cache.c: make all io-related functions return errno on error

We'll need proper return-values from these functions to make the cache
behave correctly (which includes giving proper error messages).

Noticed-by: Jim Meyering <jim@meyering.net>
Signed-off-by: Lars Hjemli <hjemli@gmail.com>

1 files changed, 24 insertions, 9 deletions

diff --git a/cache.c b/cache.c
index add647e..6847202 100644
--- a/cache.c
+++ b/cache.c
@@ -66,12 +66,16 @@ static int open_slot(struct cache_slot *slot)
 }
 
 /* Close the active cache slot */
-static void close_slot(struct cache_slot *slot)
+static int close_slot(struct cache_slot *slot)
 {
+        int err = 0;
         if (slot->cache_fd > 0) {
-                close(slot->cache_fd);
-                slot->cache_fd = -1;
+                if (close(slot->cache_fd))
+                        err = errno;
+                else
+                        slot->cache_fd = -1;
         }
+        return err;
 }
 
 /* Print the content of the active cache slot (but skip the key). */
@@ -116,12 +120,16 @@ static int is_modified(struct cache_slot *slot)
 }
 
 /* Close an open lockfile */
-static void close_lock(struct cache_slot *slot)
+static int close_lock(struct cache_slot *slot)
 {
+        int err = 0;
         if (slot->lock_fd > 0) {
-                close(slot->lock_fd);
-                slot->lock_fd = -1;
+                if (close(slot->lock_fd))
+                        err = errno;
+                else
+                        slot->lock_fd = -1;
         }
+        return err;
 }
 
 /* Create a lockfile used to store the generated content for a cache
@@ -134,7 +142,8 @@ static int lock_slot(struct cache_slot *slot)
                              S_IRUSR|S_IWUSR);
         if (slot->lock_fd == -1)
                 return errno;
-        write(slot->lock_fd, slot->key, slot->keylen + 1);
+        if (write(slot->lock_fd, slot->key, slot->keylen + 1) < 0)
+                return errno;
         return 0;
 }
 
@@ -150,7 +159,11 @@ static int unlock_slot(struct cache_slot *slot, int replace_old_slot)
                 err = rename(slot->lock_name, slot->cache_name);
         else
                 err = unlink(slot->lock_name);
-        return err;
+
+        if (err)
+                return errno;
+
+        return 0;
 }
 
 /* Generate the content for the current cache slot by redirecting
@@ -177,7 +190,9 @@ static int fill_slot(struct cache_slot *slot)
                 return errno;
 
         /* Close the temporary filedescriptor */
-        close(tmp);
+        if (close(tmp))
+                return errno;
+
         return 0;
 }