[PATCH 3/7] perf header: use struct feat_fd for write

[David Carrillo-Cisneros <davidcc@google.com>]

As preparation for using header records in pipe mode, replace
int fd with struct feat_fd fd in write functions for all header
record types.

Record types that are not used in pipe-mode (such as auxtrace) will
never be called with fd->buf set and fail if so.

Signed-off-by: David Carrillo-Cisneros <davidcc@google.com>
---
 tools/perf/util/build-id.c |  10 ++-
 tools/perf/util/build-id.h |   4 +-
 tools/perf/util/header.c   | 194 +++++++++++++++++++++++++++++----------------
 tools/perf/util/header.h   |   7 +-
 4 files changed, 140 insertions(+), 75 deletions(-)

diff --git a/tools/perf/util/build-id.c b/tools/perf/util/build-id.c
index 168cc49654e7..292e90db3924 100644
--- a/tools/perf/util/build-id.c
+++ b/tools/perf/util/build-id.c
@@ -330,7 +330,7 @@ bool dso__build_id_is_kmod(const struct dso *dso, char *bf, size_t size)
 		else
 
 static int write_buildid(const char *name, size_t name_len, u8 *build_id,
-			 pid_t pid, u16 misc, int fd)
+			 pid_t pid, u16 misc, struct feat_fd *fd)
 {
 	int err;
 	struct build_id_event b;
@@ -345,14 +345,15 @@ static int write_buildid(const char *name, size_t name_len, u8 *build_id,
 	b.header.misc = misc;
 	b.header.size = sizeof(b) + len;
 
-	err = writen(fd, &b, sizeof(b));
+	err = do_write(fd, &b, sizeof(b));
 	if (err < 0)
 		return err;
 
 	return write_padded(fd, name, name_len + 1, len);
 }
 
-static int machine__write_buildid_table(struct machine *machine, int fd)
+static int machine__write_buildid_table(struct machine *machine,
+					struct feat_fd *fd)
 {
 	int err = 0;
 	char nm[PATH_MAX];
@@ -397,7 +398,8 @@ static int machine__write_buildid_table(struct machine *machine, int fd)
 	return err;
 }
 
-int perf_session__write_buildid_table(struct perf_session *session, int fd)
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd)
 {
 	struct rb_node *nd;
 	int err = machine__write_buildid_table(&session->machines.host, fd);
diff --git a/tools/perf/util/build-id.h b/tools/perf/util/build-id.h
index a96081121179..84e5e8a52970 100644
--- a/tools/perf/util/build-id.h
+++ b/tools/perf/util/build-id.h
@@ -9,6 +9,7 @@
 
 extern struct perf_tool build_id__mark_dso_hit_ops;
 struct dso;
+struct feat_fd;
 
 int build_id__sprintf(const u8 *build_id, int len, char *bf);
 int sysfs__sprintf_build_id(const char *root_dir, char *sbuild_id);
@@ -26,7 +27,8 @@ int build_id__mark_dso_hit(struct perf_tool *tool, union perf_event *event,
 int dsos__hit_all(struct perf_session *session);
 
 bool perf_session__read_build_ids(struct perf_session *session, bool with_hits);
-int perf_session__write_buildid_table(struct perf_session *session, int fd);
+int perf_session__write_buildid_table(struct perf_session *session,
+				      struct feat_fd *fd);
 int perf_session__cache_build_ids(struct perf_session *session);
 
 char *build_id_cache__origname(const char *sbuild_id);
diff --git a/tools/perf/util/header.c b/tools/perf/util/header.c
index 2415d41282d8..5ca603b7a7a3 100644
--- a/tools/perf/util/header.c
+++ b/tools/perf/util/header.c
@@ -57,6 +57,14 @@ struct perf_file_attr {
 	struct perf_file_section	ids;
 };
 
+struct feat_fd {
+	struct perf_header *ph;
+	int fd;
+	void *buf;	/* Either buf != NULL or fd >= 0 */
+	ssize_t offset;
+	size_t size;
+};
+
 void perf_header__set_feat(struct perf_header *header, int feat)
 {
 	set_bit(feat, header->adds_features);
@@ -73,23 +81,36 @@ bool perf_header__has_feat(const struct perf_header *header, int feat)
 }
 
