tdb2: add TDB_RDONLY flag, allow setting/unsetting it.

[ccan] / ccan / tdb2 / io.c

diff --git a/ccan/tdb2/io.c b/ccan/tdb2/io.c
index 31756de341d8fd43d17a41d57c41284cbb650227..24c70084e9719a513cafae66be5ed30d3c7dcbf6 100644 (file)
--- a/ccan/tdb2/io.c
+++ b/ccan/tdb2/io.c
@@ -42,16 +42,23 @@ void tdb_munmap(struct tdb_file *file)
 
 void tdb_mmap(struct tdb_context *tdb)
 {
+       int mmap_flags;
+
        if (tdb->flags & TDB_INTERNAL)
                return;
 
        if (tdb->flags & TDB_NOMMAP)
                return;
 
+       if ((tdb->open_flags & O_ACCMODE) == O_RDONLY)
+               mmap_flags = PROT_READ;
+       else
+               mmap_flags = PROT_READ | PROT_WRITE;
+
        /* size_t can be smaller than off_t. */
        if ((size_t)tdb->file->map_size == tdb->file->map_size) {
                tdb->file->map_ptr = mmap(NULL, tdb->file->map_size,
-                                         tdb->mmap_flags,
+                                         mmap_flags,
                                          MAP_SHARED, tdb->file->fd, 0);
        } else
                tdb->file->map_ptr = MAP_FAILED;
@@ -70,7 +77,9 @@ void tdb_mmap(struct tdb_context *tdb)
 /* check for an out of bounds access - if it is out of bounds then
    see if the database has been expanded by someone else and expand
    if necessary
-   note that "len" is the minimum length needed for the db
+   note that "len" is the minimum length needed for the db.
+
+   If probe is true, len being too large isn't a failure.
 */
 static enum TDB_ERROR tdb_oob(struct tdb_context *tdb, tdb_off_t len,
                              bool probe)
@@ -84,15 +93,16 @@ static enum TDB_ERROR tdb_oob(struct tdb_context *tdb, tdb_off_t len,
               || tdb_has_expansion_lock(tdb));
 
        if (len <= tdb->file->map_size)
-               return 0;
+               return TDB_SUCCESS;
        if (tdb->flags & TDB_INTERNAL) {
-               if (!probe) {
-                       tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
-                                "tdb_oob len %lld beyond internal"
-                                " malloc size %lld",
-                                (long long)len,
-                                (long long)tdb->file->map_size);
-               }
+               if (probe)
+                       return TDB_SUCCESS;
+
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_oob len %lld beyond internal"
+                          " malloc size %lld",
+                          (long long)len,
+                          (long long)tdb->file->map_size);
                return TDB_ERR_IO;
        }
 
@@ -111,11 +121,12 @@ static enum TDB_ERROR tdb_oob(struct tdb_context *tdb, tdb_off_t len,
        tdb_unlock_expand(tdb, F_RDLCK);
 
        if (st.st_size < (size_t)len) {
-               if (!probe) {
-                       tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
-                                  "tdb_oob len %zu beyond eof at %zu",
-                                  (size_t)len, st.st_size);
-               }
+               if (probe)
+                       return TDB_SUCCESS;
+
+               tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
+                          "tdb_oob len %zu beyond eof at %zu",
+                          (size_t)len, st.st_size);
                return TDB_ERR_IO;
        }
 
@@ -130,6 +141,7 @@ static enum TDB_ERROR tdb_oob(struct tdb_context *tdb, tdb_off_t len,
 /* Endian conversion: we only ever deal with 8 byte quantities */
 void *tdb_convert(const struct tdb_context *tdb, void *buf, tdb_len_t size)
 {
+       assert(size % 8 == 0);
        if (unlikely((tdb->flags & TDB_CONVERT)) && buf) {
                uint64_t i, *p = (uint64_t *)buf;
                for (i = 0; i < size / 8; i++)
@@ -188,7 +200,7 @@ enum TDB_ERROR zero_out(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len)
        void *p = tdb->methods->direct(tdb, off, len, true);
        enum TDB_ERROR ecode = TDB_SUCCESS;
 
-       assert(!tdb->read_only);
+       assert(!(tdb->flags & TDB_RDONLY));
        if (TDB_PTR_IS_ERR(p)) {
                return TDB_PTR_ERR(p);
        }
@@ -236,12 +248,12 @@ static enum TDB_ERROR tdb_write(struct tdb_context *tdb, tdb_off_t off,
 {
        enum TDB_ERROR ecode;
 
-       if (tdb->read_only) {
+       if (tdb->flags & TDB_RDONLY) {
                return tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_USE_ERROR,
                                  "Write to read-only database");
        }
 
-       ecode = tdb->methods->oob(tdb, off + len, 0);
+       ecode = tdb->methods->oob(tdb, off + len, false);
        if (ecode != TDB_SUCCESS) {
                return ecode;
        }
@@ -271,7 +283,7 @@ static enum TDB_ERROR tdb_read(struct tdb_context *tdb, tdb_off_t off,
 {
        enum TDB_ERROR ecode;
 
-       ecode = tdb->methods->oob(tdb, off + len, 0);
+       ecode = tdb->methods->oob(tdb, off + len, false);
        if (ecode != TDB_SUCCESS) {
                return ecode;
        }
@@ -325,7 +337,7 @@ enum TDB_ERROR tdb_read_convert(struct tdb_context *tdb, tdb_off_t off,
 enum TDB_ERROR tdb_write_off(struct tdb_context *tdb,
                             tdb_off_t off, tdb_off_t val)
 {
-       if (tdb->read_only) {
+       if (tdb->flags & TDB_RDONLY) {
                return tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_USE_ERROR,
                                  "Write to read-only database");
        }
@@ -404,7 +416,7 @@ static enum TDB_ERROR tdb_expand_file(struct tdb_context *tdb,
        char buf[8192];
        enum TDB_ERROR ecode;
 
-       if (tdb->read_only) {
+       if (tdb->flags & TDB_RDONLY) {
                return tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_USE_ERROR,
                                  "Expand on read-only database");
        }
@@ -476,7 +488,7 @@ void *tdb_access_write(struct tdb_context *tdb,
 {
        void *ret = NULL;
 
-       if (tdb->read_only) {
+       if (tdb->flags & TDB_RDONLY) {
                tdb_logerr(tdb, TDB_ERR_RDONLY, TDB_LOG_USE_ERROR,
                           "Write to read-only database");
                return TDB_ERR_PTR(TDB_ERR_RDONLY);
@@ -562,7 +574,7 @@ static void *tdb_direct(struct tdb_context *tdb, tdb_off_t off, size_t len,
        if (unlikely(!tdb->file->map_ptr))
                return NULL;
 
-       ecode = tdb_oob(tdb, off + len, true);
+       ecode = tdb_oob(tdb, off + len, false);
        if (unlikely(ecode != TDB_SUCCESS))
                return TDB_ERR_PTR(ecode);
        return (char *)tdb->file->map_ptr + off;