From e35cb88328f5ca7a0aaf7a1694113af34b267a73 Mon Sep 17 00:00:00 2001
From: Thomas Schmitt <scdbackup@gmx.net>
Date: Fri, 9 Oct 2015 12:03:14 +0200
Subject: [PATCH] Made sure that iso_file_get_old_image_sections() returns
 non-NULL only if section_count > 0. Made sure that callers in libisofs expect
 all possible outcome as announced by API description.

---
 libisofs/fs_image.c |  8 ++++++--
 libisofs/libisofs.h |  3 ++-
 libisofs/node.c     | 12 ++++++------
 3 files changed, 14 insertions(+), 9 deletions(-)

diff --git a/libisofs/fs_image.c b/libisofs/fs_image.c
index 6eec9b6..a95de3d 100644
--- a/libisofs/fs_image.c
+++ b/libisofs/fs_image.c
@@ -3873,7 +3873,7 @@ int iso_analyze_isohybrid(IsoImage *image, int flag)
                                           &sections, 0);
     if (ret < 0)
         return ret;
-    if (section_count > 0)
+    if (ret > 0 && section_count > 0)
         eltorito_lba = sections[0].block;
     free(sections);
     
@@ -4728,7 +4728,7 @@ int iso_analyze_alpha_boot(IsoImage *image, IsoDataSource *src, int flag)
        file = (IsoFile *) node;
        ret = iso_file_get_old_image_sections(file, &section_count,
                                              &sections, 0);
-       if (ret > 0) {
+       if (ret > 0 && section_count > 0) {
            size = sections[0].size / 512 + !!(sections[0].size % 512);
            free(sections);
            if (size != sai->alpha_boot_image_size)
@@ -6387,6 +6387,8 @@ int iso_file_get_old_image_sections(IsoFile *file, int *section_count,
     if (flag != 0) {
         return ISO_WRONG_ARG_VALUE;
     }
+    *section_count = 0;
+    *sections = NULL;
     if (file->from_old_session != 0) {
 
         /*
@@ -6419,6 +6421,8 @@ int iso_file_get_old_image_sections(IsoFile *file, int *section_count,
         ifsdata = data->src->data;
 
         *section_count = ifsdata->nsections;
+        if (*section_count <= 0)
+            return 1;
         *sections = malloc(ifsdata->nsections *
                                 sizeof(struct iso_file_section));
         if (*sections == NULL) {
diff --git a/libisofs/libisofs.h b/libisofs/libisofs.h
index 1cf0440..489c413 100644
--- a/libisofs/libisofs.h
+++ b/libisofs/libisofs.h
@@ -5492,7 +5492,8 @@ int iso_file_get_old_image_lba(IsoFile *file, uint32_t *lba, int flag);
  * @param section_count
  *      Returns the number of extent entries in sections array.
  * @param sections
- *      Returns the array of file sections. Apply free() to dispose it.
+ *      Returns the array of file sections if section_count > 0.
+ *      In this case, apply free() to dispose it.
  * @param flag
  *      Reserved for future usage, submit 0
  * @return
diff --git a/libisofs/node.c b/libisofs/node.c
index 1ecc916..757701e 100644
--- a/libisofs/node.c
+++ b/libisofs/node.c
@@ -1193,16 +1193,17 @@ int iso_file_get_old_image_lba(IsoFile *file, uint32_t *lba, int flag)
 {
     int ret;
     int section_count;
-    struct iso_file_section *sections;
+    struct iso_file_section *sections = NULL;
+
     if (file == NULL || lba == NULL) {
         return ISO_NULL_POINTER;
     }
-    ret = iso_file_get_old_image_sections(file, &section_count, &sections, flag);
-    if (ret <= 0) {
+    ret = iso_file_get_old_image_sections(file, &section_count, &sections, 0);
+    if (ret <= 0)
         return ret;
-    }
     if (section_count != 1) {
-        free(sections);
+        if (sections != NULL)
+            free(sections);
         return ISO_WRONG_ARG_VALUE;
     }
     *lba = sections[0].block;
@@ -1211,7 +1212,6 @@ int iso_file_get_old_image_lba(IsoFile *file, uint32_t *lba, int flag)
 }
 
 
-
 /*
  * Like iso_file_get_old_image_lba(), but take an IsoNode.
  *