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Refactor pg_control parsing

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The "data_checksum_version" field towards the end of the ControlFileData struct,
meaning its position varies between versions. Previously this wasn't a problem
as it was only required for operations involving 9.5 and later, and its position
within the control file has not changed between the current release and current
HEAD.

However, in order to support pg_rewind in 9.3 and 9.4, which both have changes in
the control file format, we'll need version-specific parsing. This will also make
it easier to deal with any future changes to the control file format.
This commit is contained in:
Ian Barwick
2018-04-02 20:36:11 +09:00
parent 3ccf1cf182
commit ad24b04c35
3 changed files with 360 additions and 31 deletions
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138
controldata.c
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@@ -37,13 +37,8 @@ get_system_identifier(const char *data_directory)
uint64 system_identifier = UNKNOWN_SYSTEM_IDENTIFIER;
control_file_info = get_controlfile(data_directory);
system_identifier = control_file_info->system_identifier;
if (control_file_info->control_file_processed == true)
system_identifier = control_file_info->control_file->system_identifier;
else
system_identifier = UNKNOWN_SYSTEM_IDENTIFIER;
pfree(control_file_info->control_file);
pfree(control_file_info);
return system_identifier;
@@ -57,13 +52,8 @@ get_db_state(const char *data_directory)
control_file_info = get_controlfile(data_directory);
if (control_file_info->control_file_processed == true)
state = control_file_info->control_file->state;
else
/* if we were unable to parse the control file, assume DB is shut down */
state = DB_SHUTDOWNED;
state = control_file_info->state;
pfree(control_file_info->control_file);
pfree(control_file_info);
return state;
@@ -78,12 +68,8 @@ get_latest_checkpoint_location(const char *data_directory)
control_file_info = get_controlfile(data_directory);
if (control_file_info->control_file_processed == false)
return InvalidXLogRecPtr;
checkPoint = control_file_info->checkPoint;
checkPoint = control_file_info->control_file->checkPoint;
pfree(control_file_info->control_file);
pfree(control_file_info);
return checkPoint;
@@ -98,16 +84,8 @@ get_data_checksum_version(const char *data_directory)
control_file_info = get_controlfile(data_directory);
if (control_file_info->control_file_processed == false)
{
data_checksum_version = -1;
}
else
{
data_checksum_version = (int) control_file_info->control_file->data_checksum_version;
}
data_checksum_version = (int) control_file_info->data_checksum_version;
pfree(control_file_info->control_file);
pfree(control_file_info);
return data_checksum_version;
@@ -139,19 +117,74 @@ describe_db_state(DBState state)
/*
* we maintain our own version of get_controlfile() as we need cross-version
* We maintain our own version of get_controlfile() as we need cross-version
* compatibility, and also don't care if the file isn't readable.
*/
static ControlFileInfo *
get_controlfile(const char *DataDir)
{
ControlFileInfo *control_file_info;
int fd;
FILE *fp = NULL;
int fd, ret, version_num;
char PgVersionPath[MAXPGPATH] = "";
char ControlFilePath[MAXPGPATH] = "";
char file_version_string[64] = "";
long file_major, file_minor;
char *endptr = NULL;
void *ControlFileDataPtr = NULL;
int expected_size = 0;
control_file_info = palloc0(sizeof(ControlFileInfo));
/* set default values */
control_file_info->control_file_processed = false;
control_file_info->control_file = palloc0(sizeof(ControlFileData));
control_file_info->system_identifier = UNKNOWN_SYSTEM_IDENTIFIER;
control_file_info->state = DB_SHUTDOWNED;
control_file_info->checkPoint = InvalidXLogRecPtr;
control_file_info->data_checksum_version = -1;
/*
* Read PG_VERSION, as we'll need to determine which struct to read
* the control file contents into
*/
snprintf(PgVersionPath, MAXPGPATH, "%s/PG_VERSION", DataDir);
fp = fopen(PgVersionPath, "r");
if (fp == NULL)
{
log_warning(_("could not open file \"%s\" for reading"),
PgVersionPath);
log_detail("%s", strerror(errno));
return control_file_info;
}
file_version_string[0] = '\0';
ret = fscanf(fp, "%63s", file_version_string);
fclose(fp);
if (ret != 1 || endptr == file_version_string)
{
log_warning(_("unable to determine major version number from PG_VERSION"));
return control_file_info;
}
file_major = strtol(file_version_string, &endptr, 10);
file_minor = 0;
if (*endptr == '.')
file_minor = strtol(endptr + 1, NULL, 10);
version_num = ((int) file_major * 10000) + ((int) file_minor * 100);
if (version_num < 90300)
{
log_warning(_("Data directory appears to be initialised for %s"), file_version_string);
return control_file_info;
}
snprintf(ControlFilePath, MAXPGPATH, "%s/global/pg_control", DataDir);
@@ -163,7 +196,25 @@ get_controlfile(const char *DataDir)
return control_file_info;
}
if (read(fd, control_file_info->control_file, sizeof(ControlFileData)) != sizeof(ControlFileData))
if (version_num >= 90500)
{
expected_size = sizeof(ControlFileData95);
ControlFileDataPtr = palloc0(expected_size);
}
else if (version_num >= 90400)
{
expected_size = sizeof(ControlFileData94);
ControlFileDataPtr = palloc0(expected_size);
}
else if (version_num >= 90300)
{
expected_size = sizeof(ControlFileData93);
ControlFileDataPtr = palloc0(expected_size);
}
if (read(fd, ControlFileDataPtr, expected_size) != expected_size)
{
log_warning(_("could not read file \"%s\""),
ControlFilePath);
@@ -176,6 +227,33 @@ get_controlfile(const char *DataDir)
control_file_info->control_file_processed = true;
if (version_num >= 90500)
{
ControlFileData95 *ptr = (struct ControlFileData95 *)ControlFileDataPtr;
control_file_info->system_identifier = ptr->system_identifier;
control_file_info->state = ptr->state;
control_file_info->checkPoint = ptr->checkPoint;
control_file_info->data_checksum_version = ptr->data_checksum_version;
}
else if (version_num >= 90400)
{
ControlFileData94 *ptr = (struct ControlFileData94 *)ControlFileDataPtr;
control_file_info->system_identifier = ptr->system_identifier;
control_file_info->state = ptr->state;
control_file_info->checkPoint = ptr->checkPoint;
control_file_info->data_checksum_version = ptr->data_checksum_version;
}
else if (version_num >= 90300)
{
ControlFileData93 *ptr = (struct ControlFileData93 *)ControlFileDataPtr;
control_file_info->system_identifier = ptr->system_identifier;
control_file_info->state = ptr->state;
control_file_info->checkPoint = ptr->checkPoint;
control_file_info->data_checksum_version = ptr->data_checksum_version;
}
pfree(ControlFileDataPtr);
/*
* We don't check the CRC here as we're potentially checking a pg_control
* file from a different PostgreSQL version to the one repmgr was compiled