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Diffstat (limited to 'db2/log/log_get.c')
-rw-r--r--db2/log/log_get.c355
1 files changed, 355 insertions, 0 deletions
diff --git a/db2/log/log_get.c b/db2/log/log_get.c
new file mode 100644
index 0000000000..37eb5cb249
--- /dev/null
+++ b/db2/log/log_get.c
@@ -0,0 +1,355 @@
+/*-
+ * See the file LICENSE for redistribution information.
+ *
+ * Copyright (c) 1996, 1997
+ * Sleepycat Software. All rights reserved.
+ */
+#include "config.h"
+
+#ifndef lint
+static const char sccsid[] = "@(#)log_get.c 10.16 (Sleepycat) 8/19/97";
+#endif /* not lint */
+
+#ifndef NO_SYSTEM_INCLUDES
+#include <sys/types.h>
+
+#include <errno.h>
+#include <fcntl.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#endif
+
+#include "db_int.h"
+#include "shqueue.h"
+#include "db_page.h"
+#include "log.h"
+#include "hash.h"
+#include "common_ext.h"
+
+/*
+ * log_get --
+ * Get a log record.
+ */
+int
+log_get(dblp, alsn, dbt, flags)
+ DB_LOG *dblp;
+ DB_LSN *alsn;
+ DBT *dbt;
+ int flags;
+{
+ LOG *lp;
+ int ret;
+
+ /* Validate arguments. */
+#define OKFLAGS (DB_CHECKPOINT | \
+ DB_CURRENT | DB_FIRST | DB_LAST | DB_NEXT | DB_PREV | DB_SET)
+ if (flags != 0) {
+ if ((ret =
+ __db_fchk(dblp->dbenv, "log_get", flags, OKFLAGS)) != 0)
+ return (ret);
+ switch (flags) {
+ case DB_CHECKPOINT:
+ case DB_CURRENT:
+ case DB_FIRST:
+ case DB_LAST:
+ case DB_NEXT:
+ case DB_PREV:
+ case DB_SET:
+ case 0:
+ break;
+ default:
+ return (__db_ferr(dblp->dbenv, "log_get", 1));
+ }
+ }
+ if (F_ISSET(dblp, DB_AM_THREAD)) {
+ if (LF_ISSET(DB_NEXT | DB_PREV | DB_CURRENT))
+ return (__db_ferr(dblp->dbenv, "log_get", 1));
+ if (!F_ISSET(dbt, DB_DBT_USERMEM | DB_DBT_MALLOC))
+ return (__db_ferr(dblp->dbenv, "threaded data", 1));
+ }
+
+ lp = dblp->lp;
+
+ LOCK_LOGREGION(dblp);
+
+ /*
+ * If we get one of the log's header records, repeat the operation.
+ * This assumes that applications don't ever request the log header
+ * records by LSN, but that seems reasonable to me.
+ */
+ ret = __log_get(dblp, alsn, dbt, flags, 0);
+ if (ret == 0 && alsn->offset == 0) {
+ switch (flags) {
+ case DB_FIRST:
+ flags = DB_NEXT;
+ break;
+ case DB_LAST:
+ flags = DB_PREV;
+ break;
+ }
+ ret = __log_get(dblp, alsn, dbt, flags, 0);
+ }
+
+ UNLOCK_LOGREGION(dblp);
+
+ return (ret);
+}
+
+/*
+ * __log_get --
+ * Get a log record; internal version.
