env_server_config (pool *p, server_rec *dummy)
{
    env_server_config_rec *new =
      (env_server_config_rec *) palloc (p, sizeof(env_server_config_rec));
    new->vars = make_table (p, 50);
    new->unsetenv = "";
    new->vars_present = 0;
    return (void *) new;
}

All this code does is allocate and initialize a copy of env_server_config_rec, which gets filled in during configuration.

15.3.2. Create Per-Directory Config Structure

void *module_create_dir_config(pool *pPool,char *szDir)

This structure is called once per module, with szDir set to NULL, when the main host's configuration is initialized, and again for each <Directory>, <Location>, or <File> section in the Config files ...