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Technical Reference: Base Operating System and Extensions, Volume 1
loadquery Subroutine
Purpose
Returns error information from the load or exec subroutine; also provides a list of
object files loaded for the current process.
Syntax
int loadquery( Flags, Buffer, BufferLength)
int Flags;
void *Buffer;
unsigned int BufferLength;
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
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.
|
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:
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. |
Related Information
The exec (exec: execl, execle, execlp, execv, execve, execvp, or exect Subroutine)
subroutine, load (load Subroutine) subroutine, loadbind (loadbind Subroutine) subroutine, unload subroutine.
The ld
command.
Subroutines Overview
in AIX 5L Version 5.2 General Programming Concepts: Writing and Debugging Programs.
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