+ *
+ * PUBLIC: int __log_get __P((DB_LOG *, DB_LSN *, DBT *, int, int));
+ */
+int
+__log_get(dblp, alsn, dbt, flags, silent)
+ DB_LOG *dblp;
+ DB_LSN *alsn;
+ DBT *dbt;
+ int flags, silent;
+{
+ DB_LSN nlsn;
+ HDR hdr;
+ LOG *lp;
+ size_t len;
+ ssize_t nr;
+ int cnt, ret;
+ const char *fail;
+ char *np, *tbuf;
+ void *p, *shortp;
+
+ lp = dblp->lp;
+ fail = np = tbuf = NULL;
+
+ nlsn = dblp->c_lsn;
+ switch (flags) {
+ case DB_CHECKPOINT:
+ nlsn = dblp->lp->c_lsn;
+ if (IS_ZERO_LSN(nlsn)) {
+ __db_err(dblp->dbenv,
+ "log_get: unable to find checkpoint record: no checkpoint set.");
+ ret = ENOENT;
+ goto err2;
+ }
+ break;
+ case DB_NEXT: /* Next log record. */
+ if (!IS_ZERO_LSN(nlsn)) {
+ /* Increment the cursor by the cursor record size. */
+ nlsn.offset += dblp->c_len;
+ break;
+ }
+ /* FALLTHROUGH */
+ case DB_FIRST: /* Find the first log record. */
+ /*
+ * Find any log file. Note, we may have only entered records
+ * in the buffer, and not yet written a log file.
+ */
+ if ((ret = __log_find(dblp->dbenv, lp, &cnt)) != 0) {
+ __db_err(dblp->dbenv,
+ "log_get: unable to find the first record: no log files found.");
+ goto err2;
+ }
+
+ /* If there's anything in the buffer, it belongs to file 1. */
+ if (cnt == 0)
+ cnt = 1;
+
+ /* Now go backwards to find the smallest one. */
+ for (; cnt > 1; --cnt)
+ if (__log_valid(dblp->dbenv, NULL, cnt) != 0) {
+ ++cnt;
+ break;
+ }
+ nlsn.file = cnt;
+ nlsn.offset = 0;
+ break;
+ case DB_CURRENT: /* Current log record. */
+ break;
+ case DB_PREV: /* Previous log record. */
+ if (!IS_ZERO_LSN(nlsn)) {
+ /* If at start-of-file, move to the previous file. */
+ if (nlsn.offset == 0) {
+ if (nlsn.file == 1)
+ return (DB_NOTFOUND);
+
+ --nlsn.file;
+ nlsn.offset = dblp->c_off;
+ } else
+ nlsn.offset = dblp->c_off;
+ break;
+ }
+ /* FALLTHROUGH */
+ case DB_LAST: /* Last log record. */
+ nlsn.file = lp->lsn.file;
+ nlsn.offset = lp->lsn.offset - lp->len;
+ break;
+ case DB_SET: /* Set log record. */
+ nlsn = *alsn;
+ break;
+ }
+
+retry:
+ /* Return 1 if the request is past end-of-file. */
+ if (nlsn.file > lp->lsn.file ||
+ (nlsn.file == lp->lsn.file && nlsn.offset >= lp->lsn.offset))
+ return (DB_NOTFOUND);
+
+ /* If we've switched files, discard the current fd. */
+ if (dblp->c_lsn.file != nlsn.file && dblp->c_fd != -1) {
+ (void)__db_close(dblp->c_fd);
+ dblp->c_fd = -1;
+ }
+
+ /* If the entire record is in the in-memory buffer, copy it out. */
+ if (nlsn.file == lp->lsn.file && nlsn.offset >= lp->w_off) {
+ /* Copy the header. */
+ p = lp->buf + (nlsn.offset - lp->w_off);
+ memcpy(&hdr, p, sizeof(HDR));
+
+ /* Copy the record. */
+ len = hdr.len - sizeof(HDR);
+ if ((ret = __db_retcopy(dbt, (u_int8_t *)p + sizeof(HDR),
+ len, &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+ goto err1;
+ goto cksum;
+ }
+
+ /*
+ * Move the file descriptor to the page that has the hdr. We dealt
+ * with moving to a previous log file in the flags switch code, but
+ * we don't yet know if we'll need to move to a subsequent file.
+ *
+ * Acquire a file descriptor.
