From: Chengyu Zhu <hudson...@tencent.com>

- Add HTTP range downloads for OCI blobs
- Introduce ocierofs_iostream for virtual file I/O
- Add --oci option for OCI image mounting with NBD backend

New mount.erofs -t erofs.nbd option: -o=[options] source-image mountpoint

Supported oci options:
- oci.platform=os/arch (default: linux/amd64)
- oci=N (extract specific layer, default: all layers)
- oci.username/oci.password (basic authentication)

e.g.:
./mount/mount.erofs -t erofs.nbd  -o 'oci=1,oci.platform=linux/amd64' \
quay.io/chengyuzhu6/golang:1.22.8-erofs /tmp/test/

Signed-off-by: Chengyu Zhu <hudson...@tencent.com>
---
 lib/liberofs_oci.h |  14 +++
 lib/remotes/oci.c  | 242 +++++++++++++++++++++++++++++++++++++++++-
 mount/Makefile.am  |   2 +-
 mount/main.c       | 257 ++++++++++++++++++++++++++++++++++++++-------
 4 files changed, 476 insertions(+), 39 deletions(-)

diff --git a/lib/liberofs_oci.h b/lib/liberofs_oci.h
index ebb427a..61cfdc7 100644
--- a/lib/liberofs_oci.h
+++ b/lib/liberofs_oci.h
@@ -54,6 +54,12 @@ struct ocierofs_ctx {
        int layer_count;
 };
 
+struct ocierofs_iostream {
+       struct ocierofs_ctx *ctx;
+       struct erofs_vfile vf;
+       u64 offset;
+};
+
 int ocierofs_init(struct ocierofs_ctx *ctx, const struct ocierofs_config 
*config);
 
 /*
@@ -66,6 +72,14 @@ int ocierofs_init(struct ocierofs_ctx *ctx, const struct 
ocierofs_config *config
 int ocierofs_build_trees(struct erofs_importer *importer,
                         const struct ocierofs_config *cfg);
 
+int ocierofs_is_erofs_native_image(struct ocierofs_ctx *ctx);
+
+void ocierofs_ctx_cleanup(struct ocierofs_ctx *ctx);
+
+int ocierofs_iostream_open(struct ocierofs_iostream *oci_iostream, struct 
ocierofs_ctx *oci_ctx);
+
+void ocierofs_iostream_close(struct ocierofs_iostream *oci_iostream);
+
 #ifdef __cplusplus
 }
 #endif
diff --git a/lib/remotes/oci.c b/lib/remotes/oci.c
index 26e83d7..cfe6547 100644
--- a/lib/remotes/oci.c
+++ b/lib/remotes/oci.c
@@ -33,6 +33,9 @@
 #define OCI_MEDIATYPE_MANIFEST "application/vnd.oci.image.manifest.v1+json"
 #define OCI_MEDIATYPE_INDEX "application/vnd.oci.image.index.v1+json"
 
+/* Erofs Native Layer Media Type */
+#define EROFS_MEDIATYPE "application/vnd.erofs"
+
 struct ocierofs_request {
        char *url;
        struct curl_slist *headers;
@@ -1174,7 +1177,6 @@ out:
        return ret;
 }
 
