copy: teach copy_bytes() sendfile() support, and then replace sendfile_full() by it

4 files changed, 62 insertions, 100 deletions

diff --git a/src/shared/copy.c b/src/shared/copy.c
index 3744797b95..a863246b2b 100644
--- a/src/shared/copy.c
+++ b/src/shared/copy.c
@@ -19,17 +19,20 @@
   along with systemd; If not, see <http://www.gnu.org/licenses/>.
 ***/
 
+#include <sys/sendfile.h>
+
 #include "util.h"
 #include "copy.h"
 
 int copy_bytes(int fdf, int fdt, off_t max_bytes) {
+        bool try_sendfile = true;
+
         assert(fdf >= 0);
         assert(fdt >= 0);
 
         for (;;) {
-                char buf[PIPE_BUF];
-                ssize_t n, k;
-                size_t m = sizeof(buf);
+                size_t m = PIPE_BUF;
+                ssize_t n;
 
                 if (max_bytes != (off_t) -1) {
 
@@ -40,19 +43,44 @@ int copy_bytes(int fdf, int fdt, off_t max_bytes) {
                                 m = (size_t) max_bytes;
                 }
 
-                n = read(fdf, buf, m);
-                if (n < 0)
-                        return -errno;
-                if (n == 0)
-                        break;
+                /* First try sendfile(), unless we already tried */
+                if (try_sendfile) {
+
+                        n = sendfile(fdt, fdf, NULL, m);
+                        if (n < 0) {
+                                if (errno != EINVAL && errno != ENOSYS)
+                                        return -errno;
+
+                                try_sendfile = false;
+                                /* use fallback below */
+                        } else if (n == 0) /* EOF */
+                                break;
+                        else if (n > 0)
+                                /* Succcess! */
+                                goto next;
+                }
+
+                /* As a fallback just copy bits by hand */
+                {
+                        char buf[m];
+                        ssize_t k;
 
-                errno = 0;
-                k = loop_write(fdt, buf, n, false);
-                if (k < 0)
-                        return k;
-                if (k != n)
-                        return errno ? -errno : -EIO;
+                        n = read(fdf, buf, m);
+                        if (n < 0)
+                                return -errno;
+                        if (n == 0) /* EOF */
+                                break;
+
+                        errno = 0;
+                        k = loop_write(fdt, buf, n, false);
+                        if (k < 0)
+                                return k;
+                        if (k != n)
+                                return errno ? -errno : -EIO;
+
+                }
 
+        next:
                 if (max_bytes != (off_t) -1) {
                         assert(max_bytes >= n);
                         max_bytes -= n;
@@ -262,34 +290,39 @@ int copy_tree(const char *from, const char *to, bool merge) {
                 return -ENOTSUP;
 }
 
-int copy_file(const char *from, const char *to, int flags, mode_t mode) {
-        _cleanup_close_ int fdf = -1, fdt = -1;
-        int r;
+int copy_file_fd(const char *from, int fdt) {
+        _cleanup_close_ int fdf = -1;
 
         assert(from);
-        assert(to);
+        assert(fdt >= 0);
 
         fdf = open(from, O_RDONLY|O_CLOEXEC|O_NOCTTY);
         if (fdf < 0)
                 return -errno;
 
+        return copy_bytes(fdf, fdt, (off_t) -1);
+}
+
+int copy_file(const char *from, const char *to, int flags, mode_t mode) {
+        int fdt, r;
+
+        assert(from);
+        assert(to);
+
         fdt = open(to, flags|O_WRONLY|O_CREAT|O_CLOEXEC|O_NOCTTY, mode);
         if (fdt < 0)
                 return -errno;
 
-        r = copy_bytes(fdf, fdt, (off_t) -1);
+        r = copy_file_fd(from, fdt);
         if (r < 0) {
+                close(fdt);
                 unlink(to);
                 return r;
         }
 