 /* Return: 0 if succeded, -ERR if failed. */
-static int do_write(int fd, const void *buf, size_t size)
+int do_write(struct feat_fd *fd, const void *buf, size_t size)
 {
-	while (size) {
-		int ret = write(fd, buf, size);
+	void *addr;
 
-		if (ret < 0)
-			return -errno;
+	if (!fd->buf) {
+		ssize_t ret = writen(fd->fd, buf, size);
 
-		size -= ret;
-		buf += ret;
+		if (ret != (ssize_t)size)
+			return ret < 0 ? (int)ret : -1;
+		return 0;
 	}
+retry:
+	if (size > (fd->size - fd->offset)) {
+		addr = realloc(fd->buf, fd->size << 1);
+		if (!addr)
+			return -ENOSPC;
+		fd->buf = addr;
+		fd->size <<= 1;
+		goto retry;
+	}
+
+	memcpy(fd->buf + fd->offset, buf, size);
+	fd->offset += size;
 
 	return 0;
 }
 
 /* Return: 0 if succeded, -ERR if failed. */
-int write_padded(int fd, const void *bf, size_t count, size_t count_aligned)
+int write_padded(struct feat_fd *fd, const void *bf,
+		 size_t count, size_t count_aligned)
 {
 	static const char zero_buf[NAME_ALIGN];
 	int err = do_write(fd, bf, count);
@@ -104,7 +125,7 @@ int write_padded(int fd, const void *bf, size_t count, size_t count_aligned)
 	(PERF_ALIGN((strlen(str) + 1), NAME_ALIGN) + sizeof(u32))
 
 /* Return: 0 if succeded, -ERR if failed. */
-static int do_write_string(int fd, const char *str)
+static int do_write_string(struct feat_fd *fd, const char *str)
 {
 	u32 len, olen;
 	int ret;
@@ -151,24 +172,31 @@ static char *do_read_string(int fd, struct perf_header *ph)
 	return NULL;
 }
 
-static int write_tracing_data(int fd, struct perf_header *h __maybe_unused,
-			    struct perf_evlist *evlist)
+static int write_tracing_data(struct feat_fd *fd,
+			      struct perf_evlist *evlist)
 {
-	return read_tracing_data(fd, &evlist->entries);
+	if (fd->buf) {
+		pr_err("Unsupported write_tracing_data to memory buffer.\n");
+		return -1;
+	}
+	return read_tracing_data(fd->fd, &evlist->entries);
 }
 
-
-static int write_build_id(int fd, struct perf_header *h,
+static int write_build_id(struct feat_fd *fd,
 			  struct perf_evlist *evlist __maybe_unused)
 {
 	struct perf_session *session;
 	int err;
 
-	session = container_of(h, struct perf_session, header);
+	session = container_of(fd->ph, struct perf_session, header);
 
 	if (!perf_session__read_build_ids(session, true))
 		return -1;
 
+	if (fd->buf) {
+		pr_err("Unsupported write_build_id to memory buffer.\n");
+		return -1;
+	}
 	err = perf_session__write_buildid_table(session, fd);
 	if (err < 0) {
 		pr_debug("failed to write buildid table\n");
@@ -179,7 +207,7 @@ static int write_build_id(int fd, struct perf_header *h,
 	return 0;
 }
 
-static int write_hostname(int fd, struct perf_header *h __maybe_unused,
+static int write_hostname(struct feat_fd *fd,
 			  struct perf_evlist *evlist __maybe_unused)
 {
 	struct utsname uts;
@@ -192,7 +220,7 @@ static int write_hostname(int fd, struct perf_header *h __maybe_unused,
 	return do_write_string(fd, uts.nodename);
 }
 
-static int write_osrelease(int fd, struct perf_header *h __maybe_unused,
+static int write_osrelease(struct feat_fd *fd,
 			   struct perf_evlist *evlist __maybe_unused)
 {
 	struct utsname uts;
@@ -205,7 +233,7 @@ static int write_osrelease(int fd, struct perf_header *h __maybe_unused,
 	return do_write_string(fd, uts.release);
 }
 
-static int write_arch(int fd, struct perf_header *h __maybe_unused,
+static int write_arch(struct feat_fd *fd,
 		      struct perf_evlist *evlist __maybe_unused)
 {
 	struct utsname uts;
@@ -218,13 +246,13 @@ static int write_arch(int fd, struct perf_header *h __maybe_unused,
 	return do_write_string(fd, uts.machine);
 }
 
