exec_with_loader(2) System Calls Manual exec_with_loader(2)
NAME
exec_with_loader - Executes a file with a loader
SYNOPSIS
int exec_with_loader ( int flags, const char *loader, const char *file, char * const argv[ ], char * const envp[ ]
);
PARAMETERS
Specifies flags to be passed to the loader. Points to a pathname that identifies a regular, executable, process image file that contains
the loader. This image file must be a nonshared image. Points to a pathname that identifies a regular, executable process image file.
This image file must be a call-shared image. Specifies an array of character pointers to null-terminated strings. Specifies an array of
character pointers to null-terminated strings, constituting the environment for the new process.
DESCRIPTION
The exec_with_loader() function replaces the current process image with a new process image, in a manner similar to what the exec functions
do. Both the loader parameter and the file parameter point to pathnames that identify regular, executable files called process image files.
Unlike the exec functions, which construct the new process image from the file identified by the file parameter, exec_with_loader() con-
structs the new process image from the file identified by the loader parameter.
Note
Throughout this reference page, the regular, executable, process image file specified by the loader parameter is referred to as the program
loader, and the regular, executable, process image file specified by the file parameter is referred to as the file.
The loader image cannot be linked at the default user addresses. You must find another place to link it. One acceptable place to link the
loader image is at the address space defined for the loader in the /usr/shlib/so_locations file.
After the exec_with_loader() function successfully loads the program loader, it transfers control to the program loader and effectively
passes the file parameter. Under normal usage, the program loader will then load (that is, merge) the file into the newly constructed
process image, along with any object files upon which the program (that is, the file) depends. The typical use of exec_with_loader() is to
load programs that contain unresolved external references, for example, programs that require the use of a shared library.
The exec_with_loader() function implements and preserves all of the semantics of the exec functions, with respect to the file. These
include the handling of the argv and envp parameters, command interpreters, close-on-exec processing, signals, set user ID and set group ID
processing, the process attributes and error returns.
The loader parameter may be null, in which case the exec_with_loader() function loads the default program loader (/sbin/loader). The
exec_with_loader() function also loads the default program loader under either of the following sets of conditions, even if the loader
parameter points to a valid program loader: If the set user ID mode bit of the file is set (see the chmod() function) and the owner ID of
the file is not equal to the effective user ID of the process If the set group ID mode bit of the file is set and the group ID of the file
is not equal to the effective group ID of the process.
The setting of the user ID or set group ID mode bits on the program loader have no effect whatsoever.
RETURN VALUES
If the exec_with_loader() function returns to the calling process image, an error has occurred; the return value is -1, and errno is set to
indicate the error.
ERRORS
If the exec_with_loader() function fails, errno may be set to one of the following values: Search permission is denied for a directory
listed in either file's path prefix, or either file denies execution permission, or either file is not a regular file and the implementa-
tion does not support execution of files of its type. Note that the exec_with_loader() function references two files, one specified by the
loader parameter and one specified by the file parameter. The length of the loader or file parameters exceeds PATH_MAX, or a pathname com-
ponent is longer than NAME_MAX and _POSIX_NO_TRUNC is in effect for that file. One or more components of either file's pathname does not
exist, or the loader or file parameter points to an empty string. Note that the exec_with_loader() function references two files, one
specified by the loader parameter and one specified by the file parameter. A component of either file's path prefix is not a directory.
Note that the exec_with_loader() function references two files, one specified by the loader parameter and one specified by the file parame-
ter. The file specified by the loader parameter has the appropriate access permission but is not in the proper format. The loader or file
parameter is an invalid address. Too many symbolic links were encountered in pathname resolution. Insufficient memory is available.
RELATED INFORMATION
Functions: exec(2) delim off
exec_with_loader(2)