+ */
+ if (dblp->c_fd == -1) {
+ if ((ret = __log_name(dblp->dbenv, nlsn.file, &np)) != 0)
+ goto err1;
+ if ((ret = __db_fdopen(np, DB_RDONLY | DB_SEQUENTIAL,
+ DB_RDONLY | DB_SEQUENTIAL, 0, &dblp->c_fd)) != 0) {
+ fail = np;
+ goto err1;
+ }
+ free(np);
+ np = NULL;
+ }
+
+ /* Seek to the header offset and read the header. */
+ if ((ret = __db_lseek(dblp->c_fd, 0, 0, nlsn.offset, SEEK_SET)) != 0) {
+ fail = "seek";
+ goto err1;
+ }
+ if ((ret = __db_read(dblp->c_fd, &hdr, sizeof(HDR), &nr)) != 0) {
+ fail = "read";
+ goto err1;
+ }
+ if (nr == sizeof(HDR))
+ shortp = NULL;
+ else {
+ /* If read returns EOF, try the next file. */
+ if (nr == 0) {
+ if (flags != DB_NEXT || nlsn.file == lp->lsn.file)
+ goto corrupt;
+
+ /* Move to the next file. */
+ ++nlsn.file;
+ nlsn.offset = 0;
+ goto retry;
+ }
+
+ /*
+ * If read returns a short count the rest of the record has
+ * to be in the in-memory buffer.
+ */
+ if (lp->b_off < sizeof(HDR) - nr)
+ goto corrupt;
+
+ /* Get the rest of the header from the in-memory buffer. */
+ memcpy((u_int8_t *)&hdr + nr, lp->buf, sizeof(HDR) - nr);
+ shortp = lp->buf + (sizeof(HDR) - nr);
+ }
+
+ /*
+ * Check for buffers of 0's, that's what we usually see during
+ * recovery, although it's certainly not something on which we
+ * can depend.
+ */
+ if (hdr.len <= sizeof(HDR))
+ goto corrupt;
+ len = hdr.len - sizeof(HDR);
+
+ /* If we've already moved to the in-memory buffer, fill from there. */
+ if (shortp != NULL) {
+ if (lp->b_off < ((u_int8_t *)shortp - lp->buf) + len)
+ goto corrupt;
+ if ((ret = __db_retcopy(dbt, shortp, len,
+ &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+ goto err1;
+ goto cksum;
+ }
+
+ /* Allocate temporary memory to hold the record. */
+ if ((tbuf = (char *)malloc(len)) == NULL) {
+ ret = ENOMEM;
+ goto err1;
+ }
+
+ /*
+ * Read the record into the buffer. If read returns a short count,
+ * there was an error or the rest of the record is in the in-memory
+ * buffer. Note, the information may be garbage if we're in recovery,
+ * so don't read past the end of the buffer's memory.
+ */
+ if ((ret = __db_read(dblp->c_fd, tbuf, len, &nr)) != 0) {
+ fail = "read";
+ goto err1;
+ }
+ if (len - nr > sizeof(lp->buf))
+ goto corrupt;
+ if (nr != (ssize_t)len) {
+ if (lp->b_off < len - nr)
+ goto corrupt;
+
+ /* Get the rest of the record from the in-memory buffer. */
+ memcpy((u_int8_t *)tbuf + nr, lp->buf, len - nr);
+ }
+
+ /* Copy the record into the user's DBT. */
+ if ((ret = __db_retcopy(dbt, tbuf, len,
+ &dblp->c_dbt.data, &dblp->c_dbt.ulen, NULL)) != 0)
+ goto err1;
+ free(tbuf);
+
+cksum: if (hdr.cksum != __ham_func4(dbt->data, dbt->size)) {
+ if (!silent)
+ __db_err(dblp->dbenv, "log_get: checksum mismatch");
+ goto corrupt;
+ }
+
+ /* Update the cursor and the return lsn. */
+ dblp->c_off = hdr.prev;
+ dblp->c_len = hdr.len;
+ dblp->c_lsn = *alsn = nlsn;
+
+ return (0);
+
+corrupt:/*
+ * This is the catchall -- for some reason we didn't find enough
+ * information or it wasn't reasonable information, and it wasn't
+ * because a system call failed.
+ */
+ ret = EIO;
+ fail = "read";
+
+err1: if (!silent)
+ if (fail == NULL)
+ __db_err(dblp->dbenv, "log_get: %s", strerror(ret));
+ else
+ __db_err(dblp->dbenv,
+ "log_get: %s: %s", fail, strerror(ret));
+err2: if (np != NULL)
+ free(np);
+ if (tbuf != NULL)
+ free(tbuf);
+ return (ret);
+}
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