-static int write_version(int fd, struct perf_header *h __maybe_unused,
+static int write_version(struct feat_fd *fd,
 			 struct perf_evlist *evlist __maybe_unused)
 {
 	return do_write_string(fd, perf_version_string);
 }
 
-static int __write_cpudesc(int fd, const char *cpuinfo_proc)
+static int __write_cpudesc(struct feat_fd *fd, const char *cpuinfo_proc)
 {
 	FILE *file;
 	char *buf = NULL;
@@ -281,7 +309,7 @@ static int __write_cpudesc(int fd, const char *cpuinfo_proc)
 	return ret;
 }
 
-static int write_cpudesc(int fd, struct perf_header *h __maybe_unused,
+static int write_cpudesc(struct feat_fd *fd,
 		       struct perf_evlist *evlist __maybe_unused)
 {
 #ifndef CPUINFO_PROC
@@ -300,7 +328,7 @@ static int write_cpudesc(int fd, struct perf_header *h __maybe_unused,
 }
 
 
-static int write_nrcpus(int fd, struct perf_header *h __maybe_unused,
+static int write_nrcpus(struct feat_fd *fd,
 			struct perf_evlist *evlist __maybe_unused)
 {
 	long nr;
@@ -322,7 +350,7 @@ static int write_nrcpus(int fd, struct perf_header *h __maybe_unused,
 	return do_write(fd, &nra, sizeof(nra));
 }
 
-static int write_event_desc(int fd, struct perf_header *h __maybe_unused,
+static int write_event_desc(struct feat_fd *fd,
 			    struct perf_evlist *evlist)
 {
 	struct perf_evsel *evsel;
@@ -378,7 +406,7 @@ static int write_event_desc(int fd, struct perf_header *h __maybe_unused,
 	return 0;
 }
 
-static int write_cmdline(int fd, struct perf_header *h __maybe_unused,
+static int write_cmdline(struct feat_fd *fd,
 			 struct perf_evlist *evlist __maybe_unused)
 {
 	char buf[MAXPATHLEN];
@@ -558,8 +586,8 @@ static struct cpu_topo *build_cpu_topology(void)
 	return tp;
 }
 
-static int write_cpu_topology(int fd, struct perf_header *h __maybe_unused,
-			  struct perf_evlist *evlist __maybe_unused)
+static int write_cpu_topology(struct feat_fd *fd,
+			      struct perf_evlist *evlist __maybe_unused)
 {
 	struct cpu_topo *tp;
 	u32 i;
@@ -609,8 +637,8 @@ static int write_cpu_topology(int fd, struct perf_header *h __maybe_unused,
 
 
 
-static int write_total_mem(int fd, struct perf_header *h __maybe_unused,
-			  struct perf_evlist *evlist __maybe_unused)
+static int write_total_mem(struct feat_fd *fd,
+			   struct perf_evlist *evlist __maybe_unused)
 {
 	char *buf = NULL;
 	FILE *fp;
@@ -638,7 +666,7 @@ static int write_total_mem(int fd, struct perf_header *h __maybe_unused,
 	return ret;
 }
 
-static int write_topo_node(int fd, int node)
+static int write_topo_node(struct feat_fd *fd, int node)
 {
 	char str[MAXPATHLEN];
 	char field[32];
@@ -698,8 +726,8 @@ static int write_topo_node(int fd, int node)
 	return ret;
 }
 
-static int write_numa_topology(int fd, struct perf_header *h __maybe_unused,
-			  struct perf_evlist *evlist __maybe_unused)
+static int write_numa_topology(struct feat_fd *fd,
+			       struct perf_evlist *evlist __maybe_unused)
 {
 	char *buf = NULL;
 	size_t len = 0;
@@ -759,15 +787,23 @@ static int write_numa_topology(int fd, struct perf_header *h __maybe_unused,
  * };
  */
 
-static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
+static int write_pmu_mappings(struct feat_fd *fd,
 			      struct perf_evlist *evlist __maybe_unused)
 {
 	struct perf_pmu *pmu = NULL;
-	off_t offset = lseek(fd, 0, SEEK_CUR);
-	__u32 pmu_num = 0;
+	u32 pmu_num = 0;
 	int ret;
 