-
 /**
  * ocierofs_ctx_cleanup - Clean up OCI context and free allocated resources
  * @ctx: OCI context structure to clean up
@@ -1182,7 +1184,7 @@ out:
  * Clean up CURL handle, free all allocated string parameters, and
  * reset the OCI context structure to a clean state.
  */
-static void ocierofs_ctx_cleanup(struct ocierofs_ctx *ctx)
+void ocierofs_ctx_cleanup(struct ocierofs_ctx *ctx)
 {
        if (!ctx)
                return;
@@ -1241,3 +1243,239 @@ int ocierofs_build_trees(struct erofs_importer 
*importer,
        ocierofs_ctx_cleanup(&ctx);
        return ret;
 }
+
+static int ocierofs_download_blob_range(struct ocierofs_ctx *ctx, off_t 
offset, size_t length,
+                                       void **out_buf, size_t *out_size)
+{
+       struct ocierofs_request req = {};
+       struct ocierofs_response resp = {};
+       const char *api_registry;
+       char rangehdr[64];
+       long http_code = 0;
+       int ret;
+       int index = ctx->layer_index;
+
+       if (offset < 0)
+               return -EINVAL;
+
+       api_registry = ocierofs_get_api_registry(ctx->registry);
+       if (asprintf(&req.url, "https://%s/v2/%s/blobs/%s";,
+            api_registry, ctx->repository, ctx->layers[index]->digest) == -1)
+               return -ENOMEM;
+
+       if (length)
+               snprintf(rangehdr, sizeof(rangehdr), "Range: bytes=%lld-%lld",
+                        (long long)offset, (long long)(offset + (off_t)length 
- 1));
+       else
+               snprintf(rangehdr, sizeof(rangehdr), "Range: bytes=%lld-",
+                        (long long)offset);
+
+       if (ctx->auth_header && strstr(ctx->auth_header, "Bearer"))
+               req.headers = curl_slist_append(req.headers, ctx->auth_header);
+       req.headers = curl_slist_append(req.headers, rangehdr);
+
+       curl_easy_reset(ctx->curl);
+
+       ret = ocierofs_curl_setup_common_options(ctx->curl);
+       if (ret)
+               goto out;
+
+       ret = ocierofs_curl_setup_rq(ctx->curl, req.url, OCIEROFS_HTTP_GET,
+                                    req.headers,
+                                    ocierofs_write_callback,
+                                    &resp, NULL, NULL);
+       if (ret)
+               goto out;
+
+       ret = ocierofs_curl_perform(ctx->curl, &http_code);
+       if (ret)
+               goto out;
+
+       if (http_code == 206) {
+               *out_buf = resp.data;
+               *out_size = resp.size;
+               resp.data = NULL;
+               ret = 0;
+       } else if (http_code == 200) {
+               if (offset == 0) {
+                       *out_buf = resp.data;
+                       *out_size = resp.size;
+                       resp.data = NULL;
+                       ret = 0;
+               } else {
+                       if (offset < resp.size) {
+                               size_t available = resp.size - offset;
+                               size_t copy_size = length ? min_t(size_t, 
length, available) : available;
+
+                               *out_buf = malloc(copy_size);
+                               if (!*out_buf) {
+                                       ret = -ENOMEM;
+                                       goto out;
+                               }
+                               memcpy(*out_buf, resp.data + offset, copy_size);
+                               *out_size = copy_size;
+                               ret = 0;
+                       } else {
+                               *out_buf = NULL;
+                               *out_size = 0;
+                               ret = 0;
+                       }
+               }
+       } else {
+               erofs_err("HTTP range request failed with code %ld", http_code);
+               ret = -EIO;
+       }
+
+out:
+       if (req.headers)
+               curl_slist_free_all(req.headers);
+       free(req.url);
+       free(resp.data);
+       return ret;
+}
+
+static ssize_t ocierofs_io_pread(struct erofs_vfile *vf, void *buf, size_t 
len, u64 offset)
+{
+       struct ocierofs_iostream *oci_iostream = *(struct ocierofs_iostream 
**)vf->payload;
+       void *download_buf = NULL;
+       size_t download_size = 0;
+       ssize_t ret;
+
+       ret = ocierofs_download_blob_range(oci_iostream->ctx, offset, len,
+                                          &download_buf, &download_size);
+       if (ret < 0) {
+               memset(buf, 0, len);
+               return len;
+       }
+
+       if (download_buf && download_size > 0) {
+               memcpy(buf, download_buf, download_size);
+               free(download_buf);
+               return download_size;
+       }
+
+       return 0;
+}
+
+static ssize_t ocierofs_io_read(struct erofs_vfile *vf, void *buf, size_t len)
+{
