2. Minishell Structure

Minishell Structure

Minishell uses a set of well-defined structures to manage its internal state, environment variables, error tracking, and memory safety.

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Shell Core

Represents the central state of the shell. It holds everything needed to run, manage, and clean up commands and environments.

• env – The current environment exported to children (NULL-terminated array).
• hash_table – Custom hash table storing all environment variables.
• exit_status – Exit code of the last executed command.
• syntax_exit_status – Tracks last parsing/syntax error return value.
• allocation_error – True if a memory allocation failed (used to safely stop execution).

typedef struct s_mshell {
    char        **env;
    t_hash_tbl  *hash_table;
    uint8_t     exit_status;
    uint8_t     syntax_exit_status;
    bool        allocation_error;
} t_mshell;

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Environment Variable Node

Each environment variable is stored in a linked list node.

• key – Variable name (e.g. PATH)
• value – Value (e.g. /usr/bin:/bin)
• val_assigned – 1 if a value is assigned, 0 if only declared
• next – Next variable in case of hash collision

typedef struct s_mshell_var {
    char *key;
    char *value;
    int val_assigned;
    struct s_mshell_var *next;
} t_mshell_var;

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Hash Table

Environment variables are stored in a hash table for fast access and update.

• buckets – Each index contains a linked list of variables with the same hash index

#define HASH_SIZE 128

typedef struct s_hash_table {
    t_mshell_var *buckets[HASH_SIZE];
} t_hash_tbl;

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Built-in Command Dispatch

Maps builtin command names to their handler functions.

• name – Name of the builtin command (e.g. "cd", "exit")
• func – Pointer to the function implementing the command

typedef struct s_builtin_dispatch {
    const char *name;
    uint8_t (*func)(t_cmd *);
} t_builtin_disp;