-	/* write real pmu_num later */
+	/*
+	 * Do a first pass to count number of pmu to avoid lseek so this
+	 * works in pipe mode as well.
+	 */
+	while ((pmu = perf_pmu__scan(pmu))) {
+		if (!pmu->name)
+			continue;
+		pmu_num++;
+	}
+
 	ret = do_write(fd, &pmu_num, sizeof(pmu_num));
 	if (ret < 0)
 		return ret;
@@ -775,7 +811,6 @@ static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
 	while ((pmu = perf_pmu__scan(pmu))) {
 		if (!pmu->name)
 			continue;
-		pmu_num++;
 
 		ret = do_write(fd, &pmu->type, sizeof(pmu->type));
 		if (ret < 0)
@@ -786,12 +821,6 @@ static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
 			return ret;
 	}
 
-	if (pwrite(fd, &pmu_num, sizeof(pmu_num), offset) != sizeof(pmu_num)) {
-		/* discard all */
-		lseek(fd, offset, SEEK_SET);
-		return -1;
-	}
-
 	return 0;
 }
 
@@ -807,7 +836,7 @@ static int write_pmu_mappings(int fd, struct perf_header *h __maybe_unused,
  *	}[nr_groups];
  * };
  */
-static int write_group_desc(int fd, struct perf_header *h __maybe_unused,
+static int write_group_desc(struct feat_fd *fd,
 			    struct perf_evlist *evlist)
 {
 	u32 nr_groups = evlist->nr_groups;
@@ -850,7 +879,7 @@ int __weak get_cpuid(char *buffer __maybe_unused, size_t sz __maybe_unused)
 	return -1;
 }
 
-static int write_cpuid(int fd, struct perf_header *h __maybe_unused,
+static int write_cpuid(struct feat_fd *fd,
 		       struct perf_evlist *evlist __maybe_unused)
 {
 	char buffer[64];
@@ -865,22 +894,25 @@ static int write_cpuid(int fd, struct perf_header *h __maybe_unused,
 	return do_write_string(fd, buffer);
 }
 
-static int write_branch_stack(int fd __maybe_unused,
-			      struct perf_header *h __maybe_unused,
-		       struct perf_evlist *evlist __maybe_unused)
+static int write_branch_stack(struct feat_fd *fd __maybe_unused,
+			      struct perf_evlist *evlist __maybe_unused)
 {
 	return 0;
 }
 
-static int write_auxtrace(int fd, struct perf_header *h,
+static int write_auxtrace(struct feat_fd *fd,
 			  struct perf_evlist *evlist __maybe_unused)
 {
 	struct perf_session *session;
 	int err;
 
-	session = container_of(h, struct perf_session, header);
+	if (fd->buf) {
+		pr_err("Unsupported write_auxtrace to memory buffer.\n");
+		return -1;
+	}
+	session = container_of(fd->ph, struct perf_session, header);
 
-	err = auxtrace_index__write(fd, &session->auxtrace_index);
+	err = auxtrace_index__write(fd->fd, &session->auxtrace_index);
 	if (err < 0)
 		pr_err("Failed to write auxtrace index\n");
 	return err;
@@ -1027,8 +1059,8 @@ static int build_caches(struct cpu_cache_level caches[], u32 size, u32 *cntp)
 
 #define MAX_CACHES 2000
 
-static int write_cache(int fd, struct perf_header *h __maybe_unused,
-			  struct perf_evlist *evlist __maybe_unused)
+static int write_cache(struct feat_fd *fd,
+		       struct perf_evlist *evlist __maybe_unused)
 {
 	struct cpu_cache_level caches[MAX_CACHES];
 	u32 cnt = 0, i, version = 1;
@@ -1079,8 +1111,7 @@ static int write_cache(int fd, struct perf_header *h __maybe_unused,
 	return ret;
 }
 
