exec_cmd.c File Reference

Command execution: forks and execs external commands. More...

#include <sys/stat.h>
#include <sys/wait.h>
#include <signal.h>
#include <stdio.h>
#include <errno.h>
#include "executor.h"
#include "libft.h"
#include "env.h"
#include "ast.h"
#include "signals.h"
#include "get_next_line.h"

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Detailed Description

Command execution: forks and execs external commands.

Definition in file exec_cmd.c.

Functions
static void	handle_exec_error (char *path)
	Print an error for when execve fails. More...
static void	child_execute (char *path, char **args, char **envp, t_shell *shell)
	Replace current process with the external command (execve) More...
static int	wait_for_child (pid_t pid)
	Wait for a child process and get the correct exit status. More...
static int	prepare_exec (char **args, t_env *env, char **path, char ***envp)
	Resolve the command's path and build envp array before forking. More...
int	exec_external (char **args, t_shell *shell)
	Fork and execute an external command. More...

Function Documentation

handle_exec_error()

static void handle_exec_error ( char *  path )

static

Print an error for when execve fails.

Fallback is EACCES (Permission denied) because it's the most likely otherwise

Parameters

path	Path that failed to execute

Definition at line 32 of file exec_cmd.c.

Referenced by child_execute().

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child_execute()

static void child_execute ( char *  path, char **  args, char **  envp, t_shell *  shell  )

static

Replace current process with the external command (execve)

• Resets signals to default and calls execve
• On failure, prints an error, frees resources and exits with code 126

Parameters

path	Resolved path (free on failure)
args	Argument array for execve
envp	Environment array for execve (free on failure)
shell	Shell context (free on failure)

Definition at line 61 of file exec_cmd.c.

References t_shell::current_ast, t_shell::current_input, t_shell::env, free_ast(), free_env_list(), handle_exec_error(), and reset_child_signals().

Referenced by exec_external().

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wait_for_child()

static int wait_for_child ( pid_t  pid )

static

Wait for a child process and get the correct exit status.

Handles normal exits (WEXITSTATUS) and signal deaths (128 + signal)

Parameters

pid	PID of the child to wait for

Returns

Correct exit code (0-255)

Definition at line 85 of file exec_cmd.c.

Referenced by exec_external().

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prepare_exec()

static int prepare_exec ( char **  args, t_env *  env, char **  path, char ***  envp  )

static

Resolve the command's path and build envp array before forking.

Handles special cases: . and ..

Parameters

args	Argument array with arg[0] being the command name
env	Environment list (for PATH)
path	resolved path
envp	envp array

Returns

0 on success or an error exit code (1, 2 or 127)

Definition at line 116 of file exec_cmd.c.

References env_to_array(), exec_cmd_not_found(), and find_cmd_path().

Referenced by exec_external().

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exec_external()

int exec_external	(	char **	args,
		t_shell *	shell
	)

Fork and execute an external command.

Resolves the path, builds envp and forks a child that calls execve

• If already in a child process, executes directly without forking
• The parent waits for the child and returns its exit status code

Parameters

args	Argument array with arg[0] being the command name
shell	Shell context

Returns

exit status (0 success, 126 exec error or 127 not found)

Definition at line 150 of file exec_cmd.c.

References child_execute(), t_shell::env, t_shell::is_child, prepare_exec(), and wait_for_child().

Referenced by exec_simple_command().

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