Isolate non-standard eaccess usage in a util function.

That will be replaced soon with our own implementation, based on POSIX 
standard functions.

src/fs_local.c

@@ -13,9 +13,6 @@
 #include "fsource.h"
 #include "error.h"
 
-/* for eaccess, define in unistd.h */
-#define __USE_GNU
-
 #include <stdlib.h>
 #include <sys/types.h>
 #include <sys/stat.h>
@@ -154,33 +151,7 @@ int lfs_access(IsoFileSource *src)
     }
     data = src->data;
 
-    if (eaccess(data->path, R_OK) != 0) {
-        int err;
-
-        /* error, choose an appropriate return code */
-        switch (errno) {
-        case EACCES:
-            err = ISO_FILE_ACCESS_DENIED;
-            break;
-        case ENOTDIR:
-        case ENAMETOOLONG:
-        case ELOOP:
-            err = ISO_FILE_BAD_PATH;
-            break;
-        case ENOENT:
-            err = ISO_FILE_DOESNT_EXIST;
-            break;
-        case EFAULT:
-        case ENOMEM:
-            err = ISO_MEM_ERROR;
-            break;
-        default:
-            err = ISO_FILE_ERROR;
-            break;
-        }
-        return err;
-    }
-    return ISO_SUCCESS;
+    return iso_eaccess(data->path);
 }
 
 static

src/util.c

@@ -19,6 +19,10 @@
 #include <stdio.h>
 #include <limits.h>
 
+/* for eaccess, define in unistd.h */
+#define __USE_GNU
+#include <unistd.h>
+
 int int_pow(int base, int power)
 {
     int result = 1;
@@ -572,3 +576,43 @@ time_t iso_datetime_read_17(const uint8_t *buf)
 
     return timegm(&tm) - buf[16] * 60 * 15;
 }
+
+/**
+ * Check whether the caller process has read access to the given local file.
+ * 
+ * @return 
+ *     1 on success (i.e, the process has read access), < 0 on error 
+ *     (including ISO_FILE_ACCESS_DENIED on access denied to the specified file
+ *     or any directory on the path).
+ */
+int iso_eaccess(const char *path)
+{
+    // TODO replace non-standard eaccess with our own implementation
+    if (eaccess(path, R_OK) != 0) {
+        int err;
+
+        /* error, choose an appropriate return code */
+        switch (errno) {
+        case EACCES:
+            err = ISO_FILE_ACCESS_DENIED;
+            break;
+        case ENOTDIR:
+        case ENAMETOOLONG:
+        case ELOOP:
+            err = ISO_FILE_BAD_PATH;
+            break;
+        case ENOENT:
+            err = ISO_FILE_DOESNT_EXIST;
+            break;
+        case EFAULT:
+        case ENOMEM:
+            err = ISO_MEM_ERROR;
+            break;
+        default:
+            err = ISO_FILE_ERROR;
+            break;
+        }
+        return err;
+    }
+    return ISO_SUCCESS;
+}

src/util.h

@@ -122,6 +122,16 @@ void iso_datetime_17(uint8_t *buf, time_t t);
 time_t iso_datetime_read_7(const uint8_t *buf);
 time_t iso_datetime_read_17(const uint8_t *buf);
 
+/**
+ * Check whether the caller process has read access to the given local file.
+ * 
+ * @return 
+ *     1 on success (i.e, the process has read access), < 0 on error 
+ *     (including ISO_FILE_ACCESS_DENIED on access denied to the specified file
+ *     or any directory on the path).
+ */
+int iso_eaccess(const char *path);
+
 typedef struct iso_rbtree IsoRBTree;
 
 /**