-static int write_stat(int fd __maybe_unused,
-		      struct perf_header *h __maybe_unused,
+static int write_stat(struct feat_fd *fd __maybe_unused,
 		      struct perf_evlist *evlist __maybe_unused)
 {
 	return 0;
@@ -2186,7 +2217,7 @@ static int process_cache(struct perf_file_section *section __maybe_unused,
 }
 
 struct feature_ops {
-	int (*write)(int fd, struct perf_header *h, struct perf_evlist *evlist);
+	int (*write)(struct feat_fd *fd, struct perf_evlist *evlist);
 	void (*print)(struct perf_header *h, int fd, FILE *fp);
 	int (*process)(struct perf_file_section *section,
 		       struct perf_header *h, int fd, void *data);
@@ -2295,7 +2326,7 @@ int perf_header__fprintf_info(struct perf_session *session, FILE *fp, bool full)
 	return 0;
 }
 
-static int do_write_feat(int fd, struct perf_header *h, int type,
+static int do_write_feat(struct feat_fd *fd, struct perf_header *h, int type,
 			 struct perf_file_section **p,
 			 struct perf_evlist *evlist)
 {
@@ -2306,18 +2337,22 @@ static int do_write_feat(int fd, struct perf_header *h, int type,
 		if (!feat_ops[type].write)
 			return -1;
 
-		(*p)->offset = lseek(fd, 0, SEEK_CUR);
+		if (fd->buf) {
+			pr_err("do_write_feat to memory buffer\n");
+			return -1;
+		}
+		(*p)->offset = lseek(fd->fd, 0, SEEK_CUR);
 
-		err = feat_ops[type].write(fd, h, evlist);
+		err = feat_ops[type].write(fd, evlist);
 		if (err < 0) {
 			pr_debug("failed to write feature %s\n", feat_ops[type].name);
 
 			/* undo anything written */
-			lseek(fd, (*p)->offset, SEEK_SET);
+			lseek(fd->fd, (*p)->offset, SEEK_SET);
 
 			return -1;
 		}
-		(*p)->size = lseek(fd, 0, SEEK_CUR) - (*p)->offset;
+		(*p)->size = lseek(fd->fd, 0, SEEK_CUR) - (*p)->offset;
 		(*p)++;
 	}
 	return ret;
@@ -2327,12 +2362,22 @@ static int perf_header__adds_write(struct perf_header *header,
 				   struct perf_evlist *evlist, int fd)
 {
 	int nr_sections;
+	struct feat_fd fdd;
 	struct perf_file_section *feat_sec, *p;
 	int sec_size;
 	u64 sec_start;
 	int feat;
 	int err;
 
+	/*
+	 * may write more than needed due to dropped feature, but
+	 * this is okay, reader will skip the mising entries
+	 */
+	fdd = (struct feat_fd){
+		.fd  = fd,
+		.ph = header,
+	};
+
 	nr_sections = bitmap_weight(header->adds_features, HEADER_FEAT_BITS);
 	if (!nr_sections)
 		return 0;
@@ -2347,7 +2392,7 @@ static int perf_header__adds_write(struct perf_header *header,
 	lseek(fd, sec_start + sec_size, SEEK_SET);
 
 	for_each_set_bit(feat, header->adds_features, HEADER_FEAT_BITS) {
-		if (do_write_feat(fd, header, feat, &p, evlist))
+		if (do_write_feat(&fdd, header, feat, &p, evlist))
 			perf_header__clear_feat(header, feat);
 	}
 
@@ -2356,7 +2401,7 @@ static int perf_header__adds_write(struct perf_header *header,
 	 * may write more than needed due to dropped feature, but
 	 * this is okay, reader will skip the mising entries
 	 */
-	err = do_write(fd, feat_sec, sec_size);
+	err = do_write(&fdd, feat_sec, sec_size);
 	if (err < 0)
 		pr_debug("failed to write feature section\n");
 	free(feat_sec);
@@ -2366,14 +2411,17 @@ static int perf_header__adds_write(struct perf_header *header,
 int perf_header__write_pipe(int fd)
 {
 	struct perf_pipe_file_header f_header;
+	struct feat_fd fdd;
 	int err;
 
+	fdd = (struct feat_fd){ .fd = fd };
+
 	f_header = (struct perf_pipe_file_header){
 		.magic	   = PERF_MAGIC,
 		.size	   = sizeof(f_header),
 	};
 
