Add mtar_foreach()

This is a very convienient way of iterating over a tar archive.
It can be used for search operations or data extraction and
mtar_find() has been re-implemented using it.

2 files changed, 25 insertions, 6 deletions

diff --git a/src/microtar.c b/src/microtar.c
index 37d3f5d..97f53fb 100644
--- a/src/microtar.c
+++ b/src/microtar.c
@@ -315,20 +315,35 @@ int mtar_next(mtar_t* tar)
     return ensure_header(tar);
 }
 
-int mtar_find(mtar_t* tar, const char* name)
+int mtar_foreach(mtar_t* tar, mtar_foreach_cb cb, void* arg)
 {
-    /* seek to the beginning */
     int err = mtar_rewind(tar);
     if(err)
         return err;
 
-    /* iterate over all records */
     while((err = mtar_next(tar)) == MTAR_ESUCCESS)
-        if(!strcmp(tar->header.name, name))
-            return MTAR_ESUCCESS;
+        if((err = cb(tar, &tar->header, arg)) != 0)
+            return err;
 
-    /* hit the end of archive -> file not found */
     if(err == MTAR_ENULLRECORD)
+        err = MTAR_ESUCCESS;
+
+    return err;
+}
+
+static int find_foreach_cb(mtar_t* tar, const mtar_header_t* h, void* arg)
+{
+    (void)tar;
+    const char* name = (const char*)arg;
+    return strcmp(name, h->name) ? 0 : 1;
+}
+
+int mtar_find(mtar_t* tar, const char* name)
+{
+    int err = mtar_foreach(tar, find_foreach_cb, (void*)name);
+    if(err == 1)
+        err = MTAR_ESUCCESS;
+    else if(err == MTAR_ESUCCESS)
         err = MTAR_ENOTFOUND;
 
     return err;
diff --git a/src/microtar.h b/src/microtar.h
index c01f11d..a6d058b 100644
--- a/src/microtar.h
+++ b/src/microtar.h
@@ -43,6 +43,7 @@ enum {
     MTAR_ENOTFOUND    = -8,
     MTAR_EOVERFLOW    = -9,
     MTAR_EAPI         = -10,
+    MTAR_ELAST        = MTAR_EAPI,
 };
 
 enum {
@@ -59,6 +60,8 @@ typedef struct mtar_header mtar_header_t;
 typedef struct mtar mtar_t;
 typedef struct mtar_ops mtar_ops_t;
 
+typedef int(*mtar_foreach_cb)(mtar_t*, const mtar_header_t*, void*);
+
 struct mtar_header {
     unsigned mode;
     unsigned owner;
@@ -100,6 +103,7 @@ const mtar_header_t* mtar_get_header(const mtar_t* tar);
 
 int mtar_rewind(mtar_t* tar);
 int mtar_next(mtar_t* tar);
+int mtar_foreach(mtar_t* tar, mtar_foreach_cb cb, void* arg);
 int mtar_find(mtar_t* tar, const char* name);
 int mtar_read_data(mtar_t* tar, void* ptr, unsigned size);