LU-7276 utils: fix llog_reader loop on empty log

If llog_reader tries to read an empty log file (0 bytes) it does not
detect this as an error, since it tries to read 0 bytes from the llog
and then tries to parse an empty llog header.

Return an error if the llog file is smaller than struct llog_log_hdr.

Signed-off-by: Andreas Dilger <andreas.dilger@intel.com>
Change-Id: Ife482eb6d73b35f09cc70ca4b79bfd7b053ebb35
Reviewed-on: http://review.whamcloud.com/17627
Tested-by: Jenkins
Tested-by: Maloo <hpdd-maloo@intel.com>
Reviewed-by: Frank Zago <fzago@cray.com>
Reviewed-by: Olaf Faaland-LLNL <faaland1@llnl.gov>
Reviewed-by: Oleg Drokin <oleg.drokin@intel.com>

diff --git a/lustre/utils/llog_reader.c b/lustre/utils/llog_reader.c
index 6ebbe02..4d2f1ff 100644 (file)
--- a/lustre/utils/llog_reader.c
+++ b/lustre/utils/llog_reader.c
@@ -50,7 +50,7 @@
 #include <fcntl.h>
 #include <sys/vfs.h>
 #include <linux/magic.h>
-
+#include <errno.h>
 #include <time.h>
 #include <lnet/nidstr.h>
 #include <lustre/lustre_idl.h>
@@ -208,8 +208,8 @@ int llog_pack_buffer(int fd, struct llog_log_hdr **llog,
                     struct llog_rec_hdr ***recs,
                     int *recs_number)
 {
-       int rc = 0, recs_num, rd;
-       off_t file_size;
+       int rc = 0, recs_num, rd = 0;
+       long long file_size;
        struct stat st;
        char *file_buf = NULL, *recs_buf = NULL;
        struct llog_rec_hdr **recs_pr = NULL;
@@ -222,10 +222,14 @@ int llog_pack_buffer(int fd, struct llog_log_hdr **llog,
                llapi_error(LLAPI_MSG_ERROR, rc, "Got file stat error.");
                goto out;
        }
+
        file_size = st.st_size;
-       if (file_size == 0) {
-               rc = -1;
-               llapi_error(LLAPI_MSG_ERROR, rc, "File is empty.");
+       if (file_size < sizeof(**llog)) {
+               llapi_error(LLAPI_MSG_ERROR, rc,
+                           "File too small for llog header: "
+                           "need %zd, size %lld\n",
+                           sizeof(**llog), file_size);
+               rc = -EIO;
                goto out;
        }
 
@@ -237,20 +241,29 @@ int llog_pack_buffer(int fd, struct llog_log_hdr **llog,
        }
        *llog = (struct llog_log_hdr *)file_buf;
 
-       rd = read(fd, file_buf, file_size);
+       do {
+               rc = read(fd, file_buf + rd, file_size - rd);
+               if (rc > 0)
+                       rd += rc;
+       } while (rc > 0 && rd < file_size);
+
        if (rd < file_size) {
-               rc = -EIO; /*FIXME*/
-               llapi_error(LLAPI_MSG_ERROR, rc, "Read file error.");
+               rc = rc < 0 ? -errno : -EIO;
+               llapi_error(LLAPI_MSG_ERROR, rc,
+                           "Error reading llog header: need %zd, got %d",
+                           sizeof(**llog), rd);
                goto clear_file_buf;
        }
 
        /* the llog header not countable here.*/
        recs_num = le32_to_cpu((*llog)->llh_count) - 1;
 
-       recs_buf = malloc(recs_num * sizeof(struct llog_rec_hdr *));
+       recs_buf = malloc(recs_num * sizeof(**recs_pr));
        if (recs_buf == NULL) {
                rc = -ENOMEM;
-               llapi_error(LLAPI_MSG_ERROR, rc, "Memory Alloc for recs_buf.");
+               llapi_error(LLAPI_MSG_ERROR, rc,
+                           "Error allocating %zd bytes for recs_buf",
+                           recs_num * sizeof(**recs_pr));
                goto clear_file_buf;
        }
        recs_pr = (struct llog_rec_hdr **)recs_buf;
@@ -263,8 +276,7 @@ int llog_pack_buffer(int fd, struct llog_log_hdr **llog,
                int idx;
                unsigned long offset;
 
-               if (ptr + sizeof(struct llog_rec_hdr) >
-                   file_buf + file_size) {
+               if (ptr + sizeof(**recs_pr) > file_buf + file_size) {
                        rc = -EINVAL;
                        llapi_error(LLAPI_MSG_ERROR, rc,
                                    "The log is corrupt (too big at %d)", i);