Add writev_all() function

Use it in rhizome_write_manifest_file() instead of two separate write(2)
system calls or buffered stdio.

net.c

@@ -20,6 +20,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include <unistd.h>
 #include <errno.h>
 #include <fcntl.h>
+#include <sys/uio.h>
 #include <sys/socket.h>
 #include <netinet/in.h>
 #include <time.h>
@@ -28,6 +29,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #include "conf.h"
 #include "net.h"
 #include "str.h"
+#include "strbuf_helpers.h"
 
 struct in_addr hton_in_addr(in_addr_t addr)
 {
@@ -85,6 +87,20 @@ ssize_t _write_all(int fd, const void *buf, size_t len, struct __sourceloc __whe
   return written;
 }
 
+ssize_t _writev_all(int fd, const struct iovec *iov, int iovcnt, struct __sourceloc __whence)
+{
+  size_t len = 0;
+  int i;
+  for (i = 0; i < iovcnt; ++i)
+    len += iov[i].iov_len;
+  ssize_t written = writev(fd, iov, iovcnt);
+  if (written == -1)
+    return WHYF_perror("writev_all: writev(%d,%s len=%zu)", fd, alloca_iovec(iov, iovcnt), len);
+  if (written != len)
+    return WHYF_perror("writev_all: writev(%d,%s len=%zu) returned %zd", fd, alloca_iovec(iov, iovcnt), len, (size_t)written);
+  return written;
+}
+
 ssize_t _write_nonblock(int fd, const void *buf, size_t len, struct __sourceloc __whence)
 {
   ssize_t written = write(fd, buf, len);

net.h

@@ -35,6 +35,7 @@ struct in_addr hton_in_addr(in_addr_t);
 #define set_block(fd)                   (_set_block(fd, __WHENCE__))
 #define read_nonblock(fd,buf,len)       (_read_nonblock(fd, buf, len, __WHENCE__))
 #define write_all(fd,buf,len)           (_write_all(fd, buf, len, __WHENCE__))
+#define writev_all(fd,iov,cnt)          (_writev_all(fd, (iov), (cnt), __WHENCE__))
 #define write_nonblock(fd,buf,len)      (_write_nonblock(fd, buf, len, __WHENCE__))
 #define write_all_nonblock(fd,buf,len)  (_write_all_nonblock(fd, buf, len, __WHENCE__))
 #define write_str(fd,str)               (_write_str(fd, str, __WHENCE__))
@@ -46,6 +47,7 @@ ssize_t _read_nonblock(int fd, void *buf, size_t len, struct __sourceloc __whenc
 ssize_t _write_all(int fd, const void *buf, size_t len, struct __sourceloc __whence);
 ssize_t _write_nonblock(int fd, const void *buf, size_t len, struct __sourceloc __whence);
 ssize_t _write_all_nonblock(int fd, const void *buf, size_t len, struct __sourceloc __whence);
+ssize_t _writev_all(int fd, const struct iovec *iov, int iovcnt, struct __sourceloc __whence);
 ssize_t _write_str(int fd, const char *str, struct __sourceloc __whence);
 ssize_t _write_str_nonblock(int fd, const char *str, struct __sourceloc __whence);
 ssize_t recvwithttl(int sock, unsigned char *buffer, size_t bufferlen, int *ttl, struct sockaddr *recvaddr, socklen_t *recvaddrlen);

rhizome_bundle.c

@@ -19,6 +19,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 
 #include <stdlib.h>
 #include <assert.h>
+#include <sys/uio.h>
 #include "serval.h"
 #include "conf.h"
 #include "rhizome.h"
@@ -656,16 +657,21 @@ int rhizome_write_manifest_file(rhizome_manifest *m, const char *path, char appe
   if (fd == -1)
     return WHYF_perror("open(%s,O_WRONLY|O_CREAT%s,0666)", alloca_str_toprint(path), append ? "|O_APPEND" : "");
   int ret = 0;
-  if (write_all(fd, m->manifestdata, m->manifest_all_bytes) == -1)
+  unsigned char marker[4];
-    ret = -1;
+  struct iovec iov[2];
-  else if (append) {
+  int iovcnt = 1;
-    unsigned char marker[4];
+  iov[0].iov_base = m->manifestdata;
+  iov[0].iov_len = m->manifest_all_bytes;
+  if (append) {
     write_uint16(marker, m->manifest_all_bytes);
-    marker[2]=0x41;
+    marker[2] = 0x41;
-    marker[3]=0x10;
+    marker[3] = 0x10;
-    if (write_all(fd, marker, sizeof marker) == -1)
+    iov[1].iov_base = marker;
-      ret = -1;
+    iov[1].iov_len = sizeof marker;
+    iovcnt = 2;
   }
+  if (writev_all(fd, iov, iovcnt) == -1)
+    ret = -1;
   if (close(fd) == -1)
     ret = WHY_perror("close");
   return ret;

strbuf_helpers.c

@@ -31,6 +31,7 @@ Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA.
 #ifdef HAVE_ARPA_INET_H
 #include <arpa/inet.h>
 #endif
+#include <sys/uio.h>
 
 static inline strbuf _toprint(strbuf sb, char c)
 {
@@ -377,3 +378,16 @@ strbuf strbuf_append_strftime(strbuf sb, const char *format, const struct tm *tm
   strbuf_ncat(sb, buf, n);
   return sb;
 }
+
+strbuf strbuf_append_iovec(strbuf sb, const struct iovec *iov, int iovcnt)
+{
+  int i;
+  strbuf_putc(sb, '[');
+  for (i = 0; i < iovcnt; ++i) {
+    if (i)
+      strbuf_puts(sb, ", ");
+    strbuf_sprintf(sb, "%p#%zu", iov[i].iov_base, iov[i].iov_len);
+  }
+  strbuf_putc(sb, ']');
+  return sb;
+}

strbuf_helpers.h

@@ -129,4 +129,11 @@ strbuf strbuf_append_sockaddr(strbuf sb, const struct sockaddr *addr, socklen_t
 struct tm;
 strbuf strbuf_append_strftime(strbuf sb, const char *format, const struct tm *tm);
 
+/* Append a representation of a struct iovec[] array.
+ * @author Andrew Bettison <andrew@servalproject.com>
+ */
+struct iovec;
+strbuf strbuf_append_iovec(strbuf sb, const struct iovec *iov, int iovcnt);
+#define alloca_iovec(iov,cnt)    strbuf_str(strbuf_append_iovec(strbuf_alloca(200), (iov), (cnt)))
+
 #endif //__STRBUF_HELPERS_H__