+       struct ocierofs_iostream *oci_iostream = *(struct ocierofs_iostream 
**)vf->payload;
+       ssize_t ret;
+
+       ret = ocierofs_io_pread(vf, buf, len, oci_iostream->offset);
+       if (ret > 0)
+               oci_iostream->offset += ret;
+
+       return ret;
+}
+
+static off_t ocierofs_io_lseek(struct erofs_vfile *vf, u64 offset, int whence)
+{
+       struct ocierofs_iostream *oci_iostream = *(struct ocierofs_iostream 
**)vf->payload;
+       off_t new_offset;
+       int layer_index = oci_iostream->ctx->layer_index;
+
+       switch (whence) {
+       case SEEK_SET:
+               new_offset = offset;
+               break;
+       case SEEK_CUR:
+               new_offset = oci_iostream->offset + offset;
+               break;
+       case SEEK_END:
+               new_offset = oci_iostream->ctx->layers[layer_index]->size + 
offset;
+               break;
+       default:
+               return -1;
+       }
+
+       if (new_offset < 0 || new_offset > 
oci_iostream->ctx->layers[layer_index]->size)
+               return -1;
+
+       oci_iostream->offset = new_offset;
+       return new_offset;
+}
+
+static ssize_t ocierofs_io_sendfile(struct erofs_vfile *vout, struct 
erofs_vfile *vin,
+                              off_t *pos, size_t count)
+{
+       struct ocierofs_iostream *oci_iostream = *(struct ocierofs_iostream 
**)vin->payload;
+       char *buf = NULL;
+       ssize_t total_written = 0;
+       ssize_t ret = 0;
+
+       buf = malloc(min_t(size_t, count, 32768));
+       if (!buf)
+               return -ENOMEM;
+
+       while (count > 0) {
+               size_t to_read = min_t(size_t, count, 32768);
+               u64 read_offset = pos ? *pos : oci_iostream->offset;
+
+               ret = ocierofs_io_pread(vin, buf, to_read, read_offset);
+               if (ret <= 0) {
+                       erofs_err("OCI I/O sendfile: failed to read from OCI: 
%s",
+                                 erofs_strerror(ret));
+                       memset(buf, 0, to_read);
+                       ret = to_read;
+               }
+
+               ssize_t written = write(vout->fd, buf, ret);
+
+               if (written < 0) {
+                       erofs_err("OCI I/O sendfile: failed to write to output: 
%s",
+                                 strerror(errno));
+                       ret = -errno;
+                       break;
+               }
+
+               if (written != ret) {
+                       erofs_err("OCI I/O sendfile: partial write: %zd != 
%zd", written, ret);
+                       ret = written;
+               }
+
+               total_written += ret;
+               count -= ret;
+               if (pos)
+                       *pos += ret;
+               else
+                       oci_iostream->offset += ret;
+       }
+
+       free(buf);
+       return count;
+}
+
+static struct erofs_vfops ocierofs_io_vfops = {
+       .pread = ocierofs_io_pread,
+       .read = ocierofs_io_read,
+       .lseek = ocierofs_io_lseek,
+       .sendfile = ocierofs_io_sendfile,
+};
+
+int ocierofs_iostream_open(struct ocierofs_iostream *oci_iostream, struct 
ocierofs_ctx *oci_ctx)
+{
+       memset(oci_iostream, 0, sizeof(*oci_iostream));
+       oci_iostream->ctx = oci_ctx;
+       oci_iostream->vf.ops = &ocierofs_io_vfops;
+       oci_iostream->vf.fd = -1;
+       *(struct ocierofs_iostream **)oci_iostream->vf.payload = oci_iostream;
+
+       return 0;
+}
+
+void ocierofs_iostream_close(struct ocierofs_iostream *oci_iostream)
+{
+       close(oci_iostream->vf.fd);
+}
+
+int ocierofs_is_erofs_native_image(struct ocierofs_ctx *ctx)
+{
+       if (ctx->layer_count > 0 && ctx->layers[0] &&
+           ctx->layers[0]->media_type) {
+               if (strcmp(ctx->layers[0]->media_type, EROFS_MEDIATYPE) != 0)
+                       return -ENOENT;
+               return 0;
+       }
+       return -ENOENT;
+}
diff --git a/mount/Makefile.am b/mount/Makefile.am
index d93f3f4..0b4447f 100644
--- a/mount/Makefile.am
+++ b/mount/Makefile.am
@@ -9,5 +9,5 @@ mount_erofs_SOURCES = main.c
 mount_erofs_CFLAGS = -Wall -I$(top_srcdir)/include
 mount_erofs_LDADD = $(top_builddir)/lib/liberofs.la ${libselinux_LIBS} \
        ${liblz4_LIBS} ${liblzma_LIBS} ${zlib_LIBS} ${libdeflate_LIBS} \
-       ${libzstd_LIBS} ${libqpl_LIBS} ${libxxhash_LIBS} ${libnl3_LIBS}
+       ${libzstd_LIBS} ${libqpl_LIBS} ${libxxhash_LIBS} ${libnl3_LIBS} 
${openssl_LIBS}
 endif
diff --git a/mount/main.c b/mount/main.c
index a270f0a..177bca3 100644
--- a/mount/main.c
+++ b/mount/main.c
@@ -15,6 +15,7 @@
 #include "erofs/err.h"
 #include "erofs/io.h"
 #include "../lib/liberofs_nbd.h"
+#include "../lib/liberofs_oci.h"
 #ifdef HAVE_LINUX_LOOP_H
 #include <linux/loop.h>
 #else
@@ -34,6 +35,10 @@ struct loop_info {
 #include <sys/sysmacros.h>
 #endif
 
