io: make io vtables const struct, and add accessors for them

This reduces function pointers in heap, and unifies how the
io functions are called.

(cherry picked from commit 09ca58863af02d11e8dbf066b714464fb1638e6f)

src/apk.c

@@ -548,7 +548,7 @@ int main(int argc, char **argv)
  struct apk_bstream *bs = apk_bstream_from_file(AT_FDCWD, test_installed_db);
  if (!IS_ERR_OR_NULL(bs)) {
  apk_db_index_read(&db, bs, -1);
- bs->close(bs, NULL);
+ apk_bstream_close(bs, NULL);
  }
  }
  for (i = 0; i < test_repos->num; i++) {
@@ -576,7 +576,7 @@ int main(int argc, char **argv)
  }
 
  apk_db_index_read(&db, bs, repo);
- bs->close(bs, NULL);
+ apk_bstream_close(bs, NULL);
  if (repo != -2) {
  if (!(apk_flags & APK_NO_NETWORK))
  db.available_repos |= BIT(repo);

src/apk_io.h

@@ -54,27 +54,39 @@ struct apk_file_info {
  struct apk_xattr_array *xattrs;
 };
 
-struct apk_istream {
+struct apk_istream_ops {
  void (*get_meta)(void *stream, struct apk_file_meta *meta);
  ssize_t (*read)(void *stream, void *ptr, size_t size);
  void (*close)(void *stream);
 };
 
+struct apk_istream {
+ const struct apk_istream_ops *ops;
+};
+
 #define APK_BSTREAM_SINGLE_READ 0x0001
 #define APK_BSTREAM_EOF 0x0002
 
-struct apk_bstream {
- unsigned int flags;
+struct apk_bstream_ops {
  void (*get_meta)(void *stream, struct apk_file_meta *meta);
  apk_blob_t (*read)(void *stream, apk_blob_t token);
  void (*close)(void *stream, size_t *size);
 };
 
-struct apk_ostream {
+struct apk_bstream {
+ unsigned int flags;
+ const struct apk_bstream_ops *ops;
+};
+
+struct apk_ostream_ops {
  ssize_t (*write)(void *stream, const void *buf, size_t size);
  int (*close)(void *stream);
 };
 
+struct apk_ostream {
+ const struct apk_ostream_ops *ops;
+};
+
 #define APK_MPART_DATA 1 /* data processed so far */
 #define APK_MPART_BOUNDARY 2 /* final part of data, before boundary */
 #define APK_MPART_END 3 /* signals end of stream */
@@ -118,6 +130,18 @@ static inline struct apk_istream *apk_istream_from_url_if_modified(const char *u
 {
  return apk_istream_from_fd_url_if_modified(AT_FDCWD, url, since);
 }
+static inline void apk_istream_get_meta(struct apk_istream *is, struct apk_file_meta *meta)
+{
+ is->ops->get_meta(is, meta);
+}
+static inline ssize_t apk_istream_read(struct apk_istream *is, void *ptr, size_t size)
+{
+ return is->ops->read(is, ptr, size);
+}
+static inline void apk_istream_close(struct apk_istream *is)
+{
+ is->ops->close(is);
+}
 
 struct apk_bstream *apk_bstream_from_istream(struct apk_istream *istream);
 struct apk_bstream *apk_bstream_from_fd_pid(int fd, pid_t pid, int (*translate_status)(int));
@@ -143,11 +167,31 @@ static inline struct apk_bstream *apk_bstream_from_url_if_modified(const char *u
 {
  return apk_bstream_from_fd_url_if_modified(AT_FDCWD, url, since);
 }
+static inline void apk_bstream_get_meta(struct apk_bstream *bs, struct apk_file_meta *meta)
+{
+ bs->ops->get_meta(bs, meta);
+}
+static inline apk_blob_t apk_bstream_read(struct apk_bstream *bs, apk_blob_t token)
+{
+ return bs->ops->read(bs, token);
+}
+static inline void apk_bstream_close(struct apk_bstream *bs, size_t *size)
+{
+ bs->ops->close(bs, size);
+}
 
 struct apk_ostream *apk_ostream_to_fd(int fd);
 struct apk_ostream *apk_ostream_to_file(int atfd, const char *file, const char *tmpfile, mode_t mode);
 struct apk_ostream *apk_ostream_to_file_gz(int atfd, const char *file, const char *tmpfile, mode_t mode);
 size_t apk_ostream_write_string(struct apk_ostream *ostream, const char *string);
+static inline ssize_t apk_ostream_write(struct apk_ostream *os, const void *buf, size_t size)
+{
+ return os->ops->write(os, buf, size);
+}
+static inline int apk_ostream_close(struct apk_ostream *os)
+{
+ return os->ops->close(os);
+}
 
 apk_blob_t apk_blob_from_istream(struct apk_istream *istream, size_t size);
 apk_blob_t apk_blob_from_file(int atfd, const char *file);

src/archive.c

@@ -108,7 +108,7 @@ static ssize_t tar_entry_read(void *stream, void *ptr, size_t size)
  if (size == 0)
  return 0;
 