-	err = do_write(fd, &f_header, sizeof(f_header));
+	err = do_write(&fdd, &f_header, sizeof(f_header));
 	if (err < 0) {
 		pr_debug("failed to write perf pipe header\n");
 		return err;
@@ -2390,21 +2438,23 @@ int perf_session__write_header(struct perf_session *session,
 	struct perf_file_attr   f_attr;
 	struct perf_header *header = &session->header;
 	struct perf_evsel *evsel;
+	struct feat_fd fdd;
 	u64 attr_offset;
 	int err;
 
+	fdd = (struct feat_fd){ .fd = fd};
 	lseek(fd, sizeof(f_header), SEEK_SET);
 
 	evlist__for_each_entry(session->evlist, evsel) {
 		evsel->id_offset = lseek(fd, 0, SEEK_CUR);
-		err = do_write(fd, evsel->id, evsel->ids * sizeof(u64));
+		err = do_write(&fdd, evsel->id, evsel->ids * sizeof(u64));
 		if (err < 0) {
 			pr_debug("failed to write perf header\n");
 			return err;
 		}
 	}
 
-	attr_offset = lseek(fd, 0, SEEK_CUR);
+	attr_offset = lseek(fdd.fd, 0, SEEK_CUR);
 
 	evlist__for_each_entry(evlist, evsel) {
 		f_attr = (struct perf_file_attr){
@@ -2414,7 +2464,7 @@ int perf_session__write_header(struct perf_session *session,
 				.size   = evsel->ids * sizeof(u64),
 			}
 		};
-		err = do_write(fd, &f_attr, sizeof(f_attr));
+		err = do_write(&fdd, &f_attr, sizeof(f_attr));
 		if (err < 0) {
 			pr_debug("failed to write perf header attribute\n");
 			return err;
@@ -2449,7 +2499,7 @@ int perf_session__write_header(struct perf_session *session,
 	memcpy(&f_header.adds_features, &header->adds_features, sizeof(header->adds_features));
 
 	lseek(fd, 0, SEEK_SET);
-	err = do_write(fd, &f_header, sizeof(f_header));
+	err = do_write(&fdd, &f_header, sizeof(f_header));
 	if (err < 0) {
 		pr_debug("failed to write perf header\n");
 		return err;
@@ -2724,6 +2774,10 @@ static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,
 				       struct perf_header *ph, int fd,
 				       bool repipe)
 {
+	struct feat_fd fdd = {
+		.fd = STDOUT_FILENO,
+		.ph = ph,
+	};
 	ssize_t ret;
 
 	ret = readn(fd, header, sizeof(*header));
@@ -2738,7 +2792,7 @@ static int perf_file_header__read_pipe(struct perf_pipe_file_header *header,
 	if (ph->needs_swap)
 		header->size = bswap_64(header->size);
 
-	if (repipe && do_write(STDOUT_FILENO, header, sizeof(*header)) < 0)
+	if (repipe && do_write(&fdd, header, sizeof(*header)) < 0)
 		return -1;
 
 	return 0;
@@ -3246,6 +3300,7 @@ int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd,
 	union perf_event ev;
 	struct tracing_data *tdata;
 	ssize_t size = 0, aligned_size = 0, padding;
+	struct feat_fd fdd;
 	int err __maybe_unused = 0;
 
 	/*
@@ -3280,7 +3335,8 @@ int perf_event__synthesize_tracing_data(struct perf_tool *tool, int fd,
 	 */
 	tracing_data_put(tdata);
 
-	if (write_padded(fd, NULL, 0, padding))
+	fdd = (struct feat_fd){ .fd = fd };
+	if (write_padded(&fdd, NULL, 0, padding))
 		return -1;
 
 	return aligned_size;
diff --git a/tools/perf/util/header.h b/tools/perf/util/header.h
index d30109b421ee..9d8dcd5eb727 100644
--- a/tools/perf/util/header.h
+++ b/tools/perf/util/header.h
@@ -144,7 +144,12 @@ bool is_perf_magic(u64 magic);
 
 #define NAME_ALIGN 64
 
-int write_padded(int fd, const void *bf, size_t count, size_t count_aligned);
+struct feat_fd;
+
+int do_write(struct feat_fd *fd, const void *buf, size_t size);
+
+int write_padded(struct feat_fd *fd, const void *bf,
+		 size_t count, size_t count_aligned);
 
 /*
  * arch specific callback
-- 
2.13.0.303.g4ebf302169-goog