+#ifdef OCIEROFS_ENABLED
+static struct ocierofs_config ocicfg;
+#endif
+
 enum erofs_backend_drv {
        EROFSAUTO,
        EROFSLOCAL,
@@ -56,12 +61,76 @@ static struct erofsmount_cfg {
        long flags;
        enum erofs_backend_drv backend;
        enum erofsmount_mode mountmode;
+#ifdef OCIEROFS_ENABLED
+       bool use_oci;
+#endif
 } mountcfg = {
        .full_options = "ro",
        .flags = MS_RDONLY,             /* default mountflags */
        .fstype = "erofs",
 };
 
+enum erofs_nbd_source_type {
+       EROFSNBD_SOURCE_LOCAL,
+       EROFSNBD_SOURCE_OCI,
+};
+
+union erofs_nbd_source {
+       const char *device_path;
+       struct ocierofs_ctx *oci_ctx;
+};
+
+union erofs_nbd_source src;
+
+static int parse_oci_option(struct ocierofs_config *oci_cfg, const char 
*option)
+{
+       char *p;
+
+       p = strstr(option, "oci=");
+       if (p != NULL) {
+               p += strlen("oci=");
+               {
+                       char *endptr;
+                       unsigned long v = strtoul(p, &endptr, 10);
+
+                       if (endptr == p || *endptr != '\0')
+                               return -EINVAL;
+                       oci_cfg->layer_index = (int)v;
+               }
+       } else {
+               p = strstr(option, "oci.platform=");
+               if (p != NULL) {
+                       p += strlen("oci.platform=");
+                       free(oci_cfg->platform);
+                       oci_cfg->platform = strdup(p);
+                       if (!oci_cfg->platform)
+                               return -ENOMEM;
+               } else {
+                       p = strstr(option, "oci.username=");
+                       if (p != NULL) {
+                               p += strlen("oci.username=");
+                               free(oci_cfg->username);
+                               oci_cfg->username = strdup(p);
+                               if (!oci_cfg->username)
+                                       return -ENOMEM;
+                       } else {
+                               p = strstr(option, "oci.password=");
+                               if (p != NULL) {
+                                       p += strlen("oci.password=");
+                                       free(oci_cfg->password);
+                                       oci_cfg->password = strdup(p);
+                                       if (!oci_cfg->password)
+                                               return -ENOMEM;
+                               } else {
+                                       return -EINVAL;
+                               }
+                       }
+               }
+       }
+
+       return 0;
+}
+
 static long erofsmount_parse_flagopts(char *s, long flags, char **more)
 {
        static const struct {
@@ -90,29 +159,41 @@ static long erofsmount_parse_flagopts(char *s, long flags, 
char **more)
                comma = strchr(s, ',');
                if (comma)
                        *comma = '\0';
-               for (i = 0; i < ARRAY_SIZE(opts); ++i) {
-                       if (!strcasecmp(s, opts[i].name)) {
-                               if (opts[i].flags < 0)
-                                       flags &= opts[i].flags;
-                               else
-                                       flags |= opts[i].flags;
-                               break;
-                       }
-               }
 