- r = teis->tar_is->read(teis->tar_is, ptr, size);
+ r = apk_istream_read(teis->tar_is, ptr, size);
  if (r <= 0) {
  /* If inner stream returned zero (end-of-stream), we
  * are getting short read, because tar header indicated
@@ -133,6 +133,12 @@ static void tar_entry_close(void *stream)
 {
 }
 
+static const struct apk_istream_ops tar_istream_ops = {
+ .get_meta = tar_entry_get_meta,
+ .read = tar_entry_read,
+ .close = tar_entry_close,
+};
+
 static int blob_realloc(apk_blob_t *b, size_t newsize)
 {
  char *tmp;
@@ -191,9 +197,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
 {
  struct apk_file_info entry;
  struct apk_tar_entry_istream teis = {
- .is.get_meta = tar_entry_get_meta,
- .is.read = tar_entry_read,
- .is.close = tar_entry_close,
+ .is.ops = &tar_istream_ops,
  .tar_is = is,
  };
  struct tar_header buf;
@@ -206,7 +210,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
  odi = (struct apk_tar_digest_info *) &buf.linkname[3];
  EVP_MD_CTX_init(&teis.mdctx);
  memset(&entry, 0, sizeof(entry));
- while ((r = is->read(is, &buf, 512)) == 512) {
+ while ((r = apk_istream_read(is, &buf, 512)) == 512) {
  offset += 512;
  if (buf.name[0] == '\0') {
  if (end) break;
@@ -243,7 +247,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
  switch (buf.typeflag) {
  case 'L': /* GNU long name extension */
  if ((r = blob_realloc(&longname, entry.size+1)) != 0 ||
- (r = is->read(is, longname.ptr, entry.size)) != entry.size)
+ (r = apk_istream_read(is, longname.ptr, entry.size)) != entry.size)
  goto err;
  entry.name = longname.ptr;
  entry.name[entry.size] = 0;
@@ -293,7 +297,7 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
  paxlen = entry.size;
  entry.size = 0;
  if ((r = blob_realloc(&pax, (paxlen + 511) & -512)) != 0 ||
- (r = is->read(is, pax.ptr, paxlen)) != paxlen)
+ (r = apk_istream_read(is, pax.ptr, paxlen)) != paxlen)
  goto err;
  offset += paxlen;
  break;
@@ -321,15 +325,15 @@ int apk_tar_parse(struct apk_istream *is, apk_archive_entry_parser parser,
  toskip += 512 - ((offset + toskip) & 511);
  offset += toskip;
  if (toskip != 0) {
- if ((r = is->read(is, NULL, toskip)) != toskip)
+ if ((r = apk_istream_read(is, NULL, toskip)) != toskip)
  goto err;
  }
  }
 
  /* Read remaining end-of-archive records, to ensure we read all of
  * the file. The underlying istream is likely doing checksumming. */
  if (r == 512) {
- while ((r = is->read(is, &buf, 512)) == 512) {
+ while ((r = apk_istream_read(is, &buf, 512)) == 512) {
  if (buf.name[0] != 0) break;
  }
  }
@@ -381,15 +385,15 @@ int apk_tar_write_entry(struct apk_ostream *os, const struct apk_file_info *ae,
  put_octal(buf.chksum, sizeof(buf.chksum)-1, chksum);
  }
 
- if (os->write(os, &buf, sizeof(buf)) != sizeof(buf))
+ if (apk_ostream_write(os, &buf, sizeof(buf)) != sizeof(buf))
  return -1;
 
  if (ae == NULL) {
  /* End-of-archive is two empty headers */
- if (os->write(os, &buf, sizeof(buf)) != sizeof(buf))
+ if (apk_ostream_write(os, &buf, sizeof(buf)) != sizeof(buf))
  return -1;
  } else if (data != NULL) {
- if (os->write(os, data, ae->size) != ae->size)
+ if (apk_ostream_write(os, data, ae->size) != ae->size)
  return -1;
  if (apk_tar_write_padding(os, ae) != 0)
  return -1;
@@ -405,7 +409,7 @@ int apk_tar_write_padding(struct apk_ostream *os, const struct apk_file_info *ae
 
  pad = 512 - (ae->size & 511);
  if (pad != 512 &&
- os->write(os, padding, pad) != pad)
+ apk_ostream_write(os, padding, pad) != pad)
  return -1;
 
  return 0;