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Clean up sha1 file writing

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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>
This commit is contained in:
Linus Torvalds
2006-05-24 08:30:54 -07:00
committed by Junio C Hamano
parent f81daefe56
commit 4d548150ac
1 changed files with 81 additions and 64 deletions
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145
sha1_file.c
View File

@ -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);
}
/*
* 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)
{
size_t size;
z_stream stream;
unsigned char *unpacked;
unsigned long len;
char type[20];
char hdr[50];
int hdrlen;
void *buf;
// need to unpack and recompress it by itself
unpacked = read_packed_sha1(sha1, type, &len);
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);
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 */;
/* 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;
return buf;
}
int write_sha1_to_fd(int fd, const unsigned char *sha1)
{
ssize_t size;
int retval;
unsigned long objsize;
int posn = 0;
void *map = map_sha1_file_internal(sha1, &objsize);
void *buf = map;
void *temp_obj = NULL;
z_stream stream;
void *buf = map_sha1_file_internal(sha1, &objsize);
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);
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 */;
/* 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;
if (buf) {
retval = write_buffer(fd, buf, objsize);
munmap(buf, objsize);
return retval;
}
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);
if (map)
munmap(map, objsize);
if (temp_obj)
free(temp_obj);
return 0;
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;