-               if (more && i >= ARRAY_SIZE(opts)) {
-                       int sl = strlen(s);
-                       char *new = *more;
+               if (strncmp(s, "oci", 3) == 0) {
+#ifdef OCIEROFS_ENABLED
+                       int err = parse_oci_option(&ocicfg, s);
 
-                       i = new ? strlen(new) : 0;
-                       new = realloc(new, i + strlen(s) + 2);
-                       if (!new)
-                               return -ENOMEM;
-                       if (i)
-                               new[i++] = ',';
-                       memcpy(new + i, s, sl);
-                       new[i + sl] = '\0';
-                       *more = new;
+                       if (err < 0)
+                               return err;
+#else
+                       return -EINVAL;
+#endif
+               } else {
+                       for (i = 0; i < ARRAY_SIZE(opts); ++i) {
+                               if (!strcasecmp(s, opts[i].name)) {
+                                       if (opts[i].flags < 0)
+                                               flags &= opts[i].flags;
+                                       else
+                                               flags |= opts[i].flags;
+                                       break;
+                               }
+                       }
+
+                       if (more && i >= ARRAY_SIZE(opts)) {
+                               int sl = strlen(s);
+                               char *new = *more;
+
+                               i = new ? strlen(new) : 0;
+                               new = realloc(new, i + strlen(s) + 2);
+                               if (!new)
+                                       return -ENOMEM;
+                               if (i)
+                                       new[i++] = ',';
+                               memcpy(new + i, s, sl);
+                               new[i + sl] = '\0';
+                               *more = new;
+                       }
                }
 
                if (!comma)
@@ -120,6 +201,11 @@ static long erofsmount_parse_flagopts(char *s, long flags, 
char **more)
                *comma = ',';
                s = comma + 1;
        }
+
+#ifdef OCIEROFS_ENABLED
+       if (ocicfg.platform || ocicfg.username || ocicfg.password || 
ocicfg.layer_index != 0)
+               mountcfg.use_oci = true;
+#endif
        return flags;
 }
 
@@ -540,9 +626,64 @@ err_identifier:
        return err;
 }
 
-static int erofsmount_nbd(const char *source, const char *mountpoint,
-                         const char *fstype, int flags,
-                         const char *options)
+static int erofsmount_startnbd_oci(int nbdfd, struct ocierofs_ctx *oci_ctx)
+{
+       struct erofsmount_nbd_ctx ctx = {};
+       struct ocierofs_iostream *oci_iostream = NULL;
+       uintptr_t retcode;
+       pthread_t th;
+       int err, err2;
+       int blkbits = 12;
+       int index = oci_ctx->layer_index;
+       u64 blocks;
+
+       blocks = (oci_ctx->layers[index]->size + (1ULL << blkbits) - 1) >> 
blkbits;
+
+       oci_iostream = malloc(sizeof(struct ocierofs_iostream));
+       if (!oci_iostream)
+               return -ENOMEM;
+
+       err = ocierofs_iostream_open(oci_iostream, oci_ctx);
+       if (err) {
+               free(oci_iostream);
+               return err;
+       }
+
+       ctx.vd = oci_iostream->vf;
+
+       err = erofs_nbd_connect(nbdfd, blkbits, blocks);
+       if (err < 0) {
+               ocierofs_iostream_close(oci_iostream);
+               free(oci_iostream);
+               return err;
+       }
+       ctx.sk.fd = err;
+
+       err = -pthread_create(&th, NULL, erofsmount_nbd_loopfn, &ctx);
+       if (err) {
+               ocierofs_iostream_close(oci_iostream);
+               free(oci_iostream);
+               close(ctx.sk.fd);
+               return err;
+       }
+
+       err = erofs_nbd_do_it(nbdfd);
+       err2 = -pthread_join(th, (void **)&retcode);
+       if (!err2 && retcode) {
+               erofs_err("NBD worker failed with %s",
+                         erofs_strerror(retcode));
+               err2 = retcode;
+       }
+
+       ocierofs_iostream_close(oci_iostream);
+       free(oci_iostream);
+
+       return err ?: err2;
+}
+
+static int erofsmount_nbd(union erofs_nbd_source source, enum 
erofs_nbd_source_type source_type,
+                         const char *mountpoint, const char *fstype,
+                         int flags, const char *options)
 {
        bool is_netlink = false;
        char nbdpath[32], *id;
@@ -555,11 +696,19 @@ static int erofsmount_nbd(const char *source, const char 
*mountpoint,
                        mountcfg.fstype);
                return -ENODEV;
        }
+
        flags |= MS_RDONLY;
 