-        r = close(fdt);
-        fdt = -1;
-
-        if (r < 0) {
-                r = -errno;
-                unlink(to);
-                return r;
+        if (close(fdt) < 0) {
+                unlink_noerrno(to);
+                return -errno;
         }
 
         return 0;
diff --git a/src/shared/copy.h b/src/shared/copy.h
index 6b93107fab..62932112af 100644
--- a/src/shared/copy.h
+++ b/src/shared/copy.h
@@ -24,6 +24,7 @@
 #include <stdbool.h>
 #include <sys/types.h>
 
+int copy_file_fd(const char *from, int to);
 int copy_file(const char *from, const char *to, int flags, mode_t mode);
 int copy_tree(const char *from, const char *to, bool merge);
 int copy_bytes(int fdf, int fdt, off_t max_bytes);
diff --git a/src/shared/fileio.c b/src/shared/fileio.c
index 38028b972e..f4efc4c9f1 100644
--- a/src/shared/fileio.c
+++ b/src/shared/fileio.c
@@ -20,12 +20,12 @@
 ***/
 
 #include <unistd.h>
-#include <sys/sendfile.h>
-#include "fileio.h"
+
 #include "util.h"
 #include "strv.h"
 #include "utf8.h"
 #include "ctype.h"
+#include "fileio.h"
 
 int write_string_stream(FILE *f, const char *line) {
         assert(f);
@@ -144,77 +144,6 @@ int read_one_line_file(const char *fn, char **line) {
         return 0;
 }
 
-ssize_t sendfile_full(int out_fd, const char *fn) {
-        _cleanup_fclose_ FILE *f;
-        struct stat st;
-        int r;
-        ssize_t s;
-
-        size_t n, l;
-        _cleanup_free_ char *buf = NULL;
-
-        assert(out_fd > 0);
-        assert(fn);
-
-        f = fopen(fn, "re");
-        if (!f)
-                return -errno;
-
-        r = fstat(fileno(f), &st);
-        if (r < 0)
-                return -errno;
-
-        s = sendfile(out_fd, fileno(f), NULL, st.st_size);
-        if (s < 0)
-                if (errno == EINVAL || errno == ENOSYS) {
-                        /* continue below */
-                } else
-                        return -errno;
-        else
-                return s;
-
-        /* sendfile() failed, fall back to read/write */
-
-        /* Safety check */
-        if (st.st_size > 4*1024*1024)
-                return -E2BIG;
-
-        n = st.st_size > 0 ? st.st_size : LINE_MAX;
-        l = 0;
-
-        while (true) {
-                char *t;
-                size_t k;
-
-                t = realloc(buf, n);
-                if (!t)
-                        return -ENOMEM;
-
-                buf = t;
-                k = fread(buf + l, 1, n - l, f);
-
-                if (k <= 0) {
-                        if (ferror(f))
-                                return -errno;
-
-                        break;
-                }
-
-                l += k;
-                n *= 2;
-
-                /* Safety check */
-                if (n > 4*1024*1024)
-                        return -E2BIG;
-        }
-
-        r = write(out_fd, buf, l);
-        if (r < 0)
-                return -errno;
-
-        return (ssize_t) l;
-}
-
 int read_full_stream(FILE *f, char **contents, size_t *size) {
         size_t n, l;
         _cleanup_free_ char *buf = NULL;
diff --git a/src/shared/fileio.h b/src/shared/fileio.h
index c256915799..5ae51c1e28 100644
--- a/src/shared/fileio.h
+++ b/src/shared/fileio.h
@@ -33,7 +33,6 @@ int write_string_file_atomic(const char *fn, const char *line);
 int read_one_line_file(const char *fn, char **line);
 int read_full_file(const char *fn, char **contents, size_t *size);
 int read_full_stream(FILE *f, char **contents, size_t *size);
-ssize_t sendfile_full(int out_fd, const char *fn);
 
 int parse_env_file(const char *fname, const char *separator, ...) _sentinel_;
 int load_env_file(FILE *f, const char *fname, const char *separator, char ***l);