Clean up sha1 file writing

This cleans up and future-proofs the sha1 file writing in sha1_file.c.

In particular, instead of doing a simple "write()" call and just verifying
that it succeeds (or - as in one place - just assuming it does), it uses
"write_buffer()" to write data to the file descriptor while correctly
checking for partial writes, EINTR etc.

It also splits up write_sha1_to_fd() to be a lot more readable: if we need
to re-create the compressed object, we do so in a separate helper
function, making the logic a whole lot more modular and obvious.

Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Signed-off-by: Junio C Hamano <junkio@cox.net>

diff --git a/sha1_file.c b/sha1_file.c
index e444d9d..f77c189 100644 (file)
--- a/sha1_file.c
+++ b/sha1_file.c
@@ -1399,6 +1399,25 @@ int move_temp_to_file(const char *tmpfile, char *filename)
        return 0;
 }
 
+static int write_buffer(int fd, const void *buf, size_t len)
+{
+       while (len) {
+               ssize_t size;
+
+               size = write(fd, buf, len);
+               if (!size)
+                       return error("file write: disk full");
+               if (size < 0) {
+                       if (errno == EINTR || errno == EAGAIN)
+                               continue;
+                       return error("file write error (%s)", strerror(errno));
+               }
+               len -= size;
+               buf += size;
+       }
+       return 0;
+}
+
 int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned char *returnsha1)
 {
        int size;
@@ -1465,8 +1484,8 @@ int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned cha
        deflateEnd(&stream);
        size = stream.total_out;
 
-       if (write(fd, compressed, size) != size)
-               die("unable to write file");
+       if (write_buffer(fd, compressed, size) < 0)
+               die("unable to write sha1 file");
        fchmod(fd, 0444);
        close(fd);
        free(compressed);
@@ -1474,73 +1493,70 @@ int write_sha1_file(void *buf, unsigned long len, const char *type, unsigned cha
        return move_temp_to_file(tmpfile, filename);
 }
 
-int write_sha1_to_fd(int fd, const unsigned char *sha1)
+/*
+ * We need to unpack and recompress the object for writing
+ * it out to a different file.
+ */
+static void *repack_object(const unsigned char *sha1, unsigned long *objsize)
 {
-       ssize_t size;
-       unsigned long objsize;
-       int posn = 0;
-       void *map = map_sha1_file_internal(sha1, &objsize);
-       void *buf = map;
-       void *temp_obj = NULL;
+       size_t size;
        z_stream stream;
+       unsigned char *unpacked;
+       unsigned long len;
+       char type[20];
+       char hdr[50];
+       int hdrlen;
+       void *buf;
 
-       if (!buf) {
-               unsigned char *unpacked;
-               unsigned long len;
-               char type[20];
-               char hdr[50];
-               int hdrlen;
-               // need to unpack and recompress it by itself
-               unpacked = read_packed_sha1(sha1, type, &len);
+       // need to unpack and recompress it by itself
+       unpacked = read_packed_sha1(sha1, type, &len);
 
-               hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
+       hdrlen = sprintf(hdr, "%s %lu", type, len) + 1;
 
-               /* Set it up */
-               memset(&stream, 0, sizeof(stream));
-               deflateInit(&stream, Z_BEST_COMPRESSION);
-               size = deflateBound(&stream, len + hdrlen);
-               temp_obj = buf = xmalloc(size);
-
-               /* Compress it */
-               stream.next_out = buf;
-               stream.avail_out = size;
-               
-               /* First header.. */
-               stream.next_in = (void *)hdr;
-               stream.avail_in = hdrlen;
-               while (deflate(&stream, 0) == Z_OK)
-                       /* nothing */;
+       /* Set it up */
+       memset(&stream, 0, sizeof(stream));
+       deflateInit(&stream, Z_BEST_COMPRESSION);
+       size = deflateBound(&stream, len + hdrlen);
+       buf = xmalloc(size);
 
-               /* Then the data itself.. */
-               stream.next_in = unpacked;
-               stream.avail_in = len;
-               while (deflate(&stream, Z_FINISH) == Z_OK)
-                       /* nothing */;
-               deflateEnd(&stream);
-               free(unpacked);
-               
-               objsize = stream.total_out;
-       }
+       /* Compress it */
+       stream.next_out = buf;
+       stream.avail_out = size;
 
-       do {
-               size = write(fd, buf + posn, objsize - posn);
-               if (size <= 0) {
-                       if (!size) {
-                               fprintf(stderr, "write closed\n");
-                       } else {
-                               perror("write ");
-                       }
-                       return -1;
-               }
-               posn += size;
-       } while (posn < objsize);
+       /* First header.. */
+       stream.next_in = (void *)hdr;
+       stream.avail_in = hdrlen;
+       while (deflate(&stream, 0) == Z_OK)
+               /* nothing */;
 
-       if (map)
-               munmap(map, objsize);
-       if (temp_obj)
-               free(temp_obj);
+       /* Then the data itself.. */
+       stream.next_in = unpacked;
+       stream.avail_in = len;
+       while (deflate(&stream, Z_FINISH) == Z_OK)
+               /* nothing */;
+       deflateEnd(&stream);
+       free(unpacked);
 
-       return 0;
+       *objsize = stream.total_out;
+       return buf;
+}
+
+int write_sha1_to_fd(int fd, const unsigned char *sha1)
+{
+       int retval;
+       unsigned long objsize;
+       void *buf = map_sha1_file_internal(sha1, &objsize);
+
+       if (buf) {
+               retval = write_buffer(fd, buf, objsize);
+               munmap(buf, objsize);
+               return retval;
+       }
+
+       buf = repack_object(sha1, &objsize);
+       retval = write_buffer(fd, buf, objsize);
+       free(buf);
+       return retval;
 }
 
 int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
@@ -1579,7 +1595,8 @@ int write_sha1_from_fd(const unsigned char *sha1, int fd, char *buffer,
                                SHA1_Update(&c, discard, sizeof(discard) -
                                            stream.avail_out);
                        } while (stream.avail_in && ret == Z_OK);
-                       write(local, buffer, *bufposn - stream.avail_in);
+                       if (write_buffer(local, buffer, *bufposn - stream.avail_in) < 0)
+                               die("unable to write sha1 file");
                        memmove(buffer, buffer + *bufposn - stream.avail_in,
                                stream.avail_in);
                        *bufposn = stream.avail_in;