-       err = erofsmount_startnbd_nl(&pid, source);
-       if (err < 0) {
-               erofs_info("Fall back to ioctl-based NBD; failover is 
unsupported");
+       if (source_type == EROFSNBD_SOURCE_LOCAL) {
+               err = erofsmount_startnbd_nl(&pid, source.device_path);
+               if (err >= 0) {
+                       num = err;
+                       (void)snprintf(nbdpath, sizeof(nbdpath), "/dev/nbd%d", 
num);
+                       is_netlink = true;
+               }
+       }
+
+       if (!is_netlink) {
                num = erofs_nbd_devscan();
                if (num < 0)
                        return num;
@@ -569,14 +718,16 @@ static int erofsmount_nbd(const char *source, const char 
*mountpoint,
                if (nbdfd < 0)
                        return -errno;
 
-               if ((pid = fork()) == 0)
-                       return erofsmount_startnbd(nbdfd, source) ?
-                               EXIT_FAILURE : EXIT_SUCCESS;
+               if ((pid = fork()) == 0) {
+                       if (source_type == EROFSNBD_SOURCE_OCI) {
+                               return erofsmount_startnbd_oci(nbdfd, 
source.oci_ctx) ?
+                                       EXIT_FAILURE : EXIT_SUCCESS;
+                       } else {
+                               return erofsmount_startnbd(nbdfd, 
source.device_path) ?
+                                       EXIT_FAILURE : EXIT_SUCCESS;
+                       }
+               }
                close(nbdfd);
-       } else {
-               num = err;
-               (void)snprintf(nbdpath, sizeof(nbdpath), "/dev/nbd%d", num);
-               is_netlink = true;
        }
 
        while (1) {
@@ -594,7 +745,7 @@ static int erofsmount_nbd(const char *source, const char 
*mountpoint,
                if (err < 0)
                        err = -errno;
 
-               if (!err && is_netlink) {
+               if (!err && is_netlink && source_type == EROFSNBD_SOURCE_LOCAL) 
{
                        id = erofs_nbd_get_identifier(num);
                        if (id == ERR_PTR(-ENOENT))
                                id = NULL;
@@ -799,9 +950,43 @@ int main(int argc, char *argv[])
        }
 
        if (mountcfg.backend == EROFSNBD) {
-               err = erofsmount_nbd(mountcfg.device, mountcfg.target,
+#ifdef OCIEROFS_ENABLED
+               if (mountcfg.use_oci) {
+                       struct ocierofs_ctx ctx = {};
+
+                       ocicfg.image_ref = mountcfg.device;
+                       err = ocierofs_init(&ctx, &ocicfg);
+                       if (err) {
+                               ocierofs_ctx_cleanup(&ctx);
+                               goto exit;
+                       }
+
+                       err = ocierofs_is_erofs_native_image(&ctx);
+                       if (err) {
+                               ocierofs_ctx_cleanup(&ctx);
+                               goto exit;
+                       }
+
+                       src.oci_ctx = &ctx;
+
+                       err = erofsmount_nbd(src, EROFSNBD_SOURCE_OCI, 
mountcfg.target,
+                                            mountcfg.fstype, mountcfg.flags, 
mountcfg.options);
+                       if (err) {
+                               ocierofs_ctx_cleanup(&ctx);
+                               goto exit;
+                       }
+               } else {
+                       src.device_path = mountcfg.device;
+                       err = erofsmount_nbd(src, EROFSNBD_SOURCE_LOCAL, 
mountcfg.target,
+                                            mountcfg.fstype, mountcfg.flags,
+                                            mountcfg.options);
+               }
+#else
+               src.device_path = mountcfg.device;
+               err = erofsmount_nbd(src, EROFSNBD_SOURCE_LOCAL, 
mountcfg.target,
                                     mountcfg.fstype, mountcfg.flags,
                                     mountcfg.options);
+#endif
                goto exit;
        }
 
-- 
2.51.0


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