OpenTP1 Version 7 Programming Reference C Language
dc_dam_read - Input a logical file block
Format
ANSI C, C++
#include <dcdam.h> int dc_dam_read (int damfd, struct DC_DAMKEY *keyptr, int keyno, char *bufadr, int bufsize, DCLONG flags) |
K&R C
#include <dcdam.h> int dc_dam_read (damfd, keyptr, keyno, bufadr, bufsize, flags) int damfd; struct DC_DAMKEY *keyptr; int keyno; char *bufadr; int bufsize; DCLONG flags; |
Description
The function dc_dam_read() inputs a block (which is in the specified range) for reference or update processing from the specified logical file
When inputting a logical file block, specify the file descriptor which is the return value of the function dc_dam_open().
Arguments whose values are set in the UAP
damfd
Specify the file descriptor of the file containing a block to be input.
keyptr
Specify the address of the structure (DAM key) that indicates the block reference/update range. For the structure, specify the block range with the first relative block number and the last relative block number. The structure format is as shown below.
struct DC_DAMKEY { int fstblkno; int endblkno; }; |
keyno
Specify the number of structures (number of structure arrays) to be set for keyptr.
bufadr
Specify the address of the input buffer.
bufsize
Specify the length of the input buffer. The length must be equal to or greater than (input block length x number of blocks). You can specify a value in the range from 504 to 2147483647.
flags
Specify the type of request (reference request or update request) in the following format:
{DCDAM_REFERENCE|DCDAM_MODIFY} [|{DCDAM_EXCLUSIVE|DCDAM_NOEXCLUSIVE}] [|{DCDAM_WAIT|DCDAM_NOWAIT}] |
If both items are omitted, the subsequent processing is as follows:
The table below shows the correspondence between flag values specified for flags and the specified type of lock.
Flag 1 | Flag 2#1 | Flag 3#2 | Lock Specified for Flags |
---|---|---|---|
REFERENCE | EXCLUSIVE | WAIT | Input for reference, lock used, and waiting for release from lock if a lock error occurs |
NOWAIT | Input for reference, lock used, and error return if a lock error occurs | ||
NOEXCLUSIVE | N/A | Input for reference, and lock not used#3 | |
MODIFY | N/A | WAIT | Input for update, and waiting for release from lock if a lock error occurs |
NOWAIT | Input for update, and error return if a lock error occurs |
Return values
Return value | Return value (numeric) | Explanation |
---|---|---|
DC_OK | 0 | All blocks were input normally. |
DCDAMER_PROTO | -1600 | The function dc_rpc_open() is not called. |
The purpose of input is updating or lock-specified reference outside the transaction range. (This value is returned only when a recoverable DAM file is accessed.) | ||
N is specified for atomic_update in the user service definition. (This value is returned only when a recoverable DAM file is accessed.) | ||
The function dc_dam_start() is not called. (This value is returned only when an unrecoverable DAM file is accessed.) | ||
The UAP is incorrectly linked as follows:
|
||
DCDAMER_EXCER | -1602 | A lock error occurred. |
DCDAMER_BADF | -1603 | The file descriptor specified for damfd is not the one which was acquired by opening the file normally, or the specified file is not open. |
DCDAMER_BUFER | -1604 | The specified input buffer is too small to contain all blocks. |
The value specified for the input buffer length is outside the range of values that can be specified. | ||
DCDAMER_BNOER | -1606 | The relative block number is invalid. |
DCDAMER_NOMEM | -1607 | The memory became insufficient. |
DCDAMER_PARAM_KEYNO | -1609 | The value specified for keyno is smaller than 1. |
DCDAMER_PARAM_FLAGS | -1611 | The value specified for flags is invalid. |
DCDAMER_VERSION | -1618 | The version of the DAM library linked to the UAP does not allow the UAP to operate with the current DAM service. |
DCDAMER_JNLOV | -1613 | The number of block updates exceeded the maximum number of blocks that can be updated during one transaction according to the DAM service definition. (Returned only when a recoverable DAM file is accessed.) |
DCDAMER_IOER | -1620 | An input error occurred. |
DCDAMER_LHOLD | -1621 | The file of the file descriptor specified for damfd is in logical shutdown state. |
DCDAMER_OHOLD | -1622 | The file with the file descriptor specified for damfd is in shutdown state due to an error. |
DCDAMER_ACCESS | -1628 | A DAM file to be accessed is protected with the security facility. The UAP that called the function dc_dam_read() has no access permission. |
DCDAMER_TMERR | -1629 | An error occurred in the transaction service. (This value is returned only when a recoverable DAM file is accessed.) |
DCDAMER_DLOCK | -1642 | A deadlock occurred. |
DCDAMER_TIMOUT | -1643 | The resource could not be acquired because a timeout occurred (the wait time specified in the lock service definition was exceeded). |
DCDAMER_LCKOV | -1645 | The number of lock requests exceeds the specified maximum number of concurrent lock requests. |
DCDAMER_ACSOV | -1648 | The maximum number of blocks for access to unrecoverable DAM files is exceeded. (This value is returned only when an unrecoverable DAM file is accessed.) |
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