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NAME

       explain_execve - explain execve(2) errors

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.

SEE ALSO

       execve(2)
               execute program

       explain_execve_or_die(3)
               execute program and report errors

COPYRIGHT

       libexplain version 0.19
       Copyright (C) 2008 Peter Miller

                                                             explain_execve(3)