Purpose
Returns
error information from the load or exec subroutine;
also provides a list of object files loaded for the current process.
Description
The loadquery subroutine
obtains detailed information about an error reported on the last load or exec
subroutine executed by a calling process. The loadquery subroutine
may also be used to obtain a list of object file names for all object
files that have been loaded for the current process, or the library
path that was used at process exec time.
Parameters
Item |
Description |
Buffer |
Points to a Buffer in which to store the information. |
BufferLength |
Specifies the number of bytes available in the Buffer
parameter. |
Flags |
Specifies the action of the loadquery subroutine as
follows: - L_GETINFO
- Returns a list of all object files loaded for the current process,
and stores the list in the Buffer parameter. The object file
information is contained in a sequence of LD_INFO structures
as defined in the sys/ldr.h file. Each structure contains the
module location in virtual memory and the path name that was used
to load it into memory. The file descriptor field in the LD_INFO structure
is not filled in by this function.
- L_GETMESSAGE
- Returns detailed error information describing the failure of
a previously invoked load or exec function, and stores
the error message information in Buffer. Upon successful return
from this function the beginning of the Buffer contains an
array of character pointers. Each character pointer points to a string
in the buffer containing a loader error message. The character array
ends with a null character pointer. Each error message string consists
of an ASCII message number followed by zero or more characters of
error-specific message data. Valid message numbers are listed in
the sys/ldr.h file.
You can format the error messages returned
by the L_GETMESSAGE function and write them to standard error
using the standard system command /usr/sbin/execerror as follows:
char *buffer[1024];
buffer[0] = "execerror";
buffer[1] = "name of program that failed to load";
loadquery(L_GETMESSAGES, &buffer[2],\
sizeof buffer-2*sizeof(char*));
execvp("/usr/sbin/execerror",buffer);
This sample
code causes the application to terminate after the messages are written
to standard error.
- L_GETLIBPATH
- Returns the library path that was used at process exec time.
The library path is a null terminated character string.
- L_GETXINFO
- Returns a list of all object files loaded for the current process
and stores the list in the Buffer parameter. The object file
information is contained in a sequence of LD_XINFO structures
as defined in the sys/ldr.h file. Each structure contains the
module location in virtual memory and the path name that was used
to load it into memory. The file descriptor field in the LD_XINFO structure
is not filled in by this function.
|
Return Values
Upon successful completion, loadquery
returns the requested information in the caller's buffer specified
by the Buffer and BufferLength parameters.
Error Codes
The loadquery subroutine
returns with a return code of -1 and the errno global variable
is set to one of the following when an error condition is detected:
Item |
Description |
ENOMEM |
Indicates that the caller's buffer specified by the Buffer and
BufferLength parameters is too small to return the information
requested. When this occurs, the information in the buffer is undefined. |
EINVAL |
Indicates the function specified in the Flags parameter
is not valid. |
EFAULT |
Indicates the address specified in the Buffer parameter
is not valid. |