SYNOPSIS

#include <libexplain/execve.h>

const char *explain_execve(const char *pathname, const char *const *argv, const char *const *envp);
const char *explain_errno_execve(int errnum, const char *pathname, const char *const *argv, const char *const *envp);
void explain_message_execve(char *message, int message_size, const char *pathname, const char *const *argv, const char *const *envp);
void explain_message_errno_execve(char *message, int message_size, int errnum, const char *pathname, const char *const *argv, const char *const *envp);

DESCRIPTION

These functions may be used to obtain explanations for errors returned by the execve(2) system call.

explain_execve

const char *explain_execve(const char *pathname, const char *const *argv, const char *const *envp);

The explain_execve function is used to obtain an explanation of an error returned by the execve(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

The errno global variable will be used to obtain the error value to be decoded.

This function is intended to be used in a fashion similar to the following example:

execve(pathname, argv, envp);
fprintf(stderr, "%s\n", explain_execve(pathname, argv, envp));
exit(EXIT_FAILURE);

pathname

The original pathname, exactly as passed to the execve(2) system call.

argv

The original argv, exactly as passed to the execve(2) system call.

envp

The original envp, exactly as passed to the execve(2) system call.

Returns:

The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

explain_errno_execve

const char *explain_errno_execve(int errnum, const char *pathname, const char *const *argv, const char *const *envp);

The explain_errno_execve function is used to obtain an explanation of an error returned by the execve(2) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

This function is intended to be used in a fashion similar to the following example:

execve(pathname, argv, envp);
int err = errno;
fprintf(stderr, "%s\n", explain_errno_execve(err, pathname, argv, envp));
exit(EXIT_FAILURE);

errnum

The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.

pathname

The original pathname, exactly as passed to the execve(2) system call.

argv

The original argv, exactly as passed to the execve(2) system call.

envp

The original envp, exactly as passed to the execve(2) system call.

Returns:

The message explaining the error. This message buffer is shared by all libexplain functions which do not supply a buffer in their argument list. This will be overwritten by the next call to any libexplain function which shares this buffer, including other threads.

Note: This function is not thread safe, because it shares a return buffer across all threads, and many other functions in this library.

explain_message_execve

void explain_message_execve(char *message, int message_size, const char *pathname, const char *const *argv, const char *const *envp);

The explain_message_execve function may be used to obtain an explanation of an error returned by the execve(2) system call. The least the message will contain is the value of strerror(errno), but usually it will do much better, and indicate the underlying cause in more detail.

The errno global variable will be used to obtain the error value to be decoded.

This function is intended to be used in a fashion similar to the following example:

execve(pathname, argv, envp);
char message[3000];
explain_message_execve(message, sizeof(message), pathname, argv, envp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);

message

The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

message_size

The size in bytes of the location in which to store the returned message.

pathname

The original pathname, exactly as passed to the execve(2) system call.

argv

The original argv, exactly as passed to the execve(2) system call.

envp

The original envp, exactly as passed to the execve(2) system call.

explain_message_errno_execve

void explain_message_errno_execve(char *message, int message_size, int errnum, const char *pathname, const char *const *argv, const char *const *envp);

The explain_message_errno_execve function may be used to obtain an explanation of an error returned by the execve(2) system call. The least the message will contain is the value of strerror(errnum), but usually it will do much better, and indicate the underlying cause in more detail.

This function is intended to be used in a fashion similar to the following example:

execve(pathname, argv, envp);
int err = errno;
char message[3000];
explain_message_errno_execve(message, sizeof(message), err,
    pathname, argv, envp);
fprintf(stderr, "%s\n", message);
exit(EXIT_FAILURE);

message

The location in which to store the returned message. If a suitable message return buffer is supplied, this function is thread safe.

message_size

The size in bytes of the location in which to store the returned message.

errnum

The error value to be decoded, usually obtained from the errno global variable just before this function is called. This is necessary if you need to call any code between the system call to be explained and this function, because many libc functions will alter the value of errno.

pathname

The original pathname, exactly as passed to the execve(2) system call.

argv

The original argv, exactly as passed to the execve(2) system call.

envp

The original envp, exactly as passed to the execve(2) system call.

COPYRIGHT

libexplain version 1.4
Copyright (C) 2008 Peter Miller