Implement file positioning functions for upkg exports.

[upkg.git] / src / libupkg.c

diff --git a/src/libupkg.c b/src/libupkg.c
index 66546fd3dd80f3f1858f80d579a5f7ca7cd4b192..64b00d27818db40a3d6628bb8b621059d2e57f1b 100644 (file)
--- a/src/libupkg.c
+++ b/src/libupkg.c
@@ -47,6 +47,8 @@ struct upkg_import {
 struct upkg_private {
        FILE *f;
 
+       struct upkg_file *last_file;
+
        struct upkg_name   *names;
        struct upkg_export *exports;
        struct upkg_import *imports;
@@ -60,7 +62,7 @@ struct upkg_private {
  * Stores the result in *val and returns the number of input bytes read (or 0
  * if the input is invalid, in which case *val is undefined).
  */
-static size_t decode_index(long *val, unsigned char *bytes, size_t n)
+size_t upkg_decode_index(long *val, unsigned char *bytes, size_t n)
 {
        size_t i = 0;
 
@@ -212,11 +214,11 @@ static int pkg_init_exports(struct upkg *pkg)
                }
 
                len = 0;
-               rc = decode_index(&export->class, buf+len, nbuf-len);
+               rc = upkg_decode_index(&export->class, buf+len, nbuf-len);
                if (rc == 0) goto err;
                len += rc;
 
-               rc = decode_index(&export->super, buf+len, nbuf-len);
+               rc = upkg_decode_index(&export->super, buf+len, nbuf-len);
                if (rc == 0) goto err;
                len += rc;
 
@@ -224,7 +226,7 @@ static int pkg_init_exports(struct upkg *pkg)
                export->package = unpack_32_le(buf+len);
                len += 4;
 
-               rc = decode_index(&tmp, buf+len, nbuf-len);
+               rc = upkg_decode_index(&tmp, buf+len, nbuf-len);
                if (rc == 0 || tmp < 0 || tmp >= pkg->name_count) goto err;
                export->name = pkg->priv->names[tmp].name;
                len += rc;
@@ -233,12 +235,12 @@ static int pkg_init_exports(struct upkg *pkg)
                export->flags = unpack_32_le(buf+len);
                len += 4;
 
-               rc = decode_index(&export->size, buf+len, nbuf-len);
+               rc = upkg_decode_index(&export->size, buf+len, nbuf-len);
                if (rc == 0) goto err;
                len += rc;
 
                if (export->size) {
-                       rc = decode_index(&export->offset, buf+len, nbuf-len);
+                       rc = upkg_decode_index(&export->offset, buf+len, nbuf-len);
                        if (rc == 0) goto err;
                        len += rc;
                }
@@ -280,12 +282,12 @@ static int pkg_init_imports(struct upkg *pkg)
                }
 
                len = 0;
-               rc = decode_index(&tmp, buf+len, nbuf-len);
+               rc = upkg_decode_index(&tmp, buf+len, nbuf-len);
                if (rc == 0 || len < 0 || len >= pkg->name_count) goto err;
                import->class_package = pkg->priv->names[tmp].name;
                len += rc;
 
-               rc = decode_index(&tmp, buf+len, nbuf-len);
+               rc = upkg_decode_index(&tmp, buf+len, nbuf-len);
                if (rc == 0 || len < 0 || len >= pkg->name_count) goto err;
                import->class_name = pkg->priv->names[tmp].name;
                len += rc;
@@ -294,7 +296,7 @@ static int pkg_init_imports(struct upkg *pkg)
                import->package = unpack_32_le(buf+len);
                len += 4;
 
-               rc = decode_index(&tmp, buf+len, nbuf-len);
+               rc = upkg_decode_index(&tmp, buf+len, nbuf-len);
                if (rc == 0 || len < 0 || len >= pkg->name_count) goto err;
                import->object_name = pkg->priv->names[tmp].name;
                len += rc;
@@ -385,3 +387,80 @@ const char *upkg_get_name(struct upkg *pkg, unsigned long idx)
                return 0;
        return pkg->priv->names[idx].name;
 }
+
+struct upkg_file *upkg_export_open(struct upkg *pkg, unsigned long idx)
+{
+       struct upkg_file *f;
+
+       if (idx >= pkg->export_count)
+               return NULL;
+
+       f = malloc(sizeof *f);
+       if (f == NULL)
+               return NULL;
+
+       *f = (struct upkg_file) {
+               .pkg  = pkg,
+               .base = pkg->priv->exports[idx].offset,
+               .len  = pkg->priv->exports[idx].size,
+       };
+
+       return f;
+}
+
+void upkg_export_close(struct upkg_file *f)
+{
+       if (f->pkg->priv->last_file == f)
+               f->pkg->priv->last_file = NULL;
+       free(f);
+}
+
+long upkg_export_tell(struct upkg_file *f)
+{
+       return f->offset;
+}
+
+int upkg_export_seek(struct upkg_file *f, long offset, int whence)
+{
+       int rc = EOF;
+
+       switch (whence) {
+       case SEEK_CUR:
+               offset = f->offset + offset;
+       case SEEK_SET:
+               if (offset < 0 || offset > f->len)
+                       return EOF;
+               rc = fseek(f->pkg->priv->f, f->base + offset, SEEK_SET);
+               break;
+       case SEEK_END:
+               offset = -offset;
+               if (offset < 0 || offset > f->len)
+                       return EOF;
+               offset = f->len - offset;
+               rc = fseek(f->pkg->priv->f, f->base + offset, SEEK_SET);
+               break;
+       }
+
+       if (rc == 0)
+               f->pkg->priv->last_file = f;
+       return rc;
+}
+
+size_t upkg_export_read(struct upkg_file *f, void *buf, size_t n)
+{
+       size_t want = MIN(n, f->len - f->offset);
+       size_t rc;
+
+       if (want == 0) {
+               return 0;
+       }
+
+       if (f != f->pkg->priv->last_file) {
+               if (fseek(f->pkg->priv->f, f->base + f->offset, SEEK_SET))
+                       return 0;
+       }
+
+       rc = fread(buf, 1, want, f->pkg->priv->f);
+       f->offset += rc;
+       return rc;
+}