NAME

JAM_ChangeMsgHeader - Change a message's header

SYNOPSIS

#include <jamlib/jam.h>
int JAM_ChangeMsgHeader(s_JamBase*      Base_PS,
                        ulong           MsgNo_I,
                        s_JamMsgHeader* Header_PS);

DESCRIPTION

Writes over an old message header with a new one. Only the header - not the subfields - can be changed due to the subfields´ dynamic size.

If message have MSG_DELETED attribute set, UserCRC field in index and ActiveMsgs in base header are also updated.

Arguments

Base_PS: The message base to use
MsgNo_I: The absolute message number. Message #0 is the first in the message base.
Header_PS: A pointer to the header structure to write.

RETURN VALUE

0: if successful
JAM_IO_ERROR: if an I/O error occured. See JAM_Errno(3)
JAM_NOT_LOCKED: if the message base is not locked

EXAMPLES

s_JamMsgHeader  Header_S;
int             Result_I;
/* [lock the message base] */
Result_I = JAM_ReadMsgHeader(Base_PS, 0, &Header_S, NULL);
if (Result_I)
  printf("JAM_ReadMsgHeader returned %d.\n", Result_I);
Header_S.TimesRead++;
Result_I = JAM_ChangeMsgHeader(Base_PS, 0, &Header_S);
if (Result_I)
  printf("JAM_ChangeMsgHeader returned %d.\n", Result_I);
/* [unlock the message base] */

NOTES

Use this function with caution. It is easy to corrupt a message by giving it an incorrect header.

AUTHOR

This manual page was created by Sir Raorn <raorn@altlinux.ru>, based on original JAMlib documentation by Bjorn Stenberg <bjorn@haxx.nu> and Johan Billing <billing@df.lth.se>.