Fix EROFS support of TurboOCI-apply

 - Correct the bottom layer check;

 - Fix up pread() alignment issue.

Signed-off-by: zhuangbowei.zbw <[email protected]>
Signed-off-by: Gao Xiang <[email protected]>

Author: WaberZhuang

src/overlaybd/tar/tarerofs.cpp

@@ -25,6 +25,8 @@
 #define __stringify_1(x...)	#x
 #define __stringify(x...)	__stringify_1(x)
 
+#define LSMT_ALIGNMENT 512
+
 int TarErofs::extract_all() {
     ssize_t read;
     struct stat st;
@@ -44,7 +46,7 @@ int TarErofs::extract_all() {
          return -1;
     }
 
-    if (fs_base_file->fstat(&st)>= 0 && st.st_blocks > 0) {
+    if (!first_layer) {
         int fd = mkstemp(base_path);
         if (fd < 0) {
             LOG_ERROR("cannot generate a temporary file to dump overlaybd disk");
@@ -53,11 +55,12 @@ int TarErofs::extract_all() {
         std::strcat(command_line, " --base ");
         std::strcat(command_line, base_path);
 
-        if (fs_base_file->pread(&metasize, sizeof(metasize), 0) !=
-            sizeof(metasize)) {
+        // lsmt.pread should align to 512
+        if (fs_base_file->pread(&buf, LSMT_ALIGNMENT, 0) != LSMT_ALIGNMENT) {
             LOG_ERROR("failed to read EROFS metadata size");
             return -1;
         }
+        metasize = *(uint64_t *)buf;
 
         while (metasize) {
             int count = std::min(sizeof(buf), metasize);
@@ -89,6 +92,9 @@ int TarErofs::extract_all() {
     }
     status = pclose(fp);
 
+    if (!first_layer)
+        unlink(base_path);
+
     if (read < 0 || status) {
         return -1;
     }
@@ -110,10 +116,8 @@ int TarErofs::extract_all() {
             read = -1;
             break;
         }
-        metasize += read;
     }
 
-
     /* write mapfile */
     fp = fopen("upper.map", "r");
     if (fp == NULL) {

src/overlaybd/tar/tarerofs.h

@@ -21,8 +21,8 @@
 class TarErofs {
 public:
     TarErofs(photon::fs::IFile *file, photon::fs::IFile *target, uint64_t fs_blocksize = 4096,
-          photon::fs::IFile *bf = nullptr, bool meta_only = true)
-        : file(file), fout(target), fs_base_file(bf), meta_only(meta_only) {}
+          photon::fs::IFile *bf = nullptr, bool meta_only = true, bool first_layer = true)
+        : file(file), fout(target), fs_base_file(bf), meta_only(meta_only), first_layer(first_layer) {}
 
     int extract_all();
 
@@ -31,6 +31,7 @@ class TarErofs {
     photon::fs::IFile *fout = nullptr; // target
     photon::fs::IFile *fs_base_file = nullptr;
     bool meta_only;
+    bool first_layer;
     std::set<std::string> unpackedPaths;
     std::list<std::pair<std::string, int>> dirs; // <path, utime>
 };

src/tools/turboOCI-apply.cpp

@@ -129,8 +129,14 @@ int main(int argc, char **argv) {
     if (fstype == "erofs") {
         photon::fs::IFile* base_file = raw ? nullptr : ((ImageFile *)imgfile)->get_base();
 
+        ImageConfigNS::ImageConfig cfg;
+        if (!cfg.ParseJSON(image_config_path)) {
+            fprintf(stderr, "failed to parse image config\n");
+            exit(-1);
+        }
+
         auto tar =
-           new TarErofs(src_file, imgfile, 4096, base_file, true);
+           new TarErofs(src_file, imgfile, 4096, base_file, true, cfg.lowers().size() == 0);
 
         if (tar->extract_all() < 0) {
             fprintf(stderr, "failed to extract\n");